Helicopter cant beam folding and unfolding system and control method

Abstract

The invention belongs to the technical field of aircraft cant beam folding system design, and discloses a helicopter cant beam folding and unfolding system and a control method. The system comprises a hydraulic oil tank for storing system hydraulic oil; the electric pump sucks hydraulic oil from the hydraulic oil tank, adjusts output flow and output constant pressure according to load requirements, and is respectively connected to the oblique beam upper pin / shifting pin electromagnetic valve and the oblique beam folding / unfolding electromagnetic valve through a flow limiting valve and a pressure supply runner; the oblique beam upper pin / pull pin electromagnetic valve is a three-position four-way valve, a port A1 is connected with the electric pump, a port B1 is connected with a pin disengaging cavity of the pull pin / upper pin actuating cylinder, a port C1 is connected with an upper pin cavity of the pull pin / upper pin actuating cylinder, and a port D1 is connected with the hydraulic oil tank through an oil return flow channel; the oblique beam folding / unfolding electromagnetic valve is a three-position four-way valve, a port A2 is connected with the electric pump, a port B2 is connected with an unfolding cavity of the folding / unfolding actuator cylinder, a port C2 is connected with a folding cavity of the folding / unfolding actuator cylinder, and a port D2 is connected with the hydraulic oil tank through an oil return flow channel.

Description

Technical Field

[0001] This invention belongs to the field of aircraft slant beam folding system design technology, and discloses a helicopter slant beam folding and unfolding system and control method. Background Technology

[0002] To ensure the helicopter's slant beam folds or unfolds according to specified requirements, the system pressure transmission for folding and unfolding the slant beam needs to be controlled by manipulating modules such as the slant beam upper pin / release pin solenoid valve, the slant beam folding / unfolding solenoid valve, the slant beam release pin actuator, and the slant beam folding actuator. Previously, helicopter slant beam folding hydraulic systems were designed and arranged in a distributed manner according to their functions, with components connected by oil circuits. This resulted in drawbacks such as heavy weight, numerous channels, inconvenient installation and maintenance, and poor reliability. Furthermore, to achieve independent folding and unfolding of the slant beam, the power source and control unit are now integrated into a comprehensive design. Summary of the Invention

[0003] Purpose of the invention: To provide a helicopter slant beam folding and unfolding system and control method, which integrates various components such as electric pump, oil tank, slant beam upper pin / displacement solenoid valve, slant beam folding / unfolding solenoid valve, flow limiting valve, and safety valve into a technical solution, thereby improving the power-to-weight ratio of the system and enhancing the reliability and maintainability of the slant beam folding hydraulic system.

[0004] Technical solution: A helicopter slant beam folding and unfolding system includes: The hydraulic oil tank stores the system's hydraulic oil and is equipped with an air filter, connecting the tank to the atmosphere. The electric pump draws hydraulic oil from the hydraulic oil tank, adjusts the output flow and output constant pressure according to the load requirements, and is connected to the inclined beam upper pin / pin solenoid valve and the inclined beam folding / unfolding solenoid valve respectively through the oil supply channel. The inclined beam upper pin / pin release solenoid valve is a three-position four-way valve. Port A1 is connected to the electric pump, port B1 is connected to the pin release chamber of the pin release / pin release actuator, port C1 is connected to the upper pin chamber of the pin release / pin release actuator, and port D1 is connected to the hydraulic oil tank via the return oil line. The inclined beam folding / unfolding solenoid valve is a three-position four-way valve. Port A2 is connected to the electric pump, port B2 is connected to the unfolding chamber of the folding / unfolding actuator, port C2 is connected to the folding chamber of the folding / unfolding actuator, and port D2 connects to the hydraulic oil tank via the return oil line.

[0005] Furthermore, a pressure oil filter is installed at the outlet of the electric pump to filter the system oil and provide an oil blockage indicator to ensure oil cleanliness.

[0006] Furthermore, before the pressure supply channel branches, the return oil channel is connected via a first safety valve to provide overpressure protection and prevent damage to pipelines and accessories in the hydraulic system.

