Inner variable-pitch propeller hub structure for tilting aircraft and tilting aircraft

Abstract

The invention provides an inner variable-pitch propeller hub structure for a tilting aircraft and the tilting aircraft, and relates to the technical field of propeller hub structures of tilting aircrafts, the inner variable-pitch propeller hub structure comprises a propeller hub, propeller clamps are uniformly and rotatably arranged on the periphery of the propeller hub, the propeller clamps are used for connecting propeller blades, and connecting rods extending in the radial direction are arranged on the outer sides of the propeller clamps; the main shaft is in transmission connection with the propeller hub and is used for transmitting power of the rotary power component; one end of the variable-pitch shaft is axially arranged in the propeller hub and the main shaft in a sliding manner, and the other end of the variable-pitch shaft is connected with a steering engine; one end of the variable-pitch beam is connected with one end of the variable-pitch shaft, and the other end of the variable-pitch beam penetrates through the propeller hub and the axial sliding groove of the main shaft and extends outwards in the radial direction; the two ends of each variable-pitch connecting rod are rotationally connected with the other end of one variable-pitch beam and the outer end of one connecting rod respectively; the problem of lightweight design of a large-angle inner variable pitch control mechanism for a distributed multi-rotor electric push tilting aircraft is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of tiltrotor aircraft hub structures, and more particularly, relates to an inner variable pitch hub structure for a tiltrotor aircraft and the tiltrotor aircraft. Background Art

[0002] As a branch of vertical take-off and landing (VTOL) aircraft, distributed multi-rotor electric propulsion tiltrotor aircraft simplify the traditional helicopter's power-drive system through electric drive. Distributed multi-rotors replace the cyclic pitch control system of single-rotor helicopters to increase safety redundancy and reduce control difficulty. Multiple tiltrotors are also deployed to improve cruising speed and efficiency during fixed-wing level flight. With the increasing maturity of technologies such as motors, batteries, controllers, and battery management systems, the technology related to distributed multi-rotor electric propulsion tiltrotor aircraft has rapidly developed.

[0003] Tilt-rotating aircraft can provide lift in helicopter mode and act as a propeller to provide thrust when tilting to fixed-wing mode. Its pitch range is definitely much greater than that of traditional helicopters. Due to the special nature of tilt-rotating aircraft, propellers and rotors are interchangeable. In helicopter mode, the collective pitch of the rotor cannot be too large, otherwise it will lead to a significant increase in the required power and the occurrence of airflow separation on the blade surface; in fixed-wing mode, the collective pitch (pitch) of the propeller cannot be too small to generate sufficient thrust and cruising speed. Therefore, the pitch range of tilt-rotating aircraft is often large. For distributed multi-rotor electric propulsion tilt-rotating aircraft, due to the large changes in the pitch angle of the blades and structural requirements, it cannot be driven by simply adjusting the motor speed. Instead, a collective pitch control mechanism must be added. Since the motor is located below the hub, if an external pitch control method is used, the nacelle width will be increased, increasing the complexity of the mechanism. Therefore, the internal pitch control method has advantages.

[0004] In summary, for distributed multi-rotor electric propulsion tiltrotor aircraft, it is urgent to carry out a lightweight design of the large-angle internal variable pitch control mechanism for this model. Summary of the Invention

[0005] The purpose of the present invention is to provide an internal variable pitch hub structure for a tiltrotor aircraft and a tiltrotor aircraft, so as to solve the problem of lightweight design of a large-angle internal variable pitch control mechanism for a distributed multi-rotor electric propulsion tiltrotor aircraft.

