Cycloidal propeller control mechanism and method for driving trailing edge flap deflection with double four-bar linkage mechanism

Abstract

This invention belongs to the field of propulsion and control technology for vertical takeoff and landing (VTOL) aircraft, and discloses a cycloidal propeller control mechanism and method for driving trailing edge flap deflection using a dual four-bar linkage mechanism. Based on the traditional single four-bar linkage mechanism used to control the periodic pitch motion of the cycloidal blades, this mechanism adds a four-bar linkage mechanism with a similar structure and principle, specifically designed to independently drive the trailing edge flaps for periodic deflection. By separately setting the pitch eccentricity and pitch eccentricity angle of the pitch control four-bar linkage, and the deflection eccentricity and deflection eccentricity angle of the flap deflection four-bar linkage, the pitch motion of the blades and the deflection motion of the flaps can be independently controlled. Through numerical optimization design, a preset phase difference can be established and maintained between the deflection motion of the flaps and the pitch motion of the blades, and the maximum deflection angle of the flaps is constrained within the target amplitude range, thereby achieving effective improvement and active control of the cycloidal propeller's aerodynamic performance.

Description

Technical Field

[0001] This invention relates to the field of propulsion and control technology for vertical takeoff and landing aircraft, specifically to a cycloidal propeller control mechanism and method for driving trailing edge flap deflection using a double four-bar linkage mechanism. Background Technology

[0002] As a propulsion device for high-efficiency vertical takeoff and landing (VTOL) aircraft, the cycloidal propeller achieves vectorized control of thrust magnitude and direction through periodic pitching motions during its rotation. Traditional cycloidal propellers typically employ a single four-bar linkage to control the periodic pitching motion of the blades, and their blades often utilize symmetrical or fixed-camber airfoils. However, under the curved flow conditions of circular rotation, symmetrical airfoils, based on virtual camber theory, exhibit an aerodynamically equivalent negative camber in the upper half of the rotation, resulting in lower pressure on the lower surface of the blade compared to the upper surface, thus generating negative lift and reducing overall thrust and efficiency. If a fixed-camber airfoil is used, because its camber is unchangeable, it exhibits positive camber in the upper half and negative camber in the lower half during the periodic pitching motion, which is also detrimental to efficient thrust generation and limits the performance improvement of the cycloidal propeller.

[0003] To address the camber adaptability issue, existing technologies explore variable-camber wings. The concept is to change the camber of the airfoil itself to maintain optimal aerodynamic shape across different flight phases or rotation phases. Theoretically, applying variable-camber wings to cycloidal propellers can fundamentally solve the aerodynamic performance mismatch caused by the virtual camber effect during the rotation cycle in symmetrical or fixed-camber airfoils. However, achieving a reliable and efficient variable-camber structure faces numerous technical challenges: First, continuous and repeated camber deformation places extremely high demands on the fatigue strength, flexibility, and aerodynamic sealing of the skin material; second, complex internal drive mechanisms (such as smart material-based actuation, linkages, or hydraulic systems) lead to significant design and manufacturing difficulties, high costs, and a substantial increase in weight; third, under the harsh conditions of high-speed cycloidal propeller rotation, the reliability and maintainability of such complex mechanisms are difficult to guarantee.

[0004] Therefore, the existing technology lacks a mechanism that can easily and reliably achieve dynamic adjustment of camber on a cycloidal propeller and can precisely coordinate with the periodic pitching motion of the propeller blade. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a cycloidal propeller control mechanism that drives the trailing edge flap deflection using a double four-bar linkage mechanism. While retaining the reliability of the traditional four-bar linkage mechanism, it achieves dynamic adjustment of the equivalent camber of the propeller blades to improve the thrust characteristics and overall efficiency of the cycloidal propeller.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, embodiments of this application provide a cycloidal propeller control mechanism for driving trailing edge flap deflection using a dual four-bar linkage mechanism. The cycloidal propeller blades have trailing edge flaps at their trailing edges, including: A pitch control four-bar mechanism for controlling the periodic pitch motion of the cycloidal propeller blades. And a four-bar linkage mechanism for pitch control. Independent four-bar linkages for controlling the periodic deflection of the trailing edge flaps ; Among them, the pitch control four-bar mechanism Including the cycloidal propeller rotation center Pitch eccentricity Pitch control pivot and the blade pitch axis The pitch control pivot and the blade pitch axis Located on the blade, the pitch eccentricity is adjusted. With pitch eccentricity Controlling the actual pitch angle of the blades ; The flap deflection four-link mechanism Including the cycloidal propeller rotation center Deflection point Deflection control pivot and the blade pitch axis The deflection control pivot Located on the trailing edge flap, the deflection eccentricity is adjusted. With deflection eccentricity Controlling the deflection angle of the trailing edge flap ; The flap deflection four-link mechanism The parameters are configured such that there is a preset amplitude relationship and phase relationship between the deflection motion of the trailing edge flap and the pitch motion of the blade.

