Rotor shaft assembly, system and helicopter

Abstract

The invention relates to the technical field of helicopters, and discloses a rotor shaft assembly, a system and a helicopter.The rotor shaft assembly comprises a first rotor shaft, a second rotor shaft, a first transmission unit and a second transmission unit.The rotor shaft assembly is limited to be made of titanium alloy, and the titanium alloy has the characteristics of being light in weight, high in specific strength and the like; the weight of the rotor shaft assembly can be reduced, and meanwhile it is ensured that the rotor shaft assembly has certain tensile strength and rigidity. By arranging the first bearing, the second bearing, the third bearing and the fourth bearing, the wear resistance and the load bearing capacity of the titanium alloy rotor shaft assembly can be improved, so that the wear resistance and the bearable load of the rotor shaft assembly are the same as those of coaxial double rotors made of high-strength structural steel in related technologies; the technical effect of reducing the weight of the rotor shaft assembly can be achieved, so that the economical efficiency and the single voyage of helicopter fuel oil are improved, and then the technical effect of improving the maneuvering characteristics of a helicopter is achieved.

Description

Technical Field

[0001] This invention relates to the field of helicopter technology, and more specifically to rotor shaft assemblies, systems and helicopters. Background Technology

[0002] Coaxial counter-rotation technology is a design that uses the opposite rotation of two rotors to counteract torque and improve flight stability. A dual-rotor system has two rotors, one rotating in the same direction and the other in the opposite direction, rotating around the same theoretical axis. Because they rotate in opposite directions, the torque generated by the two rotors balances each other under constant heading conditions. The unbalanced torque generated by the differential total torque of the upper and lower rotors allows for directional control. In helicopter flight, the coaxial dual rotor serves as both the lifting surface and the control surfaces for longitudinal, lateral, and directional directions.

[0003] In existing coaxial twin-rotor helicopters, the rotor shaft is generally made of high-strength structural steel such as 35Cr2Ni4MoE, 9310, and 4340. High-strength structural steel has good rigidity, which can reduce the deformation of the rotor shaft during use. At the same time, the material itself has high hardness and high fatigue strength. However, the weight of a rotor shaft made of the above-mentioned high-strength structural steel is about twice that of a single-rotor helicopter rotor shaft. This not only reduces fuel economy but also shortens the range per flight, leading to a decrease in the helicopter's maneuverability and affecting the helicopter's normal flight.

[0004] If lightweight alloys, such as titanium alloys, are used directly as the material for the rotor shaft, although the weight of the gearbox can be reduced, the fatigue strength of the rotor shaft will also be reduced, resulting in very poor wear resistance of the rotor shaft. This makes the contact points between the rotor shaft and the rotor hub, bearings, splines, and threads prone to wear, leading to fatigue failure of the rotor shaft and reducing the service life of the helicopter.

[0005] Therefore, there is an urgent need for a rotor shaft that is lightweight and highly wear-resistant. Summary of the Invention

[0006] In view of this, the present invention provides a rotor shaft assembly, system, and helicopter to address the problem that in existing coaxial twin-rotor helicopters, the rotor shaft is made of high-strength structural steel. While this reduces rotor shaft deformation during use and ensures the required fatigue strength, the weight of a high-strength structural steel rotor shaft is approximately twice that of a single-rotor helicopter rotor shaft. This not only reduces fuel economy but also shortens the single-flight range, leading to decreased helicopter maneuverability and affecting normal flight. While using lightweight alloys, such as titanium alloys, as the rotor shaft material can reduce the weight of the gearbox, it also reduces the rotor shaft's fatigue strength, resulting in very poor wear resistance. This causes easy wear at the contact points between the rotor shaft and the rotor hub, bearings, splines, and threads, leading to rotor shaft fatigue failure and reduced helicopter service life.

[0007] In a first aspect, the present invention provides a rotor shaft assembly for connection to a rotor hub, the rotor hub including a first rotor hub and a second rotor hub, the rotor shaft assembly being made of titanium alloy, and the rotor shaft assembly comprising:

[0008] The first rotor shaft includes a first hollow structure for drive connection with the first rotor hub;

[0009] The second rotor shaft is located inside the first hollow structure, with both ends of the second rotor shaft located outside the first hollow structure. The second rotor shaft rotates in the opposite direction to the first rotor shaft, and the second rotor shaft is used for drive connection with the second rotor hub.

[0010] The first transmission unit includes a first bearing and a second bearing. Both the first bearing and the second bearing are sleeved on the first rotor shaft. The first bearing is located at the end of the first rotor shaft away from the first rotor hub, and the second bearing is located between the first rotor hub and the first bearing.

[0011] The second transmission unit includes a third bearing and a fourth bearing, both of which are sleeved on the second rotor shaft. The third bearing is located between the second rotor hub and the first rotor hub, and the fourth bearing is located at the end of the second rotor shaft away from the second rotor hub.

[0012] Beneficial effects: In the rotor shaft assembly of the present invention, compared with the coaxial dual rotor in the related art, the present invention limits the rotor shaft assembly to be made of titanium alloy. Titanium alloy has the characteristics of being lightweight and having high specific strength, which can reduce the weight of the rotor shaft assembly while ensuring that the rotor shaft assembly has a certain tensile strength and stiffness. Furthermore, by setting a first bearing, a second bearing, a third bearing, and a fourth bearing, the first bearing can withstand the radial load on the first rotor shaft, reducing the impact of the radial load on the first rotor shaft, thereby reducing the rate of fatigue damage to the first rotor shaft. The second bearing can withstand the tension of the first rotor shaft given by the first rotor hub, thereby improving the load performance of the first rotor shaft, so as to achieve the technical effect of improving the fatigue resistance and wear resistance of the first rotor shaft.

