An anti-skid pneumatic emergency brake system for aircraft wheel brakes

Abstract

The present invention relates to an anti-skid pneumatic emergency brake system for aircraft wheel brakes. The system comprises an air pressure source, a brake pressure reducing valve, a wheel, an electromagnetic valve, a pressure switch, a time delay relay, a circuit breaker contact switch, and a power supply. The air pressure source, the brake pressure reducing valve, the electromagnetic valve, and the wheel are sequentially connected; the pressure switch, the time delay relay, and the electromagnetic valve are sequentially connected via electrical signals; the pressure switch is also connected to the brake pressure reducing valve. The pressure switch senses the air pressure output by the brake pressure reducing valve and outputs an electrical signal to the time delay relay. The power supply is a 28V DC power supply that supplies power to the pressure switch and the time delay relay via the circuit breaker contact switch. The anti-skid pneumatic emergency brake system senses the emergency brake pressure through the pressure switch, and the time delay relay controls the electromagnetic valve to periodically connect and disconnect, thereby achieving periodic brake release and braking operations. This achieves anti-skid braking and solves the problem of wheel dragging caused by continuous braking.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation emergency brakes, and in particular relates to an anti-skid pneumatic emergency brake system for aircraft wheel brakes. Background Art

[0002] An aircraft's brake control system includes normal anti-skid braking, takeoff line parking brakes, emergency brakes, and towing brakes. It shortens the rollout distance after a normal landing, bringing the aircraft to a stop as quickly as possible while also preventing tire blowouts. Functionally, modern aircraft brake systems consist of two main components: braking and anti-skid control. Normal braking systems are fully functional, including anti-skid capabilities; emergency braking systems are typically simpler and lack anti-skid control. Normal anti-skid braking systems typically include a brake command sensor, speed sensor, electromagnetic hydraulic lock, pressure servo valve, hydraulic sensor, anti-skid brake control box, and switching valve. When implementing normal braking, the pilot steps on the pedal, and the brake command sensor connected to the pedal outputs a voltage signal with an amplitude proportional to the displacement of the pedal, that is, the brake signal. After the anti-skid brake control box receives the brake signal, the digital electronic calculation system inside the anti-skid brake control box performs high-speed analysis and calculation. When it determines that braking is required, it gives an unlocking signal to open the electromagnetic hydraulic lock and connect the pressure servo valve to oil. At the same time, it outputs a brake current proportional to the brake signal to the pressure servo valve, so that the pressure servo valve outputs a brake pressure proportional to the pedal to the wheel brake device to brake the wheel.

[0003] When normal braking becomes unavailable, the pilot must activate the emergency brake system. This system switches between the emergency and normal braking systems via a common switching valve. Pulling the emergency brake handle, the pilot manipulates the emergency brake pressure reducing valve, which outputs air pressure proportional to the distance the pilot has traveled, applying emergency braking. The pilot can adjust the emergency brake pressure at any time during the emergency braking process, controlling the aircraft's emergency braking and ensuring a safe stop.

[0004] Currently, aircraft emergency brake systems lack anti-skid functionality and are unable to actively adjust brake pressure. Pilots can only continuously push and pull the emergency brake handle based on aircraft speed, employing a tapping braking operation to reduce tire wear on the road surface and prevent blowouts. However, in reality, pilots must not only manipulate the emergency brake handle to control aircraft speed, but also perform course corrections based on the aircraft's taxiing attitude and perform numerous other onboard operations. During this time, pilots have no time to consider the potential risk of a blowout and are unable to implement effective tapping braking. Consequently, the aircraft cannot release the brakes in time during the emergency braking process, resulting in prolonged dragging and high brake pressure, making blowouts more likely.

[0005] Chinese invention patent publication number CN 106428533A discloses an aircraft inertial anti-skid braking system for emergency braking. By adding a control device to improve the system structure, normal braking is disabled during emergency braking, ensuring that the switch valve fully switches under emergency brake pressure. Even if emergency braking and normal braking are used simultaneously, the switch valve can switch to the emergency braking system. However, the emergency braking system described in this patent does not have an anti-skid function.

