Implementation method of a test fixing device for propellers with different shaft lengths

Abstract

The present invention relates to a method for realizing a test fixing device for propellers with different shaft lengths, belonging to the technical field of unsteady aerodynamic tests of propellers, and solves the problems that the prior art cannot adjust the length of the propeller shaft and the distance between the propeller and the wing without affecting the mechanical effect exerted on the propeller shaft by the rotation of the propeller. Based on the test propeller and various distances between the propeller and the motor base, the present invention designs various propeller shaft segments matching the propeller; based on the motor base, designs a base matching the motor bearing; based on the propeller, designs a propeller installation clamping device; processes the propeller shaft segments, the base and the propeller installation clamping device of the test fixing device, and installs them on the propeller-wing coupling static test device. The scheme has a simple and reliable structure, effectively reduces costs, avoids waste of resources, does not change the connection mode between the propeller and the propeller shaft, and does not affect the mechanical effect exerted on the propeller shaft by the rotation of the propeller.

Description

Technical Field

[0001] The present invention relates to the technical field of unsteady aerodynamic tests of propellers, and particularly relates to a method for implementing a test fixing device for propellers with different shaft lengths. Background Art

[0002] In recent years, unmanned aerial vehicles (UAVs) have been widely used, and among them, solar long-endurance UAVs are a type with broad prospects. Most solar UAVs use electric-driven propellers as the propulsion system and adopt a large-flexibility high-aspect-ratio aerodynamic layout design. In traditional aircraft design work, the propulsion system design is usually independent of the airframe design. However, the design characteristics and flight conditions of solar UAVs make such aircraft have characteristics different from traditional aircraft, such as low speed and large flexibility. Therefore, the relevant aerodynamic effects at low Reynolds numbers become important in the design work of solar UAVs. In this context, the coupling effect between the propeller and the airframe needs to be considered, and it is necessary to further study the influence of the position of the propeller relative to the wing and fuselage on the aerodynamic performance and control of solar UAVs.

[0003] In the unsteady aerodynamic test research of variable shaft length propellers, it is necessary to analyze the influence of the change in the distance between the propeller and the wing on the relevant coupled aerodynamic forces and aerodynamic loads, as well as the influence of different propeller shaft lengths on the dynamic characteristics of the propeller itself, etc. In the static thrust test of variable shaft length propellers, in order to study the influence of the distance between the propeller and the wing and the influence of the propeller shaft length, it is necessary to adjust the length of the propeller shaft on the basis of fixing the propeller. However, the test fixing devices designed by existing related methods can only play the role of fixing the propeller, and are not designed for adjusting the length of the propeller shaft. Therefore, it is impossible to adjust the length of the propeller shaft and the distance between the propeller and the wing without affecting the mechanical effect exerted on the propeller shaft by the rotation of the propeller.

[0004] In summary, the test fixing devices designed by existing related methods can only play the role of fixing the propeller, and there is a problem that they are not designed for adjusting the length of the propeller shaft, and thus it is impossible to adjust the length of the propeller shaft and the distance between the propeller and the wing without affecting the mechanical effect exerted on the propeller shaft by the rotation of the propeller. Summary of the Invention

[0005] In view of the above problems, the present invention provides a method for implementing a test fixing device for propellers with different shaft lengths, which solves the problem that the test fixing devices designed by existing related methods can only play the role of fixing the propeller, and there is a problem that they are not designed for adjusting the length of the propeller shaft, and thus it is impossible to adjust the length of the propeller shaft and the distance between the propeller and the wing without affecting the mechanical effect exerted on the propeller shaft by the rotation of the propeller.

[0006] The present invention provides a method for realizing a test fixing device for propellers with different shaft lengths, including the following steps:

[0007] Based on the propeller selected for the test and various spacings between the propeller and the motor base required by the test, design the propeller shaft section of the test fixing device that matches the propeller;

[0008] Based on the motor base selected for the test, design the base of the test fixing device that matches the motor bearing;

[0009] Based on the propeller selected for the test, design the propeller mounting and clamping device of the test fixing device;

[0010] Machine the propeller shaft section, the base, and the propeller mounting and clamping device of the test fixing device, and install them on the propeller-wing coupling static test device; wherein, the test fixing device includes a variety of test fixing sub-devices with different propeller shaft section lengths and the same base and propeller mounting and clamping device. Each of the test fixing sub-devices is used to independently complete the fixed connection with the propeller and the motor bearing, and meet one of the various spacing requirements between the propeller and the motor base;

[0011] After the test fixing device is installed, it is used to adjust the distance between the propeller and the wing and the length of the propeller shaft in the propeller-wing coupling static test device.