[0013] Furthermore, the third bearing can withstand the radial load on the second rotor shaft to reduce the impact of the radial load on the second rotor shaft, thereby reducing the fatigue damage rate of the second rotor shaft. The fourth bearing can withstand the tension exerted on the second rotor shaft by the second rotor hub to improve the load performance of the second rotor shaft, thereby achieving the technical effect of improving the fatigue resistance and wear resistance of the second rotor shaft.

[0014] Based on this, by using titanium alloy in the rotor shaft assembly and incorporating the first to fourth bearings, the wear resistance and load-bearing capacity of the titanium alloy rotor shaft assembly can be improved. This ensures that the wear resistance and load-bearing capacity of the rotor shaft assembly of this invention are comparable to those of coaxial twin rotors made of high-strength structural steel in related technologies. This allows the rotor shaft assembly of this invention to meet the required performance indicators while simultaneously reducing its weight, thereby increasing the helicopter's fuel economy and range per flight, and ultimately improving its maneuverability. Furthermore, by limiting the number of bearings to four, this invention reduces the impact on the weight of the rotor shaft assembly and extends its service life.

[0015] In one alternative embodiment, the first bearing is a cylindrical roller bearing;

[0016] And / or, the second bearing is a double-row tapered bearing;

[0017] And / or, the third bearing is a cylindrical roller bearing;

[0018] And / or, the fourth bearing is a tapered roller bearing.

[0019] Beneficial effects: The cylindrical roller bearings can withstand the radial load on the first rotor shaft, and the double-row tapered roller bearings can withstand the tensile force exerted on the first rotor shaft by the first rotor hub, thereby improving the load-bearing capacity of the first rotor shaft and thus enhancing its fatigue and wear resistance. Furthermore, the cylindrical roller bearings can withstand the radial load on the second rotor shaft, reducing its impact, while the tapered roller bearings can withstand the tensile force exerted on the second rotor shaft by the second rotor hub, further improving its load-bearing capacity. Based on the limitations on the types of bearings used from the first to the fourth bearing, the fatigue life of the rotor shaft assembly is at least 2000 hours, thereby improving the reliability of the rotor shaft assembly.

[0020] In one optional embodiment, the first rotor hub includes a transmission section and an extension section. The transmission section is used for transmission connection with the first rotor shaft. The extension section is located on the side of the transmission section near the second rotor hub and is radially arranged along the second rotor shaft. The extension section is spaced apart from the second rotor shaft. The third bearing is located within the space between the extension section and the second rotor shaft.

[0021] Beneficial effects: By limiting the position of the third bearing, making it as close as possible to the second rotor hub, and maximizing the support span between the third and fourth bearings, this ensures that the span matches the strength and stiffness of the titanium alloy, thereby achieving the technical effect of improving the fatigue strength of the rotor shaft assembly.

[0022] In one alternative implementation, the first rotor hub is keyed to the first rotor shaft.

[0023] And / or, the second rotor hub is keyed to the second rotor shaft.

[0024] In one alternative implementation, the first rotor hub is connected to the first rotor shaft via a first spline.

[0025] And / or, the second rotor hub is connected to the second rotor shaft via a second spline.

[0026] Beneficial effects: By limiting the connection between the first rotor hub and the first rotor shaft to a first spline, and the connection between the second rotor hub and the second rotor shaft to a second spline, the load distribution between the spline teeth between the first rotor hub and the first rotor shaft, and between the second rotor hub and the second rotor shaft, is more uniform, thereby achieving the technical effect of improving the transmission accuracy of the rotor shaft assembly.

[0027] In one alternative embodiment, the length of the first spline along the axial direction of the first rotor shaft is in the range of 80mm to 100mm.

[0028] And / or, along the axial direction of the second rotor shaft, the length of the second spline is in the range of 80mm to 100mm.

[0029] Beneficial effects: By limiting the lengths of the first and second splines, the stress on the first and second splines is optimized, which neither accelerates the wear of the first and second splines and affects their slippage, nor causes uneven stress on the first and second splines, thereby achieving the technical effect of improving the reliability of the rotor shaft assembly.

[0030] In one optional embodiment, a positioning groove is provided on the second rotor shaft along its circumferential direction, and the rotor shaft assembly includes:

[0031] A positioning unit is disposed on one side of the second spline. The positioning unit is disposed in the positioning groove. The positioning unit includes a second hollow structure, and the second rotor shaft is sleeved inside the second hollow structure.

[0032] Along an axial direction parallel to the second rotor shaft, the positioning unit is spaced apart from the second spline;

[0033] A locking unit is located on the side of the positioning unit away from the second spline and is sleeved on the second rotor shaft. The locking unit is used to axially position the positioning unit.

[0034] Beneficial effects: By setting a positioning unit, the coaxiality between the second rotor shaft and the second rotor hub can be increased, thereby improving the torque transmission accuracy between the second rotor shaft and the second rotor hub, and thus achieving the technical effect of improving the connection reliability between the second rotor shaft and the second rotor hub. By limiting the spacing between the positioning unit and the second spline, wear between the second rotor shaft and the second rotor hub can be avoided during the transmission process of the rotor shaft assembly. This invention can improve the wear resistance of the second rotor shaft, thereby achieving the technical effect of improving the reliability of the rotor shaft assembly.

[0035] By setting a locking unit, the locking unit can fix the position of the positioning unit along the axial direction of the second rotor shaft, thereby achieving the technical effect of improving the positional reliability of the rotor shaft assembly.

