A transmission-fuselage system based on a small coaxial helicopter

Abstract

The invention discloses a transmission-fuselage system based on a small coaxial helicopter, comprising a fuselage and a transmission system connected to the fuselage, wherein the transmission system comprises a transmission gear and four concentric shafts, wherein the four concentric shafts are an outer shaft, an intermediate shaft, an inner shaft and a core shaft from the outside to the inside in sequence; the transmission gear comprises a reduction gear and a reversing gear, wherein the reversing gear comprises an upper bevel gear, a side bevel gear and a lower bevel gear; the upper bevel gear is fixedly connected to the outer shaft, and the lower bevel gear is fixedly connected to the inner shaft; the reduction gear is located between the motor gear and the lower bevel gear; the fuselage comprises a transmission component accommodating space in the upper part and other component accommodating space in the lower part. The transmission-fuselage system based on a small coaxial helicopter can significantly reduce the weight of the mechanism structure, reduce the size of the mechanism, and improve the flight time, reliability and portability of the small electric coaxial helicopter.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft design, and more particularly to a transmission-fuselage system based on a small coaxial helicopter. Background Art

[0002] Coaxial helicopters use coaxial, counter-rotating upper and lower rotors to generate lift. They achieve directional control by altering the counter-torque created by the two rotors, eliminating the need for a tail rotor. They are compact, efficient, and offer high hovering efficiency. In China, Beihang University independently developed a coaxial unmanned helicopter in the 1980s, successfully achieving autonomous navigation and flight, and has since begun applying it to various fields. With the widespread adoption of lithium-ion battery-powered motors for drones, the Beihang University Helicopter Research Institute has also successfully developed a 50kg-class electric coaxial unmanned helicopter.

[0003] For electric coaxial unmanned helicopters, empty weight is a crucial parameter. It determines various performance indicators, including flight time and payload. Therefore, reducing structural weight is a key design objective for electric coaxial unmanned helicopters.

[0004] In recent years, with increasing consumer demand for tasks like aerial photography and mapping, modern small electric unmanned helicopters have rapidly gained popularity. These aircraft must meet mission requirements such as portability and long flight time. Coaxial helicopters, with their high aerodynamic efficiency and compact size, are well-suited to meeting these demands and serving consumers. However, the relatively heavy structure of traditional coaxial unmanned helicopters offsets their aerodynamic advantages, making them unable to meet the requirements of modern unmanned helicopters for smallness, lightness, and portability.

[0005] The weight of a coaxial unmanned helicopter primarily consists of the following components: the transmission system, fuselage, rotor system, control system, and powertrain. The transmission system and fuselage together account for a significant portion of the total weight. Therefore, improving the transmission-fuselage system and reducing its structural weight and complexity are key technologies for improving the flight performance of electric coaxial unmanned helicopters.

[0006] For coaxial unmanned helicopters, the problem of GPS obstruction by the rotor has been a significant technical challenge that has needed to be addressed in recent years. The simplest solution is to place the GPS device outside the rotor radius, but this increases the size of the aircraft and significantly reduces its portability. Some researchers have addressed this issue by changing the GPS signal reception and transmission frequencies to avoid the rotor speed frequency. However, this method requires adjusting the GPS signal frequency for each aircraft, which is not universal and increases the difficulty of flight control debugging. Therefore, how to solve this problem without increasing the size of the aircraft and ensuring the universality of the flight control system is a key consideration for helicopter designers. Summary of the Invention

[0007] To this end, the purpose of the present invention is to propose a transmission-fuselage system based on a small coaxial helicopter to reduce the size and weight of the transmission system, improve the flight time of the small electric coaxial helicopter, and increase the portability of the small coaxial helicopter. The specific technical solution is as follows:

[0008] A transmission-fuselage system based on a small coaxial helicopter comprises a fuselage and a transmission system connected to the fuselage, wherein:

