A power system for unmanned aerial vehicles

Abstract

This invention provides a power system for a drone, belonging to the field of drone technology. It solves the problem of how to improve the flight stability of a drone. The power system of this drone includes an engine housing, a crankshaft, and a propeller shaft. The crankshaft is arranged along the front-rear direction of the drone and has an output section extending out of the engine housing at its rear end. The propeller shaft is arranged parallel above the output section. A support is fixed to the engine housing, and two spaced-apart bearings are installed in the support. The propeller shaft is rotatably connected to the support through the bearings and is connected to the output section through a transmission mechanism. A starter motor is fixed to the engine housing directly below the support, and the motor shaft of the starter motor is coaxially arranged and fixed to the output section. Through the above design, the tail of the drone achieves high balance and stability, and the arrangement structure is reasonable and reliable, thereby greatly improving the flight stability of the drone.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) technology and relates to a power system for an UAV. Background Technology

[0002] Unmanned aerial vehicles (UAVs), also known as drones, are unmanned aircraft controlled by radio remote control equipment and their own programmed control devices. With the development of market demand, some UAVs tend to develop towards larger sizes, such as cargo drones or spraying drones, while others are increasingly developing towards smaller and lighter designs to meet users' demands for convenience. Currently, there are many types of UAVs, which can be divided into rotary-wing UAVs and fixed-wing UAVs according to their wing type.

[0003] For fixed-wing aircraft, the propeller and the engine that drives the propeller are generally installed at the tail of the fuselage. In the prior art, in order to ensure the balance of the aircraft, the propeller shaft is generally coaxial with the crankshaft of the engine. For example, a linear unmanned aerial vehicle (UAV) disclosed in Chinese patent CN206092173U adopts such a structure. Specifically, the engine of this UAV includes a gas generator, a drive unit, a transmission unit, and an exhaust unit. The transmission unit includes: a crankshaft body, a connecting rod, blades, a central screw, a propeller seat, a magnet, a front housing, a semi-circular key, a bracket, and a rear housing. The connecting rod is installed on the crankshaft body. The blades are connected to the propeller seat through the central screw and to the front housing through the magnet on the left side of the propeller seat. The front housing is connected to the right side of the crankshaft body through the semi-circular key, and the rear housing is connected to the left side of the crankshaft body through the bracket.

[0004] However, the existing coaxial arrangement of the propeller shaft and engine crankshaft has the following drawbacks: As a driving component that generates airflow at the tail to propel the aircraft, the propeller shaft experiences significant radial shear force due to the combined effects of airflow and centrifugal force. Since the propeller shaft is coaxially connected to the crankshaft, the crankshaft also experiences considerable radial shear force. After a period of engine use, this radial shear force can cause mechanical wear at the crankshaft's rotating joints, leading to abnormal radial runout of the crankshaft. This results in severe vibration of the engine body, ultimately causing irregular vibration at the tail of the UAV. As the tail is a crucial part for maintaining flight stability, these adverse factors can severely impact the UAV's stable flight. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a power system for unmanned aerial vehicles (UAVs). The technical problem this invention aims to solve is how to improve the flight stability of UAVs.

[0006] The objective of this invention can be achieved through the following technical solution: A power system for an unmanned aerial vehicle (UAV) includes an engine housing, a crankshaft, and a propeller shaft. The crankshaft is arranged along the longitudinal direction of the UAV and has an output section extending out of the engine housing at its rear end. The propeller shaft is arranged parallel above the output section. A support is fixedly connected to the engine housing. Two spaced-apart bearings are provided in the support. The propeller shaft is rotatably connected to the support through the bearings and is connected to the output section through a transmission mechanism. A starter motor is fixedly connected to the engine housing directly below the support. The motor shaft of the starter motor is coaxially arranged and fixedly connected to the output section.