[0036] In one optional embodiment, the distance between the positioning unit and the second spline along the axial direction parallel to the second rotor shaft is in the range of 3mm to 4mm.

[0037] And / or, the locking unit is threadedly connected to the second rotor shaft.

[0038] Beneficial effects: Along the axial direction parallel to the second rotor shaft, the distance between the positioning unit and the second spline is within the range of 3mm to 4mm. This prevents wear between the second rotor shaft and the second rotor hub, which could cause the positioning unit to sink and lose the preload of the locking unit, thus exacerbating wear between the second rotor shaft and the second rotor hub. Simultaneously, it also prevents the distance between the positioning unit and the second spline from being too large, thus affecting the axial length of the rotor shaft assembly.

[0039] By limiting the locking unit to be threadedly connected to the second rotor shaft, the stability of the locking unit in fixing the axial position of the positioning unit is improved.

[0040] In one alternative embodiment, the surfaces of the first rotor shaft, the second rotor shaft, the first spline, the second spline, and the locking unit are all coated with a wear-resistant layer.

[0041] Beneficial effects: By setting a wear-resistant layer, the wear resistance between the first rotor shaft, the second rotor shaft, the first spline, the second spline, and the locking unit can be increased.

[0042] In an optional embodiment, the wear-resistant layer on the mounting surface of the first rotor shaft and the first rotor hub, and / or the mounting surface of the second rotor shaft and the second rotor hub, and / or the surface of the first spline, and / or the surface of the second spline is set as one or more of the following: Co17 coating, chromium oxide-titanium oxide coating, chromium oxide coating, nickel-chromium-chromium carbide coating and 10Co4Cr coating.

[0043] And / or, the wear-resistant layer of the threaded surface of the locking unit and / or the threaded surface of the second rotor shaft is set as a solid lubricating layer.

[0044] In one optional embodiment, a cross section is made along the axial direction of the first rotor shaft, and the connection position between one end of the first rotor hub and the first rotor shaft is a first inclined plane. The angle between the first inclined plane and the axis of the first rotor shaft is in the range of 25° to 35°, which is used to limit the position of the first rotor hub.

[0045] And / or, a cross section is made along the axial direction of the second rotor shaft, and the connection position between one end of the second rotor hub and the second rotor shaft is a second inclined plane, the angle between the second inclined plane and the axis of the second rotor shaft is in the range of 25° to 35°, which is used to define the position of the second rotor hub.

[0046] Secondly, the present invention also provides a rotor shaft system, comprising:

[0047] The aforementioned rotor shaft assembly;

[0048] The first rotor hub is connected to the first rotor shaft for rotation under the drive of the first rotor shaft;

[0049] The second rotor hub is connected to the second rotor shaft and is used to rotate under the drive of the second rotor shaft.

[0050] Beneficial effects: Since the rotor shaft system includes a rotor shaft assembly, it has the same effects as the rotor shaft assembly, which will not be elaborated here.

[0051] Thirdly, the present invention also provides a helicopter, comprising:

[0052] The aforementioned rotor shaft system.

[0053] Beneficial effects: Since helicopters include a rotor shaft system, they have the same effects as rotor shaft systems, which will not be elaborated here. Attached Figure Description

[0054] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0055] Figure 1 This is a schematic diagram of the rotor shaft assembly in this embodiment;

[0056] Figure 2This is a cross-sectional view of the second rotor shaft, second rotor hub, second inclined surface, positioning unit, and locking unit in the rotor shaft assembly of this embodiment;

[0057] Figure 3 This is a schematic diagram of the structure of the second rotor shaft in the rotor shaft assembly of this embodiment.

[0058] Explanation of reference numerals in the attached figures:

[0059] 1. First rotor shaft; 2. Second rotor shaft;

[0060] 3. First propeller hub; 301. Transmission unit; 302. Extension unit;

[0061] 4. Second propeller hub;

[0062] 5. First transmission unit; 501. First bearing; 502. Second bearing;

[0063] 6. Second transmission unit; 601. Third bearing; 602. Fourth bearing;

[0064] 7. Second spline; 8. Second inclined plane; 9. Positioning unit; 10. Locking unit. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] The following is combined with Figures 1 to 3 The following describes embodiments of the present invention.

[0067] According to an embodiment of the present invention, in one aspect, a rotor shaft assembly is provided for connection to a rotor hub, the rotor hub including a first rotor hub 3 and a second rotor hub 4, the rotor shaft assembly being made of titanium alloy, and the rotor shaft assembly comprising:

[0068] The first rotor shaft 1 includes a first hollow structure for transmission connection with the first rotor hub 3;

[0069] The second rotor shaft 2 is located inside the first hollow structure, with both ends of the second rotor shaft 2 located outside the first hollow structure. The second rotor shaft 2 rotates in the opposite direction to the first rotor shaft 1. The second rotor shaft 2 is used for transmission connection with the second rotor hub 4.

[0070] The first transmission unit 5 includes a first bearing 501 and a second bearing 502. Both the first bearing 501 and the second bearing 502 are sleeved on the first rotor shaft 1. The first bearing 501 is located at the end of the first rotor shaft 1 away from the first rotor hub 3, and the second bearing 502 is located between the first rotor hub 3 and the first bearing 501.

[0071] The second transmission unit 6 includes a third bearing 601 and a fourth bearing 602. Both the third bearing 601 and the fourth bearing 602 are sleeved on the second rotor shaft 2. The third bearing 601 is located between the second rotor hub 4 and the first rotor hub 3, and the fourth bearing 602 is located at the end of the second rotor shaft 2 away from the second rotor hub 4.