[0009] The transmission system includes a transmission gear and four concentric shafts, which are an outer shaft, an intermediate shaft, an inner shaft and a core shaft from the outside to the inside. The outer shaft and the intermediate shaft, the intermediate shaft and the inner shaft, and the inner shaft and the core shaft are isolated by corresponding bearings. The outer shaft and the inner shaft are rotating shafts, and the intermediate shaft and the core shaft are non-rotating shafts. The outer shaft is used to connect and drive the lower rotor; the intermediate shaft is used to fix the helicopter control system; the inner shaft is used to connect and drive the upper rotor; the core shaft is used to support The equipment on the top of the whole machine; the transmission gear includes a reduction gear and a reversing gear, and the reversing gear includes an upper bevel gear, a side bevel gear, and a lower bevel gear. The upper and lower ends of the side bevel gear are respectively engaged with the upper bevel gear and the lower bevel gear, so that the upper bevel gear and the lower bevel gear rotate in opposite directions; the upper bevel gear is fixedly connected to the outer shaft, and the lower bevel gear is fixedly connected to the inner shaft; the reduction gear is located between the motor gear and the lower bevel gear, and is used to reduce the speed transmitted by the motor and transmit the torque to the lower bevel gear;

[0010] The fuselage includes a transmission component accommodating space in the upper part and a other component accommodating space in the lower part. The transmission component accommodating space is a box-shaped structure and the box-shaped structure is divided into three layers. The top layer is fixed with a first angular contact bearing that matches the outer shaft, the middle layer is fixed with a side bevel gear bearing seat and serves as an intermediate support of the box-shaped structure, and the bottom layer is fixed with a second angular contact bearing that matches the inner shaft and the motor; the other component accommodating space is used to place batteries, various devices and various control elements.

[0011] The transmission-fuselage system based on a small coaxial helicopter can significantly reduce the weight of the mechanism structure, reduce the mechanism size, and improve the flight time, reliability and portability of the small electric coaxial helicopter.

[0012] On the basis of the above technical solution, the present invention can also make the following improvements:

[0013] Preferably, the intermediate shaft is used to fix the recliner ball joint and the ball joint cannot move up and down.

[0014] Preferably, a certain distance is left between the intermediate shaft and the outer shaft for placing and supporting the pull rod of the helicopter control system.

[0015] Preferably, the core shaft is used to support the GPS and / or related detection equipment on the top of the entire aircraft. The core shaft is hollow inside for arranging cables. The cables of the GPS and / or related detection equipment pass through the inner hole of the core shaft and are connected to the flight control computer and transponder at the bottom of the fuselage.

[0016] The present invention adopts a GPS top-mounted solution, which fully utilizes the internal space of the hollow core shaft of the coaxial helicopter. Without increasing the fuselage size, adding too many parts, and meeting the universality of flight control, it solves the problem of the coaxial helicopter's GPS and other upward detection signals (including images) being blocked by the rotor.

[0017] The present invention also adds photoelectric or other related detection equipment to the platform where the GPS is placed, that is, the top of the core shaft. The upper equipment and the lower equipment work simultaneously, so that this coaxial drone has a 360-degree viewing angle, which expands the use of the coaxial drone and greatly enhances the advantages of the coaxial drone, giving it great development space in all aspects of civilian and military use.

[0018] Preferably, the bearings between the outer shaft and the intermediate shaft are the first bearing and the second bearing, the bearings between the intermediate shaft and the inner shaft are the third bearing and the fourth bearing, and the bearings between the inner shaft and the core shaft are the fifth bearing and the sixth bearing. The bearing seats of the first bearing, the second bearing, the third bearing, the fourth bearing, the fifth bearing and the sixth bearing can achieve precise radial and axial positioning of the four concentric shafts to ensure that the shafts do not collide with or move against each other.

[0019] Preferably, the motor gear is a small spur gear, and the reduction gear is a large spur gear. The small spur gear drives the large spur gear to rotate, forming a first-stage reduction.

[0020] Preferably, the fuselage is composed of a plurality of panels, which together form a fuselage structure through necessary connections.

[0021] Preferably, when the upper bevel gear and the lower bevel gear are installed, the upper and lower rotors are required not to overlap at azimuth angles of 90° and 270°.

