Flywheel shafting structure and preparation method thereof

Abstract

The invention relates to a flywheel shafting structure and a preparation method thereof.The flywheel shafting structure comprises a shafting support, a flywheel rotor and a hub, one end of the hub is connected with the shafting support, the flywheel rotor is arranged at the other end of the hub, and the flywheel rotor is used for storing and releasing energy; the hub comprises a metal layer, a spiral layer and an annular layer, the metal layer is arranged outside the shafting support, the spiral layer is arranged on the outer side of the metal layer, and the annular layer is arranged at the end, connected with the shafting support, of the spiral layer. The flywheel rotor comprises a transition layer and a reinforcing layer, one end of the transition layer is connected with the spiral layer, and the other end of the transition layer is provided with the reinforcing layer. Compared with the prior art, the flywheel shaft system structure is manufactured by co-molding the composite material flywheel rotor and the hub, an integrated machining mode containing the composite material hub is provided based on winding molding, and the overall rigidity of the shaft system is improved and radial deformation is improved by implementing a spiral and annular alternate winding method on a metal layer.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage flywheels, and in particular to a flywheel shafting structure and a preparation method thereof. Background Art

[0002] The flywheel rotor system is composed of a metal shafting, a rotor and a hub. In order to increase the ultimate speed of the flywheel rotor system, a fiber-reinforced material / resin composite material is usually used to prepare the flywheel rotor. The hub connects the rotor to the metal shafting to transmit torque to achieve the overall function of the shafting. As the maximum speed continues to increase, not only does the flywheel rotor system need to consider the overall modal characteristics according to dynamics, but the natural frequency of the hub is also affected.

[0003] In addition, both the hub and the rotor will undergo axial shrinkage and radial deformation. There is a large difference in the thermal expansion coefficients between the metal hub and the composite flywheel rotor, and the pre-compression stress provided by the commonly used interference fitting method is limited. If the centrifugal force is greater than the interference stress between the hub and the rotor during the speed-up process, the two may become disengaged.

[0004] In addition, the density of the metal is relatively high, which affects the total weight of the flywheel rotor system, and the support bearings need to bear a large load. Especially for large-capacity flywheel energy storage systems, it is difficult to machine a large metal hub in one go. Summary of the Invention

[0005] The purpose of the present invention is to provide a flywheel shafting structure and a preparation method thereof. The flywheel shafting structure is obtained by co-molding a composite flywheel rotor and a hub. In order to improve the radial stress and strain of the composite flywheel rotor at high speeds, an integrated processing method with a composite hub is proposed based on winding molding. By implementing a method of alternately winding helically and circumferentially on the metal layer, the overall stiffness of the shafting is improved and the radial deformation is improved. Compared with the conventional cold interference fitting process of "metal hub + composite rotor", wet winding is used to achieve the integrated molding of the hub and the rotor, greatly reducing the risk of interface cracking and improving the overall modal performance.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A flywheel shafting structure, the flywheel shafting includes a shafting support, a flywheel rotor and a hub. One end of the hub is connected to the shafting support, and a flywheel rotor is provided at the other end of the hub. The flywheel rotor is used for storing and releasing energy;

[0008] The hub includes a metal layer, a helical layer and a circumferential layer. A metal layer is provided outside the shafting support, a helical layer is provided outside the metal layer, and the circumferential layer is provided at one end where the helical layer is connected to the shafting support;

[0009] The flywheel rotor includes a transition layer and a reinforcement layer. One end of the transition layer is connected to the spiral layer, and the other end of the transition layer is provided with a reinforcement layer.

[0010] Further, the metal layer is a circular arched top with a hollow interior, and the spiral layer is made of fiber.

[0011] Further, the materials of the metal layer include steel, aluminum alloy, titanium alloy, magnesium alloy, cast iron, etc.

[0012] As a preferred technical solution, the steel includes carbon steel (such as 45# steel) and alloy steel (such as 42CrMo, 40Cr), etc.

[0013] The aluminum alloy includes 6-series aluminum alloy (such as 6061-T6) and 7-series aluminum alloy (such as 7075-T6), etc.

[0014] The titanium alloy includes Ti-6Al-4V, etc.

[0015] The magnesium alloy includes AZ91D and AM60, etc.

[0016] The cast iron includes gray cast iron (such as HT200) and ductile cast iron (such as QT400-15), etc.

[0017] Further, the spiral layer has multiple layers, which are, from the inside to the outside, a high-modulus fiber layer, a high-strength fiber layer, and a glass fiber layer in sequence.

