Hydraulic system for retracting and unlocking landing gear of air car

Abstract

The application provides a hydraulic system for retracting and unlocking an air car landing gear, and belongs to the technical field of landing gear retracting control, and solves the problems of complex structure and high cost of the existing hydraulic system. The hydraulic system comprises a front landing gear unlocking hydraulic control circuit, a rear landing gear unlocking hydraulic control circuit, a rear landing gear retracting and releasing hydraulic control circuit and a front landing gear retracting and releasing hydraulic control circuit, the front landing gear unlocking hydraulic control circuit, the rear landing gear unlocking hydraulic control circuit, the rear landing gear retracting and releasing hydraulic control circuit and the front landing gear retracting and releasing hydraulic control circuit are connected with a bidirectional constant displacement pump, and the front landing gear unlocking hydraulic control circuit, the rear landing gear unlocking hydraulic control circuit, the rear landing gear retracting and releasing hydraulic control circuit and the front landing gear retracting and releasing hydraulic control circuit are provided with electromagnetic reversing valves. The opening and closing of the air car landing gear retracting and locking are controlled through the forward and reverse rotation of the bidirectional constant displacement pump and the on-off of the electromagnetic reversing valve, the hydraulic system has simple structure and is easy to integrate, the expensive electro-hydraulic servo valve is abandoned, the weight is light, and the anti-pollution ability is strong.

Description

Technical Field

[0001] This invention belongs to the field of landing gear retraction and extension control technology, specifically to a hydraulic system for the retraction, extension, and unlocking of landing gear for a flying car. Background Technology

[0002] With current urban traffic congestion, enabling cars to take off and fully utilize low-altitude airspace has become an urgent problem to solve. With the large-scale commercialization of new energy vehicles and drones, flying cars are gradually entering the public eye. As a new type of transportation tool for urban air mobility and future travel, flying cars are receiving increasing attention from the automotive and aviation industries, becoming an important development trend of cross-industry integration of automotive and aviation technologies. The types of flying cars on the market mainly include fixed-wing, helicopter, and rotorcraft. Fixed-wing flying cars combine traditional cars with fixed-wing aircraft. Typically, when a flying car is in flight mode, its fixed wings, folded and mounted on the vehicle surface, unfold, transforming the car from a traditional car into a fixed-wing aircraft to achieve flight. However, fixed-wing flying cars have a significant drawback: they require a sufficiently long runway for takeoff. Helicopter flying cars combine traditional cars with helicopters. Unlike fixed-wing flying cars, which require a runway, helicopter flying cars use an engine to drive a rotor to generate lift and complete takeoff, i.e., vertical takeoff and landing. Compared to helicopter-type flying cars, rotorcraft-type flying cars rely on a tail propeller to propel themselves forward. During the forward movement, the airflow causes the rotor to rotate, generating lift, which can avoid the stall problem caused by engine failure in the air.

[0003] As an urban air transportation tool, flying cars must meet urban noise and emission control requirements and should have the basic characteristics of vertical take-off and landing, low noise, and new energy. Therefore, flying cars are different from ordinary aircraft. The performance of flying cars mainly involves key technologies such as lightweighting, battery power, and control systems.

[0004] Flying cars are equipped with landing gear, which primarily supports their own weight, transmits ground loads, absorbs landing energy, and controls landing overload. It enables ground maneuvers such as takeoff, taxiing, and parking. Simultaneously, it prevents resonance with the ground and wobbling during taxiing and runway maneuvers, making it a crucial component for taxiing and vertical takeoff and landing. The landing gear retraction and extension system, a vital part of the flying car, ensures that the landing gear is unlocked before being lowered and retracted before being locked. Its performance directly impacts the flying car's safety and maneuverability. The landing gear control system mainly includes two types: electric and hydraulic. Electric systems are easily limited by the weight-to-power ratio and are costly, especially when there are multiple actuators, resulting in significant weight. Hydraulic systems, on the other hand, are more technologically mature, lower in cost, and allow actuators to share a power source. Because flying cars have stricter requirements for the safety, reliability, weight, and power-to-weight ratio of the landing gear system, the landing gear retraction system of flying cars is driven by a hydraulic transmission system, which is lightweight, small in size, has high power density, and fast response.

