Rotor periodic diameter-changing device, control method, and helicopter rotor blade device

Abstract

The present invention discloses a rotor periodic diameter-changing device, a control method and a helicopter rotor blade device. It comprises a crank main shaft arranged at the center of the rotor, on which a connecting disk is fixed; the connecting disk is connected to the sliding shaft via a connecting rod, and the distal end of the sliding shaft is fixedly connected to the rotor blade and can slide axially inside the hub; a hub gear is provided at the outer bottom of the hub and is engaged with a power gear driven by an engine to realize the driven rotation of the rotor system. During the rotation of the rotor, the crank drives the connecting rod to move periodically, driving the sliding shaft to move back and forth, thereby driving the rotation radius of the blade to change periodically. The rotation radius of the forward blade of the present invention is reduced, reducing its linear velocity; while the radius of the backward blade is increased, increasing its linear velocity, improving the uneven lift distribution problem of the forward and backward blades of the rotor, and significantly improving the maximum flight speed of the helicopter, improving the flight stability and efficiency at high speed, and is particularly suitable for high-speed helicopters, compound rotorcraft and other fields.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation systems, and in particular to a rotor periodic diameter-changing device, a control method, and a helicopter rotor blade device. Background Art

[0002] The maximum forward flight speed of mainstream helicopters is around 300 km / h. Generally speaking, the normal cruising speed is between 200 and 240 km / h, usually not exceeding 280 km / h. Compared with the 300-800 km / h flight speeds of fixed-wing aircraft, helicopter flight speeds are not outstanding. The main reason for this phenomenon is that the flight speed of helicopters is severely limited by the linear speed of the rotor blade tips. A helicopter's rotors need to rotate at high speeds to generate lift. Even when the helicopter is hovering, the linear speed of the rotor blade tips must reach 400-600 km / h to generate sufficient lift. If a helicopter flies forward, even at speeds as low as 300 km / h, the oncoming airflow velocity adds to the linear velocity of the forward-spinning rotor blades (forward blades), easily pushing the blade tips into the transonic range (greater than Mach 0.75), significantly reducing efficiency and causing severe vibration. As the rotor rotates, the forward blades turn rearward, where their linear velocity subtracts from the airflow velocity, resulting in a sharp decrease in blade lift. This creates an imbalance in the lift generated by the rotor blades during each rotation, making control more difficult. Furthermore, as forward flight speed increases, the airflow velocity over the rotor blades fluctuates more dramatically, causing significant vibration and noise in high-speed forward flight, and in even more serious cases, damage to the aircraft structure. These drawbacks severely restrict further increases in forward flight speed. To overcome these difficulties, high-rigidity coaxial twin-rotor technology has emerged. Two rotors with opposite rotation directions are arranged one above the other, rotating around the same axis, balancing the lift on the rotor disc. At the same time, the precise aerodynamic design and control of the high-rigidity rotors can reduce vibration, thereby increasing the helicopter's upper limit for forward flight speed (Doctoral dissertation: Study on the Aerodynamic Characteristics of High-Speed ​​Helicopter Coaxial Rigid Twin Rotors Based on CFD Methods; Study on the Aerodynamic Characteristics of High-Speed ​​Helicopter Rigid Rotors with High Forward Ratios). However, it should be noted that while this technology can effectively reduce negative aerodynamic effects such as vibration and lift imbalance, it still cannot avoid the phenomenon of blade tip supersonic speed caused by the superposition of the advancing blades and the forward flight speed. Therefore, the improvement in the upper limit for forward flight speed is relatively limited. Summary of the Invention

[0003] In order to solve the problems of the prior art, the present invention provides a rotor periodic diameter changing device and a control method, which is characterized in that when the rotor rotates, the rotation radius of each independent blade can be automatically changed, such as: reducing the rotation radius and linear speed of the forward blade, and increasing the rotation radius and linear speed of the backward blade, thereby increasing the maximum allowable flight speed of the helicopter and improving the lift distribution of the rotor disc.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solution: a rotor periodic diameter-changing device, comprising:

[0005] The crank spindle is located on top of the helicopter;

[0006] a connecting plate mounted on the crank of the crank spindle;

[0007] a connecting rod, one end of which is connected to the connecting plate;

[0008] A sliding shaft connected to the other end of the connecting rod, and a rotor blade is installed on the other end of the sliding shaft;

[0009] a propeller hub, which is sleeved on the outside of the crank shaft, the connecting plate and the connecting rod, and the sliding shaft passes through the opening on the side of the propeller hub, and the crank shaft passes through the bottom center of the propeller hub;

[0010] a propeller hub gear mounted on the center of the outer side of the propeller hub bottom and coaxial with the crank shaft;

[0011] A power gear meshes with the hub gear and is powered by a helicopter engine, thereby driving the hub gear and causing the hub to rotate;

[0012] Preferably, a connecting plate gear is installed on the connecting plate; a synchronous gear is installed on the propeller hub; a direction-changing gear is installed on the crank of the crank spindle and meshes with the connecting plate gear and the synchronous gear, so that the connecting plate and the propeller hub have equal rotational speeds and the same direction.