[0012] Further, the propeller mounting and clamping device of the test fixing sub-device includes an upper clamping device and a lower clamping device; the upper clamping device is a fixing cap, and the lower clamping device is a self-tightening nut.

[0013] Further, the propeller shaft section of the test fixing sub-device includes a threaded section and a smooth shaft section; wherein,

[0014] A variety of the test fixing sub-devices have the same threaded section; the part of the threaded section away from the smooth shaft section is used to cooperate with the propeller and the fixing cap; the part close to the smooth shaft section is used to cooperate with the self-tightening nut; the threaded section is a reverse-thread thread;

[0015] A variety of the test fixing sub-devices have smooth shaft sections with the same diameter and different lengths; wherein, the lengths of the various smooth shaft sections are determined according to the various spacings between the propeller and the motor base required by the test, and are the results obtained by subtracting the thickness of the self-tightening nut from the various spacings between the propeller and the motor base required by the test.

[0016] Furthermore, the base is integrally formed with the paddle shaft section, close to the optical axis section and far from the threaded section; the base is a straight cylinder and coaxial with the paddle shaft section; three identical bolt holes for mating with the motor bearing are evenly distributed around the axis of the base; the axes of the three bolt holes are evenly distributed on the side surface of the cylinder coaxial with the base; the bolt holes are two-stage stepped through holes, the first-stage step is on the side of the base close to the paddle shaft section; the second-stage step is on the side of the base far from the paddle shaft section; there is a blind hole on the side of the base far from the paddle shaft section for accommodating the motor bearing head.

[0017] Furthermore, the thread diameter of the threaded section is M6, and the total length of the threaded section is 29.3 mm; among them, the length of the part far from the optical axis section is 23.5 mm, and the length of the part close to the optical axis section is 5.8 mm.

[0018] Furthermore, the bottom diameter of the base is 21 mm and the height is 5.5 mm; the bottom diameter of the cylinder coaxial with the base and with the axes of the three bolt holes evenly distributed on its side surface is 15 mm; the bottom diameter of the first-stage step is 4.8 mm and the depth is 3.5 mm; the bottom diameter of the second-stage step is 2.7 mm and the depth is 2 mm; the bottom diameter of the blind hole is 9 mm and the depth is 3.1 mm.

[0019] Furthermore, the self-locking nut is an M6 self-locking nut, the round end diameter is 12.48 mm, the distance between the opposite sides of the hexagonal end is 9.8 mm, and the thickness is 5.8 mm; during installation, the hexagonal end of the M6 self-locking nut faces the optical axis section of the paddle shaft section, and the nut is screwed to the root of the threaded section.

[0020] Furthermore, there are 4 types of distances between the propeller and the motor base required by the test, which are 10 mm, 20 mm, 30 mm, and 40 mm respectively; then the lengths of the optical axis sections are divided into 4 types, which are 4.2 mm, 14.2 mm, 24.2 mm, and 34.2 mm respectively.

[0021] Furthermore, the propeller-wing coupling static test device includes a motor, a wing, a fairing, a bracket, internal sensors, and a test fixing device for different shaft-length propellers, which is used to simulate the combined form of a high aspect ratio UAV propeller and wing, and obtain the coupling aerodynamic force by measuring the forces on the motor, wing, and propeller-wing coupling static test device.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] (1) The implementation method of the test fixture for different shaft-length propellers of the present invention is used for the unsteady aerodynamic test of variable shaft-length propellers of high aspect ratio solar UAVs. While effectively fixing the propellers and ensuring normal operation, it provides a series of determined distances between the propellers and the motor base / wing, meeting the requirements for analyzing the influence effects of the distance change between the propellers and the wing on the relevant coupled aerodynamic forces and aerodynamic loads, as well as the influence of different propeller shaft lengths on the dynamic characteristics of the propellers themselves in related researches such as changing the propeller shaft length. The structure is simple and reliable, effectively reducing costs and avoiding waste of resources.