[0007] Unlike existing technologies, this invention improves the traditional layout of the UAV's power system to enhance flight stability. Specifically, it alters the propeller shaft's position, placing it parallel above the output section. This decouples the propeller shaft from the crankshaft, preventing radial shear forces from affecting crankshaft rotation and thus avoiding radial runout. Consequently, it prevents irregular shaking in the tail area. Furthermore, the design of the support base and two bearings provides two-point support for the propeller shaft, improving its rotational stability and reducing radial wobble, further enhancing tail stability. Additionally, the increased space required for the two bearings reduces the impact of radial wobble. This causes the support to protrude axially backward, affecting the overall center of gravity of the power system and causing a shift. To address this, the present invention cleverly utilizes the starter motor to compensate for the aforementioned center of gravity shift. Specifically, by placing the starter motor directly below the support with its shaft coaxial with the output section, the starter motor acts as a counterweight. The power system is rebalanced through the counterweight of the starter motor, allowing the center of gravity of the power system to return to the correct position. This ensures that the stability of the propeller rotation is improved without affecting the overall balance of the UAV. Therefore, through the improved design of the propeller shaft installation position and structure, combined with the design of the starter motor, not only is irregular shaking in the tail area of ​​the UAV avoided after a period of use, but the stability of the propeller shaft rotation is also greatly improved. The combination of these two aspects ultimately results in a significant improvement in the flight stability of the UAV.

[0008] In the aforementioned UAV power system, the starter motor is a magneto, including a stator fixedly connected to the engine housing. A rotor shaft passes through the stator, and the motor shaft is the rotor shaft. A cylindrical rotor shell covers the stator, and the rotor shell is fitted onto and fixedly connected to the rotor shaft. The rear end of the rotor shell has several blades evenly arranged circumferentially. This invention cleverly utilizes the rotor structure of the magneto. When the UAV is in flight, the blade design at the rear end of the rotor shell can balance the disturbance wake generated by the propeller, thereby providing auxiliary balance for the UAV's flight attitude and further improving the stability of the UAV's flight.

[0009] In the aforementioned UAV power system, the output section has a tapered connecting part at its end. The rotor shaft is a hollow shaft with a tapered hole matching the connecting part at its end near the output section. The connecting part is inserted into the tapered hole. A coaxially arranged screw passes through the end of the rotor shaft away from the output section. The rotor shaft and the output section are fixedly connected by the screw. Through the coordinated design of the tapered hole, connecting part, and screw, the rotor shaft can be firmly kept coaxially connected to the crankshaft, thereby preventing shaking at the connection point and affecting the stability of the crankshaft rotation, thus improving the flight stability of the UAV.

[0010] In the aforementioned UAV power system, the support base is cylindrical, and its internal central section has an annular positioning part. Two bearings are located on either side of the positioning part. A bushing is fitted onto the propeller shaft, passing through the positioning part and with its two ends abutting against the corresponding bearings. The outer diameter of the bushing is slightly smaller than the inner diameter of the positioning part. Through the coordinated design of the positioning part, bushing, and two bearings, when the propeller shaft experiences radial sway, the positioning part provides a support point, allowing the propeller shaft to quickly stabilize. Combined with the two-point support of the two bearings, this significantly improves the rotational stability of the propeller shaft, thereby enhancing the flight stability of the UAV.

[0011] In the aforementioned UAV power system, a cylindrical bearing housing is integrally formed on the rear end face of the engine housing, and the front end of the propeller shaft is rotatably connected to the bearing housing via a second bearing. This design, combined with two first bearings, provides three-point support for the propeller shaft, resulting in more stable rotation and thus improving the flight stability of the UAV.

[0012] In the aforementioned UAV power system, an end cap is fixedly connected to the rear end of the engine housing. The support base is integrally formed on the upper half of the end cap, and a cylindrical mounting portion is integrally formed on the lower half of the end cap. The starter motor is fixedly connected to the mounting portion. This end cap design makes the power system structure more compact, helps reduce vibrations generated by the power system, and thus improves the flight stability of the UAV.