[0007] Furthermore, a first flow limiting valve is provided near the A1 port of the inclined beam upper pin / pin-pulling solenoid valve in the oil supply channel to control the operating speed of the pin-pulling / pin-upper actuator.

[0008] Furthermore, a first hydraulic lock is provided between the B1 port of the inclined beam upper pin / pin release solenoid valve and the pin release chamber of the pin release / pin release actuator, and a second hydraulic lock is provided between the C1 port of the inclined beam upper pin / pin release solenoid valve and the pin release / pin release actuator. The B1 and C1 ports of the inclined beam upper pin / pin-pulling solenoid valve respectively notify the control oil circuit to connect the first hydraulic lock and the second hydraulic lock. Considering the large internal leakage of the solenoid valve, the hydraulic lock is used to maintain a state of near zero leakage to prevent the pin-pulling / pin-upper pin actuator from accidentally extending or retracting.

[0009] Furthermore, the upper pin chamber of the pin-pulling / pin-upping actuator is also connected to the return oil passage through a second safety valve for overpressure protection, preventing damage to pipelines and accessories in the hydraulic system; The pin release chamber of the pin release / pin release actuator is also connected to the return oil passage through a third safety valve for overpressure protection, preventing damage to pipelines and accessories in the hydraulic system.

[0010] Furthermore, a second flow limiting valve is installed near the A2 port of the inclined beam folding / unfolding solenoid valve in the oil supply line to control the actuation speed of the inclined beam folding / unfolding actuator.

[0011] Furthermore, the folding chamber of the inclined beam folding / unfolding solenoid valve is also connected to the return oil line through a fourth safety valve; The unfolding chamber of the inclined beam folding / unfolding solenoid valve is also connected to the return oil line via a fifth safety valve for overpressure protection, preventing damage to pipelines and accessories in the hydraulic system.

[0012] Furthermore, a first check valve is connected to port D1 of the solenoid valve on the inclined beam, and a second check valve is connected to port D2 of the solenoid valve on the inclined beam folding / unfolding to prevent the system return oil pressure from affecting the system.

[0013] A control method for a helicopter slant beam folding and unfolding system. Methods for folding inclined beams include: Step 1: When the electric pump 1 is powered on, the pressure oil is supplied to the inclined beam upper pin / pin release solenoid valve 7. When the inclined beam upper pin / pin release solenoid valve 7 is powered on, the pressure oil is supplied to the pin release chamber of the pin release / pin release actuator cylinder 10 through the hydraulic lock 8, so as to realize the pin release. Step 2: After the inclined beam is disengaged and held in position, the micro switch gives a signal that the disengagement is in place, and the inclined beam upper pin / pin release solenoid valve 7 is de-energized; the hydraulic lock 8 is maintained in a state of near zero leakage, so that the pin release / pin release actuator is kept in the disengaged position, preventing the pin from accidentally extending and damaging the machine structure during the unfolding of the inclined beam. Step 3: When the inclined beam folding / unfolding solenoid valve 16 is energized, the high-pressure hydraulic oil enters the folding / unfolding actuator cylinder through the inclined beam folding / unfolding solenoid valve 16, and the pressure oil is supplied to the folding cavity of the folding / unfolding actuator cylinder 11 to realize the folding of the inclined beam; Step 4: When the inclined beam folding micro switch gives the signal to be in position, the inclined beam folding / unfolding solenoid valve 16 is de-energized, and the inclined beam remains in the folded position. Methods for unfolding inclined beams include: Step 1: When the electric pump 1 is powered on, the pressure oil is supplied to the inclined beam folding / unfolding solenoid valve 16. When the inclined beam folding / unfolding solenoid valve 16 is powered on, the high-pressure hydraulic oil enters the folding / unfolding actuator cylinder through the inclined beam folding / unfolding solenoid valve 16. The pressure oil is supplied to the unfolding chamber of the folding / unfolding actuator cylinder 11 to realize the unfolding of the inclined beam. Step 2: When the inclined beam unfolds, the micro switch gives a signal to be in position, the inclined beam upper pin / pin release solenoid valve 7 is energized, and the pressure oil is supplied to the upper pin chamber of the pin release / pin release actuator cylinder 10 through the hydraulic lock 9 to realize the pin release; Step 3: De-energize the inclined beam folding / unfolding solenoid valve 16 to disconnect the hydraulic system from supplying pressure to the inclined beam folding / unfolding actuator cylinder; Step 4: De-energize the solenoid valve 7 for the upper pin / pin release of the inclined beam, thus disconnecting the hydraulic system from supplying pressure to the actuating cylinder of the upper pin / pin release of the inclined beam.