[0006] In order to achieve the above object, the present invention provides an inner variable pitch propeller hub structure for a tiltrotor aircraft, comprising:

[0007] A propeller hub, wherein propeller clamps are evenly distributed and rotatably provided on the outer periphery of the propeller hub, the propeller clamps are used to connect the propeller blades, and a radially extending connecting rod is provided on the outer side of the propeller clamp;

[0008] a main shaft, the main shaft being drivingly connected to the propeller hub and used to transmit power of the rotating power component;

[0009] a pitch shaft, one end of which is axially slidably disposed within the propeller hub and the main shaft, and the other end of which is connected to a steering gear;

[0010] a pitch-variable beam, one end of which is connected to the one end of the pitch-variable shaft, and the other end of which passes through the axial slots of the hub and the main shaft and extends radially outward;

[0011] The variable pitch connecting rods are configured such that the two ends of each variable pitch connecting rod are rotatably connected to the other end of a variable pitch beam and the outer end of a connecting rod respectively.

[0012] Optionally, the servo is an automatic reset servo, which can automatically reset to the extended state when power is lost. When the pitch beam moves to the first extreme position away from the servo, the chord of the blade is parallel to the axis of the main shaft, and the connecting rod, the pitch connecting rod and the pitch beam reach a dead point position.

[0013] Optionally, a first guide hole and a second guide hole that are interconnected are provided in the hub and the main shaft, the pitch change shaft is slidingly engaged with the first guide hole and the second guide hole, the hole walls of the first guide hole and the second guide hole are respectively provided with a first slide groove and a second slide groove, each of the first slide grooves is connected to a second slide groove to form an axial slide groove.

[0014] Optionally, the cross section of the pitch-variable shaft is in the shape of a city surrounded by three identical outwardly protruding circular arcs.

[0015] Optionally, one end of all the variable pitch beams is integrally connected to a connecting component, the end face of the one end of the variable pitch shaft is provided with a groove, at least part of the connecting component is inserted into the groove and is detachably connected to the variable pitch shaft.

[0016] Optionally, one end of the variable pitch link is connected to the connecting rod via a single plane rotation structure.

[0017] Optionally, the main shaft and the hub are plug-fitted through a slot and connected by bolt fasteners.

[0018] Optionally, the pitch-variable shaft is rotationally connected to the servo, so that the pitch-variable shaft can rotate along with the main shaft.

[0019] Optionally, one end of the propeller clamp is rotatably connected to a support shaft connected to the outer periphery of the hub, and the other end of the propeller clamp is provided with a pair of connecting ears, and the root of the blade is provided between the pair of connecting ears and is fastened to the connecting ears.

[0020] The present invention also provides a tilting aircraft, comprising the above-mentioned inner variable pitch hub structure for the tilting aircraft.

[0021] The present invention provides an internal variable pitch propeller hub structure for a tilting aircraft and a tilting aircraft, the beneficial effects of which are as follows: the internal variable pitch propeller hub structure for the tilting aircraft inserts one end of the variable pitch shaft into the propeller hub and the main shaft, and the other end of the variable pitch shaft is connected to the servo. Under the action of the servo, the variable pitch shaft can drive the variable pitch beam connected to one end thereof to move axially along the propeller hub and the main shaft, and the variable pitch beam is rotatably connected to the outer end of the connecting rod on the radial outer side of the propeller clamp through a variable pitch connecting rod to form a connecting rod mechanism. The movement of the variable pitch beam can utilize the connecting rod mechanism to drive the propeller clamp and the blade connected thereto to rotate, thereby realizing the pitch change of the blade. Compared with the traditional variable pitch control mechanism, the internal variable pitch propeller hub structure for the tilting aircraft can reduce the weight of the rotor system and the internal variable pitch control mechanism structure. The structure is simpler and lighter. The variable pitch connecting rod is pushed by the servo to drive the blade to rotate, which can meet the demand of large blade pitch angle while maintaining a faster corresponding speed of the blade in helicopter mode.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0024] Figure 1 A three-dimensional schematic diagram of an inner variable pitch hub structure for a tiltrotor aircraft according to an embodiment of the present invention is shown.

[0025] Figure 2 A schematic diagram of an inner variable pitch propeller hub shaft outer belt rotation structure in the prior art is shown.