[0013] In the aforementioned UAV power system, the front left side of the engine housing has an upwardly extending connecting arm one and a downwardly extending connecting arm two; the front right side of the engine housing has an upwardly extending connecting arm three; and the middle right side of the engine housing has a downwardly extending connecting arm four. Connecting arms one, two, three, and four are all used to connect to the UAV frame. The connection points of connecting arms one and three are higher than the horizontal plane where the propeller shaft axis is located, while the connection points of connecting arms two and four are lower than the horizontal plane where the output section axis is located. Through the arrangement of these connecting arms and the design of their connection points, the balance and installation stability of the engine housing when connected to the UAV frame can be well guaranteed, thereby improving the flight stability of the UAV.

[0014] In the aforementioned UAV power system, the engine housing has connecting arms five and six on the left and right sides of its rear end, respectively. Both connecting arms five and six are used to connect the UAV's frame and are arranged symmetrically relative to the propeller shaft. This design helps ensure the balance of the engine housing after connection, thereby improving the UAV's flight stability.

[0015] In the aforementioned UAV power system, the transmission mechanism includes a driving gear sleeved and fixed to the output section, and a driven gear sleeved and fixed to the propeller shaft, with the driving gear and driven gear meshing with each other. This design enables the propeller shaft and crankshaft to be connected non-coaxially. Alternatively, the transmission mechanism includes pulleys fixed to the output section and the propeller shaft respectively, with the two pulleys connected by a transmission belt.

[0016] In the aforementioned UAV power system, the active gear has an umbrella-shaped body with the small end facing inward, and several meshing teeth are distributed on the outer circumferential surface of the body. This special design of the active gear shape makes it less prone to axial displacement during transmission, resulting in a more stable structure. This improves transmission stability and prevents crankshaft or propeller shaft instability due to transmission instability, thereby enhancing the UAV's flight stability.

[0017] Compared with existing technologies, the power system of this UAV has the following advantages: By ingeniously improving the position and installation structure of the propeller shaft, and in combination with the arrangement design of the starter motor, the tail of the UAV achieves high balance and stability. The arrangement structure is reasonable and reliable, thereby greatly improving the flight stability of the UAV. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the power system layout on the drone.

[0019] Figure 2 This is a three-dimensional structural diagram of the power system of this drone.

[0020] Figure 3 This is a partial cross-sectional schematic diagram of the power system of this UAV.

[0021] Figure 4 This is a schematic diagram showing the assembly of some components in the transmission mechanism of the power system of this drone.

[0022] Figure 5 This is a schematic diagram of the starter motor in the power system of this drone. Figure 1 .

[0023] Figure 6 This is a schematic diagram of the starter motor in the power system of this drone. Figure 2 .

[0024] Figure 7 This is a schematic diagram of the upper cover structure of the power system of this drone.

[0025] In the diagram, 1. Engine housing; 1a. Bearing housing; 2. Crankshaft; 21. Output section; 211. Connecting part; 3. Propeller shaft; 4. Support seat; 41. Positioning part; 5. Bearing one; 6. Starter motor; 61. Stator; 62. Rotor shaft; 621. Tapered hole; 63. Rotor housing; 631. Blade; 7. Screw; 8. Bushing; 9. Bearing two; 10. End cover; 101. Mounting part; 11. Connecting arm one; 12. Connecting arm two; 13. Connecting arm three; 14. Connecting arm four; 15. Connecting arm five; 16. Connecting arm six; 17. Driving gear; 171. Body; 18. Driven gear. Detailed Implementation