[0018] Further, the material of the transition layer is a resin matrix, which can better achieve the composite material performance and is prepared by an optimized process.

[0019] Further, the reinforcement layer includes a glass fiber reinforcement layer, a high-strength fiber reinforcement layer, and a high-modulus fiber reinforcement layer that are wound circumferentially in sequence. The glass fiber reinforcement layer is wound circumferentially outside the transition layer.

[0020] As a preferred technical solution, the lengths of the transition layer, the glass fiber reinforcement layer, and the high-strength fiber reinforcement layer are equal;

[0021] The length of the high-modulus fiber reinforcement layer is greater than the length of the high-strength fiber reinforcement layer, leaving space for subsequent adjustment of the dynamic balance state of the flywheel rotor.

[0022] As a preferred technical solution, resin is used as the matrix material, and its main function is to bond and transfer loads; fiber is used as the reinforcement material, and its main function is to bear the main loads and provide strength and stiffness. Resin and fiber combine to form a fiber-reinforced composite material (i.e., high-modulus fiber, high-strength fiber, and glass fiber). Fiber determines the strength, and resin determines the comprehensive performance (such as toughness and processability).

[0023] Further, the flywheel shafting further includes a motor, and the shafting support is connected to the motor.

[0024] As a preferred technical solution, the flywheel shafting is a rotating component, and after the flywheel shafting is combined with the stator assembly and the control device, it becomes a flywheel energy storage system.

[0025] A preparation method for a flywheel shafting structure is as follows:

[0026] S1. Determine the stiffness, strength, and strain of the flywheel rotor and the hub, and determine the shape and ply layup according to the rotational speed of the flywheel shafting and the type of composite material.

[0027] S2. Perform circumferential and helical winding in layers on the hub to complete the preparation of the composite material layer on the hub.

[0028] S3. Cut the hub part according to the height of the flywheel rotor, and then add a baffle according to the thickness of the flywheel rotor.

[0029] S4. Perform circumferential layer winding and curing molding of the flywheel rotor in sequence according to the ply layup of the flywheel rotor. After the flywheel rotor is cured, the flywheel shafting structure is obtained.

[0030] Further, in step S1, the method for determining the stiffness, strength, and strain of the flywheel rotor and the hub, and determining the shape and ply layup according to the rotational speed of the flywheel shafting and the type of composite material is as follows:

[0031] According to the designed rotational speed ω of the flywheel shafting, combined with the material properties and the shape coefficient k = r 内 ^2 / r 外 ^2, the maximum stress distribution of the flywheel rotor and the hub under high-speed rotation can be determined.

[0032] The maximum centrifugal stress of the flywheel rotor can be calculated by the following formula:

[0033]

[0034] where ρ is the material density, r 内 and r 外 are the inner and outer radii of the rotor respectively.

[0035] As a preferred technical solution, one of the design focuses of the flywheel rotor and the hub is to control the interlayer deformation outside the composite material fibers. To ensure effective control of strain during high-speed rotation, the modulus gradient design and ply layup strategy of the composite material should be combined. By optimizing the strain distribution through the distribution of high modulus (such as carbon fiber) in the outer layer and low modulus (such as glass fiber) in the inner layer, the stability of the shafting can be improved. In the ply layup design, the following strategies can be adopted:

[0036] 1. Ply sequence: According to the centrifugal force distribution, high-modulus fibers (such as carbon fibers) are used in the outer layer of the rotor to enhance the radial strength and stiffness, and low-modulus fibers (such as glass fibers) are used in the inner layer to improve the deformation ability. The hub is the opposite to achieve a tight fit between the rotor and the hub under working conditions. While meeting the strength requirements, sufficient pre-compressive stress is provided to significantly improve the stability of the shafting.

[0037] 2. Ply angle: Combining circumferential (90°) and helical (±θ°) alternating ply designs to control the axial and circumferential stress distributions.

[0038] 3. Thickness ratio: On the premise of ensuring a safety margin, the thicknesses of different layers are reasonably allocated to optimize the total weight and moment of inertia. Combining modal analysis, the angles and number of layers of the helical layer are optimized to meet the stability and dynamic balance requirements of the flywheel shafting during high-speed rotation.

[0039] 4. Overall process integration: The wet winding process is adopted to integrally form the hub and the rotor, improving the consistency of the contact surface and effectively enhancing the interface bonding performance.

[0040] Finally, by optimizing the ply thickness and modulus gradient, the strength, stiffness and strain requirements of the flywheel rotor and hub at high rotational speeds can be met, while ensuring dynamic balance and long-term stability.