[0024] (2) The implementation method of the test fixture for different shaft-length propellers of the present invention does not change the connection method between the propellers and the propeller shafts and does not affect the mechanical effects exerted by the rotation of the propellers on the propeller shafts. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings are only for the purpose of showing specific embodiments and are not considered as a limitation to the present invention.

[0026] Figure 1 It is a schematic structural view of the propeller shaft section and the base in the propeller test fixture proposed by the embodiment of the present invention;

[0027] Figure 2 It is a schematic structural view of the propeller shaft section and the base in a series of test fixtures for different shaft-length propellers proposed by the embodiment of the present invention;

[0028] Figure 3 It is a schematic installation view of the self-locking nut;

[0029] Figure 4 It is a schematic installation view of the propeller;

[0030] Figure 5 It is a schematic view of the installation of the propeller test fixture on the propeller-wing coupling static test device proposed by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0032] A specific embodiment of the present invention discloses an implementation method of a test fixture for different shaft-length propellers, including the following steps:

[0033] Step 1: Based on the selected propeller for the test and the various spacings between the propeller and the motor base required by the test, design the propeller shaft section of the test fixture that matches the propeller.

[0034] The test fixture includes multiple test fixture sub-devices with different propeller shaft section lengths but the same base and propeller mounting and clamping devices. Each test fixture sub-device is used to independently complete the fixed connection with the propeller and the motor bearing and meet one of the various spacing requirements between the propeller and the motor base. That is, each test fixture sub-device includes the same base and propeller mounting and clamping devices, as well as different propeller shaft sections. By replacing the sub-devices with different propeller shaft section lengths, the adjustment of the spacing between the propeller and the wing and the length of the propeller shaft in the propeller-wing coupling static test device is realized, which is used to study the influence of the spacing between the propeller and the wing on the coupling aerodynamic force and the influence of the propeller shaft length on the dynamic characteristics of the propeller itself.

[0035] Specifically, according to the model and size of the selected propeller and the matching fixing cap for the test, as well as the spacing between the propeller and the motor base required by the test, design the propeller shaft section that matches the propeller.

[0036] The propeller shaft section includes a threaded section and a smooth shaft section, as Figure 1 shown.

[0037] Multiple test fixture sub-devices have the same threaded section. To ensure reliable operation, the part for propeller fixation adopts a threaded post design. The total length of the threaded section is 29.3 mm. Based on the original propeller fixation design, a position is reserved for the mounting and clamping device below the propeller. The length of the threaded section close to the smooth shaft section is 5.8 mm, which is used to cooperate with the M6 self-locking nut. The length of the threaded section far from the smooth shaft section is 23.5 mm, which is used to cooperate with the propeller and the fixing cap. The thread diameter is M6. To achieve the rotational self-locking of the fixture, the threaded section is a reverse-thread thread.

[0038] To provide the spacing between the propeller and the motor base required by the test, a smooth shaft section is arranged between the threaded section and the base. Multiple test fixture sub-devices have smooth shaft sections with the same diameter but different lengths; among them, the diameter of the smooth shaft section is 6 mm, and the lengths of multiple smooth shaft sections are determined according to the various spacings between the propeller and the motor base required by the test, which are the results obtained by subtracting the thickness of the self-locking nut from the various spacings between the propeller and the motor base required by the test.

[0039] The diameter of the smooth shaft section is 6 mm. According to the test requirements, optionally, the spacings between the propeller and the motor base include four types: 10 mm, 20 mm, 30 mm, and 40 mm, as Figure 2As shown in the figure, the length of the corresponding optical axis section is obtained by subtracting the thickness of 5.8 mm of the self-locking nut from each spacing, which are 4.2 mm, 14.2 mm, 24.2 mm and 34.2 mm respectively. When the propeller spacing needs to be adjusted, just replace the device with the corresponding length.

[0040] Step 2: Based on the motor base selected for the test, design the base of the test fixture that matches the motor bearing.