[0007] In one alternative approach, in the flap deflection four-bar mechanism, the deflection control pivot... The connecting rod and the flap deflection axis Connection, the flap deflection axis Located at the junction of the propeller blade and the trailing edge flap; the deflection axis of the flap With respect to the pitch axis of the blade Deflection control pivot The geometric relationship between them determines the flap deflection angle. Virtual pitch angle of flaps and the actual pitch angle of the blades The kinematic relationship between them.

[0008] In one alternative approach, the flap deflection angle It is determined by the following relationship: in, This is the actual pitch angle of the propeller blade. For the virtual pitch angle of the flaps, The flap deflection axis Length from the leading edge of the blade For the blade pitch axis Length from the leading edge of the blade Deflection control pivot To the blade pitch axis The length of the connecting line.

[0009] In one alternative approach, the actual pitch angle of the blade Virtual pitch angle of flaps As the blade azimuth angle The change is determined by the following relationship: in, , For pitch eccentricity point To the blade pitch axis The length of the connection line, For the deflection eccentricity point To the blade pitch axis The length of the connection line, The radius of rotation of the cycloidal propeller. As the pitch control pivot To the blade pitch axis The length of the connecting line.

[0010] In one alternative approach, flap control parameters The amplitude of the flap deflection angle was determined through numerical optimization methods. Match the preset target amplitude At the same time, the azimuth angle at which the flap deflection angle reaches its amplitude. The azimuth angle at which the blade pitch angle reaches its amplitude The difference, i.e., the phase difference Match the preset target phase difference .

[0011] Secondly, embodiments of this application also provide a cycloidal propeller control method for driving trailing edge flap deflection using a double four-bar linkage mechanism, for determining the flap control parameters in the aforementioned cycloidal propeller control mechanism. This includes the following steps: The target amplitude of the flap deflection angle is set. Phase difference with target ; Construct about the deflection eccentricity and deflection eccentricity The objective function is defined as the magnitude of the flap deflection angle calculated under the current parameters. and phase difference With the target amplitude and target phase difference The overall deviation; The flap control parameters Within the feasible region, the objective function is minimized using a numerical optimization algorithm to obtain the optimal parameter combination. .

[0012] In an alternative approach, the objective function takes the form of a sum of squared errors: in, and These are the weighting coefficients.

[0013] In one alternative approach, the numerical optimization algorithm is the Nelder-Mead simplex method.

[0014] The beneficial effects of this invention are as follows: (1) Significantly improved aerodynamic performance: By periodically and dynamically deflecting the trailing edge flap, the equivalent camber of the blade is optimized locally in real time, which effectively overcomes the problems of negative lift generated by symmetrical airfoils during the first half of the rotation cycle and the camber of fixed camber airfoils not adapting during the rotation cycle, so that the blade can maintain good aerodynamic characteristics throughout the entire cycle, thereby significantly improving the overall thrust output and propulsion efficiency.

[0015] (2) Precise and flexible motion control: The dual four-bar linkages are independent of each other and can precisely control the pitch motion of the blades and the deflection motion of the flaps. By optimizing the calculation of the deflection eccentricity and deflection eccentricity angle, the maximum deflection angle of the flaps can reach the target preset amplitude and maintain the preset optimal phase difference between it and the maximum pitch angle of the blades, thereby achieving fine and active control of aerodynamic characteristics.