[0013] Preferably, a crank gear is mounted on the crank main shaft; and a control gear is provided on the helicopter control mechanism and meshes with the crank gear, thereby being able to change the direction of the crank main shaft to control the helicopter.

[0014] The present invention also provides a method for controlling a rotor periodic diameter-changing device, which is characterized by comprising the following steps:

[0015] When in hovering state, the control gear drives the crank gear to rotate, thereby driving the crank of the crank main shaft toward the nose of the helicopter. At this time, the rotation radius of the blades located toward the nose of the helicopter is larger, and the rotation radius of the blades toward the tail is smaller. Through pre-arrangement, the center of gravity of the entire helicopter and the lift center of the rotor coincide in the vertical direction, so that the gravity and lift of the helicopter are balanced.

[0016] When in high-speed forward flight, the control gear drives the crank gear to rotate, driving the crank spindle so that the crank faces the side of the helicopter's rearward blades. At this time, viewed from the side, the helicopter's center of gravity is located in front of the rotor's lift center. The torque of gravity and lift helps the helicopter to produce a nose-down action, thereby increasing the forward pulling force of the rotor.

[0017] The present invention also discloses a helicopter rotor blade device, which is characterized in that the device includes the above-mentioned rotor periodic diameter-changing device. Beneficial effects

[0018] When the helicopter rotor is rotating, the rotation radius of each independent blade is automatically changed, reducing the rotation radius and linear speed of the forward blade and increasing the rotation radius and linear speed of the backward blade, thereby increasing the maximum allowable flight speed of the helicopter and improving the lift distribution of the rotor disc.

[0019] The control method of the rotor cyclic diameter changing device can automatically generate the required nose-down moment when the helicopter flies forward. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a top view of the present invention;

[0021] Figure 2 Shown is an axonometric view of the present invention.

[0022] In the figure, 1-crank shaft, 2-connecting plate, 3-connecting rod, 4-sliding shaft, 5-propeller hub, 6-synchronizing gear, 7-changing gear, 8-connecting plate gear, 9-power gear, 10-propeller hub gear, 11-crank gear, 12-control gear. DETAILED DESCRIPTION

[0023] A rotor cyclic diameter changing device, such as Figure 1As shown, the rotor cyclic diameter reducing device includes a crankshaft 1, with a freely rotatable connecting disc 2 mounted on the crank of the crankshaft 1. A connecting rod 3 is mounted on the connecting disc 2, the other end of which is connected to a sliding shaft 4, the other end of which is fixed to the helicopter's rotor blades. The hub 5 can be manufactured as a hollow, thin shell structure, housing the crank of the crankshaft 1, the connecting disc 2, and the connecting rod 3. The sliding shaft 4 passes through an opening in the side of the hub 5, forming a sliding fit with the hub 5. A hub gear 10 is fixed to the bottom center of the hub 5. The crankshaft 1 passes through the hub 5 and the hub gear 10 and is mounted on the top of the helicopter. A power gear 9, driven by the helicopter engine, meshes with the hub gear 10, thereby driving the hub 5 to rotate relative to the crankshaft 1. The rotational motion of the hub 5 is transmitted to the sliding shaft 4, thereby driving the rotation of the rotor blades. Because sliding shaft 4 is indirectly connected to the crank of crank main shaft 1 through connecting rod 3 and connecting plate 2, when the rotor rotates, the eccentricity formed by the crank will continuously drive sliding shaft 4 axially relative to hub 5 through connecting rod 3. Every time the hub 5 rotates one circle, sliding shaft 4 also slides back and forth, thereby achieving the effect of periodically changing the rotation radius of the blade.

[0024] Under ideal conditions, the connecting disk 2 will rotate synchronously with the hub 5 driven by the connecting rod 3. However, in reality, friction, interference, etc. are inevitable, so the connecting disk will not rotate synchronously with the hub 5 as ideal, resulting in uneven movement between the connecting rod 3, the sliding shaft 4, etc., affecting the rotor's periodic diameter change effect. Therefore, a synchronous gear 6 is provided inside the hub 5, which meshes with the direction-changing gear 7, and the direction-changing gear 7 is installed on the crank of the crankshaft 1. A connecting disk gear 8 is fixed on the connecting disk 2, which meshes with the direction-changing gear 7. The number of teeth of the synchronous gear 6 and the connecting disk gear 8 is equal, so when the hub 5 rotates, the synchronous gear 6 will drive the connecting disk gear 8 through the direction-changing gear 7, so that the connecting disk 2 and the hub 5 produce rotational motion in the same direction and at the same speed.