[0005] Currently, most helicopter landing gear retraction and extension hydraulic systems adopt valve-controlled throttling speed-regulating servo hydraulic systems. By controlling the opening of the throttling valve, the flow rate and pressure of the system are controlled to realize the retraction and extension of the landing gear. This system has high requirements for hydraulic precision, complex structure, high cost, and cannot avoid the system temperature rise and heat dissipation difficulties caused by throttling and overflow losses, resulting in low efficiency. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a hydraulic system for the retraction, extension, and unlocking of the landing gear of a flying car. The system controls the retraction, extension, and locking of the landing gear and the opening and closing of the lock by using a bidirectional quantitative pump in both forward and reverse directions in conjunction with the on / off state of an electromagnetic reversing valve. This hydraulic system has a simple structure and is easy to integrate, abandons the expensive electro-hydraulic servo valve, is lightweight, and has strong anti-pollution capabilities.

[0007] The technical solution adopted in this invention is as follows:

[0008] A hydraulic system for the retraction and unlocking of landing gear in a flying car includes a front landing gear unlocking hydraulic control circuit, a rear landing gear unlocking hydraulic control circuit, a rear landing gear retraction and extension hydraulic control circuit, and a front landing gear retraction and extension hydraulic control circuit. Each of these circuits is connected to a bidirectional quantitative pump for controlling the forward or reverse movement of hydraulic oil. Each of these circuits is equipped with an electromagnetic directional valve for controlling the on / off state of the hydraulic circuit.

[0009] Preferably, the bidirectional quantitative pump is connected in parallel with a directional check valve, the directional check valve is connected to an unloading circuit, and the unloading circuit is connected to an oil tank.

[0010] Preferably, the unloading circuit includes an overflow valve and a first solenoid directional valve connected in parallel with the overflow valve, wherein the first solenoid directional valve is normally closed.

[0011] Preferably, the oil tank is connected to at least two check valves, which are connected to the forward and reverse outlet pipes of the bidirectional metering pump via pipelines, and the check valves are normally open.

[0012] Preferably, both the forward and reverse outlet pipes of the bidirectional metering pump are connected to filters.

[0013] Preferably, the front landing gear unlocking hydraulic control circuit and the rear landing gear unlocking hydraulic control circuit are equipped with pin actuators, and the rear landing gear retraction hydraulic control circuit and the front landing gear retraction hydraulic control circuit are equipped with landing gear actuators.

[0014] Preferably, the pin actuator and landing gear actuator include a piston cylinder and a piston rod that is movably sealed in the piston cylinder, and the rod chamber of the piston cylinder is connected to an electromagnetic reversing valve through a pipe.

[0015] Preferably, the pin actuator is provided with a spring, and the spring is located in the rodless chamber of the piston cylinder.

[0016] Preferably, a displacement sensor is provided in front of the piston rod.

[0017] Preferably, four pin actuators and landing gear actuators are provided.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0019] The landing gear retraction and locking of the flying car are controlled by the forward and reverse rotation of a bidirectional quantitative pump in conjunction with the on / off state of an electromagnetic reversing valve. This hydraulic system has a simple structure and is easy to integrate. It abandons the expensive electro-hydraulic servo valve, is lightweight, and has strong anti-pollution capabilities. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart provided for an embodiment of the present invention;

[0022] Figure descriptions: 1-Bidirectional quantitative pump; 2-Directional check valve; 3-Unloading circuit; 4-Fuel tank; 5-Filter; 6-Front landing gear unlocking hydraulic control circuit; 7-Pin actuator; 8-Rear landing gear unlocking hydraulic control circuit; 9-Fifth solenoid directional valve; 10-Rear landing gear retraction / extension hydraulic control circuit; 11-Front landing gear retraction / extension hydraulic control circuit; 12-Landing gear actuator; 13-Second solenoid directional valve; 14-Check valve; 15-Relief valve; 16-Third solenoid directional valve; 17-First solenoid directional valve; 18-Fourth solenoid directional valve. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] In the description of this invention, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, they are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0026] The following is combined with Figure 1 The present invention will be described in detail below.