[0014] In summary, the beneficial effects of the present invention are as follows: This invention provides a helicopter slant beam folding and unfolding system and control method. It integrates the hydraulic components controlling the folding and unfolding pressure of the slant beam, employing an independent hydraulic energy unit that is not interconnected with the flight control hydraulic system. This allows for independent folding and unfolding of the slant beam or its coordination with the rotor folding and unfolding system. The system is compact, lightweight, and small in size. It reduces external piping connections, minimizes flow resistance, and significantly lowers the risk of oil leakage. The entire device is bolted to the aircraft structure for easy installation and disassembly. Each hydraulic component can be individually disassembled and replaced for easy maintenance and replacement. A combination of a solenoid valve and a hydraulic lock is provided to prevent accidental extension or retraction of the pin / up pin actuator due to internal leakage in the solenoid valve, ensuring that the pin / up pin actuator remains in the pin-up or pin-off position. Attached Figure Description

[0015] Figure 1 A schematic diagram of the principle of a helicopter slanted beam folding and unfolding system; 1. Hydraulic oil tank; 2. Electric pump; 3. Pressure oil filter; 4. First safety valve; 5. First check valve; 6. First flow limiting valve; 7. Inclined beam upper pin / pin release solenoid valve; 8. First hydraulic lock; 9. Second hydraulic lock; 10. Pin release / pin release actuator; 11. Folding / unfolding actuator; 12. Second safety valve; 13. Third safety valve; 14. Fourth safety valve; 15. Fifth safety valve; 16. Inclined beam folding / unfolding solenoid valve; 17. Second flow limiting valve; 18. Second check valve.

[0016] Figure 2 : A schematic diagram of a helicopter inclined beam folding and unfolding system. Detailed Implementation

[0017] A helicopter slant beam folding and unfolding system, such as Figure 1 As shown, it includes: Hydraulic oil tank 1, which stores the system hydraulic oil and is equipped with a venting device; Electric pump 2, as the power source of the folding hydraulic system, provides hydraulic oil with a certain pressure and flow rate; The first flow limiting valve 6 is used to limit the flow rate of hydraulic oil into the inclined beam pin pulling / up pin actuating cylinder, thereby controlling the speed of the inclined beam pin pulling / up pin. The inclined beam upper pin / pin release solenoid valve 7 is used to control the flow of high-pressure hydraulic oil into the pin release / pin release actuator. When the upper electromagnet is energized, the hydraulic oil is supplied to the upper pin chamber of the inclined beam pin release / pin release actuator through the flow limiting valve 6 and the inclined beam upper pin / pin release solenoid valve 7, and the inclined beam pin is released. When the lower electromagnet is energized, the hydraulic oil is supplied to the pin release chamber of the inclined beam pin release / pin release actuator through the flow limiting valve 6 and the inclined beam upper pin / pin release solenoid valve 7, and the inclined beam pin is released. The second flow limiting valve 17 is used to limit the flow rate of hydraulic oil into the inclined beam folding / unfolding actuator cylinder, thereby controlling the speed of the inclined beam folding / unfolding. The inclined beam folding / unfolding solenoid valve 16 is used to control the flow of high-pressure hydraulic oil into the folding / unfolding actuator cylinder. After the inclined beam is pulled into place, when the upper electromagnet is energized, the hydraulic oil is supplied to the folding chamber of the inclined beam folding / unfolding actuator cylinder through the flow limiting valve 17 and the inclined beam folding / unfolding solenoid valve 16, and the inclined beam folds. When the lower electromagnet is energized, the hydraulic oil is supplied to the unfolding chamber of the inclined beam folding / unfolding actuator cylinder through the inclined beam folding / unfolding solenoid valve 16, and the inclined beam unfolds. The system also includes: Pressure oil filter 3 filters the system pressure oil and provides an oil blockage indicator; The first safety valve 4 is located downstream of the power source pressure supply oil circuit. The first safety valve 4 is used to protect the system pressure supply oil circuit pressure from not exceeding the system's specified value. The second safety valve 12 is located downstream of the pressure supply oil circuit of the upper pin on the inclined beam. The second safety valve 13 is used to protect the pressure of the pressure supply oil circuit of the upper pin on the inclined beam from not exceeding the system's specified value. The third safety valve 13 is located downstream of the pressure supply oil circuit of the inclined beam pin, and the third safety valve 14 is used to protect the pressure of the pressure supply oil circuit of the inclined beam pin from not exceeding the system's specified value. The fourth safety valve 14 is located downstream of the inclined beam folding pressure supply oil circuit, and the fourth safety valve 15 is used to protect the pressure of the inclined beam folding pressure supply oil circuit from not exceeding the system's specified value; The fifth safety valve 15 is located downstream of the inclined beam deployment pressure supply oil circuit, and the fifth safety valve 16 is used to protect the pressure of the inclined beam deployment pressure supply oil circuit from not exceeding the system's specified value; The first one-way valve 5 is installed on the return oil passage of the pin puller / pin mounter to prevent reverse oil backflow from affecting the folding hydraulic system when the system pulls / mounts the inclined beam.

