Correctable skid landing gear for helicopter takeoffs and landings at high altitudes and its control method

Abstract

This invention provides a skid-type landing gear for helicopter takeoff and landing at high altitudes and its control method. The landing gear includes a strut, a brushless DC motor, a universal joint, a worm gear mechanism, a main skid, and a skid for correction. The main skid and the skid for correction can effectively adapt to soft and undulating surfaces such as snow, sand, and swamp at high altitudes. The brushless DC motor, through the force transmission of the universal joint and the worm gear mechanism, ensures that one skid for correction contacts the ground while the other skid remains initially off the ground. The difference in ground friction between the two sides generates a yaw torque on the aircraft, which is the correction torque. This effectively solves the problem of difficult correction during takeoff and landing for helicopters equipped with skid-type landing gear. Through the self-locking principle of the worm gear mechanism, the motor is protected from counter-torque and structural damage when the skid for correction is subjected to a large impact force from an uneven road surface.

Description

Technical Field

[0001] This invention relates to the field of skid-type landing gear correction, specifically a skid-type landing gear with correctable deviation for helicopter take-off and landing at high altitudes and its control method. Background Technology

[0002] High-altitude helicopter takeoffs and landings typically refer to helicopters performing takeoff and landing missions at high-altitude airports. The greatest challenge facing high-altitude helicopter takeoffs and landings stems from the severe impact of the unique natural environment on helicopter takeoff, landing, and low-altitude flight. The unique characteristics of the high-altitude environment include high altitude, low atmospheric pressure, low air density, and complex terrain. This unique natural environment presents helicopters with two main difficulties during high-altitude takeoffs and landings:

[0003] First, the available engine power is significantly reduced. The higher the altitude, the lower the air density, resulting in lower rotor power and less lift. When helicopters take off in high-altitude areas, measures must be taken to reduce takeoff weight, including reducing fuel and payload, which significantly decreases their ability to perform missions in high-altitude regions. In modern times, high-altitude helicopters often employ a taxiing takeoff and landing method, increasing the initial speed to increase engine air intake, thus addressing the problem of insufficient power caused by the thin air at high altitudes.

[0004] Secondly, the complex terrain of high-altitude mountainous areas means that helicopters often take off and land on snow, sand, or swampy surfaces. These surfaces are soft and undulating, posing a significant threat to helicopter safety. However, most existing high-altitude helicopters use tricycle landing gear, which requires a flat and firm runway for takeoff and landing. Helicopters experience reduced maneuverability at high altitudes, increased acceleration and deceleration distances, and larger turning radii. This necessitates longer and wider runways for tricycle helicopters, which is clearly difficult to implement in high-altitude environments. Furthermore, the frequent occurrence of strong winds, sandstorms, blizzards, and dense fog at high altitudes makes accurate landings extremely challenging, severely hindering helicopter takeoff and landing and posing a significant safety threat.

[0005] Current domestic patents regarding corrective skid landing gear primarily focus on fixed-wing aircraft. Chinese invention patent CN109835471A, entitled "A Corrective Skid Landing Device," proposes a landing device with landing skids and corrective skids, which uses a hydraulic actuator to lower and retract the corrective skids to achieve directional correction. However, the performance of the hydraulic actuator is significantly affected by ambient temperature; in high-altitude, low-temperature environments, its performance may deteriorate or even malfunction. Furthermore, the hydraulic actuator has a complex structure and is relatively heavy, making it unsuitable for helicopters requiring minimal weight for high-altitude takeoffs and landings.

[0006] Chinese invention patent CN109774926A, titled "Hypersonic Aircraft Wheel-Skid Combined Takeoff and Landing Device," proposes a takeoff and landing device that uses a combination of wheels and skids for correction. It achieves directional correction by retracting the skids and allowing the wheels to intermittently contact the ground. Chinese invention patent CN111516862A, titled "A Corrective Skid-Type Landing Device with Auxiliary Wheels Suitable for Confined Spaces," proposes a takeoff and landing device that uses a combination of skids and multiple auxiliary wheels for correction. It achieves directional correction through the lateral force provided by the intermittent contact of the auxiliary wheels with the ground. However, both of these patents, due to the small contact area between the wheels and the road surface, generate high pressure, making them unsuitable for soft, high-altitude surfaces. Furthermore, the large weight of the wheels cannot meet the lightweight requirements for helicopter takeoff and landing at high altitudes.