[0041] Further, in step S2, the winding angle, starting position and layer sequence set for the hub can be adjusted according to design requirements to achieve different axial stiffnesses.

[0042] Further, in step S2, the metal layer of the hub is a circular arched top with a hollow interior. During winding, a dome-shaped cover plate is added to form a winding mold with the same size of winding holes at both ends. The helical layer is wound on the outer surface of the winding mold according to the ply scheme, and the circumferential layer is wound at the ends.

[0043] Further, in step S2, the hub can be formed with different winding angles according to the design requirements of the flywheel shafting. The helical layer can be wound at least two layers, but not necessarily limited to this. Any number of adjustments can be made according to the winding diameter, requirements of layer-by-layer curing, shafting frequencies corresponding to different rotational speeds, etc.;

[0044] As the winding thickness increases, the winding angle is modified according to the actual situation: the first-layer helical angle can be smaller than the second-layer helical angle. By changing the winding angle, the axial stiffness of the hub is improved, and the types of composite materials for each layer of the hub are arranged in the order of decreasing modulus from the inside to the outside. For example, the first layer is mainly reinforced with high-modulus fibers, the second layer is mainly reinforced with high-strength fibers, and the outermost layer is mainly reinforced with glass fibers. In this way, during high-speed rotation, the hub will expand towards the inner wall of the rotor, and a more firm connection is maintained between the two;

[0045] The overall stiffness of the helical layer can be adjusted by changing the winding start position of the composite material to distinguish the overlapping areas between the fibers. The circumferential layer wound on the shafting support can also enhance the connection between the hub and the shafting, meeting the assembly requirements of the components.

[0046] After winding, the hub is sent to an oven for rotational curing, so that the resin inside each layer can be evenly distributed, facilitating the subsequent dynamic balance treatment.

[0047] Furthermore, in step S2, during the winding process, the hollow interior of the hub is filled with clay to prevent excessive mechanical size changes of the hub during winding and curing, which may affect subsequent assembly.

[0048] Furthermore, in step S2, the modulus of the hub decreases sequentially from the inside to the outside.

[0049] Furthermore, in step S2, the ply layup scheme of the hub is as follows:

[0050] The modulus gradient decreases layer by layer from the inside to the outside. Carbon fiber (high modulus, initial stiffness) is used in the inner layer, high-strength fiber (transition layer) is used in the middle layer, and glass fiber (low modulus, deformation absorption) is used in the outer layer;

[0051] Winding angle: The inner and middle layers are mainly wound helically, and the outer layer is mainly wound circumferentially;

[0052] Thickness ratio: 1:2:1 (example), which is optimized and adjusted in combination with the flywheel rotation speed.

[0053] As a preferred technical solution, in step S2, circumferential winding and helical winding are conventional technical means in the field of composite material forming and are widely used in the manufacture of rotating bodies and high-pressure vessels. In view of the dynamic requirements of the hub and the rotor, the present invention combines conventional process technologies to attempt to solve the problems of weak interfacial bonding and interlayer cracking. The effects of these two winding methods are as follows: Circumferential winding: provides radial restraint and effectively controls the radial deformation under the action of centrifugal force; Helical winding: enhances the axial stiffness and optimizes the dynamic response characteristics by adjusting the fiber winding angle.

[0054] Furthermore, in step S4, the modulus of the flywheel rotor increases sequentially from the inside to the outside.

[0055] Furthermore, in step S4, the curing process is low-speed rotational heating in layers, and the curing regime varies according to the type of resin matrix selected.

[0056] Further, in step S4, the winding methods of the transition layer, the glass fiber reinforced layer, the high-strength fiber reinforced layer, and the high-modulus fiber reinforced layer are all circumferential winding, that is, the winding angle is 90°. The modulus of the rotor increases layer by layer from the inside to the outside. At high speeds, the inner layer is extruded towards the outermost layer, and the high-modulus fiber reinforced material is used to offset the tendency of radial expansion and prevent the fibers between layers from loosening or breaking.

[0057] Further, in step S4, the rotor layup scheme is as follows:

[0058] The modulus gradient increases layer by layer from the inside to the outside. Glass fiber (low modulus, absorbs deformation) is used in the inner layer, high-strength fiber (high strength, supports interlayer stress) is used in the middle layer, and carbon fiber (high modulus, resists radial deformation) is used in the outer layer;

[0059] Winding angle: combined circumferential (90°) winding and helical (±30° to ±45°) winding;

[0060] Thickness ratio: 1 mm for the inner layer, 4 mm for the middle layer, 1 mm for the outer layer (example), and further optimized in combination with finite element analysis.

