A rotor with variable negative torsion and a rotor negative torsion adjustment device

Abstract

The present invention discloses a rotor with variable negative twist and a rotor negative twist adjustment device, which relates to the technical field of aircraft rotor design. It includes a first rigid section, a torsion section, and a second rigid section that are sequentially connected along its span. In the hover state, the negative twist of the first rigid section changes linearly, and it is transitionally connected to the second rigid section through the torsion section. The torsion section can twist around the span of the rotor. At the same time, the rotor negative twist adjustment device further includes a negative twist adjustment mechanism that can apply a torsional force to the rotor to adjust the rotor negative twist. By setting the rotor as a segmented structure and arranging a torsion section between adjacent rigid sections, the present invention can change its negative twist according to the flight state of the helicopter, which is beneficial to improving the flight performance of the rotor. And by adjusting the rotor negative twist through the negative twist adjustment mechanism, the structure is simpler and the cost is lower.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft rotor design, and particularly to a rotor with variable negative twist and a rotor negative twist adjustment device. Background Art

[0002] Due to its unique low-altitude and low-speed performance, helicopters have extensive and irreplaceable applications in both military and civil fields. As the main lift source of a helicopter, improving the performance of the rotor can reduce the power requirement of the helicopter, directly improve the flight performance and flight quality of the helicopter, and thus has always been a research hotspot.

[0003] To achieve this goal, since the 1940s, researchers have analyzed the influence of parameters including the twist angle, rotor radius, rotor speed, chord length distribution, taper ratio, and section airfoil on rotor performance. Flight tests during the same period also showed that after optimizing the above parameters, the hover pull at the same power increased by 15%, the power required for level flight decreased by 20%, and the autorotation glide performance also increased by 15%. However, Gessow pointed out that among many parameters, rotor negative twist is the most effective measure to increase the maximum flight speed of a helicopter and reduce the power loss required under the conditions of a given lift coefficient and tip speed. Quackenbush et al. used the free wake method to conduct research on the aerodynamic shape optimization of the rotor in hover and axial flow flight states, and also showed that the rotor twist distribution is one of the most important parameters affecting rotor performance. A large number of studies have pointed out that rotor negative twist can redistribute lift, delay tip stall, reduce vibration levels, weaken the strength of tip vortices, reduce high-speed pulse noise, reduce the induced power and profile drag power of the rotor, etc. And the effects that can be produced by the negative twist changes at different positions of the rotor are different. Traditional rotors can only flip the entire rotor and do not yet have the function of changing the negative twist of a certain section in the rotor according to the flight state. Summary of the Invention

[0004] The purpose of the present invention is to provide a rotor with variable negative twist and a rotor negative twist adjustment device to solve the problems existing in the prior art. By setting the rotor as a segmented structure and arranging a twist section between adjacent rigid sections, and cooperating with a torque adjustment mechanism, the negative twist can be changed according to the flight state of the helicopter, which is beneficial to improving the flight performance of the rotor.

[0005] To achieve the above object, the present invention provides the following solution: The present invention provides a rotor with variable negative twist, including a first rigid section, a twist section, and a second rigid section that are sequentially connected along its span. In the hover state, the negative twist of the first rigid section changes linearly and is transitionally connected to the second rigid section through the twist section, and the twist section can twist around the span of the rotor.

[0006] Preferably, the second rigid section includes a plurality of middle sections and tip sections arranged in sequence along the span of the rotor. One of the middle sections at one end is connected to the first rigid section through the torsion section. In the hovering state, the negative torsion of the middle sections and the tip section both change linearly, and adjacent middle sections, and between the middle section and the tip section are all connected through the torsion section for transition.

[0007] The present invention also provides a rotor negative torsion adjustment device, which includes the above-mentioned rotor with variable negative torsion, a negative torsion adjustment mechanism and a pitch change rod. One end of the pitch change rod is connected to a drive mechanism for driving the rotation of the rotor, and the other end extends into the interior of the rotor and is fixedly connected to the end of the second rigid section. The negative torsion adjustment mechanism includes a power part. The output end of the power part is connected with a connecting part and can drive the connecting part to move along the axial direction of the output end. The axial direction of the output end is perpendicular to the axial direction of the pitch change rod. The end of the connecting part is fixedly connected to the first rigid section.

[0008] Preferably, a bearing is arranged between the first rigid section and the pitch change rod.

[0009] Preferably, the power part includes a stepping motor installed on the pitch change rod. A screw rod is fixed on the output shaft of the stepping motor. A screw sleeve is rotatably connected to the screw rod. The screw sleeve is fixedly connected to one end of the connecting part, and the other end of the connecting part is fixedly connected to the first rigid section.

[0010] Preferably, an ear plate is arranged on the pitch change rod. The stepping motor is hinged on the ear plate, and the hinge axis is parallel to the pitch change rod.

[0011] Preferably, the connecting part includes a pull rod. One end of the pull rod is fixedly connected to the screw sleeve, and the other end is fixedly connected to the first rigid section.