[0072] In the rotor shaft assembly of this embodiment, compared with the coaxial dual rotor in the related art, the rotor shaft assembly of the coaxial dual rotor in this embodiment is made of titanium alloy. Titanium alloy has the characteristics of being lightweight and having high specific strength, which can reduce the weight of the rotor shaft assembly while ensuring that the rotor shaft assembly has a certain tensile strength and rigidity. Furthermore, by setting a first bearing 501, a second bearing 502, a third bearing 601, and a fourth bearing 602, the first bearing 501 can withstand the radial load on the first rotor shaft 1, reducing the impact of the radial load on the first rotor shaft 1, thereby reducing the rate of fatigue damage to the first rotor shaft 1. The second bearing 502 can withstand the tension given to the first rotor shaft 1 by the first hub 3, thereby improving the load performance of the first rotor shaft 1, so as to achieve the technical effect of improving the fatigue resistance and wear resistance of the first rotor shaft 1.

[0073] Furthermore, the third bearing 601 can withstand the radial load on the second rotor shaft 2 to reduce the influence of the radial load on the second rotor shaft 2, thereby reducing the fatigue damage rate of the second rotor shaft 2. The fourth bearing 602 can withstand the tension of the second rotor shaft 2 given by the second rotor hub 4 to improve the load performance of the second rotor shaft 2, thereby achieving the technical effect of improving the fatigue resistance and wear resistance of the second rotor shaft 2.

[0074] Based on this, by using titanium alloy in the rotor shaft assembly and incorporating the first bearing 501 to the fourth bearing 602, the wear resistance and load-bearing capacity of the titanium alloy rotor shaft assembly can be improved. This ensures that the wear resistance and load-bearing capacity of the rotor shaft assembly in this embodiment are comparable to those of coaxial twin rotors made of high-strength structural steel in related technologies. This allows the rotor shaft assembly in this embodiment to meet the required performance indicators while simultaneously reducing its weight, thereby increasing the helicopter's fuel economy and single-flight range, and ultimately improving the helicopter's maneuverability. Furthermore, by limiting the number of bearings to four, this embodiment reduces the impact on the weight of the rotor shaft assembly and extends its service life.

[0075] Through static and fatigue tests, it has been confirmed that the rotor shaft assembly of this embodiment has a fatigue life of at least 2000 hours under specified loads.

[0076] Combination Figure 1 As shown, preferably, the first rotor hub 3 includes a transmission part 301 and an extension part 302. The transmission part 301 is used for transmission connection with the first rotor shaft 1. The extension part 302 is disposed on the side of the transmission part 301 near the second rotor hub 4 and along the radial direction of the second rotor shaft 2. The extension part 302 is spaced apart from the second rotor shaft 2. The third bearing 601 is disposed in the gap between the extension part 302 and the second rotor shaft 2.

[0077] Based on this, the third bearing 601 is placed as close as possible to the second rotor hub 4, so that the support span between the third bearing 601 and the fourth bearing 602 is as large as possible, ensuring that the span can match the strength and stiffness of the titanium alloy, thereby achieving the technical effect of improving the fatigue strength of the rotor shaft assembly.

[0078] Furthermore, the span between the first bearing 501 and the second bearing 502 is also as large as possible, that is, the second bearing 502 is as close as possible to the first rotor hub 3, so as to ensure that the span can match the strength and stiffness of the titanium alloy, thereby achieving the technical effect of improving the fatigue strength of the rotor shaft assembly.

[0079] Preferably, in this embodiment, the first bearing 501 is a cylindrical roller bearing, the second bearing 502 is a double-row tapered bearing, the third bearing 601 is a cylindrical roller bearing, and the fourth bearing 602 is a tapered roller bearing.

[0080] By using cylindrical roller bearings, the radial load on the first rotor shaft 1 can be withstood. By using double-row tapered bearings, the tensile force exerted on the first rotor shaft 1 by the first rotor hub 3 can be withstood, thereby improving the load-bearing capacity of the first rotor shaft 1 and thus enhancing its fatigue resistance and wear resistance. Furthermore, the cylindrical roller bearings can withstand the radial load on the second rotor shaft 2, reducing the impact of the radial load on the second rotor shaft 2. The tapered roller bearings can withstand the tensile force exerted on the second rotor shaft 2 by the second rotor hub 4, while also improving the load-bearing capacity of the second rotor shaft 2. Based on the limitation of the types of bearings from the first bearing 501 to the fourth bearing 602, the fatigue life of the rotor shaft assembly is at least 2000 hours, thereby improving the reliability of the rotor shaft assembly.

[0081] Of course, in other embodiments, depending on the design of the rotor shaft assembly, the types of the first bearing 501, the second bearing 502, the third bearing 601, and the fourth bearing 602 can be adjusted to achieve bearings that can bear the radial load on the first rotor shaft 1, improve the load performance of the first rotor shaft 1, bear the radial load on the second rotor shaft 2, and improve the load performance of the second rotor shaft 2. All of these are within the protection scope of this invention.

[0082] As an alternative implementation, it is also possible to limit the first bearing 501 to a cylindrical roller bearing, the second bearing 502 to a double-row tapered bearing, the third bearing 601 to a cylindrical roller bearing, and the fourth bearing 602 to a tapered roller bearing, or a combination of two or three structures, all of which are within the protection scope of this invention.