[0016] (3) Simple and reliable structure with strong practicality: The mechanism is based on the mature and robust four-bar linkage principle, which does not require complex electrical control, hydraulic systems or intelligent material actuators, thus avoiding the difficulties in skin material, structural design and manufacturing of variable camber wings. The mechanism has a compact structure, direct power transmission and rapid response, and is particularly suitable for long-term reliable operation under the harsh conditions of high-speed and high-frequency reciprocating motion of cycloidal propellers. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a two-dimensional structure of a cycloidal propeller with trailing edge flaps deflecting the blades, provided in an embodiment of the present invention (taking a four-bladed propeller as an example).

[0019] Figure 2 This is a schematic diagram of the global double four-bar linkage mechanism of the cycloidal propeller control mechanism that drives the trailing edge flap deflection according to an embodiment of the present invention.

[0020] Figure 3 yes Figure 2 A magnified schematic diagram of a portion of the propeller blades.

[0021] Figure 4 The variation of various angles with the blade azimuth angle when the actual pitch angle amplitude of the blade is 25°, the flap deflection angle amplitude is 10°, and the phase difference is 0°.

[0022] Figure 5 The variation of various angles with the blade azimuth angle when the actual pitch angle amplitude of the blade is 25°, the flap deflection angle amplitude is 15°, and the phase difference is 0°.

[0023] Figure 6 The variation of the blade azimuth angle with respect to the actual pitch angle amplitude of the blade, the flap deflection angle amplitude of 15°, and the phase difference between the flap deflection and the actual pitch angle of the blade of 10°.

[0024] Figure 7 The variation of the blade azimuth angle with the actual pitch angle amplitude of the blade is 25°, the flap deflection angle amplitude is 15°, and the phase difference between the flap deflection and the actual pitch angle of the blade is 10°. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0026] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used solely for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In the description of the present invention, unless otherwise stated, "a plurality of" means two or more. Furthermore, the terms "first" and "second" are merely used for descriptive distinction and have no special meaning.

[0029] This invention provides a cycloidal propeller control mechanism for driving trailing edge flap deflection using a dual four-bar linkage, such as... Figures 1 to 3 As shown, where, Center of rotation of the cycloidal propeller Let be the radius of rotation of the cycloidal propeller, and let the cycloidal propeller rotate around... Rotate counterclockwise. for The blade azimuth angle at a given moment is defined as the angle at which the blade rotates counterclockwise from the right side of the horizontal axis. For pitch eccentricity, For pitch eccentricity, For pitch eccentricity, The axis of pitch of the propeller blades for Length from the leading edge, As the pitch control pivot, The length of the connection is Actual pitch angle of the propeller blade The actual chord direction of the blade tangential direction of rotational speed The angle between the two elements. The above describes the single four-bar linkage mechanism commonly used in traditional cycloidal propellers to control the periodic pitch motion of the blades, visually represented as a pitch control four-bar linkage mechanism. By adjusting the pitch eccentricity With pitch eccentricity It can control the magnitude and direction of the vector thrust separately.

[0030] Preferably, the mechanism for driving the trailing edge flap based on the double four-bar linkage is as follows: by adding another four-bar linkage similar to pitch control, the periodic beneficial deflection of the trailing edge flap is achieved, which is intuitively manifested as a flap deflection four-bar linkage mechanism. .in, For the deflection eccentricity point, To deflect the eccentricity, To deflect the eccentric angle, As the flap deflection axis, for Length from the leading edge, As the deflection control fulcrum, The length of the connection is Virtual pitch angle of flaps for Direction of connection tangential direction of rotational speed The included angle. According to the typical motion equation of a four-bar linkage, the actual pitch angle of the blade can be obtained. Virtual pitch angle of flaps As the blade azimuth angle The changes can be uniformly represented as: in, , and They are respectively and The length of the connecting line.

[0031] In obtuse triangle middle, . Length of connection , Length of connection Then, by the Law of Sines, we can obtain: Trailing edge flap deflection angle That is If the angles are complementary, then we have: In all geometric parameters of the double four-bar linkage mechanism and pitch eccentricity And pitch eccentricity Under certain conditions, the amplitude of the blade pitch angle can be determined. and the corresponding blade azimuth angle To ensure that flap deflection has a beneficial effect on improving the aerodynamic performance of the cycloidal propeller, the flap deflection motion and the blade pitch motion need to maintain a certain phase difference or be synchronized (i.e., the phase difference is 0). In this system, this is represented by the difference in blade azimuth angle when the flap deflection motion and the blade pitch motion reach their amplitudes. Furthermore, to achieve optimal efficiency, the blade pitch angle amplitude is used as the reference point. The amplitude of the trailing edge flap deflection angle The constraints are within a certain range. Therefore, the deflection eccentricity is obtained through numerical optimization calculation. and deflection eccentricity This causes the flap deflection angle amplitude to be... It equals the target set amplitude, and simultaneously makes it reach the target value. and The phase difference is equal to the target set value, that is... .