[0007] Chinese invention patent CN111498093A, entitled "A Skid-Type Landing Gear Correction System," proposes a landing device that uses a combination of skids and drag pins for correction. It achieves directional correction by inserting drag pins into the ground to increase drag, offering the advantage of lightweight construction. However, when the drag pins are subjected to significant impact forces caused by ground undulations, the motor experiences substantial counter-torque, potentially leading to structural damage. Furthermore, the interleaved shaft helical gear mechanism has poor load-bearing capacity and is susceptible to structural damage from ground impacts. This results in poor safety during helicopter taxiing takeoffs and landings, making it unsuitable for high-altitude takeoffs and landings. Summary of the Invention

[0008] To address the problems of existing technologies, this invention provides a skid-type landing gear and its control method specifically designed for take-off and landing of helicopters on soft and undulating landing surfaces such as snow, sand, and swamp. This design has lower requirements for take-off and landing sites, wider applicability, and stronger ability to cope with extreme environments.

[0009] This invention provides a skid-type landing gear for helicopter takeoff and landing at high altitudes, comprising a strut, a brushless DC motor, a universal joint, a worm gear mechanism, a main skid, and a correction skid. The strut and the main skid are connected via a revolute joint, and the main skid has rotational freedom about the strut. A brushless DC motor is installed inside the strut and is connected to the worm gear mechanism via the universal joint. The worm gear mechanism includes a worm wheel and a worm that mesh inside the main skid. The upper end of the worm is coaxially fixed to the lower rotating shaft of the universal joint, and the bottom of the worm is connected to the bottom surface of the main skid via a revolute joint. The brushless DC motor drives the worm to rotate around its own axis via the universal joint. The worm wheel is fixed inside the main skid via a fixed shaft and rotates around the fixed shaft under the drive of the worm. The correction skid is fixed to the worm wheel and is driven by the rotation of the worm wheel.

[0010] Further improvements include a self-locking worm gear mechanism where the worm wheel and worm form a self-locking worm gear mechanism. In this mechanism, when the lead angle of the worm is less than the equivalent friction angle between the meshing teeth, the mechanism exhibits self-locking properties, achieving reverse self-locking, meaning only the worm can drive the worm wheel. When the alignment skid is subjected to a large ground impact force, its reverse self-locking property prevents the motor from experiencing reverse torque and causing structural damage, thus providing safety protection for the motor.

[0011] In a further improvement, the universal joint mechanism includes an active universal joint fork and a driven universal joint fork connected by a cross shaft. The active universal joint fork is connected to a brushless DC motor, and the driven universal joint fork is connected to a worm gear.

[0012] In a further improvement, the coefficient of friction between the main skid and the ground is less than that between the corrective skid and the ground. After the corrective skid on one side of the main lift is lowered and exerts pressure on the ground, the frictional force generated on that side is greater than the frictional force on the other side of the main lift, thereby generating a corrective torque to correct the helicopter's taxiing.

[0013] Further improvements include a long configuration for the correction skid, which effectively increases the touchdown time and thus improves the helicopter's correction performance.

[0014] This invention also provides a control method for a skid-type landing gear for helicopter take-off and landing at high altitudes, comprising the following steps: when the helicopter deviates from the center of the runway during take-off and landing, the brushless DC motor transmits force through the universal joint and worm gear mechanism to make one side of the skid-type landing gear touch the ground, while the other side of the skid-type landing gear remains in its initial off-ground state. The yaw torque generated by the difference in ground friction on both sides on the aircraft body is the corrective torque, which makes the helicopter return to the normal take-off and landing trajectory; when differential correction is not performed, the skid-type landing gear on both sides does not have a braking effect when it is off the ground.

[0015] Further improvements include: if the helicopter veers to the left while taxiing, the right-side corrective skid is lowered to touch the ground, while the left-side corrective skid is retracted and lifted off the ground, thus applying a corrective torque to the right; if the helicopter veers to the right while taxiing, the left-side corrective skid is lowered to touch the ground, while the right-side corrective skid is retracted and lifted off the ground, thus applying a corrective torque to the left.

[0016] The beneficial effects of this invention are as follows:

[0017] 1. During ground gliding, the main skid and the correction skid have a large contact area with the ground, which can adapt well to soft road surfaces and avoid structural damage caused by excessive local pressure.

[0018] 2. When the road surface is uneven, the landing gear may partially lift off the ground. The long configuration of the correction skid can effectively increase the touchdown time, thereby improving the helicopter's correction effect.

[0019] 3. Self-locking worm gear mechanism. When the lead angle of the worm is less than the equivalent friction angle between the meshing gear teeth, the mechanism has self-locking properties and can achieve reverse self-locking, meaning that only the worm can drive the worm wheel, and the worm wheel cannot drive the worm. When the alignment skid is subjected to a large ground impact force, its reverse self-locking property can prevent the motor from being subjected to reverse torque and causing structural damage, thus providing safety protection for the motor.

