A continuous automatic torque-changing propeller

Abstract

The present invention relates to a continuous automatic torque-changing propeller, comprising blades, a torque-changing spiral slide, a sleeve, a return spring, an adjusting bolt, an axial slider and a power output shaft. Each blade can deform along with the torque-changing spiral slide under the centrifugal force load to achieve the torque change of the blade; the power output shaft is fixedly connected to the axial slider, and when the power output shaft rotates, the axial slider is driven to rotate synchronously; the axial slider comprises a small diameter section and a large diameter section, and an adjusting bolt is connected to the small diameter section to axially limit the sleeve for adjusting the initial pitch angle of the blade; a boss is provided in the radial direction on the large diameter section. The present invention utilizes the centrifugal force difference between high and low idle speeds to achieve the automatic and continuous change of the pitch angle of the blade, without the need for an actuating mechanism and energy supply, greatly simplifies the composition of the propeller pitch-changing mechanism, improves reliability, and reduces system weight.

Description

Technical Field

[0001] The invention relates to a continuous automatic torque-changing propeller, belonging to the technical field of propeller aircraft propulsion design. Background Art

[0002] The propulsion system of high-altitude, long-endurance solar-powered aircraft is generally a solar-electric-propeller propulsion method. Due to the limitations of the operating environment, fixed-pitch propellers are used. However, it is difficult for fixed-pitch propellers to meet performance requirements at both high and low altitudes. The traditional solution is to use heavy high-power electric motors. High-power motors can meet low-altitude propulsion requirements, but high-power operation is not required during high-altitude cruising. Therefore, the electric motors occupy the limited carrying capacity of the aircraft and reduce the performance of the aircraft.

[0003] In order to make the propeller have high efficiency in the entire working range, variable pitch is an optional approach, but the traditional torque conversion mechanism is complex and heavy, and is not suitable for high-altitude long-endurance solar aircraft. However, if a fixed pitch propeller is used, when flying at low altitude, due to the high air density on the ground, the propeller requires a large input power to work, and the propeller cannot work normally. Therefore, combining the advantages of variable pitch propellers and fixed pitch propellers to enable the propeller to have variable torque within a certain angle range is of great practical significance for reducing the weight of the motor and improving the performance of the aircraft. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to propose a continuous automatic torque-variable propeller, to realize the automatic variable pitch function of the propeller of a near-space solar aircraft, to take into account high and low altitude working conditions, and to maximize the performance of the propeller propulsion system at high and low altitudes.

[0005] The solution of the present invention is:

[0006] A continuous automatic torque-changing propeller comprises a blade, a torque-changing spiral chute, a sleeve, a return spring, an adjusting bolt, an axial slider and a power output shaft. Each blade can deform along with the torque-changing spiral chute under a centrifugal force load to achieve torque change of the blade.

[0007] The power output shaft is fixedly connected to the shaft-type slider, and when the power output shaft rotates, the shaft-type slider is driven to rotate synchronously;

[0008] The shaft-type slider includes a small diameter section and a large diameter section. The small diameter section is connected with an adjusting bolt to axially limit the sleeve and is used to adjust the initial pitch angle of the blade. The large diameter section is provided with a boss in the radial direction.

[0009] The sleeve is a hollow structure, which is integrally sleeved on the shaft-type slider, and the end close to the power output shaft is a thick-walled end. The return spring is sleeved on the shaft-type slider, and one end of the return spring presses on the thick-walled end of the sleeve, and the other end presses on the shoulder of the large-diameter section of the shaft-type slider;

[0010] The other end of the sleeve is fixedly connected with a paddle;

[0011] A torque-changing spiral sliding groove is arranged at the middle position of the sleeve, and the boss is placed in the torque-changing spiral sliding groove.

[0012] Furthermore, when the blade is located at the initial pitch angle, the adjusting bolt contacts the sleeve to limit the position.

[0013] Furthermore, the boss and the torque-changing spiral slide groove have a clearance fit, and the fit clearance is 0.2-0.5 mm.

[0014] Furthermore, the torque-changing spiral chute is a spiral curve.

[0015] Furthermore, at least one shaft-type slider is arranged on the power output shaft.

[0016] Furthermore, the rotation of the power output shaft drives the axial slider to rotate synchronously, and then drives the sleeve and the blade to rotate synchronously.