[0026] Figure 3 A three-dimensional schematic diagram of an inner variable pitch hub structure for a tilt aircraft in helicopter mode according to an embodiment of the present invention is shown.

[0027] Figure 4 A schematic diagram of a pitch shaft of an inner pitch hub structure for a tilting aircraft according to an embodiment of the present invention is shown.

[0028] Figure 5 A schematic top view of an internal variable pitch hub structure for a tilt-rotating aircraft in fixed-wing mode according to an embodiment of the present invention is shown.

[0029] Figure 6A schematic diagram of the blade and hub structure of a tiltrotor aircraft in helicopter mode according to an embodiment of the present invention is shown.

[0030] Figure 7 A schematic diagram of the blade and hub structure of a tiltrotor aircraft in a fixed-wing mode according to an embodiment of the present invention is shown.

[0031] Figure 8 A schematic diagram of the blade and hub structure of a tilting aircraft in a feathering condition according to an embodiment of the present invention is shown.

[0032] Description of reference numerals:

[0033] 1. Propeller blade; 2. Propeller clamp; 3. Pitch connecting rod; 4. Pitch beam; 5. Pitch shaft; 6. Propeller hub; 7. Main shaft; 8. Servo; 9. Single plane rotating structure; 10. External shaft rotating structure; 11. Pitch rod. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Instead, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0035] like Figure 1 As shown, the present invention provides an inner variable pitch hub structure for a tilting aircraft, comprising:

[0036] The hub 6 has blade clamps 2 evenly distributed and rotatably arranged on its outer periphery. The blade clamps 2 are used to connect the blades 1. A radially extending connecting rod is arranged on the outer side of the blade clamps 2.

[0037] The main shaft 7 is connected to the hub 6 and is used to transmit power to the rotating power component;

[0038] A pitch shaft 5, one end of which is axially slidably disposed within the propeller hub 6 and the main shaft 7, and the other end of which is connected to a steering gear 8;

[0039] A pitch beam 4, one end of which is connected to one end of the pitch shaft 5, and the other end of which passes through the axial slots of the hub 6 and the main shaft 7 and extends radially outward;

[0040] The variable pitch connecting rods 3 have two ends which are rotatably connected to the other end of a variable pitch beam 4 and the outer end of a connecting rod respectively.

[0041] Specifically, in order to solve the problem of lightweight design of a large-angle internal pitch control mechanism for a distributed multi-rotor electric propulsion tilting aircraft, the present invention provides an internal pitch-variable propeller hub 6 structure for a tilting aircraft. One end of the pitch-variable shaft 5 is inserted into the propeller hub 6 and the main shaft 7, and the other end of the pitch-variable shaft 5 is connected to the steering gear 8. Under the action of the steering gear 8, the pitch-variable shaft 5 can drive the pitch-variable beam 4 connected to one end thereof to move axially along the propeller hub 6 and the main shaft 7. The pitch-variable beam 4 is rotatably connected to the outer end of the connecting rod on the radial outside of the propeller clamp 2 through the pitch-variable connecting rod 3. A connecting rod mechanism is formed, and the movement of the pitch beam 4 can be used to drive the propeller clamp 2 and the blade 1 connected thereto to rotate, thereby realizing the pitch change of the blade 1. Compared with the traditional pitch control mechanism, the internal pitch hub 6 structure for the tilt-rotating aircraft can reduce the rotor system and the internal pitch control mechanism structure. It is simpler and lighter in weight, and the pitch connecting rod 3 is pushed by the servo 8 to drive the blade 1 to rotate, which can meet the requirement of a large pitch angle of the blade 1 while maintaining a faster response speed in the helicopter mode.