[0018] The second check valve 18 is installed on the return oil channel of the inclined beam folding / unfolding to prevent reverse oil backflow from affecting the folding hydraulic system when the system folds / unfolds the inclined beam.

[0019] Hydraulic lock 8 ensures that the pin-pulling / pin-raising actuator remains in the disengaged position; Hydraulic lock 9 ensures that the pin-pulling / pin-raising actuator remains in the pin-raising position.

[0020] A method for controlling the folding and unfolding of a helicopter's slant beam, comprising a folding method and an unfolding method.

[0021] Methods for folding inclined beams include: Step 1: When the electric pump 1 is powered on, the pressure oil passes through the pressure oil filter 3 and the first safety valve 4 and is supplied to the inclined beam upper pin / pin release solenoid valve 7. When the inclined beam upper pin / pin release solenoid valve 7 is powered on, the pressure oil passes through the first hydraulic lock 8 and the third safety valve 13 and is supplied to the pin release chamber of the pin release / pin release actuator cylinder 10 to realize pin release. Step 2: After the inclined beam is disengaged and held in position, the micro switch gives a signal that the disengagement is in place, and the inclined beam upper pin / pin release solenoid valve 7 is de-energized; the first hydraulic lock 8 is maintained in a state of near zero leakage, so that the pin release / pin release actuator is kept in the disengaged position, preventing the pin from accidentally extending and damaging the machine structure during the unfolding of the inclined beam. Step 3: When the inclined beam folding / unfolding solenoid valve 16 is energized, the high-pressure hydraulic oil enters the folding / unfolding actuator cylinder through the inclined beam folding / unfolding solenoid valve 16, and the pressure oil is supplied to the folding chamber of the folding / unfolding actuator cylinder 11 through the fourth safety valve 14 to realize the folding of the inclined beam. Step 4: When the inclined beam folding micro switch gives the signal to be in position, the inclined beam folding / unfolding solenoid valve 16 is de-energized, and the inclined beam remains in the folded position.

[0022] Methods for unfolding inclined beams include: Step 1: When the electric pump 1 is powered on, the pressure oil passes through the pressure oil filter 3 and the first safety valve 4 and is supplied to the inclined beam folding / unfolding solenoid valve 16. When the inclined beam folding / unfolding solenoid valve 16 is powered on, the high-pressure hydraulic oil enters the folding / unfolding actuator cylinder through the inclined beam folding / unfolding solenoid valve 16. The pressure oil is supplied to the unfolding chamber of the folding / unfolding actuator cylinder 11 through the fifth safety valve 15, so as to realize the unfolding of the inclined beam. Step 2: When the inclined beam unfolds, the micro switch gives a signal to be in position, the inclined beam upper pin / pin release solenoid valve 7 is energized, and the pressure oil is supplied to the upper pin chamber of the pin release / pin release actuator cylinder 10 through the second hydraulic lock 9 and the third safety valve 13 to realize the pin release; Step 3: De-energize the inclined beam folding / unfolding solenoid valve 16 to disconnect the hydraulic system from supplying pressure to the inclined beam folding / unfolding actuator cylinder; Step 4: De-energize the solenoid valve 7 for the upper pin / pin release of the inclined beam, thus disconnecting the hydraulic system from supplying pressure to the actuating cylinder of the upper pin / pin release of the inclined beam.