[0083] Furthermore, in this embodiment, the first rotor hub 3 is keyed to the first rotor shaft 1, and the second rotor hub 4 is keyed to the second rotor shaft 2, so that torque can be transmitted between the first rotor hub 3 and the first rotor shaft 1, and between the second rotor hub 4 and the second rotor shaft 2. That is, the first rotor hub 3 can rotate with the first rotor shaft 1, and the second rotor hub 4 can rotate with the second rotor shaft 2.

[0084] The first rotor hub 3 is connected to the first rotor shaft 1, and the second rotor hub 4 is connected to the second rotor shaft 2 via splines. Specifically, combined with Figure 2 As shown, the first rotor hub 3 is connected to the first rotor shaft 1 via the first spline, and the second rotor hub 4 is connected to the second rotor shaft 2 via the second spline 7.

[0085] Specifically, the length of the first spline and the second spline 7 can change the load transmission path of the rotor shaft assembly. If the lengths of the first spline and the second spline 7 are too small, the load-bearing capacity of the first spline and the second spline 7 will increase, and the stress level of the first spline and the second spline 7 will be increased, making the first spline and the second spline 7 more prone to wear. This will lead to an increase in the amount of slippage of the first spline and the second spline 7 along the axial direction of the first rotor shaft 1, accelerating the wear of the first rotor shaft 1 and the second rotor shaft 2.

[0086] If the lengths of the first spline and the second spline 7 are too long, the first spline and the second spline 7 are prone to uneven stress and off-center loading, which will increase the local stress and make the first rotor shaft 1 and the second rotor shaft 2 prone to breakage, affecting the service life of the first rotor shaft 1 and the second rotor shaft 2.

[0087] In this embodiment, the first spline and the second spline 7 have the same specifications and dimensions. The second spline 7 is used as an example, and the first spline is not described in detail.

[0088] Preferably, combined with Figure 2As shown, the length L of the second spline 7 along the axial direction of the second rotor shaft 2 is 80mm. At this time, the stress on the second spline 7 is optimal, which neither accelerates the wear of the second spline 7 and affects the slippage of the second spline 7, nor causes uneven stress on the second spline 7, thereby achieving the technical effect of improving the reliability of the rotor shaft assembly.

[0089] As an alternative implementation, the lengths of the first spline and the second spline 7 can be 100mm, or any value between 80mm and 100mm, all of which can achieve the technical effect of improving the wear resistance of the rotor shaft assembly made of titanium alloy.

[0090] Of course, in other embodiments, depending on the design of the rotor shaft assembly, the connection methods between the first rotor hub 3 and the first rotor shaft 1, and between the second rotor hub 4 and the second rotor shaft 2, can be adjusted. For example, other methods can be used to fix the first rotor hub 3 and the first rotor shaft 1, and between the second rotor hub 4 and the second rotor shaft 2, all of which are within the scope of protection of this invention. As the rotor shaft assembly is used for longer periods, it is more prone to vibration leading to detachment between the rotor hub and the rotor shaft compared to other embodiments. In this embodiment, the keyed connection can both transmit torque and optimize the structure of the rotor shaft assembly, thereby reducing the fatigue resistance of the first rotor shaft 1 and the second rotor shaft 2, and thus achieving the technical effect of improving the service life of the first rotor shaft 1 and the second rotor shaft 2.

[0091] In other embodiments, depending on the design of the rotor shaft assembly, the connection between the first rotor hub 3 and the first rotor shaft 1 may be limited to a keyed connection, or the connection between the second rotor hub 4 and the second rotor shaft 2 may be limited to a keyed connection. Alternatively, the first spline and the second spline 7 may have different dimensions.

[0092] As an alternative implementation, the first rotor hub 3 and the first rotor shaft 1, as well as the second rotor hub 4 and the second rotor shaft 2, can be connected by a conventional key. Compared to other embodiments, this embodiment specifies that the key is a spline, which allows for a more uniform distribution of load between the spline teeth between the first rotor hub 3 and the first rotor shaft 1, and between the second rotor hub 4 and the second rotor shaft 2, thereby achieving the technical effect of improving the transmission accuracy of the rotor shaft assembly.

[0093] Of course, in other embodiments, depending on the design of the rotor shaft assembly, it is possible to limit the connection between the first rotor hub 3 and the first rotor shaft 1 to be via the first spline, or to limit the connection between the second rotor hub 4 and the second rotor shaft 2 to be via the second spline 7. All of these are within the scope of protection of the present invention.

[0094] In other embodiments, depending on the design of the rotor shaft assembly, either the length of the first spline is limited to the range of 80mm to 100mm, or the length of the second spline 7 is limited to the range of 80mm to 100mm, both of which are within the protection scope of this invention.

[0095] In addition, in this embodiment, a cross section is made along the axial direction of the first rotor shaft 1. The connection position between one end of the first rotor hub 3 and the first rotor shaft 1 is a first inclined plane. The angle between the first inclined plane and the axis of the first rotor shaft 1 is in the range of 25° to 35°, which is used to limit the position of the first rotor hub 3.

[0096] Combination Figure 2 As shown, a cross section is taken along the axial direction of the second rotor shaft 2. The connection position between one end of the second rotor hub 4 and the second rotor shaft 2 is the second inclined plane 8. The angle α between the second inclined plane 8 and the axis of the second rotor shaft 2 is in the range of 25° to 35°, which is used to limit the position of the second rotor hub 4.