[0020] 4. The meshing tooth surfaces of the worm gear and worm are in line contact, and its load-bearing capacity is much higher than that of the staggered shaft helical gear mechanism.

[0021] 5. Compared to wheeled landing gear, this skid-type landing gear occupies less space and is lighter; the transmission structure is simple and reliable, and the maintenance cost is low. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of this patent;

[0024] Figure 2 This is a schematic diagram of the brushless motor, universal joint, and worm gear working together in this patent.

[0025] Figure 3 This is a schematic diagram of the universal joint structure of this patent;

[0026] Figure 4 This is a schematic diagram of the worm gear structure of this patent.

[0027] In the diagram, 1-support column, 2-brushless DC motor, 3-universal joint, 4-active universal joint fork, 5-driven universal joint fork, 6-cross shaft, 7-worm gear, 8-worm wheel, 9-main skid, 10-correction skid. Detailed Implementation

[0028] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figure 1As shown, the present invention discloses a skid-type landing gear for helicopter take-off and landing at high altitudes, comprising a strut 1, a brushless DC motor 2, a universal joint 3, a worm gear mechanism, a main skid 9, and a skid 10 for correcting the trajectory.

[0030] The support column 1 is connected to the main skid 9, which has one degree of rotational freedom and can adapt to the undulations of the road surface when sliding on the ground.

[0031] The brushless DC motor 2 is fixed on the support column 1, and its output shaft and the upper rotating shaft of the universal joint are coaxially fixed.

[0032] The upper end of the universal joint 3 is coaxially connected to the support column 1, and has only one degree of freedom of rotation along the axis. This rotational motion is driven by a brushless DC motor.

[0033] The worm gear mechanism includes a worm wheel 8 and a worm 7 that mesh with each other. Both the worm wheel and the worm are set inside the main skid. The upper end of the worm is coaxially fixed to the lower end of the universal joint's rotating shaft, and the lower end is connected to the bottom surface of the main skid by a rotating pair, so that the worm can rotate freely around its axis. The worm wheel is fixed by a long shaft passing through the center of the circle and rotates along the fixed shaft under the drive of the worm.

[0034] The correction skid is fixedly connected to the worm gear and is driven to move by the rotation of the worm gear.

[0035] like Figure 2 As shown, after receiving the actuation command from the control system, the brushless DC motor drives the universal joint to rotate, which in turn drives the worm gear to rotate. The worm gear then drives the worm wheel to rotate, which in turn causes the correction skid, which is fixed to the worm wheel, to either lower to the ground or lift off the ground.

[0036] The coefficient of friction between the main skid and the ground is less than that between the corrective skid and the ground. When the corrective skid on one side of the main lift is lowered and exerts pressure on the ground, the friction force generated on that side is greater than the friction force on the other side of the main lift, thereby generating a corrective torque to correct the helicopter's taxiing.

[0037] If the helicopter veers to the left while taxiing, the right-side corrective skid is lowered to the ground while the left-side corrective skid is retracted and lifted off the ground, applying a corrective torque to the right. Conversely, if the helicopter veers to the right while taxiing, the left-side corrective skid is lowered to the ground while the right-side corrective skid is retracted and lifted off the ground, applying a corrective torque to the left. This process achieves directional correction for the helicopter during ground taxiing.

[0038] like Figure 3 As shown, the universal joint consists of an active universal joint fork 4, a driven universal joint fork 5, and a cross shaft 6. When the main skid rotates relative to the support column, the universal joint can ensure that the torque generated by the motor is stably transmitted to the correction skid.

[0039] like Figure 4As shown, the worm gear mechanism consists of a worm wheel and a worm meshing with each other, forming a self-locking worm mechanism. When the lead angle of the worm is less than the equivalent friction angle between the meshing teeth, the mechanism exhibits self-locking properties, enabling reverse self-locking. This means that only the worm can drive the worm wheel, not the other way around. When the steering skid is subjected to a large ground impact, its reverse self-locking property prevents the motor from suffering massive counter-torque and structural damage, thus providing safety protection for the motor. Furthermore, the meshing tooth surfaces of the worm gear mechanism are in line contact, resulting in a significantly higher load-bearing capacity than that of a staggered-axis helical gear mechanism, effectively reducing structural damage to the meshing teeth caused by ground impact. This improves the reliability of the steering control system and the safety of helicopter takeoff and landing.