[0023] A device for controlling the folding and unfolding of a helicopter slant beam integrates various functional hydraulic components for folding and unfolding the slant beam, providing a method for controlling the folding and unfolding of the helicopter slant beam. The embodiments are described in detail below with reference to the accompanying drawings.

[0024] The device described herein includes: a hydraulic oil tank 1, an electric pump 2, a pressure oil filter 3, a first safety valve 4, a first check valve 5, a first flow limiting valve 6, a solenoid valve for the inclined beam upper pin / push pin 7, a first hydraulic lock 8, a second hydraulic lock 9, a second safety valve 12, a second safety valve 13, a second safety valve 14, a second safety valve 15, a solenoid valve for folding / unfolding the inclined beam 16, a second flow limiting valve 17, and a second check valve 18, see [link to details]. Figure 2 .

[0025] The inclined beam upper pin / pin release solenoid valve 7 and the inclined beam folding / unfolding solenoid valve 16 are bolted to the device. The first safety valve 4, the first check valve 5, the first flow limiting valve 6, the first hydraulic lock 8, the second hydraulic lock 9, the second safety valve 12, the third safety valve 13, the fourth safety valve 14, the fifth safety valve 15, and the second check valve 18 are threaded onto the device. The safety valves are used to protect the pressure of the inclined beam folding / unfolding oil circuit from exceeding the system's specified value. The first check valve 5 and the second check valve 18 are used to prevent reverse oil backflow during inclined beam folding / unfolding from affecting the folding hydraulic system. The first flow limiting valve 6 and the second flow limiting valve 17 are used to control the speed of the inclined beam pin release / pin release and the speed of the inclined beam folding / unfolding, respectively. The first hydraulic lock and the second hydraulic lock are maintained in a state of near-zero leakage to prevent the pin release / pin release actuator from accidentally extending or retracting. While meeting the pressure transmission control function and performance requirements of the folding / unfolding of the inclined beam, the integrated design makes the device compact and lightweight, which is convenient for on-machine layout and maintenance. It also reduces external pipeline connections, thus greatly reducing the risk of oil leakage during the folding and unfolding of the inclined beam.

[0026] The device is bolted to the helicopter structure for easy installation and disassembly.

[0027] A method for controlling the folding and unfolding of a helicopter's slant beam is described below: Upon receiving the folding command for the inclined beam, the electric pump 1 is energized and draws hydraulic oil from the hydraulic oil tank 1. The resulting pressurized oil passes through the pressure oil filter 3, safety valve 4, and flow limiting valve 6, and is supplied to the inclined beam upper pin / pin release solenoid valve 7. The inclined beam upper pin / pin release solenoid valve 7 is energized according to the control logic, and the pressurized oil passes through the hydraulic lock 8 and safety valve 13 to the pin release chamber of the pin release / pin release actuator cylinder 10, thereby achieving pin release.

[0028] Once the inclined beam is disengaged from the pin, the inclined beam folding / unfolding solenoid valve 16 is energized according to the control logic. The pressure oil generated by the electric pump enters the folding / unfolding actuator cylinder through the inclined beam folding / unfolding solenoid valve 16. The pressure oil is supplied to the folding chamber of the folding / unfolding actuator cylinder 11 via the safety valve 15. The inclined beam can be folded to a specified angle through the proximity switch signal. At the same time, the position is maintained by controlling the on / off state of the electric pump and the pressure oil circuit.