[0042] In fixed-wing mode, propeller engines are more prone to failure risks. When an engine fails during flight, feathering is performed to avoid damage to the propeller it drives. This involves turning the blade 1 nearly parallel to the direction of flight to reduce drag. Traditional propeller aircraft feather their propellers using hydraulic drive, but electric propulsion aircraft generally do not intentionally configure an additional hydraulic system for this purpose. Instead, Figure 2 As shown, feathering is typically performed by lifting the off-axis rotating structure 10, thereby driving the pitch rod 11 upward. This method has the disadvantages of heavy structural weight and the need to lengthen the pitch rod 5 axially to achieve feathering. This increased structural weight also requires more space in the nacelle for the pitch rod 5 during normal flight. Furthermore, if an engine failure causes the generator to fail, powering off the servo system and causing the servo 8 to fail, feathering becomes impossible. Therefore, to ensure flight safety and reduce structural complexity, the specific method for feathering after an engine failure should be considered from the outset of the hub 6 design.

[0043] Optionally, the servo 8 is an automatic reset servo, which can automatically reset to the extended state when power is lost. When the pitch beam 4 moves to the first extreme position away from the servo 8, the chord of the blade 1 is parallel to the axis of the main shaft 7, and the connecting rod, pitch link 3 and pitch beam 4 reach the dead point position.

[0044] Specifically, in order to ensure that the blades 1 can rotate at a large angle and can also realize feathering control conveniently and effectively, the internal variable pitch hub 6 structure for the tilting aircraft is designed for the scenario where the propeller engine fails in the fixed-wing mode. The engine failure causes the generator to fail, which causes the servo system to lose power and lose control. At this time, if Figure 5As shown, the servo 8 automatically resets to the extended state, the pitch shaft 5 drives the pitch beam 4 to automatically restore to the highest position, the pitch beam 4 and the pitch connecting rod 3 are on the same horizontal plane, and the connecting rod on the propeller clamp 2 is perpendicular to the horizontal plane, forming a dead point of the connecting rod mechanism. The blade 1 always remains in the feathering position without receiving the thrust of the servo 8, avoiding the uncontrollable attitude of the blade 1 due to failure of the servo 8, and ensuring that the resistance caused by the air on the blade 1 under this working condition is always kept to a minimum. At the same time, the servo 8 does not need to always output thrust to maintain this working condition; and compared with the design of the traditional off-axis rotating structure 10, the weight is greatly reduced.

[0045] Furthermore, the automatic reset principle of the automatic reset servo can be spring reset, capacitor energy storage reset or microcontroller control reset.

[0046] Optionally, a first guide hole and a second guide hole that are interconnected are provided in the hub 6 and the main shaft 7, the pitch change shaft 5 is slidingly engaged with the first guide hole and the second guide hole, and the hole walls of the first guide hole and the second guide hole are respectively provided with a first slide groove and a second slide groove, each first slide groove is connected to a second slide groove to form an axial slide groove.

[0047] In this embodiment, three blades 1 and three blade clamps 2 are respectively provided. Correspondingly, three axial slide grooves are evenly distributed in the circumference of the hub 6 and the main shaft 7. When the pitch change shaft 5 moves along the first guide hole and the second guide hole, it can drive the three pitch change beams 4 to slide synchronously in the three axial slide grooves.

[0048] Optionally, the cross section of the pitch-variable shaft 5 is in the shape of a city wall formed by three identical outwardly protruding circular arcs.

[0049] Specifically, the interior of the main shaft 7 and the hub 6 are clearance-fitted with the pitch shaft 5. The cross-sectional shape of the pitch shaft 5 is similar to an equilateral triangle, and the three side lines are all arc-shaped convex outwards, thereby eliminating the concentrated stress on the edges of the pitch shaft 5 caused by the main shaft 7 during the torque transmission process, and transmitting torque through the fit between surfaces.

[0050] Optionally, one end of all the variable pitch beams 4 is integrally connected to a connecting component, and the end face of one end of the variable pitch shaft 5 is provided with a groove, and at least part of the connecting component is inserted into the groove and is detachably connected to the variable pitch shaft 5.