[0017] Furthermore, when the speed of the power output shaft changes, the centrifugal force of the blade changes, and the centrifugal force causes the sleeve to move along the axial slider. The boss acts on the torque-changing spiral groove, and the sleeve rotates relative to the axial slider, thereby driving the blade to rotate and changing the blade's pitch angle.

[0018] Furthermore, the pitch angle of the blades changes by 0°-20°.

[0019] Furthermore, the pitch angle change angle θ satisfies: Among them, R is the radius of the sleeve, L is the axial stroke of the sleeve, and f is the friction coefficient between the boss and the slide groove.

[0020] Furthermore, the spring rate is restored Among them, F d is the centrifugal load on the blade at cruising altitude, F i is the centrifugal load at the blade ground height, and L is the axial stroke of the sleeve.

[0021] Furthermore, the free state length of the return spring is Fi / E+L, where F i is the centrifugal force load at the blade ground height, E is the return spring stiffness, and L is the axial stroke of the sleeve.

[0022] The beneficial effects of the present invention compared with the prior art are:

[0023] (1) The present invention combines the advantages of simple connection and light weight of the fixed-pitch propeller, while also having a variable torque function within a certain angle range, thereby reducing the requirements for the motor and improving the efficiency of the motor-propeller propulsion system at medium and low altitudes;

[0024] (2) The present invention utilizes the centrifugal force difference between high and low idle speeds to achieve automatic and continuous change of the propeller pitch angle, without the need for an actuating mechanism and energy supply, thereby greatly simplifying the composition of the propeller pitch change mechanism, improving reliability, and reducing system weight;

[0025] (3) Compared with the prior art of increasing the power of the electric motor or equipping a variable-torque propeller, the present invention targets the requirements of propellers covering high and low altitudes for near-space solar aircraft, and provides a good technical foundation for the use of variable-torque propellers in future high-altitude and long-flight solar aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the continuous automatic torque-changing propeller of the present invention;

[0027] Figure 2 It is a positional relationship diagram of the sleeve, spiral chute and boss of the present invention;

[0028] Figure 3 The present invention is a flow chart of a method for determining a continuous automatic torque-changing propeller. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the embodiments.

[0030] A continuously variable torque propeller, such as Figure 1 , 2 As shown, it includes a blade 3, a torque-changing spiral chute 25, a sleeve 24, a return spring 23, an adjusting bolt 22, an axial slider 21 and a power output shaft 1. Each blade can deform along with the torque-changing spiral chute 25 under the centrifugal force load to achieve the torque change of the blade;

[0031] The power output shaft 1 is fixedly connected to the shaft-type slider 21. When the power output shaft 1 rotates, the shaft-type slider 21 is driven to rotate synchronously.

[0032] The shaft slider 21 includes a small diameter section and a large diameter section. The small diameter section is connected with an adjusting bolt 22 to axially limit the sleeve 24 for adjusting the initial pitch angle of the blade 3. The large diameter section is provided with a boss 26 in the radial direction.

[0033] The sleeve 24 is a hollow structure, which is integrally sleeved on the shaft slider 21, and the end close to the power output shaft 1 is a thick-walled end. The return spring 23 is sleeved on the shaft slider 21, and one end of the return spring 23 presses on the thick-walled end of the sleeve 24, and the other end presses on the shoulder of the large-diameter section of the shaft slider 21;

[0034] The other end of the sleeve 24 is fixedly connected with a blade 3;

[0035] A torque-changing spiral groove 25 is provided in the middle of the sleeve 24 , and the boss is placed in the torque-changing spiral groove 25 .

[0036] When the blade 3 is located at the initial pitch angle, the adjusting bolt 22 contacts and limits the position of the sleeve 24 .

[0037] The boss and the torque-changing spiral slide groove 25 are clearance matched, and the clearance is 0.2-0.5mm.

[0038] The torque-changing spiral chute 25 is a spiral curve.

[0039] At least one shaft-type slider 21 is arranged on the power output shaft 1 .

[0040] The rotation of the power output shaft 1 drives the shaft slider 21 to rotate synchronously, and further drives the sleeve 24 and the blade 3 to rotate synchronously.

[0041] When the rotation speed of the power output shaft 1 changes, the centrifugal force of the blade 3 changes, and the centrifugal force causes the sleeve 24 to move along the axial slider 21. The boss acts on the torque-changing spiral groove 25, and the sleeve 24 rotates relative to the axial slider 21, thereby driving the blade 3 to rotate and changing the pitch angle of the blade 3.