[0025] The crankshaft of the present invention is fixed to the top of the helicopter, and the blade root is connected to the crank's connecting plate via a connecting rod. The propeller hub and crankshaft are coaxial, and driven by the engine, the blade rotates at an angular velocity Ω. Due to the eccentricity A between the crank and the main shaft, the blade's rotation radius changes periodically during each rotation. To achieve the desired effect, the crank should be oriented toward the trailing blade. Assuming the blade length is R and ignoring the radius of the connecting plate, the linear velocity of the leading blade tip is:

[0026]

[0027] The linear velocity of the retreating blade tip is:

[0028]

[0029] obvious , which means that the linear velocity of the blade tip of the forward propeller is small, and the linear velocity of the blade tip of the backward propeller is large, and As we all know, when the helicopter flies forward V When it is too high, the tip speed of the leading blade and forward flight speed V The superposition will cause the helicopter to enter the supersonic region, which will cause a series of problems such as vibration and flow field mutation, which will cause great damage to the helicopter structure. Therefore, the forward flight speed of the helicopter is V Always less than the speed of sound V s The linear speed of the blade tip V f The difference is:

[0030]

[0031] This technology reduces the tip linear velocity of the forward blade and delays the time when the forward blade tip enters the supersonic region. Therefore, under the condition that the speed of sound remains unchanged, the upper limit of the forward flight speed of the helicopter can be increased, allowing the helicopter to fly forward at a higher speed. At the same time, the backward blade of the helicopter has a higher tip linear velocity. , so it will generate greater lift and improve the lift distribution of the propeller disc.

[0032] like Figure 2 As shown, the control device of the helicopter is connected to a control gear 12, which is engaged with a crank gear 11. The crank gear 11 is fixed to the crank main shaft 1. The control gear 12 can drive the crank gear 11, driving the crank main shaft 1 to rotate, thereby changing the direction of the crank.

[0033] The control method of the rotor cyclic diameter-changing device disclosed in the present invention can generate the required control torque by changing the direction of the crank. When the helicopter is hovering, the "propeller disk" is required to be completely horizontal so that the lift is vertically upward and coincides with the center of gravity. At this time, the crank of the crank main shaft 1 is driven forward by the control gear 12, so that the rotation radius of the blade in the direction of the nose is larger, the rotation radius of the blade in the direction of the tail is smaller, and the lift of the propeller disk is on the longitudinal axis of the helicopter; then, by means of pre-adding counterweights, changing the mass distribution, etc., the center of gravity of the helicopter is adjusted to be directly below the lift, so as to achieve the requirement of stable hovering. When the helicopter needs to fly forward, the control gear 12 drives the crank so that it faces the side of the helicopter and moves the blade backward. At this time, the lift moves to the side and rear, forming two torques: rolling torque and nose-down torque. The rolling torque can be eliminated by the helicopter's own cyclic pitch control means; and the nose-down torque can control the helicopter to automatically tilt forward, so that the lift generates a forward component force, driving the helicopter to fly forward.

[0034] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for controlling a rotor cyclic diameter-changing device, characterized by: In the hovering state, the crank gear is driven to rotate by the control gear, and the crank end of the crank main shaft is adjusted to face the nose direction, so that the rotation radius of the blades in the nose direction is increased and the rotation radius of the blades in the tail direction is reduced. Through pre-design, the overall center of gravity of the helicopter and the lift center of the rotor are vertically aligned, so that the gravity and lift of the helicopter are balanced; In high-speed forward flight, the crank gear is driven to rotate by the control gear, and the crank end of the crank main shaft is adjusted toward the side of the retreating blade to generate a moment on the propeller disc plane that causes the nose to pitch, thereby increasing forward thrust. The rotor periodic diameter-changing device comprises: a crank spindle, the lower end of which can be connected to the helicopter transmission system; A connecting plate, fixedly mounted on the crank end of the crank spindle; a connecting rod, one end of which is hinged to the connecting plate, and the other end of which is hinged to the proximal end of the sliding shaft; The sliding shaft can slide back and forth in the radial direction through the guide hole of the hub, and the distal end of the sliding shaft is fixedly connected to the rotor blade; A propeller hub is coaxially sleeved on the outside of the crank main shaft, with a main shaft hole provided at the bottom center and a guide hole provided on the side wall for the sliding shaft to radially pass through; The hub gear is coaxially fixed to the outside of the hub bottom; a power gear meshing with the hub gear and driven by the engine; When the hub gear rotates, it drives the sliding shaft to rotate synchronously, and the connecting rod drives the sliding shaft to move back and forth in the radial direction, so that the rotation radius of the rotor blade changes periodically as the rotor rotates.

2. The method according to claim 1, wherein: The connecting disk is provided with a connecting disk gear on its circumference, the hub is provided with a synchronous gear, and the crank end is provided with a direction-changing gear, which is engaged with the synchronous gear and the connecting disk gear at the same time to keep the connecting disk and the hub rotating at the same speed and in the same direction.

3. The method according to claim 1, wherein: A crank gear is provided on the crank main shaft, and the helicopter control mechanism is provided with a control gear which is meshed with the crank gear to adjust the crank phase and control the helicopter.

4. A helicopter rotor blade device, characterized by: The device is controlled according to the method according to any one of claims 1 to 3.

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