[0027] Example

[0028] A hydraulic system for the retraction and unlocking of landing gear on a flying car, such as... Figure 1As shown, the system includes a front landing gear unlocking hydraulic control circuit 6, a rear landing gear unlocking hydraulic control circuit 8, a rear landing gear retraction hydraulic control circuit 10, and a front landing gear retraction hydraulic control circuit 11. Each of these circuits is connected to a bidirectional quantitative pump 1 for controlling the forward or reverse movement of hydraulic oil. Each of these circuits is equipped with an electromagnetic directional valve for controlling the on / off state of the hydraulic circuit. The front landing gear unlocking hydraulic control circuit 6 and the rear landing gear unlocking hydraulic control circuit 8 are equipped with pin actuators 7, and the rear landing gear retraction and extension hydraulic control circuit 10 and the front landing gear retraction and extension hydraulic control circuit 11 are equipped with landing gear actuators 12. The bidirectional quantitative pump 1 drives the pin actuators 7 and landing gear actuators 12 to move through hydraulic oil, thereby controlling the retraction and extension of the landing gear and the opening and closing of the locks.

[0029] A bidirectional fixed displacement pump 1 is connected in parallel with a directional check valve 2. The directional check valve 2 is connected to an unloading circuit 3, and the unloading circuit 3 is connected to an oil tank 4. The high-pressure hydraulic oil driven by the bidirectional fixed displacement pump 1 enters the unloading circuit 3 after passing through the directional check valve 2, and finally flows into the oil tank 4. This effectively reduces the pulsating impact of the bidirectional fixed displacement pump 1, reduces power loss, and extends the service life of the bidirectional fixed displacement pump 1.

[0030] The unloading circuit 3 includes a relief valve 15 and a first solenoid directional valve 17 connected in parallel with the relief valve 15. The first solenoid directional valve 17 is normally closed. When the bidirectional fixed displacement pump 1 starts working, the first solenoid directional valve 17 is not energized, and the high-pressure hydraulic oil in the bidirectional fixed displacement pump 1 passes through the relief valve 15 to complete the pressure relief. After the bidirectional fixed displacement pump 1 stops working, the first solenoid directional valve 17 is energized (so that hydraulic oil can pass through it after energization), and the high-pressure hydraulic oil in the pin actuator 7 and the landing gear actuator 12 passes through the first solenoid directional valve 17 to complete the pressure relief. It can also remove the air in the hydraulic circuit to ensure the accuracy of the hydraulic transmission.

[0031] The oil tank 4 is connected to at least two check valves 14. The check valves 14 are connected to the forward and reverse outlet pipes of the bidirectional quantitative pump 1 through pipelines. The check valves 14 are normally open. By setting the normally open check valves 14, when the bidirectional quantitative pump 1 is working, the high-pressure hydraulic oil generated will push the valve core of the check valves 14 to move and close the check valves 14. During the process of closing the check valves 14, the pulsating impact of the bidirectional quantitative pump 1 can be further reduced.

[0032] Both the forward and reverse outlet pipes of the bidirectional fixed displacement pump 1 are connected to filters 5. Filters 5 filter the hydraulic oil output by the bidirectional fixed displacement pump 1 to ensure the cleanliness of the hydraulic oil and prevent the control of the landing gear and lock from being affected.

[0033] like Figure 1 As shown, the pin actuator 7 and the landing gear actuator 12 include a piston cylinder and a piston rod that is movably sealed within the piston cylinder. The rod chamber of the piston cylinder is connected to an electromagnetic directional valve via a pipe. The piston rod moves within the piston cylinder, moving the pin or the landing gear to achieve position control of the pin and the landing gear.

[0034] The pin actuator 7 is equipped with a spring, which is located in the rodless chamber of the piston cylinder. The spring keeps the piston rod in the extended state, that is, keeps the pin in the locked state, preventing the landing gear from being unlocked due to the depressurization of high-pressure hydraulic oil through the first solenoid directional valve 17, which would affect flight safety.

[0035] A displacement sensor is installed in front of the piston rod. When the piston rod extends to a designated position (mainly two positions, corresponding to the retraction and extension of the landing gear and the opening and closing of the pins), the displacement sensor detects the piston rod and transmits the signal to the controller, which then controls other related mechanisms to begin operating.