[0051] Specifically, such as Figure 4 As shown, a triangular groove is provided in the middle of one end of the pitch-variable shaft 5, into which the connecting part of the pitch-variable beam 4 can be inserted and fixed by a hexagon socket bolt. Figure 5As shown, three variable-pitch beams 4 extend outward from the three vertices of the triangular connecting component at the center. The triangular connecting component at the center can ensure that the three variable-pitch beams 4 will not be deformed due to the torque in the torsional direction. The variable-pitch beams 4 are mainly subjected to the operating force brought by the up and down movement of the variable-pitch shaft 5. The variable-pitch beams 4 can be ensured not to bend and deform by their own external design and the supporting ribs extending out of the connecting component at the center.

[0052] Optionally, one end of the variable pitch link 3 is connected to the connecting rod via a single plane rotating structure 9 .

[0053] Specifically, compared with the design of the pitch rod 11 of a traditional helicopter, during actual flight of the helicopter, the pitch link 3 is connected by two ball joints, so it will always vibrate irregularly in the form of high frequency. The solution is to add an additional damping device to absorb the energy of the vibration; the ball joint at one end of the internal pitch hub 6 structure used for the tilt-rotating aircraft can be replaced with a rotating pair. Without changing the original control mechanism, the degree of freedom of the pitch link 3 is limited to one plane, and the unique position and posture of the pitch link 3 are determined only by the up and down movement of the pitch shaft 5, eliminating the collision of the pitch link 3 with the blade clamp 2 and the pitch beam 4, and there is no need to install an additional damping device.

[0054] Optionally, the main shaft 7 and the hub 6 are plug-fitted through a slot and connected by bolt fasteners.

[0055] Specifically, the main shaft 7 and the propeller hub 6 can be matched through a slot and then tightened by bolts, thereby realizing transmission from the main shaft 7 to the propeller hub 6.

[0056] Optionally, the pitch-variable shaft 5 is rotationally connected to the steering gear 8 so that the pitch-variable shaft 5 can rotate along with the main shaft 7 .

[0057] Specifically, the internal variable pitch hub 6 structure for the tilting aircraft not only reduces the complexity of the structure, but also greatly reduces the total weight of the internal variable pitch control mechanism by reducing the length of the variable pitch link 3 and the length of the variable pitch shaft 5 while ensuring that the variable pitch shaft 5 can rotate and change pitch synchronously with the main shaft 7.

[0058] Optionally, one end of the propeller clamp 2 is rotatably connected to a support shaft connected to the outer periphery of the hub 6, and the other end of the propeller clamp 2 is provided with a pair of connecting ears, and the root of the blade 1 is provided between the pair of connecting ears and is fastened to the connecting ears.

[0059] Specifically, such as Figure 3 As shown, the root of the blade 1 is accommodated between a pair of connecting ears, and the blade 1 is fastened through the mounting holes on the connecting ears.

[0060] The present invention further provides a tilting aircraft, comprising the above-mentioned inner variable pitch hub 6 structure for the tilting aircraft.

[0061] Specifically, the tilting aircraft is equipped with the above-mentioned internal variable pitch hub 6 structure for tilting aircraft, such as Figures 6 to 8 As shown, the incoming flow direction, the extension direction of the main shaft 7, the moving direction of the pitch shaft 5, and the rotation direction of the main shaft 7 are represented by straight arrows, dotted lines, solid lines, and arc arrows respectively; in the helicopter mode, as shown in FIG. Figure 6 As shown, in order to avoid the occurrence of excessive power requirements and airflow separation on the surface of the blade 1, the rotor collective pitch is adjusted to a smaller value, and the servo 8 is in a retracted state; in the fixed-wing mode, as shown Figure 7 As shown, in order to ensure sufficient pulling force and cruising speed, the propeller collective pitch is adjusted to a larger value, and the steering gear 8 is in the extended state; in the feathering condition, as shown Figure 8 As shown, when the external force is removed, the servo 8 automatically restores the pitch shaft 5 to the highest position, and the chord line of the blade 1 is parallel to the axis of the main shaft 7, so that the rotor is feathered during the tilt-to-horizontal flight. The pitch beam 4, the pitch link 3 and the connecting rod just reach the dead point position, which can ensure that the resistance caused by the air on the blade 1 is always kept to a minimum. At the same time, the servo 8 does not need to output thrust all the time to maintain this working condition, and relies on self-locking to feather the rotor.