[0097] Based on this, by limiting the angle between the first inclined plane and the axis of the first rotor shaft 1 and the angle between the second inclined plane 8 and the axis of the second rotor shaft 2, the contact stress between the first rotor shaft 1 and the first rotor hub 3, and between the second rotor shaft 2 and the second rotor hub 4, can be uniformly distributed. This avoids stress concentration on the contact surface due to uneven stress distribution between the first rotor shaft 1 and the first rotor hub 3, and between the second rotor shaft 2 and the second rotor hub 4, which would lead to increased wear. This achieves the technical effect of improving the reliability of contact fatigue strength between the first rotor shaft 1 and the first rotor hub 3, and between the second rotor shaft 2 and the second rotor hub 4.

[0098] The angle between the first inclined plane and the axis of the first rotor shaft 1 can be 25°, 35°, or any value between 25° and 35°. The angle between the second inclined plane 8 and the axis of the second rotor shaft 2 can be 25°, 35°, or any value between 25° and 35°.

[0099] As an alternative implementation, the cross-section can be limited to the axial direction of the first rotor shaft 1, with the connection position between one end of the first rotor hub 3 and the first rotor shaft 1 being the first inclined plane; or the cross-section can be limited to the axial direction of the first rotor shaft 1, with the connection position between one end of the second rotor hub 4 and the second rotor shaft 2 being the second inclined plane 8. Both are within the protection scope of this invention.

[0100] In addition, combined Figure 2 As shown, in this embodiment, a positioning groove is provided on the second rotor shaft 2 along the circumferential direction, and the rotor shaft assembly includes:

[0101] The positioning unit 9 is located on one side of the second spline 7. The positioning unit 9 is located in the positioning groove. The positioning unit 9 includes a second hollow structure, and a second rotor shaft 2 is sleeved inside the second hollow structure.

[0102] The positioning unit 9 is spaced apart from the second spline 7 along the axial direction parallel to the second rotor shaft 2;

[0103] The locking unit 10 is located on the side of the positioning unit 9 away from the second spline 7 and is sleeved on the second rotor shaft 2. The locking unit 10 is used to axially position the positioning unit 9.

[0104] By setting the positioning unit 9, the coaxiality between the second rotor shaft 2 and the second rotor hub 4 can be increased, thereby improving the torque transmission accuracy between the second rotor shaft 2 and the second rotor hub 4, and thus achieving the technical effect of improving the connection reliability between the second rotor shaft 2 and the second rotor hub 4. By limiting the spacing between the positioning unit 9 and the second spline 7, wear between the second rotor shaft 2 and the second rotor hub 4 can be avoided during the transmission process of the rotor shaft assembly. This embodiment can improve the wear resistance of the second rotor shaft 2, thereby achieving the technical effect of improving the reliability of the rotor shaft assembly.

[0105] By setting the locking unit 10, the locking unit 10 can fix the position of the positioning unit 9 along the axial direction of the second rotor shaft 2, thereby achieving the technical effect of improving the positional reliability of the rotor shaft assembly.

[0106] Among them, the positioning unit 9 is a conical ring, and the contact surface between the positioning unit 9 and the second rotor hub 4 is an inclined surface, so as to reduce the local stress between the positioning unit 9 and the second rotor hub 4 and improve the load-bearing capacity of the rotor shaft assembly.

[0107] Preferably, the locking unit 10 is threadedly connected to the second rotor shaft 2, thereby improving the stability of the locking unit 10 in fixing the axial position of the positioning unit 9. The locking unit 10 is a locking nut. Specifically, the locking unit 10 has a threaded hole, and the second rotor shaft 2 has threads. The threaded connection between the threads and the threaded hole ensures reliable connection between the locking unit 10 and the second rotor shaft 2.

[0108] Alternatively, the locking unit 10 can be inserted into the second rotor shaft 2.

[0109] Of course, in other embodiments, depending on the design of the rotor shaft assembly, the types of positioning unit 9 and locking unit 10 can be adjusted, or the shape of the contact surface between positioning unit 9 and second rotor hub 4 can be adjusted.

[0110] Preferably, the distance D between the positioning unit 9 and the second spline 7 along the axial direction parallel to the second rotor shaft 2 is within the range of 3mm to 4mm. This prevents wear between the second rotor shaft 2 and the second rotor hub 4, which could cause the positioning unit 9 to sink and lose the preload of the locking unit 10, thus exacerbating wear between the second rotor shaft 2 and the second rotor hub 4. Simultaneously, it also prevents the distance between the positioning unit 9 and the second spline 7 from being too large, thus affecting the axial length of the rotor shaft assembly.

[0111] Of course, in other embodiments, the distance between the positioning unit 9 and the second spline 7 may be adjusted according to the different designs of the rotor shaft assembly, and any adjustment exceeding 3mm is within the protection scope of this invention.

[0112] As an alternative implementation, the distance between the positioning unit 9 and the second spline 7 may be limited to 3mm to 4mm along the axial direction parallel to the second rotor shaft 2, or the locking unit 10 may be limited to being threadedly connected to the second rotor shaft 2.

[0113] Furthermore, a positioning unit 9 and a locking unit 10 are also provided between the first rotor shaft 1 and the first rotor hub 3. The positioning unit 9 and the locking unit 10 of the first rotor shaft 1 are defined in the same way as the positioning unit 9 and the locking unit 10 of the second rotor shaft 2, and will not be described in detail here.

[0114] Of course, in other embodiments, depending on the definition of the rotor shaft assembly, the positioning unit 9 and locking unit 10 provided between the first rotor shaft 1 and the first rotor hub 3 are defined differently from the positioning unit 9 and locking unit 10 of the second rotor shaft 2, and both are within the protection scope of the present invention.

[0115] In addition, in this embodiment, the surfaces of the first rotor shaft 1, the second rotor shaft 2, the first spline, the second spline 7, and the locking unit 10 are all coated with a wear-resistant layer.