[0006] Chinese utility model patent publication number CN 210526840 U discloses an aircraft emergency and parking brake system. The system includes a pressure accumulator, a brake valve, and a handle. Turning the handle controls the brake valve's corresponding hydraulic pressure output, actuating the brake mechanism and applying emergency braking to the aircraft's wheels. However, the emergency brake system described in the patent lacks an anti-skid function.

[0007] Chinese utility model patent publication number CN 204775196 U discloses an aircraft rear cabin emergency brake system. The system includes a brake handle, a pull rod, a steel cable, a mounting bracket, an emergency brake pressure reducing valve, a valve compression rod, and a rocker mechanism. By utilizing the rocker mechanism to increase torque, the system reduces operating force and minimizes maintenance. However, the emergency brake system described in the patent lacks an anti-skid function.

[0008] Chinese utility model patent publication number CN 209051583 U discloses an emergency brake system capable of remote control. The system includes a brake command sensor, an electromagnetic hydraulic lock, an electro-hydraulic pressure servo valve, a fuse, a brake command sensor, a power supply, and a landing gear position switch. The brake command sensor, installed in the cockpit, directly controls the electromagnetic hydraulic lock and electro-hydraulic pressure servo valve installed in the main landing gear bay, enabling remote control of the emergency brake system. However, the emergency brake system described in the patent lacks an anti-skid function.

[0009] Chinese invention patent publication number CN 110606195 A discloses an aircraft emergency brake system. This system includes a hydraulic solenoid valve, a hydraulic relay, a hydraulic pressure-reducing brake valve, a 28V DC power supply, and an oil return line. The hydraulic solenoid valve is controlled on and off by a single-pole, double-set switch in the hydraulic relay. When the oil pressure is equal to or greater than the hydraulic relay's contact-on pressure, the hydraulic relay contacts close, connecting the 28V DC power supply to the hydraulic solenoid valve. This actively adjusts the brake pressure, reducing the pressure in the emergency brake system and achieving active anti-skid capabilities. However, this emergency brake system uses a hydraulic system as its pressure source, not a pneumatic emergency brake system. It is significantly affected by the output pressure of the pressure-reducing brake valve. Once the hydraulic relay is connected, the hydraulic solenoid valve relieves pressure, and the wheels continue to relieve pressure. The hydraulic solenoid valve resumes supplying pressure to the wheels only when the pressure-reducing brake valve output pressure drops to the hydraulic relay's contact-off pressure. However, during this period, the wheels are in a depressurized state, and the depressurization time is long, which affects the braking efficiency and safety of the aircraft. Moreover, this function relies on hydraulic pressure to control the active anti-skid function. If the aircraft is in danger of running off the runway, this function cannot be released. The pilot loses control of the emergency brake, affecting the safety of the aircraft. Summary of the Invention

[0010] In order to solve the problem that the spare pneumatic emergency brake in the aircraft wheel brake system does not have an anti-skid function, the present invention discloses an anti-skid pneumatic emergency brake system for aircraft wheel brakes.

[0011] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0012] An anti-skid pneumatic emergency brake system for aircraft wheel brakes includes an air pressure source, a brake pressure reducing valve, a wheel, an electromagnetic valve, a pressure switch, a time delay relay, a circuit breaker contact switch, and a power supply. The air pressure source, the brake pressure reducing valve, the electromagnetic valve, and the wheel are sequentially connected. The pressure switch, the time delay relay, and the electromagnetic valve are sequentially connected via electrical signals. The pressure switch is also connected to the brake pressure reducing valve. The pressure switch senses the air pressure output by the brake pressure reducing valve and outputs an electrical signal to the time delay relay. The power supply, which is a 28V DC power supply, supplies power to the pressure switch and the time delay relay via the circuit breaker contact switch.

[0013] In the above-mentioned anti-skid pneumatic emergency brake system, the air intake pipe interface of the electromagnetic valve and the brake pipe interface of the brake pressure reducing valve are connected through an air pressure pipeline; the output pipe interface of the electromagnetic valve is connected to the wheel through an air pressure pipeline; the connection terminal of the electromagnetic valve is connected to the electrical signal output terminal of the delay relay; in the non-powered state, the air intake pipe joint of the electromagnetic valve and the brake pipe joint are communicated, and the exhaust hole on the electromagnetic valve housing and the brake pipe joint are in a disconnected state; when the delay relay controls the electromagnetic valve to be energized, the air intake pipe interface of the electromagnetic valve is closed, and the gas flow between the brake pressure reducing valve and the wheel brake device is disconnected.