[0041] Specifically, as Figure 1 shown, the base is integrally formed with the propeller shaft section, close to the optical axis section and far from the threaded section; the base is a straight cylinder with a bottom diameter of 21 mm and a height of 5.5 mm, and the base is coaxial with the propeller shaft section; three identical bolt holes for mating with the motor bearing are evenly distributed around the axis of the base; the axes of the three bolt holes are evenly distributed on the side surface of a cylinder with a bottom diameter of 15 mm and coaxial with the base; the bolt holes are two-stage stepped through holes, the bottom diameter of the first-stage step is 4.8 mm, located on the side of the base close to the propeller shaft section, with a depth of 3.5 mm; the bottom diameter of the second-stage step is 2.7 mm, located on the side of the base far from the propeller shaft section, with a depth of 2 mm; there is a blind hole with a diameter of 9 mm and a depth of 3.1 mm on the side of the base far from the propeller shaft section, which is used to accommodate the motor bearing head.

[0042] Step 3: Based on the propeller selected for the test, design the propeller mounting and clamping device of the test fixture.

[0043] Specifically, the propeller mounting and clamping device of the test fixture includes an upper clamping device and a lower clamping device; the upper clamping device is a fixing cap matching the propeller, and the lower clamping device is an M6 self-locking nut.

[0044] The M6 self-locking nut used as the lower pad is a standard part, with a round end diameter dc = 12.48 mm, a hexagon end across flat distance s = 9.8 mm, and a thickness m = 5.8 mm.

[0045] Step 4: Machine the propeller shaft section, base and propeller mounting and clamping device of the test fixture, and install them on the propeller-wing coupling static test device.

[0046] As Figure 3 shown, during installation, the propeller is clamped in place by the self-locking nut below and the propeller fixing cap above; among them, the hexagon end of the M6 self-locking nut faces the optical axis section of the propeller shaft, and the nut is screwed to the root of the threaded section. The propeller fixing cap used as the upper clamping device adopts a standard model matching the propeller, and the installation process is the same as the standard installation method of the propeller. After passing the propeller through the propeller shaft and screwing it in from above, the propeller is pressed tightly on the nut pad, then the installation of the propeller is completed.

[0047] The propeller-wing coupled static test device includes a motor, a wing, a fairing, a bracket, internal sensors, and a test fixture for propellers with different shaft lengths, which is used to simulate the combined form of the propeller and wing of a high aspect ratio unmanned aerial vehicle. By measuring the forces on the motor, wing, and propeller-wing coupled static test device, data such as coupled aerodynamic forces are obtained, and relevant research is carried out. The connection process of the test fixture for propellers with different shaft lengths to the propeller-wing coupled static test device is the same as the standard installation method of the propeller. The device is connected to the motor shaft through the bolt holes on the base, and thread glue can be injected to strengthen the connection. When changing the propeller shaft length according to the test requirements, the corresponding experimental fixture sub-device with the appropriate shaft length is disassembled and replaced.

[0048] A propeller installed with a test fixture sub-device proposed in an embodiment of the present invention is as Figure 4 shown. The test fixture sub-device is installed on the propeller-wing coupled static test device as Figure 5 shown.

[0049] Compared with the prior art, the implementation method of the test fixture for propellers with different shaft lengths proposed in an embodiment of the present invention is used for the unsteady aerodynamic force test of variable shaft length propellers of high aspect ratio solar unmanned aerial vehicles. While effectively fixing the propeller and ensuring normal operation, it provides a series of determined distances between the propeller and the motor base / wing, meeting the requirements for analyzing the influence effects of the distance change between the propeller and the wing on relevant coupled aerodynamic forces and aerodynamic loads, as well as the influence of different propeller shaft lengths on the dynamic characteristics of the propeller itself. The structure is simple and reliable, effectively reducing costs and avoiding waste of resources; it does not change the connection method between the propeller and the propeller shaft and does not affect the mechanical effect exerted by the rotation of the propeller on the propeller shaft.