[0062] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An internal variable pitch propeller hub structure for a tiltrotor aircraft, characterized in that: include: A propeller hub, wherein propeller clamps are evenly distributed and rotatably provided on the outer periphery of the propeller hub, the propeller clamps are used to connect the propeller blades, and a radially extending connecting rod is provided on the outer side of the propeller clamp; a main shaft, the main shaft being drivingly connected to the propeller hub and used to transmit power of the rotating power component; a pitch shaft, one end of which is axially slidably disposed within the propeller hub and the main shaft, and the other end of which is connected to a steering gear; a pitch-variable beam, one end of which is connected to the one end of the pitch-variable shaft, and the other end of which passes through the axial slots of the hub and the main shaft and extends radially outward; The variable pitch connecting rods are configured such that the two ends of each variable pitch connecting rod are rotatably connected to the other end of a variable pitch beam and the outer end of a connecting rod respectively.

2. The internal variable pitch hub structure for a tiltrotor aircraft according to claim 1, characterized in that: The servo is an automatic reset servo, which can automatically reset to the extended state when power is lost. When the pitch beam moves to the first extreme position away from the servo, the chord of the blade is parallel to the axis of the main shaft, and the connecting rod, the pitch connecting rod and the pitch beam reach the dead point position.

3. The internal variable pitch hub structure for a tiltrotor aircraft according to claim 1, characterized in that: The hub and the main shaft are provided with a first guide hole and a second guide hole that are interconnected. The pitch variable shaft is slidably fitted with the first guide hole and the second guide hole. The walls of the first guide hole and the second guide hole are respectively provided with a first slide groove and a second slide groove. Each of the first slide grooves is connected to one of the second slide grooves to form an axial slide groove.

4. The internal variable pitch propeller hub structure for a tiltrotor aircraft according to claim 3, characterized in that: The cross section of the pitch-variable shaft is in the shape of three identical circular arcs bulging outwards.

5. The internal variable pitch hub structure for a tiltrotor aircraft according to claim 1, characterized in that: One end of all the variable pitch beams is integrally connected to a connecting component, the end surface of the one end of the variable pitch shaft is provided with a groove, at least part of the connecting component is inserted into the groove and is detachably connected to the variable pitch shaft.

6. The internal variable pitch propeller hub structure for a tiltrotor aircraft according to claim 1, characterized in that: One end of the variable pitch connecting rod is connected to the connecting rod through a single plane rotation structure.

7. The internal variable pitch propeller hub structure for a tiltrotor aircraft according to claim 1, characterized in that: The main shaft and the hub are plug-fitted through a slot and connected by bolt fasteners.

8. The internal variable pitch propeller hub structure for a tiltrotor aircraft according to claim 1, characterized in that: The pitch-variable shaft is rotationally connected to the steering gear so that the pitch-variable shaft can rotate along with the main shaft.

9. The internal variable pitch hub structure for a tiltrotor aircraft according to claim 1, characterized in that: One end of the propeller clamp is rotatably connected to a support shaft connected to the outer periphery of the propeller hub, and the other end of the propeller clamp is provided with a pair of connecting ears. The root of the propeller blade is provided between the pair of connecting ears and is fastened to the connecting ears.

10. A tiltrotating aircraft, characterized in that: The invention comprises the inner variable pitch hub structure for a tilting aircraft according to any one of claims 1 to 9.

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