[0042] The pitch angle change of blade 3 is 0°-20°.

[0043] The pitch angle change angle θ satisfies: Among them, R is the radius of the sleeve, L is the axial stroke of the sleeve, and f is the friction coefficient between the boss and the slide groove.

[0044] Return spring rate Among them, F d is the centrifugal load on the blade at cruising altitude, F i is the centrifugal load at the blade ground height, and L is the axial stroke of the sleeve.

[0045] The free state length of the return spring is Fi / E+L, where F i is the centrifugal force load at the blade ground height, E is the return spring stiffness, and L is the axial stroke of the sleeve.

[0046] like Figure 3 The present invention proposes a method for determining a continuous automatic variable torque propeller, wherein the automatic variable pitch mechanism is applicable to a propeller with two blades, each blade being capable of rotational deformation under a tensile load, and the steps of the determination method are as follows:

[0047] (1) First, according to the requirements of the cruise condition, the aerodynamic shape of the propeller blade is designed using the currently common vortex theory method. The vortex theory method is modified from the strip theory. When designing the aerodynamic shape of the propeller blade, multiple sections are first divided according to the blade radius. Generally, 10 sections can achieve sufficient accuracy. The selected airfoil is placed at the section. According to the composite speed of the cruise speed and the propeller speed, the chord length and twist angle distribution of each section are determined through iteration. The aerodynamic shape of the propeller blade in the cruise state is determined, that is, the shape chord length distribution and twist angle β of the propeller blade are determined. d The cruise condition includes the propeller speed ω d and forward speed Vd;

[0048] (2) Secondly, the propeller operating conditions at ground level are studied. The propeller operating conditions mainly include forward speed, propeller speed, air density, propeller thrust and torque. The propeller shape determination method described in (1) is still used to determine the new torsion angle distribution β d -θ, where θ is the same in all sections of the blade. The steps are as follows: First, an initial torque angle θ0 and an initial speed ω0 are given. According to the eddy current theory described in (1), the propeller blade is checked at the torsion angle β d In the -θ state, whether the propeller torque meets the thrust and torque requirements, which can be calculated by pressing P motorns =P propns Determine θ and ω by iterative calculation i . Among them, P motorns is the output power of the motor at the cruising point, P propns is the propeller input power at the cruise point; the ground altitude stated is the ground altitude at takeoff;

[0049] (3) Determine the torque angle θ and initial speed ω in step (2) i , the radial extension of the blade is taken as 0.01Rb, where Rb is the propeller radius.

[0050] (4) Calculate the aerodynamic loads based on the aerodynamic shape determined in step (1), determine the preliminary structure of the propeller blades based on the loads and general propeller structure design methods, and verify the preliminary structure with the centrifugal force generated by the propeller speed at the cruise point to ensure that the structure meets the strength and stiffness requirements;

[0051] (5) Based on the blade structure determined in step (4), the mass distribution of the blade structure can be obtained, and the centrifugal force load of the propeller blade can be calculated based on the propeller speed and mass distribution. Calculate the centrifugal force load F at ground height i =mω i 2 r and the centrifugal load F at cruising altitude d =mω d2 r, where m is the propeller mass and r is the radius of the propeller blade center of mass;

[0052] (6) According to the working load at ground height, according to the preliminary structure of the blade given in step (4), it is necessary to determine the initial structure in more detail, and according to the centrifugal load given in (5), determine the basic parameters of the spiral torque converter mechanism, including the radius R of the spiral sleeve, the spiral angle, the materials of the slider and the sleeve, and the stiffness of the return spring, specifically:

[0053] First, according to the relation Determine the torque angle 0 when the blade is extended L = 0.01Rb, and the torque angle -θ when the blade is not extended. The two angles transition linearly, and the θ direction is the direction that increases the blade torque angle.

[0054] Secondly, according to the relation Select the spring stiffness and the outer diameter of the spring according to the spiral sleeve radius Rh, where h is the thickness of the spiral sleeve.

[0055] Finally, select the spring length according to Fi / E+L so that the blade is under load ΔF=F d -F i Under the action of , the overall pitch angle of the blade rotates by θ, but the speed is less than ω i When the propeller pitch angle is kept at -θ degrees, the speed is greater than ω d When the propeller is at a speed of 0°, the propeller torque angle is kept at 0 radians, which is consistent with the aerodynamic shape at the cruise point. Thus, the propeller with continuous automatic torque change is obtained.