[0026] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0027] Specifically, such as Figure 1 and Figure 3As shown, the power system of this UAV includes an engine housing 1, a crankshaft 2, and a propeller shaft 3. The crankshaft 2 is arranged along the longitudinal direction of the UAV and has an output section 21 extending out of the engine housing 1 at its rear end. The propeller shaft 3 is arranged parallel above the output section 21. A support 4, which is fixedly connected to the engine housing 1, is provided outside the propeller shaft 3. Two spaced bearings 5 ​​are provided inside the support 4. The propeller shaft 3 is rotatably connected to the support 4 through the bearings 5 ​​and is connected to the output section 21 through a transmission mechanism. A starter motor 6, which is fixedly connected to the engine housing 1, is located directly below the support 4. The motor shaft of the starter motor 6 is coaxially arranged with and fixedly connected to the output section 21. As shown... Figure 4 As shown, in this example, the transmission mechanism includes a driving gear 17 sleeved and fixed to the output section 21, and a driven gear 18 sleeved and fixed to the propeller shaft 3. The driving gear 17 and the driven gear 18 mesh with each other and are located in the same vertical plane. The driving gear 17 has an umbrella-shaped body 171 with the small end facing inward, and several meshing teeth are distributed on the outer peripheral surface of the body 171. Figure 5 and Figure 6 As shown, the starter motor 6 is a magneto, including a stator 61 fixedly connected to the engine housing 1. A rotor shaft 62 is installed inside the stator 61, and the motor shaft is the rotor shaft 62. A cylindrical rotor shell 63 is installed outside the stator 61, and the rotor shell 63 is fitted onto the rotor shaft 62 and fixedly connected to it. The rear end of the rotor shell 63 has several blades 631 evenly arranged circumferentially. The end of the output section 21 has a tapered connecting part 211. The rotor shaft 62 is a hollow shaft, and the end near the output section 21 has a tapered hole 621 that matches the connecting part 211. The connecting part 211 is inserted into the tapered hole 621. A coaxially arranged screw 7 is installed at the end of the rotor shaft 62 away from the output section 21. The rotor shaft 62 and the output section 21 are fixedly connected by the screw 7.

[0028] More specifically, for example Figure 3 and Figure 7 As shown, the support base 4 is cylindrical, and its inner middle section has an annular positioning part 41. Two bearings 5 ​​are located on both sides of the positioning part 41. A bushing 8 is fitted onto the propeller shaft 3, passing through the positioning part 41 and with its two ends abutting against the corresponding bearings 5. The outer diameter of the bushing 8 is slightly smaller than the inner diameter of the positioning part 41. A cylindrical bearing seat 1a is integrally formed on the rear end face of the engine housing 1. The front end of the propeller shaft 3 is rotatably connected to the bearing seat 1a via a bearing 9. An end cover 10 is fixedly connected to the rear end of the engine housing 1. The support base 4 is integrally formed on the upper half of the end cover 10. A cylindrical mounting part 101 is also integrally formed on the lower half of the end cover 10. The starter motor 6 is fixedly connected to the mounting part 101.

[0029] For example Figure 2As shown, in this embodiment, the connection structure of the engine housing 1 is further improved. Specifically, the front left side of the engine housing 1 has an upwardly extending connecting arm 11 and a downwardly extending connecting arm 12; the front right side of the engine housing 1 has an upwardly extending connecting arm 13; and the middle right side of the engine housing 1 has a downwardly extending connecting arm 14. Connecting arms 11, 22, 33, and 414 are all used for connecting the UAV frame. The connection points of connecting arms 11 and 313 are higher than the horizontal plane where the axis of the propeller shaft 3 is located, while the connection points of connecting arms 22 and 414 are lower than the horizontal plane where the axis of the output section 21 is located. The rear left and right sides of the engine housing 1 respectively have connecting arms 515 and 616. Connecting arms 515 and 616 are both used for connecting the UAV frame and are symmetrically arranged relative to the propeller shaft 3.

[0030] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0031] Although this document frequently uses terms such as engine housing 1, bearing housing 1a, crankshaft 2, output section 21, connecting part 211, propeller shaft 3, support base 4, positioning part 41, bearing one 5, starter motor 6, stator 61, rotor shaft 62, tapered bore 621, rotor housing 63, blade 631, screw 7, bushing 8, bearing two 9, end cover 10, mounting part 101, connecting arm one 11, connecting arm two 12, connecting arm three 13, connecting arm four 14, connecting arm five 15, connecting arm six 16, driving gear 17, body 171, driven gear 18, etc., the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A power system for an unmanned aerial vehicle (UAV), comprising an engine housing (1), a crankshaft (2), and a propeller shaft (3), wherein the crankshaft (2) is arranged along the longitudinal direction of the UAV and has an output section (21) extending out of the engine housing (1) at its rear end, characterized in that, The propeller shaft (3) is arranged in parallel above the output section (21). A support seat (4) protruding backward along the axial direction is fixedly connected to the engine housing (1). Two bearings (5) are arranged at intervals inside the support seat (4). The propeller shaft (3) is rotatably connected to the support seat (4) through the bearings (5) and is connected to the output section (21) through a transmission mechanism. A starter motor (6) is fixedly connected to the engine housing (1) directly below the support seat (4). The starter motor (6) is a magneto motor. The motor shaft of the starter motor (6) is coaxially arranged and fixedly connected to the output section (21). The rear end of the rotor housing (63) of the starter motor (6) has several blades (631) evenly arranged in the circumferential direction.