[0014] In the aforementioned anti-skid pneumatic emergency brake system, the pressure switch senses the brake pressure reducing valve output air pressure P. The pressure switch's activation pressure is P1, P1 = 5 MPa, and its disconnection pressure is P2, P2 = 4 MPa. The pressure switch's air pressure pipe interface is connected to the air pressure pipeline of the brake pressure reducing valve output interface. The pressure switch's electrical signal input is connected to the electrical signal output of the circuit breaker contact switch, which in turn is connected to the electrical signal control terminal of the time delay relay.

[0015] When P≥P1, the pressure switch microswitch is turned on, thereby transmitting the power signal output by the circuit breaker contact switch to the delay relay through the microswitch.

[0016] When P≤P2, the pressure switch microswitch is disconnected, thereby disconnecting the circuit connection between the circuit breaker contact switch and the time delay relay, and sending an electrical signal to the time delay relay.

[0017] In the aforementioned anti-skid pneumatic emergency brake system, the time delay relay is a programmable time relay capable of outputting a cyclic voltage signal. The time delay relay's electrical signal ports include an electrical signal output terminal, an electrical signal input terminal, and an electrical signal control terminal. The time delay relay's electrical signal input terminal is connected to the circuitry of the output terminal of the circuit breaker contact switch, the electrical signal control terminal is connected to the electrical signal output terminal of the pressure switch, and the electrical signal output terminal is connected to the terminal of the electromagnetic valve. When the time delay relay's electrical signal input terminal and electrical signal control terminal are simultaneously energized, the time delay relay's electrical signal output terminal outputs a cyclical on / off circuit signal.

[0018] In the aforementioned anti-skid pneumatic emergency brake system, the disconnect contact switch is normally in the on state, with one end connected to the power source and the other end connected to the pressure switch and the time delay relay, respectively. The disconnect contact switch is located in the cabin, and pressing the disconnect contact switch disconnects the power source from the pressure switch and the time delay relay.

[0019] The beneficial effects of the present invention are:

[0020] Currently, the aircraft's pneumatic emergency brake is achieved by the pilot controlling the emergency brake handle to manipulate the brake pressure reducing valve to output brake pressure, thereby braking the wheels. To prevent the tire from dragging due to high brake pressure, the pilot needs to continuously push and pull the emergency brake handle to control the brake pressure, which places a certain operational burden on the pilot.

[0021] An anti-skid air pressure emergency brake system for aircraft wheel brakes adds a pressure switch, a time delay relay, a circuit breaker contact switch, and an electromagnetic valve to the existing air pressure emergency brake system. After the pilot pulls the emergency brake handle, when the brake pressure reducing valve output pressure P is less than the starting pressure P1 of the pressure switch, P1 is the critical pressure value for the wheel to drag the tire. The pressure switch, time delay relay, and electromagnetic valve are in a non-working state. The electromagnetic valve is a channel. The compressed gas from the air pressure source passes through the brake pressure reducing valve and the electromagnetic valve in sequence to the wheel brake device, applying continuous braking to the wheel without an anti-skid braking function. At this time, the pilot does not need to push or pull the emergency brake handle, and there is no risk of the wheel dragging the tire. After the pilot pulls the emergency brake handle, the brake pressure reducing valve output pressure P is greater than When the pressure equals the trigger pressure P1 of the pressure switch, the pressure switch, time delay relay, and electromagnetic valve enter the operating state. The circuit between the pressure switch and the time delay relay is connected, and the time delay relay begins to operate and periodically outputs a voltage signal, thereby periodically controlling the electromagnetic valve on and off, completing the braking and releasing of the wheels and realizing the emergency brake anti-skid function. This solves the problem of high and long-lasting braking pressure in the pneumatic emergency brake system, which can cause wheel drag or tire blowout accidents. During this process, the pilot does not need to push or pull the emergency brake handle, and there is no risk of wheel drag. When implementing anti-skid braking, the pilot can also press the disconnect contact switch in the cockpit to simultaneously disconnect the pressure switch and time delay relay from the power supply, de-energizing the pressure switch and delay relay, and releasing the anti-skid function of the anti-skid pneumatic emergency brake.