[0116] By setting a wear-resistant layer, the wear resistance of the first rotor shaft 1, the second rotor shaft 2, the first spline, the second spline 7, and the locking unit 10 can be increased.

[0117] Based on calculations and experiments conducted on the contact stress of the wear-resistant layer, the sliding amount of the rotor shaft assembly, and the wear of the wear-resistant layer, the wear-resistant layer on the mounting surface of the first rotor shaft 1 and the first rotor hub 3, the mounting surface of the second rotor shaft 2 and the second rotor hub 4, the first spline, the second spline 7, the shoulder connecting the first rotor shaft 1 and the reducer, and the shoulder connecting the second rotor shaft 2 and the reducer is a 10Co4Cr coating (tungsten carbide coating), which can achieve the technical effect of improving the wear resistance of the rotor shaft assembly.

[0118] Furthermore, in the rotor shaft assembly of this embodiment, in addition to the first spline and the second spline 7, the wear-resistant layer provided on the threaded surface S3 or key surface S2 of the first rotor shaft 1 and the second rotor shaft 2 that are connected to the reducer transmission, the threaded surface of the locking unit 10, and the threaded surface S1 of the second rotor shaft 2 is a solid lubricating layer. This enhances the wear resistance of the above structure by reducing friction, thereby achieving the technical effect of reducing wear. The specific type of the fixed lubricating layer is not limited.

[0119] Specifically, in combination Figure 3 As shown, taking the second rotor shaft 2 as an example, after grinding the second rotor shaft 2, the thickness of the 10Co4Cr coating on the surface A1 of the second spline 7, the shoulder A3 and A4 connecting the second rotor shaft 2 with the reducer, and the second inclined surface A2 is in the range of 0.1mm to 0.15mm. That is, the thickness of the 10Co4Cr coating in regions A1, A2, A3, and A4 is in the range of 0.1mm to 0.15mm. After grinding, the hardness of the coating is in the range of HV300:1000 to 1400, that is, under a 300gf load, the Vickers hardness value of the coating is in the range of 1000 to 1400, and the adhesion and bonding strength of the wear-resistant layer are not less than 69MPa. Based on this, the wear resistance of the rotor shaft assembly made of titanium alloy is enhanced.

[0120] Furthermore, in addition to the first spline and the second spline 7, the thickness of the solid lubricating layer on the key surface S2 of the first rotor shaft 1 and the second rotor shaft 2 that are connected to the reducer is in the range of 0.008mm to 0.013mm. The thickness of the solid lubricating layer on the threaded surface S1 of the first rotor shaft 1 and the second rotor shaft 2 that are connected to the reducer, the locking unit 10 and the threaded surface S3 of the second rotor shaft 2 is in the range of 0.005mm to 0.01mm. This avoids scratching and sticking of the threads and splines during transmission, and further improves the wear resistance of the titanium alloy rotor shaft assembly.

[0121] Furthermore, the machining processes of the first rotor shaft 1 and the second rotor shaft 2 are the same, and no further restrictions will be imposed here.

[0122] Of course, in other embodiments, the type and thickness of the wear-resistant layers in regions A1, A2, A3, and A4, as well as in regions S1, S2, and S3, can be adjusted. For example, for regions A1, A2, A3, and A4, a high-temperature alloy GH4169 can be sprayed using supersonic cold spraying. The coating thickness is in the range of 0.1mm to 0.15mm after grinding, the coating hardness is HV0.3: 500 to 550, and the adhesion and bonding strength of the wear-resistant layer are not less than 100MPa. This can also achieve the technical effect of improving the wear resistance of the rotor shaft assembly.

[0123] As an alternative implementation, the wear-resistant layer can be a Co17 coating (tungsten carbide coating), a chromium oxide-titanium oxide coating, a pure chromium oxide coating, or a nickel-chromium-chromium carbide coating. Based on simulation results, the 10Co4Cr coating exhibits the best wear resistance compared to other coatings.

[0124] In other embodiments, the coating application method is adjusted depending on the design of the rotor shaft assembly.

[0125] As an alternative implementation, the wear-resistant layer of one or more of the following structures—the mounting surface of the first rotor shaft 1 and the first rotor hub 3, the mounting surface of the second rotor shaft 2 and the second rotor hub 4, the first spline, and the second spline 7—can be a combination of one or more of the following: a Co17 coating, a chromium oxide-titanium oxide coating, a chromium oxide coating, a nickel-chromium-chromium carbide coating, and a 10Co4Cr coating.

[0126] Alternatively, in a different implementation, the wear-resistant layer of one or more of the structures of the first spline, the second spline 7, the threads of the locking unit 10, and the threads of the second rotor shaft 2 may be a solid lubricating layer.

[0127] According to an embodiment of the present invention, in another aspect, a rotor shaft system is also provided, comprising:

[0128] The rotor shaft assembly of this embodiment;

[0129] The first rotor hub 3 is connected to the first rotor shaft 1 for rotation under the drive of the first rotor shaft 1;

[0130] The second rotor hub 4 is connected to the second rotor shaft 2 for rotation under the drive of the second rotor shaft 2.

[0131] According to an embodiment of the present invention, in another aspect, a helicopter is also provided, comprising:

[0132] The rotor shaft system of this embodiment.