[0012] Preferably, a limit block for limiting the stroke of the screw sleeve is also fixed to one end of the screw rod away from the output shaft.

[0013] Preferably, the helix angle of the screw rod is less than the friction angle.

[0014] The present invention has achieved the following technical effects compared with the prior art:

[0015] 1. By setting the rotor as a segmented structure and arranging a torsion section between adjacent rigid sections, the present invention can change its negative torsion according to the flight state of the helicopter, which is beneficial to improving the flight performance of the rotor.

[0016] 2. By adjusting the rotor negative torsion through the negative torsion adjustment mechanism, the structure of the present invention is simpler and the cost is lower.

[0017] 3. In the present invention, the helix angle of the screw is less than the friction angle, so that self-locking can occur when the stepping motor stops rotating, achieving the purpose of precise negative torque adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic diagram of the overall structure of the rotor in the present invention;

[0020] Figure 2 It is a schematic diagram of the structure of the negative torque adjustment mechanism in the present invention;

[0021] Wherein, 1. First rigid section; 2. Middle section; 3. Tip section; 4. Torsion section; 5. Pitch change rod; 6. Negative torque adjustment mechanism; 7. Stepping motor; 8. Screw; 9. Screw sleeve; 10. Pull rod; 11. Limit block; 12. Bearing; 13. Ear plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] The purpose of the present invention is to provide a rotor with variable negative torque and a rotor negative torque adjustment device to solve the problems existing in the prior art. By setting the rotor as a segmented structure and arranging a torsion section between adjacent rigid sections, and cooperating with the torque adjustment mechanism, the negative torque can be changed according to the flight state of the helicopter, which is beneficial to the improvement of the flight performance of the rotor.

[0024] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0025] Embodiment 1:

[0026] As Figure 1As shown in the figure, this embodiment provides a rotor with variable negative twist, which includes a first rigid section 1, a torsion section 4, and a second rigid section that are sequentially connected along its span. In the hover state, the negative twist of the first rigid section 1 changes linearly and is transitionally connected to the second rigid section through the torsion section 4. The torsion section 4 can not only ensure the structural stiffness of the rotor in the span direction but also twist around the span direction of the rotor. Among them, the torsion section 4 uses a tension-torsion band, which is a composite material with wound wire in the middle and deformable rubber material on the outside. In this embodiment, the shape of the tension-torsion band is the airfoil shape of the rotor.

[0027] Since the torsion section 4 is provided in the rotor of this embodiment, when the first rigid section 1 is subjected to torsion, the torsion section 4 will twist, causing the first rigid section 1 to change its negative twist value and increasing the angle of attack of the first rigid section 1 (the inner section of the rotor), which is beneficial to reducing the required power of the rotor during hover. The negative twist of the first rigid section 1 will cause lift loss in the middle of the rearward side rotor and at the tip of the forward side rotor during forward flight, which is not conducive to improving the rotor performance. Therefore, when the helicopter needs to fly forward, the negative twist of the first rigid section 1 can be adjusted again to an appropriate state. Thus, by setting the rotor as a segmented structure and arranging the torsion section 4 between adjacent rigid sections in this embodiment, the negative twist can be changed according to the flight state of the helicopter, which is beneficial to improving the flight performance of the rotor.

[0028] Furthermore, in this embodiment, the second rigid section includes a plurality of middle sections 2 and tip sections 3 that are sequentially arranged along the span of the rotor. The middle section 2 at one end is connected to the first rigid section 1 through the torsion section 4. In the hover state, the negative twists of the middle sections 2 and the tip sections 3 both change linearly, and the adjacent middle sections 2, and between the middle section 2 and the tip section 3 are all transitionally connected through the torsion section 4. By further setting the second rigid section as multiple middle sections 2 and tip sections 3, when the negative twist of the first rigid section 1 is adjusted, the torsion sections 4 between adjacent middle sections 2 and the torsion sections 4 between the middle section 2 and the tip section 3 will all twist, causing the negative twist of the middle section 2, which can greatly increase the angle of attack of the first rigid section 1 (the inner section) and the middle section 2 of the rotor, and the angle of attack of the tip section 3 of the rotor decreases significantly. For the helicopter rotor in the hover and high-speed forward flight states, the higher the negative twist rate of the middle section 2, the lower the required power of the rotor. During cruise flight, a middle section negative twist exceeding 12° / R is not conducive to improving the rotor flight performance. At the same time, since the torsion starts from the first rigid section 1 and the negative twist gradually decreases along the span of the rotor, the lift distribution of the rotor along the span can be made more uniform, which can effectively improve the aerodynamic environment of the rotor and increase the rotor efficiency.

[0029] It should be noted that the lengths of the torsion section 4, the first rigid section 1, the middle section 2, and the tip section 3, and the number of the middle sections 2 can be reasonably designed according to the actual rotor blade type. There are 2 middle sections 2 in the attached figure.