2. The power system of the UAV according to claim 1, characterized in that, The starter motor (6) includes a stator (61) fixedly connected to the engine housing (1), a rotor shaft (62) is inserted inside the stator (61), the motor shaft is the rotor shaft (62), and a cylindrical rotor shell (63) is provided on the outside of the stator (61). The rotor shell (63) is sleeved on the rotor shaft (62) and fixedly connected to the rotor shaft (62).

3. The power system of the UAV according to claim 2, characterized in that, The output section (21) has a tapered connecting part (211) at its end. The rotor shaft (62) is a hollow shaft and has a tapered hole (621) that matches the connecting part (211) at one end near the output section (21). The connecting part (211) is inserted into the tapered hole (621). A coaxially arranged screw (7) passes through the end of the rotor shaft (62) away from the output section (21). The rotor shaft (62) and the output section (21) are fixedly connected by the screw (7).

4. The power system of the UAV according to claim 1, 2, or 3, characterized in that, The support base (4) is cylindrical, and the inner middle section of the support base (4) has an annular positioning part (41). Two bearings (5) are located on both sides of the positioning part (41). A bushing (8) is fitted on the propeller shaft (3). The bushing (8) passes through the positioning part (41) and its two ends abut against the corresponding bearings (5). The outer diameter of the bushing (8) is slightly smaller than the inner diameter of the positioning part (41).

5. The power system of the UAV according to claim 1, 2, or 3, characterized in that, The rear end face of the engine box (1) is integrally formed with a cylindrical bearing seat (1a), and the front end of the propeller shaft (3) is rotatably connected to the bearing seat (1a) through a bearing (9).

6. The power system of the UAV according to claim 1, 2, or 3, characterized in that, An end cover (10) is fixedly connected to the rear end of the engine box (1). The support seat (4) is integrally formed on the upper half of the end cover (10). The lower half of the end cover (10) is also integrally formed with a cylindrical mounting part (101). The starter motor (6) is fixedly connected to the mounting part (101).

7. The power system of the UAV according to claim 1, 2, or 3, characterized in that, The front left side of the engine box (1) has an upwardly extending connecting arm 1 (11) and an downwardly extending connecting arm 2 (12). The front right side of the engine box (1) has an upwardly extending connecting arm 3 (13). The right side of the middle section of the engine box (1) has a downwardly extending connecting arm 4 (14). The connecting arms 1 (11), 2 (12), 3 (13) and 4 (14) are all used for connecting the frame of the UAV. The connection point of the connecting arms 1 (11) and 3 (13) is higher than the horizontal plane where the axis of the propeller shaft (3) is located. The connection point of the connecting arms 2 (12) and 4 (14) is lower than the horizontal plane where the axis of the output section (21) is located.

8. The power system of the UAV according to claim 1, 2, or 3, characterized in that, The engine housing (1) has connecting arm five (15) and connecting arm six (16) on the left and right sides of the rear end, respectively. Both connecting arm five (15) and connecting arm six (16) are used to connect the frame of the UAV and are arranged symmetrically relative to the propeller shaft (3).

9. The power system of the UAV according to claim 1, 2, or 3, characterized in that, The transmission mechanism includes a drive tooth (17) sleeved and fixed on the output section (21), and a driven tooth (18) sleeved and fixed on the propeller shaft (3), wherein the drive tooth (17) and the driven tooth (18) mesh with each other.

10. The power system of the UAV according to claim 9, characterized in that, The active tooth (17) has an umbrella-shaped body (171) with the small end facing inward, and a number of meshing teeth are distributed on the outer peripheral surface of the body (171).

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