[0022] The bevel gear transmission (reversing) part of the present invention can ensure that the upper and lower rotors do not appear at the closest phase angle at the same time, which allows the distance between the upper and lower rotors to be further reduced, reducing the size of the entire machine and reducing the weight of the shaft system.

[0023] Preferably, all components in the transmission-fuselage system based on the small coaxial helicopter follow the principle of minimum size and are used in conjunction with the corresponding new control system, thereby minimizing the number of parts and reducing the weight and size of the entire machine.

[0024] Compared with the prior art, the advantages of the transmission-fuselage system based on a small coaxial helicopter of the present invention are:

[0025] (1) Shorten the length of each axis in the traditional coaxial UAV transmission-fuselage system.

[0026] (2) Shaft end bearings are provided between each shaft.

[0027] (3) The structure of lightweight reduction gears and reversing gears is further simplified.

[0028] (4) The fuselage (i.e., the space for accommodating the transmission components) where the core load-bearing components are located is a box-shaped structure, and no other supporting components are required.

[0029] (5) The number, size and weight of parts are significantly reduced, resulting in greater load capacity, longer flight time and better reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0031] Figure 1 The accompanying drawing is a cross-sectional view of a transmission-fuselage system based on a small coaxial helicopter provided by the present invention (without rotors).

[0032] Figure 2 The accompanying drawing is an axonometric view (with rotors) of a transmission-fuselage system based on a small coaxial helicopter provided by the present invention.

[0033] Among them, in the figure,

[0034] 1-outer shaft, 2-intermediate shaft, 3-inner shaft, 4-core shaft, 5-lower rotor, 6-upper rotor, 7-upper bevel gear, 8-side bevel gear, 9-lower bevel gear, 10-reduction gear, 11-motor, 12-transmission component accommodating space, 13-other component accommodating space, 14-first angular contact bearing, 15-side bevel gear bearing seat, 16-second angular contact bearing, 17-GPS, 18-first bearing, 19-second bearing, 20-third bearing, 21-fourth bearing, 22-fifth bearing, 23-sixth bearing. DETAILED DESCRIPTION

[0035] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0036] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0038] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature. Example

[0040] The following is based on Figure 1-2A transmission-fuselage system based on a small coaxial helicopter according to an embodiment of the present invention is described in detail.

[0041] like Figure 1 、 2 As shown, an embodiment of the present invention discloses a transmission-fuselage system based on a small coaxial helicopter, including a fuselage and a transmission system connected to the fuselage through an angular contact bearing. Specifically,

[0042] The transmission system includes transmission gears and four concentric shafts. The four concentric shafts are outer shaft 1, intermediate shaft 2, inner shaft 3 and core shaft 4 from outside to inside. The shaft ends of outer shaft 1 and intermediate shaft 2, intermediate shaft 2 and inner shaft 3, and inner shaft 3 and core shaft 4 are isolated by corresponding bearings. Figure 1 As shown, the bearings between the outer shaft 1 and the intermediate shaft 2 are the first bearing 18 and the second bearing 19, the bearings between the intermediate shaft 2 and the inner shaft 3 are the third bearing 20 and the fourth bearing 21, and the bearings between the inner shaft 3 and the core shaft 4 are the fifth bearing 22 and the sixth bearing 23. The first bearing 18, the second bearing 19, the third bearing 20, the fourth bearing 21, the fifth bearing 22 and the sixth bearing 23 can separate the ends of the shafts from each other, and each shaft can fully realize the radial and axial precise positioning of the four concentric shafts through the bearing seats corresponding to the bearings, ensuring that the shafts will not collide with or move with each other.

[0043] The outer shaft 1 and the inner shaft 3 are rotating shafts, while the intermediate shaft 2 and the core shaft 4 are non-rotating shafts. The outer shaft 1 is used to connect and drive the lower rotor 5. The inner shaft 3 is used to connect and drive the upper rotor 6.

[0044] The intermediate shaft 2 is used to fix the helicopter control system, more specifically, to fix the tilter ball joint and prevent the ball joint from moving up and down. A certain distance is left between the intermediate shaft 2 and the outer shaft 1 for placing the tie rods supporting the helicopter control system.