[0056] The present invention combines the advantages of simple connection and light weight of the fixed-pitch propeller, and at the same time has a variable torque function within a certain angle range, reduces the requirements for the motor, and improves the efficiency of the motor-propeller propulsion system at medium and low altitudes;

[0057] The present invention utilizes the centrifugal force difference between high and low idle speeds to realize the automatic and continuous change of the propeller pitch angle, without the need for an actuating mechanism and energy supply, greatly simplifies the composition of the propeller pitch change mechanism, improves reliability, and reduces system weight;

[0058] Compared with the prior art of increasing the power of the electric motor or equipping a variable-torque propeller, the present invention aims at the requirements of propeller coverage of high and low altitudes for near-space solar aircraft, and provides a good technical foundation for the use of variable-torque propellers in future high-altitude and long-flight solar aircraft.

[0059] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A continuously variable torque propeller, characterized in that: It comprises a blade (3), a torque-changing spiral slide groove (25), a sleeve (24), a return spring (23), an adjusting bolt (22), an axial slider (21) and a power output shaft (1), wherein each blade can deform along with the torque-changing spiral slide groove (25) under a centrifugal force load to achieve torque change of the blade; The power output shaft (1) is fixedly connected to the shaft-type slider (21), and when the power output shaft (1) rotates, the shaft-type slider (21) is driven to rotate synchronously; The shaft-type slider (21) comprises a small diameter section and a large diameter section, and an adjusting bolt (22) is connected to the small diameter section to axially limit the sleeve (24) for adjusting the initial pitch angle of the blade (3); a boss (26) is provided in the radial direction on the large diameter section; The sleeve (24) is a hollow structure, and is integrally sleeved on the shaft-type slider (21), and the end close to the power output shaft (1) is a thick-walled end. The return spring (23) is sleeved on the shaft-type slider (21), and one end of the return spring (23) is pressed against the thick-walled end of the sleeve (24), and the other end is pressed against the shoulder of the large-diameter section of the shaft-type slider (21); The other end of the sleeve (24) is fixedly connected with a blade (3); A torque-changing spiral chute (25) is arranged at the middle position of the sleeve (24), and the boss is placed in the torque-changing spiral chute (25).

2. A continuously variable torque propeller according to claim 1, characterized in that: When the blade (3) is located at the initial pitch angle, the adjusting bolt (22) contacts the sleeve (24) to limit the position.

3. A continuously variable torque propeller according to claim 1, characterized in that: The boss and the torque-changing spiral slideway (25) are clearance matched, and the matching clearance is 0.2-0.5mm.

4. A continuously variable torque propeller according to claim 1, characterized in that: The torque-changing spiral chute (25) is a spiral curve.

5. The continuous automatic torque-changing propeller according to claim 1, characterized in that: At least one shaft-type sliding block (21) is arranged on the power output shaft (1).

6. A continuously variable torque propeller according to claim 1, characterized in that: The power output shaft (1) rotates to drive the shaft-type slider (21) to rotate synchronously, thereby driving the sleeve (24) and the blade (3) to rotate synchronously.

7. A continuously variable torque propeller according to claim 6, characterized in that: When the rotation speed of the power output shaft (1) changes, the centrifugal force of the blade (3) changes, and the centrifugal force causes the sleeve (24) to move along the axial slider (21). The boss acts on the torque-changing spiral slide groove (25), and the sleeve (24) rotates relative to the axial slider (21), thereby driving the blade (3) to rotate and changing the pitch angle of the blade (3).

8. A continuously variable torque propeller according to claim 7, characterized in that: The pitch angle change of the blade (3) is 0°-20°.

9. A continuously variable torque propeller according to claim 8, characterized in that: The pitch angle change angle θ satisfies: Among them, R is the radius of the sleeve, L is the axial stroke of the sleeve, and f is the friction coefficient between the boss and the slide groove.

10. The continuously variable torque propeller according to claim 1, characterized in that: Return spring rate Among them, F d is the centrifugal load on the propeller blade at cruising altitude, F i is the centrifugal load at the blade ground height, and L is the axial stroke of the sleeve.

11. The continuous automatic torque-converting propeller according to claim 1, characterized in that: The free state length of the return spring is Fi / E+L, where F i is the centrifugal force load at the blade ground height, E is the return spring stiffness, and L is the axial stroke of the sleeve.

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