[0032] Based on the above known conditions and objective settings, this numerical optimization problem can be reduced to: finding a set of optimal flap control parameters (deflection eccentricity) under the kinematic model constraints of the double four-bar linkage mechanism. With deflection eccentricity This causes the flap deflection angle amplitude to be... Match the preset target amplitude At the same time, the flap deflection angle reaches the amplitude. The azimuth angle at which the blade pitch angle reaches its amplitude The difference, i.e., the phase difference Match the preset target phase difference The specific numerical optimization calculation process is as follows: Construct a multi-objective function to measure the deviation between the current parameter and the target value. The error is expressed in the form of the sum of squared errors, i.e.: in, and These are weighting coefficients used to balance the importance of the two objectives; they must be equally precise, i.e., both should be set to 1. The optimization objective is to find a system that makes the two objectives equal in importance. The objective function is to minimize (ideally zero) the combination of parameters. The Nelder-Mead simplex method using Matlab's built-in `fminsearch` function is employed to solve for the objective function. The optimization process involves optimizing the parameters... The algorithm automatically searches within the feasible region, continuously updating parameters through iterative calculations to drive the objective function value to converge to its minimum. When the optimization algorithm meets the convergence condition (such as the objective function value falling below a set tolerance or the number of iterations reaching the upper limit), its final parameter solution is output. This is what we are looking for. At this point, the amplitude of the flap motion determined by this set of parameters... Phase difference It will simultaneously meet or be very close to the preset target values, thereby achieving precise and synchronous customization of the flap deflection motion to meet specific aerodynamic performance improvement requirements.

[0033] like Figures 4 to 7 As shown, the actual pitch angle of the blade under typical conditions is illustrated. Virtual pitch angle of flaps and flap deflection angle As the blade azimuth angle The changes. Figure 4 The variation of various angles with the blade azimuth angle when the actual pitch angle amplitude of the blade is 25°, the flap deflection angle amplitude is 10°, and the phase difference is 0°. Figure 5 The variation of various angles with the blade azimuth angle when the actual pitch angle amplitude of the blade is 25°, the flap deflection angle amplitude is 15°, and the phase difference is 0°. Figure 6 The variation of the blade azimuth angle with respect to the actual pitch angle amplitude of the blade, the flap deflection angle amplitude of 15°, and the phase difference between the flap deflection and the actual pitch angle of the blade of 10°. Figure 7 The variation of the blade azimuth angle with the actual pitch angle amplitude of the blade is 25°, the flap deflection angle amplitude is 15°, and the phase difference between the flap deflection and the actual pitch angle of the blade is 10°. Figures 4 to 7 The curves showing the variation of various angles with the blade azimuth angle intuitively and quantitatively demonstrate that this design can accurately achieve the preset control target and optimize aerodynamic performance.

[0034] Specifically, Figures 4 to 7 Together, they demonstrate the independent controllability of the flap deflection angle relative to the actual pitch angle of the propeller blades. By setting different deflection eccentricity and deflection eccentricity angles, the mechanism provided by this invention can accurately output different flap motion modes. Figure 4 and Figure 5 Under the same blade pitch angle amplitude (25°) and zero phase difference conditions, flap deflection angle amplitudes of 10° and 15° were achieved, respectively, proving that the mechanism can independently control the flap deflection amplitude to meet different aerodynamic requirements. Figure 6 and Figure 7This further demonstrates that, with a fixed pitch angle amplitude (25°) and flap deflection angle amplitude (15°), the mechanism can achieve precise phase difference control of the flap deflection relative to the blade pitch, either leading (+10°) or lagging (-10°). The figure clearly shows that the difference between the azimuth angle corresponding to the peak point of the flap deflection angle curve and the azimuth angle of the actual blade pitch angle curve peak point perfectly matches the preset phase difference value. These characteristics fully verify that the double four-link parameters determined by the above numerical optimization method can enable the flap deflection motion to simultaneously satisfy the two key objectives of amplitude and phase. Therefore, the attached figures confirm that this mechanism and control method can flexibly and accurately set the flap deflection motion to a form with an optimal coordination relationship with the blade pitch motion, thereby improving the flow field and increasing lift by dynamically adjusting the local camber, ultimately achieving the core invention objective of improving the overall thrust and efficiency of the cycloidal propeller.