[0029] Upon receiving the command to deploy the inclined beam, the electric pump 1 is energized and draws hydraulic oil from the hydraulic oil tank 1. The resulting pressurized oil passes through the pressure oil filter 3 and the safety valve 4, and is supplied to the inclined beam folding / deploying solenoid valve 16. The inclined beam folding / deploying solenoid valve 16 is energized according to the control logic, and the pressurized oil passes through the safety valve 15 to the deployment chamber of the folding / deploying actuator cylinder 11, thereby deploying the inclined beam. The inclined beam can be deployed to a specified angle by means of a proximity switch signal, and the position can be maintained by controlling the on / off of the pressure oil circuit through the solenoid valve.

[0030] When the inclined beam is fully extended, the micro switch for extending the inclined beam gives a signal indicating that it is in position. The solenoid valve 7 for the upper pin / pin release is energized according to the control logic. Pressure oil is supplied to the upper pin chamber of the pin release / pin release actuator 10 through the hydraulic lock 9 and the safety valve 13 to realize the pin release. After the upper pin is in position, the micro switch gives a signal indicating that the position is maintained by the on / off switch of the electric pump and the pressure oil circuit.

[0031] In this embodiment, to ensure that the pin-pulling / pin-upping actuator is reliably locked in the designated pin-upping or pin-removing position, a combination of inclined beam pin-upping / pin-pulling solenoid valve 7 and hydraulic locks 8 and 9 is adopted to maintain a state of near-zero leakage, preventing internal leakage of the solenoid valve from causing the pin-pulling / pin-upping actuator to extend or retract unexpectedly. To control the speed of folding and unfolding the inclined beam, throttle valves are installed on the pins and pull pins of the inclined beam, as well as in the oil circuits for folding and unfolding the inclined beam. This ensures that the folding and unfolding of the inclined beam is completed within the specified time, while preventing the structure from being damaged due to excessive speed of folding and unfolding.

[0032] To prevent structural damage caused by excessive pressure during the lifting and lowering of the inclined beam pins, safety valves are installed at the rear end of the pressure supply oil circuits for these pins. When the pressure exceeds the specified value, the safety valve opens to relieve pressure through the return oil circuit, ensuring system pressure. Similarly, a safety valve is installed at the rear end of the folding / unfolding pressure supply oil circuit. This safety valve also opens to relieve pressure through the return oil circuit, ensuring system pressure. The device also includes a check valve to prevent return oil pressure from affecting the folding hydraulic system during the folding and unfolding of the inclined beam. The integrated throttle valve and safety valve enhance the safety and reliability of the inclined beam folding and unfolding hydraulic system.

[0033] In this embodiment, the device can independently fold and unfold the inclined beam when the onboard rotor is hydraulically or electrically folded, or it can be used in conjunction with the onboard rotor hydraulically or electrically folding to fold and unfold the inclined beam. It is also equipped with ground pressure supply and return oil interfaces for connecting to a ground hydraulic source to provide energy for the inclined beam folding / unfolding hydraulic system.

Claims

1. A helicopter slant beam folding and unfolding system, characterized in that, include: The hydraulic oil tank stores the system's hydraulic oil and is equipped with an air filter, connecting the tank to the atmosphere. The electric pump draws hydraulic oil from the hydraulic oil tank, adjusts the output flow and output constant pressure according to the load requirements, and is connected to the inclined beam upper pin / pin solenoid valve and the inclined beam folding / unfolding solenoid valve respectively through the oil supply channel. The inclined beam upper pin / pin release solenoid valve is a three-position four-way valve. Port A1 is connected to the electric pump, port B1 is connected to the pin release chamber of the pin release / pin release actuator, port C1 is connected to the upper pin chamber of the pin release / pin release actuator, and port D1 is connected to the hydraulic oil tank through the return oil passage. The inclined beam folding / unfolding solenoid valve is a three-position four-way valve. Port A2 is connected to the electric pump, port B2 is connected to the unfolding chamber of the folding / unfolding actuator, port C2 is connected to the folding chamber of the folding / unfolding actuator, and port D2 is connected to the hydraulic oil tank through the return oil channel.

2. The system according to claim 1, characterized in that, A pressure oil filter is installed at the outlet of the electric pump.

3. The system according to claim 1, characterized in that, Before the pressure supply channel branches, the return oil channel is connected via the first safety valve.