[0050] The above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for implementing a test fixture for propellers with different shaft lengths, characterized in that The steps are as follows: Based on the selected propeller for the test and various spacings between the propeller and the motor mount required by the test, design the propeller shaft section of the test fixture that matches the propeller; Based on the selected motor mount for the test, design the base of the test fixture that matches the motor bearing; Based on the selected propeller for the test, design the propeller mounting and clamping device of the test fixture; Machine the propeller shaft section, base, and propeller mounting and clamping device of the test fixture, and install them on the propeller-wing coupling static test device; wherein, the test fixture includes multiple test fixture sub-devices with different lengths of propeller shaft sections and the same base and propeller mounting and clamping device. Each test fixture sub-device is used to independently complete the fixed connection with the propeller and the motor bearing, and meet one of the various spacing requirements between the propeller and the motor mount; After the test fixture is installed, it is used to adjust the distance between the propeller and the wing and the length of the propeller shaft in the propeller-wing coupling static test device; The propeller mounting and clamping device of the test fixture sub-device includes an upper clamping device and a lower clamping device; the upper clamping device is a fixing cap, and the lower clamping device is a self-tightening nut; The propeller shaft section of the test fixture sub-device includes a threaded section and a smooth shaft section; wherein, Multiple test fixture sub-devices have the same threaded section; the part of the threaded section away from the smooth shaft section is used to cooperate with the propeller and the fixing cap; the part close to the smooth shaft section is used to cooperate with the self-tightening nut; the threaded section is a reverse-thread thread; Multiple test fixture sub-devices have smooth shaft sections with the same diameter but different lengths; wherein, the lengths of the multiple smooth shaft sections are determined according to the various spacings between the propeller and the motor mount required by the test, and are respectively the results obtained by subtracting the thickness of the self-tightening nut from the various spacings between the propeller and the motor mount required by the test.

2. The implementation method of the test fixture for the non-coaxial length propeller according to claim 1, characterized in that The base is integrally formed with the propeller shaft section, close to the smooth shaft section and away from the threaded section; the base is a straight cylinder, coaxial with the propeller shaft section; three identical bolt holes for cooperating with the motor bearing are evenly distributed around the axis of the base; the axes of the three bolt holes are evenly distributed on the side surface of the cylinder coaxial with the base; the bolt holes are two-stage stepped through holes, the first-stage step is located on the side of the base close to the propeller shaft section; the second-stage step is located on the side of the base away from the propeller shaft section; there is a blind hole on the side of the base away from the propeller shaft section for accommodating the motor bearing head.

3. The implementation method of the test fixing device for the non-coaxial length propeller according to claim 2, characterized in that The thread diameter of the threaded section is M6, and the total length of the threaded section is 29.3 mm; wherein, the length of the part away from the smooth shaft section is 23.5 mm, and the length of the part close to the smooth shaft section is 5.8 mm.

4. The implementation method of the test fixture for the non-coaxial length propeller according to claim 3, characterized in that, The bottom diameter of the base is 21 mm, and the height is 5.5 mm; the bottom diameter of the cylinder coaxial with the base and with the axes of the three bolt holes evenly distributed on its side surface is 15 mm; the bottom diameter of the first-stage step is 4.8 mm, and the depth is 3.5 mm; the bottom diameter of the second-stage step is 2.7 mm, and the depth is 2 mm; the bottom diameter of the blind hole is 9 mm and the depth is 3.1 mm.

5. The implementation method of the test fixture for propellers with different shaft lengths according to claim 4, characterized in that, The self-locking nut is an M6 self-locking nut with a round end diameter of 12.48 mm, a hexagon end across flats of 9.8 mm, and a thickness of 5.8 mm. During installation, the hexagon end of the M6 self-locking nut faces the smooth shaft section of the propeller shaft, and the nut is screwed to the root of the threaded section.

6. The implementation method of the test fixture for the propeller with different shaft lengths according to claim 5, characterized in that The distances between the propeller and the motor base required by the test include four types, which are 10 mm, 20 mm, 30 mm, and 40 mm respectively. Then the lengths of the smooth shaft sections are divided into four types, which are 4.2 mm, 14.2 mm, 24.2 mm, and 34.2 mm respectively.

7. The implementation method of the test fixing device for the propeller with different shaft lengths according to claim 6, characterized in that, The propeller-wing coupling static test device includes a motor, a wing, a fairing, a bracket, internal sensors, and a test fixing device for propellers with different shaft lengths, and is used to simulate the combined form of a high aspect ratio UAV propeller and wing. By measuring the forces on the motor, wing, and propeller-wing coupling static test device, the coupled aerodynamic force is obtained.

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