[0133] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A rotor shaft assembly for connection to a rotor hub, the rotor hub comprising a first rotor hub (3) and a second rotor hub (4), characterized in that, The rotor shaft assembly is made of titanium alloy and includes: The first rotor shaft (1) includes a first hollow structure for transmission connection with the first rotor hub (3); The second rotor shaft (2) is located inside the first hollow structure. Both ends of the second rotor shaft (2) are located outside the first hollow structure. The rotation direction of the second rotor shaft (2) is opposite to that of the first rotor shaft (1). The second rotor shaft (2) is used for transmission connection with the second rotor hub (4). The first transmission unit (5) includes a first bearing (501) and a second bearing (502). The first bearing (501) and the second bearing (502) are both sleeved on the first rotor shaft (1). The first bearing (501) is located at the end of the first rotor shaft (1) away from the first rotor hub (3). The second bearing (502) is located between the first rotor hub (3) and the first bearing (501). The second transmission unit (6) includes a third bearing (601) and a fourth bearing (602). The third bearing (601) and the fourth bearing (602) are both sleeved on the second rotor shaft (2). The third bearing (601) is located between the second rotor hub (4) and the first rotor hub (3). The fourth bearing (602) is located at the end of the second rotor shaft (2) away from the second rotor hub (4).

2. The rotor shaft assembly according to claim 1, characterized in that, The first bearing (501) is a cylindrical roller bearing; And / or, the second bearing (502) is a double-row tapered bearing; And / or, the third bearing (601) is a cylindrical roller bearing; And / or, the fourth bearing (602) is a tapered roller bearing.

3. The rotor shaft assembly according to claim 1, characterized in that, The first rotor hub (3) includes a transmission part (301) and an extension part (302). The transmission part (301) is used for transmission connection with the first rotor shaft (1). The extension part (302) is located on the side of the transmission part (301) close to the second rotor hub (4) along the radial direction of the second rotor shaft (2). The extension part (302) is spaced apart from the second rotor shaft (2). The third bearing (601) is located within the gap between the extension part (302) and the second rotor shaft (2).

4. The rotor shaft assembly according to any one of claims 1-3, characterized in that, The first rotor hub (3) is keyed to the first rotor shaft (1); And / or, the second rotor hub (4) is keyed to the second rotor shaft (2).

5. The rotor shaft assembly according to claim 4, characterized in that, The first rotor hub (3) is connected to the first rotor shaft (1) via a first spline; And / or, the second rotor hub (4) is connected to the second rotor shaft (2) via a second spline (7).

6. The rotor shaft assembly according to claim 5, characterized in that, Along the axial direction of the first rotor shaft (1), the length of the first spline is in the range of 80mm to 100mm; And / or, along the axial direction of the second rotor shaft (2), the length of the second spline (7) is in the range of 80mm to 100mm.

7. The rotor shaft assembly according to claim 5 or 6, characterized in that, Along the circumferential direction of the second rotor shaft (2), a positioning groove is provided on the second rotor shaft (2), and the rotor shaft assembly includes: A positioning unit (9) is provided on one side of the second spline (7). The positioning unit (9) is provided in the positioning groove. The positioning unit (9) includes a second hollow structure. The second rotor shaft (2) is sleeved inside the second hollow structure. Along an axial direction parallel to the second rotor shaft (2), the positioning unit (9) is spaced apart from the second spline (7); A locking unit (10) is located on the side of the positioning unit (9) away from the second spline (7) and is sleeved on the second rotor shaft (2). The locking unit (10) is used to axially position the positioning unit (9).

8. The rotor shaft assembly according to claim 7, characterized in that, Along the axial direction parallel to the second rotor shaft (2), the distance between the positioning unit (9) and the second spline (7) is in the range of 3mm to 4mm; And / or, the locking unit (10) is threadedly connected to the second rotor shaft (2).

9. The rotor shaft assembly according to claim 8, characterized in that, The surfaces of the first rotor shaft (1), the second rotor shaft (2), the first spline, the second spline (7), and the locking unit (10) are all coated with a wear-resistant layer.

10. The rotor shaft assembly according to claim 9, characterized in that, The wear-resistant layer on the mounting surface of the first rotor shaft (1) and the first rotor hub (3), and / or the mounting surface of the second rotor shaft (2) and the second rotor hub (4), and / or the surface of the first spline, and / or the surface of the second spline (7) is set as one or a combination of Co17 coating, chromium oxide-titanium oxide coating, chromium oxide coating, nickel chromium carbide coating and 10Co4Cr coating; And / or, the wear-resistant layer of the threaded surface of the locking unit (10) and / or the threaded surface of the second rotor shaft (2) is set as a solid lubricating layer.

11. The rotor shaft assembly according to any one of claims 1-3, characterized in that, A cross section is made along the axial direction of the first rotor shaft (1). The connection position between one end of the first rotor hub (3) and the first rotor shaft (1) is a first inclined plane. The angle between the first inclined plane and the axis of the first rotor shaft (1) is in the range of 25° to 35°, which is used to limit the position of the first rotor hub (3). And / or, a cross section is made along the axial direction of the second rotor shaft (2), and the connection position between one end of the second rotor hub (4) and the second rotor shaft (2) is the second inclined plane (8), and the angle between the second inclined plane (8) and the axis of the second rotor shaft (2) is in the range of 25° to 35°, which is used to limit the position of the second rotor hub (4).

12. A rotor shaft system, characterized in that, include: The rotor shaft assembly according to any one of claims 1 to 11; The first rotor hub (3) is connected to the first rotor shaft (1) for rotation under the drive of the first rotor shaft (1); The second rotor hub (4) is connected to the second rotor shaft (2) for rotation under the drive of the second rotor shaft (2).

13. A helicopter, characterized in that, include: The rotor shaft system of claim 12.

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