[0045] The core shaft 4 is used to support the equipment on the top of the entire aircraft. Specifically, the core shaft 4 is used to support the GPS 17 and / or related detection equipment on the top of the entire aircraft. This structural design solves the problem that the coaxial helicopter GPS 17 and other upward detection signals (including images) are blocked by the rotor.

[0046] The core shaft 4 is hollow inside and is used to arrange electrical cables or other cables. The cables of GPS 17 and / or related detection equipment pass through the inner hole of the core shaft 4 and are connected to the flight control computer and transponder at the bottom of the fuselage. This design ensures the autonomous take-off and landing and autonomous navigation flight of the aircraft.

[0047] Photoelectric or other related detection equipment is further added to the platform where GPS 17 is placed. The upper and lower equipment work simultaneously, so that this coaxial drone has a 360° viewing angle, which expands the use of the coaxial drone.

[0048] The transmission gear includes a reduction gear 10 and a reversing gear. The reversing gear includes an upper bevel gear 7, a side bevel gear 8, and a lower bevel gear 9. The upper and lower ends of the side bevel gear 8 are respectively engaged with the upper bevel gear 7 and the lower bevel gear 9, so that the upper bevel gear 7 and the lower bevel gear 9 rotate in opposite directions. The upper bevel gear 7 is fixedly connected to the outer shaft 1, and the lower bevel gear 9 is fixedly connected to the inner shaft 3.

[0049] The reduction gear 10 is located between the motor gear and the lower bevel gear 9, and is used to reduce the speed transmitted by the motor 11 and transmit the torque to the lower bevel gear 9. Specifically, the motor gear connected to the output shaft of the motor 11 is a small spur gear, and the reduction gear 10 is a large spur gear. The small spur gear drives the large spur gear to rotate, forming a first-stage reduction. The large spur gear is engaged with the lower bevel gear 9, and the lower bevel gear 9 is fixedly connected to the inner shaft 3. The lower bevel gear 9 drives the side bevel gear 8 and finally drives the outer shaft 1 fixedly connected to the upper bevel gear 7, so as to achieve the purpose of reversing the upper and lower rotors.

[0050] The fuselage is composed of several carbon plates, which are connected together to form the fuselage structure. The fuselage includes an upper transmission component storage space 12 and a lower other component storage space 13. Transmission component storage space 12 (where the core transmission components are located) is a box-like structure that effectively eliminates vibration and provides shear, tensile, and bending stiffness, meeting strength requirements without the need for additional support. Specifically, the box-like structure is divided into three layers. The top layer secures a first angular contact bearing 14 that mates with the outer shaft 1. The middle layer secures a side bevel gear bearing seat 15, which serves as the intermediate support for the box-like structure. The side bevel gear is secured to the side bevel gear bearing seat. The bottom layer secures a second angular contact bearing 16 that mates with the inner shaft 3 and the motor 11. The first and second angular contact bearings 14, 16 are used to resist the pull generated by the upper and lower rotors. The other component storage space 13 is used to accommodate batteries, various devices (such as pods), and various control components.

[0051] In order to further optimize the technical solution of the above embodiment, when the upper bevel gear 7 and the lower bevel gear 9 are installed, it is required that the upper and lower rotors do not overlap at the azimuth angles of 90° and 270°, so as to ensure that the upper and lower rotors do not appear at the closest phase angle at the same time, avoiding interference between the upper and lower rotors in paddling. This allows the distance between the upper and lower rotors to be further reduced, reducing the size of the entire machine and reducing the weight of the shaft system.

[0052] In order to further optimize the technical solution of the above embodiment, all components in the transmission-fuselage system based on the small coaxial helicopter follow the principle of minimum size and are used in conjunction with the corresponding new control system, thereby minimizing the number of parts and reducing the weight and size of the entire machine.