[0022] Compared to existing emergency brake systems, this pneumatic anti-skid emergency brake system eliminates the need for pilots to control brake pressure by pulling the emergency brake handle, effectively reducing the pilot's operational burden and ensuring a safe aircraft shutdown. The pilot can disable the active anti-skid function at any time by assessing flight parameters, and this active anti-skid function is controllable.

[0023] The anti-skid air pressure emergency brake system senses the emergency brake pressure through a pressure switch, thereby activating the active anti-skid function; under the periodic control characteristics of the delay relay, the electromagnetic valve is controlled to be periodically connected and disconnected, thereby achieving a periodic decrease and increase in the emergency brake pressure, and the wheel achieves periodic release and braking operations, that is, anti-skid braking. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and examples.

[0025] Figure 1 This is a structural diagram of the present invention, where the discontinuous lines represent the pneumatic pipelines and the continuous solid lines represent the electrical circuits;

[0026] Figure 2 This is a diagram showing how the brake pressure of the present invention changes over time. DETAILED DESCRIPTION

[0027] Example 1

[0028] The invention discloses an anti-skid air pressure emergency brake system for aircraft wheel brakes, comprising an air pressure source, a brake pressure reducing valve, an aircraft wheel, an electromagnetic valve, a pressure switch, a time delay relay, a circuit breaker contact switch and a power supply.

[0029] like Figure 1 As shown, the air pressure source, brake pressure reducing valve, electromagnetic valve, and wheel are connected in sequence; the compressed gas from the air pressure source passes through the brake pressure reducing valve and electromagnetic valve to the wheel in sequence, and the compressed gas reaching the wheel generates braking force to achieve wheel braking.

[0030] The pressure switch, the time delay relay and the electromagnetic valve are connected in sequence through electrical signals, and the pressure switch controls the electromagnetic valve to be turned on or off through the time delay relay.

[0031] The pressure switch is also connected to the brake pressure reducing valve. The pressure switch senses the air pressure P output by the brake pressure reducing valve and outputs an electrical signal to the delay relay.

[0032] The power supply is supplied to the pressure switch and the time delay relay through the circuit breaker contact switch. When the circuit breaker contact switch is connected, the pressure switch and the time delay relay are supplied with power; when the circuit breaker contact switch is disconnected, the pressure switch and the time delay relay are de-energized.

[0033] The air pressure source is a compressed gas cylinder with a pressure of 11 to 14 MPa. The air pressure source is connected to the brake pressure reducing valve to supply pressure to the anti-skid air pressure emergency brake system.

[0034] The brake pressure reducing valve has a pressure-reducing function. The pilot controls the output pressure of the brake pressure reducing valve by pulling the emergency brake handle. The brake pressure reducing valve's inlet pipe connection is connected to the air pressure source; the brake pressure reducing valve's output pipe connection is connected to the pressure switch pipe connection and the solenoid valve's inlet pipe connection via air pressure lines. The exhaust port on the brake pressure reducing valve housing is connected to the atmosphere to release brake pressure. Initially, the brake pressure reducing valve is inoperative, the inlet pipe connection is closed, and the brake pipe connection is connected to the exhaust port on the brake pressure reducing valve housing. When the pilot pulls the emergency brake handle, the brake pressure reducing valve opens the inlet pipe connection, supplying pressure to the anti-skid air pressure emergency brake system.

[0035] The solenoid valve has three air pressure interfaces: an intake pipe interface, an output pipe interface, an exhaust pipe interface, and one wiring terminal. The intake pipe interface of the solenoid valve is connected to the brake pipe interface of the brake pressure reducing valve via an air pressure line; the output pipe interface of the solenoid valve is connected to the wheel via an air pressure line; and the wiring terminal of the solenoid valve is connected to the electrical signal output terminal of the delay relay. When de-energized, the solenoid valve is in a non-operating state. The intake and output pipe interfaces of the solenoid valve are connected, and the exhaust pipe interface is connected to the atmosphere and disconnected from the brake pipe interface. When the delay relay controls the solenoid valve to energize, the intake pipe interface of the solenoid valve closes, disconnecting the air flow between the brake pressure reducing valve and the wheel brake system; the brake pipe interface and the exhaust pipe interface are connected to the atmosphere, achieving wheel pressure relief and brake release.