[0030] Embodiment 2:

[0031] As Figure 2 shown in the figure, this embodiment provides a rotor negative torque adjustment device, which includes the above-mentioned rotor with variable negative torque, a negative torque adjustment mechanism 6 and a pitch rod 5. One end of the pitch rod 5 is connected to a drive mechanism for driving the rotor to rotate, and the other end extends into the rotor and is fixedly connected to the end of the second rigid section; the negative torque adjustment mechanism 6 includes a power unit. The output end of the power unit is connected with a connecting piece and can drive the connecting piece to move axially along the output end. The axial direction of the output end is perpendicular to the axial direction of the pitch rod 5; the end of the connecting piece is fixedly connected to the first rigid section 1.

[0032] During the flight of the helicopter, the rotor negative torque can be adjusted according to different flight states. The adjustment process is as follows: The power unit acts to drive the connecting piece to move axially along the output end of the power unit, thereby driving the first rigid section 1 to twist around the pitch rod 5. Since several middle sections 2 are also connected through the torsion section 4, the middle sections 2 can also twist around the pitch rod 5, thereby realizing the change of the rotor negative torque.

[0033] Specifically, the power unit includes a stepping motor 7 installed on the pitch rod 5. An ear plate 13 is provided on the pitch rod 5. The stepping motor 7 is hinged on the ear plate 13, and the hinge axis is parallel to the pitch rod 5; a screw rod 8 is fixed on the output shaft of the stepping motor 7. A nut sleeve 9 is rotatably connected to the screw rod 8. A limit block 11 for preventing the nut sleeve 9 from slipping off is provided at the end of the screw rod 8. The nut sleeve 9 is fixedly connected to one end of a pull rod 10, and the other end of the pull rod 10 is welded to the first rigid section 1. The output shaft of the stepping motor 7 drives the screw rod 8 to rotate, causing the nut sleeve 9 to translate along the screw rod 8, pulling the first rigid section 1 to flip through the pull rod 10, and thus changing the rotor negative torque. At the same time, in this embodiment, the stepping motor 7 is hinged on the ear plate 13, enabling the stepping motor 7 to flip around the hinge axis, so that the rotor can smoothly adjust the negative torque.

[0034] Furthermore, a bearing 12 is provided between the first rigid section 1 and the pitch rod 5 in this embodiment.

[0035] Furthermore, the helix angle of the screw rod 8 in this embodiment is less than the friction angle, so that self-locking can occur when the stepping motor 7 stops rotating, achieving the purpose of precise negative torque adjustment.

[0036] Adaptations made according to actual needs are within the protection scope of the present invention.

[0037] It should be noted that for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A rotor negative torque adjustment device, characterized in that, It includes a rotor with variable negative twist, a negative twist adjusting mechanism and a pitch change rod. The rotor includes a first rigid section, a torsion section and a second rigid section connected in sequence along its span direction. In the hover state, the negative twist of the first rigid section changes linearly, and it is transitionally connected to the second rigid section through the torsion section. The torsion section can twist around the span direction of the rotor; the outer shape of the torsion section is the airfoil shape of the rotor. The second rigid section includes a number of middle sections and tip sections arranged in sequence along the span direction of the rotor. The middle section at one end is connected to the first rigid section through the torsion section; in the hover state, the negative twists of the middle section and the tip section both change linearly, and adjacent middle sections, and between the middle section and the tip section are all transitionally connected through the torsion section. One end of the pitch change rod is connected to a drive mechanism for driving the rotor to rotate, and the other end extends into the rotor and is fixedly connected to the end of the second rigid section; the negative twist adjusting mechanism includes a power part, and the output end of the power part is connected with a connecting piece and can drive the connecting piece to move axially along the output end. The axial direction of the output end is perpendicular to the axial direction of the pitch change rod; the end of the connecting piece is fixedly connected to the first rigid section.

2. The rotor negative torque adjustment device according to claim 1, characterized in that, The torsion section is a tension-torsion band.

3. The rotor negative torque adjustment device according to claim 1, characterized in that, A bearing is provided between the first rigid section and the pitch change rod.

4. The rotor negative torque adjustment device according to claim 1, characterized in that The power part includes a stepping motor installed on the pitch change rod. A screw rod is fixed on the output shaft of the stepping motor. A nut sleeve is rotatably connected to the screw rod. The nut sleeve is fixedly connected to one end of the connecting piece, and the other end of the connecting piece is fixedly connected to the first rigid section.

5. The rotor negative torque adjusting device according to claim 4, wherein, An ear plate is provided on the pitch change rod, and the stepping motor is hinged on the ear plate, and the hinge axis is parallel to the pitch change rod.

6. The rotor negative torque adjustment device according to claim 5, characterized in that The connecting piece includes a pull rod. One end of the pull rod is fixedly connected to the nut sleeve, and the other end is fixedly connected to the first rigid section.

7. The rotor negative torque adjustment device according to claim 6, characterized in that, A limit block for limiting the stroke of the nut sleeve is also fixed to the end of the screw rod far from the output shaft.

8. The rotor negative torque adjustment device according to claim 7, characterized in that, The helix angle of the screw rod is less than the friction angle.

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