4. The system according to claim 1, characterized in that, A first flow limiting valve is installed near the A1 port of the solenoid valve on the inclined beam in the pressure supply channel.

5. The system according to claim 1, characterized in that, A first hydraulic lock is provided between the B1 port of the inclined beam upper pin / pin release solenoid valve and the pin release chamber of the pin release / pin release actuator, and a second hydraulic lock is provided between the C1 port of the inclined beam upper pin / pin release solenoid valve and the pin release / pin release actuator. The B1 port and C1 port of the solenoid valve on the inclined beam are connected to the first hydraulic lock and the second hydraulic lock through the control oil circuit, respectively.

6. The system according to claim 1, characterized in that, The upper pin chamber of the pin-pulling / pin-upping actuator is also connected to the return oil passage through a second safety valve; The pin release chamber of the pin-pulling / pin-upping actuator is also connected to the return oil passage via a third safety valve.

7. The system according to claim 1, characterized in that, A second flow limiting valve is installed near the A2 port of the inclined beam folding / unfolding solenoid valve in the oil supply channel.

8. The system according to claim 1, characterized in that, The folding chamber of the inclined beam folding / unfolding solenoid valve is also connected to the return oil channel through a fourth safety valve; The unfolding chamber of the inclined beam folding / unfolding solenoid valve is also connected to the return oil flow channel through the fifth safety valve.

9. The system according to claim 3, characterized in that: A first check valve is connected to port D1 of the solenoid valve on the inclined beam, and a second check valve is connected to port D2 of the solenoid valve on the inclined beam folding / unfolding.

10. A control method for a helicopter slant beam folding and unfolding system, used to control the system according to any one of claims 1-9, characterized in that: Methods for folding inclined beams include: Step 1: When the electric pump (1) is powered on, the pressure oil is supplied to the inclined beam upper pin / pin-pulling solenoid valve (7). When the inclined beam upper pin / pin-pulling solenoid valve (7) is powered on, the pressure oil is supplied to the pin-pulling chamber of the pin-pulling / upper pin actuating cylinder (10) through the hydraulic lock (8) to realize the pin removal. Step 2: After the inclined beam is disengaged and held in position, the micro switch gives a signal that the disengagement is in place, and the inclined beam upper pin / pin release solenoid valve (7) is de-energized; the hydraulic lock (8) is maintained in a state of near zero leakage, so that the pin release / pin release actuator is kept in the disengaged position, preventing the pin from accidentally extending and damaging the machine structure during the unfolding of the inclined beam; Step 3: When the inclined beam folding / unfolding solenoid valve (16) is energized, the high-pressure hydraulic oil enters the folding / unfolding actuator cylinder through the inclined beam folding / unfolding solenoid valve (16), and the pressure oil is supplied to the folding cavity of the folding / unfolding actuator cylinder (11) to realize the folding of the inclined beam; Step 4: When the inclined beam folding micro switch gives the signal to be in position, the inclined beam folding / unfolding solenoid valve (16) is de-energized, and the inclined beam remains in the folded position; Methods for unfolding inclined beams include: Step 1: The electric pump (1) is powered on, and the pressure oil is supplied to the inclined beam folding / unfolding solenoid valve (16). When the inclined beam folding / unfolding solenoid valve (16) is powered on, the high pressure hydraulic oil enters the folding / unfolding actuator cylinder through the inclined beam folding / unfolding solenoid valve (16). The pressure oil is supplied to the unfolding chamber of the folding / unfolding actuator cylinder (11) to realize the unfolding of the inclined beam. Step 2: When the inclined beam unfolds, the micro switch gives a signal to be in position, the inclined beam upper pin / pin release solenoid valve (7) is energized, and the pressure oil is supplied to the upper pin chamber of the pin release / pin release actuator (10) through the hydraulic lock (9) to realize the pin release; Step 3: De-energize the inclined beam folding / unfolding solenoid valve (16) to disconnect the hydraulic system from supplying pressure to the inclined beam folding / unfolding actuator cylinder; Step 4: De-energize the solenoid valve (7) of the inclined beam upper pin / pin release valve to disconnect the hydraulic system from supplying pressure to the inclined beam pin release / pin release actuator.

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