[0036] The pressure switch senses the brake pressure reducing valve's output air pressure, P. The switch's activation pressure is P1, the near-miss pressure at which the wheel poses a risk of dragging the tire (P1 = 5 MPa). The switch's disconnect pressure is P2, which is 4 MPa. The pressure switch's air pressure line is connected to the brake pressure reducing valve's output line. The pressure switch's electrical signal input is connected to the circuit breaker's electrical signal output, which in turn is connected to the time-delay relay's electrical signal control terminal.

[0037] When P≥P1, the micro switch inside the pressure switch is turned on, thereby transmitting the power signal output by the circuit breaker contact switch to the delay relay through the micro switch.

[0038] When P≤P2, the micro switch inside the pressure switch is disconnected, thereby disconnecting the circuit connection between the pressure switch and the time delay relay, and sending an electrical signal to the time delay relay.

[0039] A time delay relay is a programmable time relay that outputs a cyclic voltage signal. Its electrical signal ports include an electrical signal output terminal, an electrical signal input terminal, and an electrical signal control terminal. The time delay relay's electrical signal input terminal is connected to the circuitry of the disconnect contact switch's output terminal, the electrical signal control terminal is connected to the electrical signal output terminal of the pressure switch, and the electrical signal output terminal is connected to the wiring terminal of the electromagnetic valve. When both the electrical signal input and electrical signal control terminals of the time delay relay are energized simultaneously, the time delay relay's electrical signal output terminal outputs a cyclical on / off signal.

[0040] The disconnect contact switch is normally closed, meaning it's usually on. One end is connected to the power supply, and the other end is connected to the pressure switch and time delay relay. Located in the cockpit, pressing the disconnect contact switch disconnects the power supply from the pressure switch and time delay relay, disabling the anti-skid brake and providing continuous air pressure braking.

[0041] The power supply is 28V DC.

[0042] The working process of the anti-skid emergency braking system is as follows:

[0043] When the pilot pulls the emergency brake handle, when P < P1, that is, when the output air pressure P of the brake pressure reducing valve is less than the starting pressure P1 of the pressure switch, the pressure switch, the time-delay relay, and the solenoid valve are in a non-operating state. The solenoid valve is the passage, and the compressed gas from the air pressure source passes through the brake pressure reducing valve and the solenoid valve to the wheel brake device in sequence, implementing continuous braking on the wheels without the anti-skid braking function.

[0044] When the pilot pulls the emergency brake handle, when P ≥ P1, that is, when the output air pressure P of the brake pressure reducing valve is greater than or equal to the starting pressure P1 of the pressure switch, the circuit between the pressure switch and the time-delay relay is connected, and the time-delay relay starts to work and count time; when the time counted by the time-delay relay reaches the braking time T0, the braking time T0 is set according to the wheel model, T0 = 1s, the operating part in the time-delay relay is connected, and the air inlet interface of the solenoid valve is closed, closing the passage of the compressed gas of the brake pressure reducing valve to the wheel brake device. The brake port and the exhaust port of the solenoid valve are connected and release the emergency brake pressure in the wheel brake device. The emergency brake pressure decreases, and the wheels resume rolling. The time-delay relay continues to count time. When the duration of closing the solenoid valve reaches the brake release time T1, the brake release time is T1, T1 = 1s, the time-delay relay disconnects the electrical signal connection with the solenoid valve, the exhaust port of the solenoid valve is closed, the air inlet and the brake port are connected, the passage of the brake pressure reducing valve to the brake device is restored, the emergency brake pressure starts to rise, and enters the braking state. The time-delay relay counts the braking time T2. T2 = T0. Under the control of the time-delay relay, the solenoid valve brakes, releases the brake, brakes, and releases the brake periodically, that is, anti-skid braking. The relationship between the braking and brake release pressure and time is as Figure 2 shown. As the periodic braking and brake release process continues, the compressed gas in the air pressure source is gradually released. When the pressure in the air pressure source decreases and the output air pressure of the brake pressure reducing valve is less than or equal to the cut-off pressure of the pressure switch, that is, P ≤ P2, the circuit between the pressure switch and the time-delay relay is disconnected, the solenoid valve is powered on and connected, and the brake pressure reducing valve outputs compressed gas to the wheel brake device to implement continuous braking on the wheels.