[0036] There are four pin actuators 7 and landing gear actuators 12. The landing gear of the flying car mainly includes four wheels. Each wheel is equipped with a pin actuator 7 and a landing gear actuator 12 to control the extension, retraction and locking of the wheel.

[0037] The solenoid directional valve in the front landing gear retraction hydraulic control circuit 11 is the second solenoid directional valve 13, the solenoid directional valve in the rear landing gear retraction hydraulic control circuit 10 is the third solenoid directional valve 16, the solenoid directional valve in the front landing gear unlocking hydraulic control circuit 6 is the fourth solenoid directional valve 18, and the solenoid directional valve in the rear landing gear unlocking hydraulic control circuit 8 is the fifth solenoid directional valve 9.

[0038] Control Process: When the flight car control system releases the command to lower the front landing gear, the bidirectional quantitative pump 1 rotates forward, and at the same time, the fourth solenoid directional valve 18 is energized. Hydraulic oil is output from port A of the bidirectional quantitative pump 1. Part of the hydraulic oil enters the directional check valve 2 from port C, then flows out from port E into the unloading circuit 3 and is unloaded through the overflow valve 15, finally flowing into the oil tank 4. The other part of the hydraulic oil output from port A continues to move, first contacting the check valve 14 to force it to close, and then passing through the filter 5 into the front landing gear unlocking hydraulic control circuit 6. The hydraulic oil enters the rod chamber of the pin actuator 7 through the fourth solenoid directional valve 18, pushing the piston rod to move into the piston cylinder, thereby opening the pin and releasing the front landing gear lock. After the displacement sensor detects that the piston rod has moved to the designated position, the controller controls the second solenoid directional valve 13 to be energized and the fourth solenoid directional valve 18 to be de-energized. Hydraulic oil enters the landing gear actuator 12 from the rodless chamber and pushes the piston rod out of the piston cylinder, thereby releasing the nose landing gear. When the displacement sensor detects that the piston rod has moved to the designated position, the controller controls the second solenoid directional valve 13 to be de-energized, the fourth solenoid directional valve 18 to be energized, and the bidirectional quantitative pump 1 to be reversed. Hydraulic oil is output from port B. Part of the hydraulic oil enters the directional check valve 2 from port D and pushes the valve core to move towards port C. Then it flows out from port E and enters the unloading circuit 3 for unloading. Another portion of the hydraulic oil output from port B continues to move, first contacting check valve 14 and forcing it to close, then passing through filter 5 and entering the front landing gear unlocking hydraulic control circuit 6. The hydraulic oil pushes the piston rod out of the piston cylinder. When the displacement sensor detects that the piston rod has moved to the designated position, the controller controls the fourth solenoid directional valve 18 to be de-energized and shuts down the bidirectional quantitative pump 1. The first solenoid directional valve 17 is then energized again to discharge the high-pressure hydraulic oil and gas in the hydraulic circuit. After that, the first solenoid directional valve 17 is de-energized, realizing the unlocking, lowering, and locking actions of the front landing gear structure of the flying car.

[0039] The process of lowering the rear landing gear of the flying car is roughly the same as that of lowering the front landing gear; it only requires controlling the on / off state of the third solenoid directional valve 16 and the fifth solenoid directional valve 9.

[0040] When the flight vehicle control system releases the command to retract the nose landing gear, the bidirectional metering pump 1 rotates forward, and simultaneously, the fourth solenoid directional valve 18 is energized. Hydraulic oil controls the pin actuator 7 in the nose landing gear unlocking hydraulic control circuit 6 to actuate, causing the piston rod of the pin actuator 7 to retract into the piston cylinder, releasing the nose landing gear from its lock. The controller then energizes the second solenoid directional valve 13, de-energizes the fourth solenoid directional valve 18, and reverses the bidirectional metering pump 1. Hydraulic oil enters the landing gear actuator 12 in the nose landing gear retraction / extension hydraulic control circuit 11, and the hydraulic oil... The piston rod is pushed back, thereby retracting the front landing gear; the controller then de-energizes the second solenoid directional valve 13 and energizes the fourth solenoid directional valve 18, the bidirectional metering pump 1 continues to reverse, the piston rod of the pin actuator 7 is pushed out, realizing the locking operation, and finally the fourth solenoid directional valve 18 is de-energized and the bidirectional metering pump 1 is shut off, the first solenoid directional valve 17 is energized again, the high-pressure hydraulic oil and gas in the hydraulic circuit are discharged, and then the first solenoid directional valve 17 is de-energized, realizing the unlocking, retraction and locking actions of the front landing gear structure of the flying car.