[0053] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A transmission-fuselage system based on a small coaxial helicopter, comprising a fuselage and a transmission system connected to the fuselage, characterized in that: The transmission system comprises a transmission gear and four concentric shafts, wherein the four concentric shafts are, from the outside to the inside, an outer shaft (1), an intermediate shaft (2), an inner shaft (3) and a core shaft (4), and the shaft ends of the outer shaft (1) and the intermediate shaft (2), the intermediate shaft (2) and the inner shaft (3), and the inner shaft (3) and the core shaft (4) are isolated by corresponding bearings; the outer shaft (1) and the inner shaft (3) are rotating shafts, and the intermediate shaft (2) and the core shaft (4) are non-rotating shafts; the outer shaft (1) is used to connect and drive a lower rotor (5); the intermediate shaft (2) is used to fix a helicopter control system; the inner shaft (3) is used to connect and drive an upper rotor (6); the core shaft (4) is used to The transmission gear comprises a reduction gear (10) and a reversing gear, wherein the reversing gear comprises an upper bevel gear (7), a side bevel gear (8), and a lower bevel gear (9), wherein the upper and lower ends of the side bevel gear (8) are respectively meshed with the upper bevel gear (7) and the lower bevel gear (9), so that the upper bevel gear (7) and the lower bevel gear (9) rotate in opposite directions; the upper bevel gear (7) is fixedly connected to the outer shaft (1), and the lower bevel gear (9) is fixedly connected to the inner shaft (3); the reduction gear (10) is located between the motor gear and the lower bevel gear (9), and is used to reduce the rotation speed transmitted by the motor (11) and transmit the torque to the lower bevel gear (9); The fuselage comprises an upper transmission component accommodating space (12) and a lower other component accommodating space (13); the transmission component accommodating space (12) is a box-shaped structure and the box-shaped structure is divided into three layers, the top layer is fixed with a first angular contact bearing (14) matching with the outer shaft (1), the middle layer is fixed with a side bevel gear bearing seat (15) and serves as an intermediate support of the box-shaped structure, and the bottom layer is fixed with a second angular contact bearing (16) matching with the inner shaft (3) and the motor (11); the other component accommodating space (13) is used to place batteries, various devices and various control elements; The core shaft (4) is used to support the GPS (17) and / or related detection equipment on the top of the entire aircraft. The core shaft (4) is hollow inside and is used to arrange cables. The cables of the GPS (17) and / or related detection equipment pass through the inner hole of the core shaft (4) and are connected to the flight control computer and transponder at the bottom of the aircraft. When the upper bevel gear (7) and the lower bevel gear (9) are installed, it is required that the upper and lower rotors do not overlap at azimuth angles of 90° and 270°.

2. A transmission-fuselage system based on a small coaxial helicopter according to claim 1, characterized in that: The intermediate shaft (2) is used to fix the tilter ball joint, and the ball joint cannot move up and down.

3. A transmission-fuselage system based on a small coaxial helicopter according to claim 2, characterized in that: A certain distance is left between the intermediate shaft (2) and the outer shaft (1) for placing and supporting the pull rod of the helicopter control system.

4. A transmission-fuselage system based on a small coaxial helicopter according to claim 1, characterized in that: The bearings between the outer shaft (1) and the intermediate shaft (2) are a first bearing (18) and a second bearing (19), the bearings between the intermediate shaft (2) and the inner shaft (3) are a third bearing (20) and a fourth bearing (21), and the bearings between the inner shaft (3) and the core shaft (4) are a fifth bearing (22) and a sixth bearing (23), and the bearing seats of the first bearing (18), the second bearing (19), the third bearing (20), the fourth bearing (21), the fifth bearing (22) and the sixth bearing (23) can achieve precise radial and axial positioning of the four concentric shafts.

5. The transmission-fuselage system based on a small coaxial helicopter according to claim 1, characterized in that: The motor gear is a small spur gear, the reduction gear (10) is a large spur gear, and the small spur gear drives the large spur gear to rotate, thereby forming a first-stage reduction.

6. A transmission-fuselage system based on a small coaxial helicopter according to claim 1, characterized in that: The fuselage is composed of a plurality of panels, which are connected to form a fuselage structure.

7. The transmission-fuselage system based on a small coaxial helicopter according to claim 1, characterized in that: All components in the transmission-fuselage system based on a small coaxial helicopter follow the principle of minimum size.

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