[0045] When pulling the emergency brake handle to implement anti-skid braking, the pilot can also press the open-circuit contact switch in the cockpit to simultaneously disconnect the connections of the pressure switch, the time-delay relay and the power supply, power off the pressure switch and the time-delay relay, and解除 the anti-skid function of the anti-skid air pressure emergency brake.

Claims

1. An anti-skid air pressure emergency brake system for aircraft wheel brakes, characterized in that: The device comprises an air pressure source, a brake pressure reducing valve, a wheel, an electromagnetic valve, a pressure switch, a time delay relay, a circuit breaker contact switch, and a power supply. The air pressure source, the brake pressure reducing valve, the electromagnetic valve, and the wheel are sequentially connected; the pressure switch, the time delay relay, and the electromagnetic valve are sequentially connected via electrical signals; the pressure switch is also connected to the brake pressure reducing valve, senses the air pressure output by the brake pressure reducing valve, and outputs an electrical signal to the time delay relay; the power supply supplies power to the pressure switch and the time delay relay via the circuit breaker contact switch, and the power supply is a 28V DC power supply. The air inlet pipe interface of the electromagnetic valve is connected to the brake pipe interface of the brake pressure reducing valve via a pneumatic pipeline; the output pipe interface of the electromagnetic valve is connected to the wheel via a pneumatic pipeline; the connection terminal of the electromagnetic valve is connected to the electrical signal output terminal of the delay relay; in an off-state, the air inlet pipe connector of the electromagnetic valve is in communication with the brake pipe connector, and the exhaust hole on the electromagnetic valve housing is disconnected from the brake pipe connector; when the delay relay controls the electromagnetic valve to be energized, the air inlet pipe connector of the electromagnetic valve is closed, disconnecting the air flow between the brake pressure reducing valve and the wheel brake device; The pressure switch senses the output air pressure P of the brake pressure reducing valve. The starting pressure of the pressure switch is P1, P1=5MPa, and the disconnecting pressure of the pressure switch is P2, P2=4MPa. The air pressure pipe interface of the pressure switch is connected to the air pressure pipeline of the output pipe interface of the brake pressure reducing valve. The electrical signal input end of the pressure switch is connected to the electrical signal output end of the circuit breaker contact switch, and the electrical signal output end of the pressure switch is connected to the electrical signal control end of the delay relay. When P≥P1, the pressure switch microswitch is turned on, thereby transmitting the power signal output by the circuit breaker contact switch to the delay relay through the microswitch; When P≤P2, the pressure switch microswitch is disconnected, thereby disconnecting the circuit connection between the circuit breaker contact switch and the time delay relay, and sending an electrical signal to the time delay relay.

2. The anti-skid pneumatic emergency brake system for aircraft wheel brakes according to claim 1, characterized in that: The time delay relay is a programmable time relay with an output periodic cyclic voltage signal. The electrical signal port of the time delay relay includes an electrical signal output terminal, an electrical signal input terminal, and an electrical signal control terminal. The electrical signal input terminal of the time delay relay is connected to the circuit of the output terminal of the circuit breaker contact switch, the electrical signal control terminal is connected to the electrical signal output terminal of the pressure switch, and the electrical signal output terminal is connected to the connection terminal of the electromagnetic valve. When the electrical signal input terminal and the electrical signal control terminal of the time delay relay are energized at the same time, the electrical signal output terminal of the time delay relay outputs a circuit signal that is periodically connected and disconnected.

3. The anti-skid pneumatic emergency brake system for aircraft wheel brakes according to claim 1, characterized in that: The circuit breaker contact switch is usually in the on state, with one end connected to the power supply and the other end connected to the pressure switch and the time delay relay respectively; the circuit breaker contact switch is located in the cockpit, and the power supply is disconnected from the pressure switch and the time delay relay by pressing the circuit breaker contact switch.

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