[0041] The process of retracting the rear landing gear of the flying car is roughly the same as that of retracting the front landing gear; it only requires controlling the on / off state of the third electromagnetic reversing valve 16 and the fifth electromagnetic reversing valve 9.

[0042] The above control process is automatically operated by the controller, realizing intelligent operation.

[0043] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hydraulic system for the retraction and unlocking of landing gear for a flying car, comprising a front landing gear unlocking hydraulic control circuit (6), a rear landing gear unlocking hydraulic control circuit (8), a rear landing gear retraction and extension hydraulic control circuit (10), and a front landing gear retraction and extension hydraulic control circuit (11), characterized in that, The front landing gear unlocking hydraulic control circuit (6), the rear landing gear unlocking hydraulic control circuit (8), the rear landing gear retraction hydraulic control circuit (10), and the front landing gear retraction hydraulic control circuit (11) are connected to a bidirectional quantitative pump (1) for controlling the forward or reverse movement of hydraulic oil. Each of these circuits is equipped with an electromagnetic directional valve for controlling the on / off state of the hydraulic circuit. The bidirectional quantitative pump (1) is connected in parallel to a directional check valve (2), which is connected to an unloading circuit. 3) The unloading circuit (3) is connected to the oil tank (4). The unloading circuit (3) includes an overflow valve (15) and a first electromagnetic directional valve (17) connected in parallel with the overflow valve (15). The first electromagnetic directional valve (17) is normally closed. When the bidirectional quantitative pump (1) starts working, the first electromagnetic directional valve (17) is not energized, and the high-pressure hydraulic oil in the bidirectional quantitative pump (1) passes through the overflow valve (15). After the bidirectional quantitative pump (1) stops working, the first electromagnetic directional valve (17) is energized, and the high-pressure hydraulic oil passes through the first electromagnetic directional valve (17) and removes the gas in the hydraulic circuit.

2. The hydraulic system for retracting and unlocking the landing gear of a flying car according to claim 1, characterized in that, The oil tank (4) is connected to at least two check valves (14). The check valves (14) are connected to the forward outlet pipe and the reverse outlet pipe of the bidirectional metering pump (1) through pipelines. The check valves (14) are normally open.

3. The hydraulic system for retracting and unlocking the landing gear of a flying car according to claim 1, characterized in that, The bidirectional metering pump (1) is equipped with filters (5) on both its forward and reverse outlet pipes.

4. The hydraulic system for retracting and unlocking the landing gear of a flying car according to claim 1, characterized in that, The front landing gear unlocking hydraulic control circuit (6) and the rear landing gear unlocking hydraulic control circuit (8) are equipped with pin actuators (7), and the rear landing gear retraction hydraulic control circuit (10) and the front landing gear retraction hydraulic control circuit (11) are equipped with landing gear actuators (12).

5. The hydraulic system for retracting and unlocking the landing gear of a flying car according to claim 4, characterized in that, The pin actuator (7) and landing gear actuator (12) include a piston cylinder and a piston rod that is movably sealed in the piston cylinder. The rod chamber of the piston cylinder is connected to an electromagnetic reversing valve through a pipe.

6. The hydraulic system for retracting and unlocking the landing gear of a flying car according to claim 5, characterized in that, The pin actuator (7) is equipped with a spring, and the spring is located in the rodless chamber of the piston cylinder.

7. The hydraulic system for retracting and unlocking the landing gear of a flying car according to claim 5, characterized in that, A displacement sensor is installed in front of the piston rod.

8. The hydraulic system for retracting and unlocking the landing gear of a flying car according to claim 4, characterized in that, The pin actuator (7) and landing gear actuator (12) are provided in four parts.

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