[0035] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0036] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A cycloidal propeller control mechanism for driving trailing edge flap deflection via a double four-bar linkage, characterized in that, The cycloidal propeller blades are provided with trailing edge flaps, including: A pitch control four-bar mechanism for controlling the periodic pitch motion of the cycloidal propeller blades. And a four-bar linkage mechanism for pitch control. Independent four-bar linkages for controlling the periodic deflection of the trailing edge flaps ; Among them, the pitch control four-bar mechanism Including the cycloidal propeller rotation center Pitch eccentricity Pitch control pivot and the blade pitch axis The pitch control pivot and the blade pitch axis Located on the blade, the pitch eccentricity is adjusted. With pitch eccentricity Controlling the actual pitch angle of the blades ; The flap deflection four-link mechanism Including the cycloidal propeller rotation center Deflection point Deflection control pivot and the blade pitch axis The deflection control pivot Located on the trailing edge flap, the deflection eccentricity is adjusted. With deflection eccentricity Controlling the deflection angle of the trailing edge flap ; The flap deflection four-link mechanism The parameters are configured such that there is a preset amplitude relationship and phase relationship between the deflection motion of the trailing edge flap and the pitch motion of the blade.

2. The cycloidal propeller control mechanism according to claim 1, characterized in that, In the aforementioned flap deflection four-bar mechanism, the deflection control pivot point The connecting rod and the flap deflection axis Connection, the flap deflection axis Located at the junction of the propeller blade and the trailing edge flap; the deflection axis of the flap With respect to the pitch axis of the blade Deflection control pivot The geometric relationship between them determines the flap deflection angle. Virtual pitch angle of flaps and the actual pitch angle of the blades The kinematic relationship between them.

3. The cycloidal propeller control mechanism according to claim 2, characterized in that, The flap deflection angle It is determined by the following relationship: ， in, This is the actual pitch angle of the propeller blade. For the virtual pitch angle of the flaps, The flap deflection axis Length from the leading edge of the blade For the blade pitch axis Length from the leading edge of the blade Deflection control pivot To the blade pitch axis The length of the connecting line.

4. The cycloidal propeller control mechanism according to claim 3, characterized in that, The actual pitch angle of the blade Virtual pitch angle of flaps As the blade azimuth angle The change is determined by the following relationship: ， in, , For pitch eccentricity point To the blade pitch axis The length of the connection line, For the deflection eccentricity point To the blade pitch axis The length of the connection line, The radius of rotation of the cycloidal propeller. As the pitch control pivot To the blade pitch axis The length of the connecting line.

5. The cycloidal propeller control mechanism according to any one of claims 1 to 4, characterized in that, flap control parameters The amplitude of the flap deflection angle was determined through numerical optimization methods. Match the preset target amplitude At the same time, the azimuth angle at which the flap deflection angle reaches its amplitude. The azimuth angle at which the blade pitch angle reaches its amplitude The difference, i.e., the phase difference Match the preset target phase difference .

6. A cycloidal propeller control method for driving trailing edge flap deflection via a double four-bar linkage mechanism, used to determine the flap control parameters in the cycloidal propeller control mechanism described in claim 5. Its characteristics are, Includes the following steps: The target amplitude of the flap deflection angle is set. Phase difference with target ; Construct about the deflection eccentricity and deflection eccentricity The objective function is defined as the magnitude of the flap deflection angle calculated under the current parameters. and phase difference With the target amplitude and target phase difference The overall deviation; The flap control parameters Within the feasible region, the objective function is minimized using a numerical optimization algorithm to obtain the optimal parameter combination. .

7. The method according to claim 6, characterized in that, The objective function is in the form of a sum of squared errors: ， in, and These are the weighting coefficients.

8. The method according to claim 6 or 7, characterized in that, The numerical optimization algorithm is the Nelder-Mead simplex method.

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