[0040] The working principle of the skid-type landing gear correction device is as follows:

[0041] When the helicopter deviates from the runway center during takeoff, the control system transmits commands to the brushless DC motor. The brushless DC motor, through a universal joint and worm gear mechanism, causes one side of the correction skid to contact the ground, while the other side remains initially off the ground. The difference in ground friction between the two sides generates a yawing torque on the aircraft, which is the correction torque, returning the helicopter to its normal takeoff trajectory. Without differential correction, the two correction skids do not provide braking when off the ground.

[0042] It should be specifically mentioned here that the self-locking principle of the worm gear mechanism prevents external impact forces from generating counter-torque on the motor, greatly protecting the motor from structural damage. Simultaneously, the meshing tooth surfaces of the worm gear mechanism have line contact, and its load-bearing capacity is far higher than that of the staggered-axis helical gear mechanism, effectively reducing structural damage to the meshing teeth caused by ground impact forces. This improves the reliability of this steering correction control system and the safety of helicopter taxiing, takeoff, and landing processes.

[0043] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, for the device embodiments, the above descriptions are merely preferred embodiments of the present invention. Since they are fundamentally similar to the method embodiments, the descriptions are relatively simple, and relevant parts can be referred to the descriptions of the method embodiments. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention, without departing from the principle of the present invention, should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A skid-type landing gear with correctable yaw rate for helicopter take-off and landing at high altitudes, characterized in that: The system includes a support column, a brushless DC motor, a universal joint, a worm gear mechanism, a main skid, and a correction skid. The support column and the main skid are connected via a revolute joint. The main skid has rotational freedom around the support column. The brushless DC motor is installed inside the support column and is connected to the worm gear mechanism via the universal joint. The worm gear mechanism includes a worm wheel and a worm that mesh inside the main skid. The upper end of the worm is coaxially fixed to the lower rotating shaft of the universal joint, and the bottom of the worm is connected to the bottom surface of the main skid via a revolute joint. The brushless DC motor drives the worm to rotate around its own axis via the universal joint. The worm wheel is fixed inside the main skid via a fixed shaft and rotates around the fixed shaft under the drive of the worm. The correction skid is fixed to the worm wheel and is driven by the rotation of the worm wheel.

2. The skid-type landing gear for helicopter high-altitude takeoff and landing as described in claim 1, characterized in that: In a worm gear mechanism, the worm wheel and worm form a self-locking worm gear mechanism.

3. The skid-type landing gear for helicopter high-altitude takeoff and landing as described in claim 2, characterized in that: In the self-locking worm gear mechanism, when the lead angle of the worm is less than the equivalent friction angle between the meshing gear teeth, the mechanism has self-locking properties and achieves reverse self-locking, that is, only the worm can drive the worm wheel.

4. The correctable skid landing gear for helicopter take-off and landing at high altitudes according to claim 1 or 2, characterized in that: The universal joint mechanism includes a driving universal joint fork and a driven universal joint fork connected by a cross shaft. The driving universal joint fork is connected to a brushless DC motor, and the driven universal joint fork is connected to a worm gear.

5. The skid-type landing gear for helicopter high-altitude takeoff and landing as described in claim 1, characterized in that: The coefficient of friction between the main skid and the ground is less than the coefficient of friction between the correction skid and the ground.

6. The skid-type landing gear for helicopter high-altitude takeoff and landing as described in claim 1, characterized in that: The correction skid has a long configuration.

7. A control method for a skid-mounted landing gear for helicopter high-altitude takeoff and landing, employing the skid-mounted landing gear for helicopter high-altitude takeoff and landing as described in claim 1, characterized in that... Includes the following steps: When the helicopter deviates from the center of the runway during takeoff, the brushless DC motor transmits force through the universal joint and worm gear mechanism to make one side of the correction skid touch the ground, while the other side of the correction skid remains in its initial off-ground state. The yaw torque generated by the difference in ground friction on both sides is the correction torque, which brings the helicopter back to the normal takeoff trajectory. When differential correction is not performed, the two correction skids do not have a braking effect when they are off the ground.

8. The control method for a skid-type landing gear for helicopter high-altitude takeoff and landing according to claim 7, characterized in that: If the helicopter veers to the left while taxiing, the right-side skid is lowered to touch the ground, while the left-side skid is retracted and lifted off the ground, thus applying a rightward corrective torque to the helicopter. If the helicopter veers to the right while taxiing, the left-side skid is lowered to touch the ground, while the right-side skid is retracted and lifted off the ground, thus applying a leftward corrective torque to the helicopter.

Images