[0061] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0062] 1. The present invention selects approximate types of composite materials to prepare the flywheel rotor and the hub in the flywheel shafting structure. The outer surface of the hub is processed by wet winding molding during the shafting support, and the rotor is wound after rotation curing. The above process is rotationally cured in layers according to the layup, and finally an integral product is formed to ensure that the hub and the rotor on the shafting do not come off, and the two are closely attached during high-speed rotation, effectively improving the ultimate speed and stability of the flywheel rotor system.

[0063] 2. To prevent the interface between the composite material flywheel rotor and the hub from coming off and improve the processing efficiency of the composite material flywheel shafting. The present invention considers winding the same composite material as the flywheel rotor on the inner layer of the dome metal in multiple layers. First, a flywheel hub with a modulus decreasing from the inside to the outside is prepared, and then the flywheel rotor is wound and formed directly based on the above hub, and finally the integral preparation of the composite material flywheel rotor and the hub is completed.

[0064] 3. The preparation method of the flywheel shafting structure provided by the present invention prepares the composite material hub by using the low-cost and efficient wet winding process, and then completes the processing of the composite material rotor. The rotor and the hub are prepared with similar materials to meet the strength and radial deformation design requirements, ensuring the dynamic stability of the entire rotor system. This method can improve the interface performance between the composite material flywheel rotor and the hub, ensure strength and stiffness, and prevent the two from coming off at high speeds.

[0065] 4. The multi-layer composite material winding forming technology is adopted for both the flywheel rotor and the supporting hub, which not only improves the production efficiency, but also improves the synchronous state of radial deformation, effectively preventing the separation between the rotor and the hub when the flywheel system rotates at high speed.

[0066] 5. In addition, compared with the metal hub, the axial stiffness can be adjusted by adjusting the shape and layup of the hub according to the rotational speed and application scenario of the flywheel energy storage system, reducing the overall weight of the shafting. Description of the Drawings

[0067] Figure 1 is a schematic process flow diagram of the flywheel shafting structure;

[0068] Figure 2 is a schematic diagram of the curve of the stress in the middle of the flywheel changing with the radius under the A layup scheme;

[0069] Figure 3 is a schematic diagram of the curve of the stress in the middle of the flywheel changing with the radius under the B layup scheme;

[0070] Figure 4 is a schematic diagram of the structure of the hub;

[0071] Figure 5 is a schematic diagram of the winding processing process of the hub;

[0072] Figure 6 is a schematic diagram of the winding processing process of the flywheel rotor.

[0073] Description of the drawing numbers: 100a, flywheel shafting; 100, metal layer; 100b, dome-shaped cover plate; 200, helical layer; 300, circumferential layer; 401, transition layer; 402, glass fiber reinforced layer; 403, high-strength fiber reinforced layer; 404, high-modulus fiber reinforced layer; 500, baffle. Detailed Embodiment

[0074] The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and the detailed implementation manner and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0075] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0076] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0077] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0078] The following will describe in detail some embodiments of the present invention with reference to the drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0079] Embodiment 1

[0080] See Figures 4 to 6 , this embodiment provides a flywheel shafting structure. The flywheel shafting 100a includes a shafting support, a flywheel rotor, and a hub. One end of the hub is connected to the shafting support, and a flywheel rotor is provided at the other end of the hub. The flywheel rotor is used for storing and releasing energy;

[0081] The hub includes a metal layer 100, a spiral layer 200, and a circumferential layer 300. The metal layer 100 is provided outside the shafting support. The spiral layer 200 is provided outside the metal layer 100. The circumferential layer 300 is provided at one end where the spiral layer 200 is connected to the shafting support;

[0082] The flywheel rotor includes a transition layer 401 and a reinforcement layer. One end of the transition layer 401 is connected to the spiral layer 200, and the reinforcement layer is provided at the other end of the transition layer 401.

[0083] Further, the metal layer 100 is a circular arch top with a hollow interior, and the material of the spiral layer 200 is fiber.

[0084] Further, the spiral layer 200 has multiple layers, which are, from the inside to the outside, a high-modulus fiber layer, a high-strength fiber layer, and a glass fiber layer.

[0085] Further, the material of the transition layer 401 is a resin matrix, which can better realize the composite material performance and is prepared by an optimized process method.

[0086] Further, the reinforcing layer includes a glass fiber reinforcing layer 402, a high-strength fiber reinforcing layer 403, and a high-modulus fiber reinforcing layer 404 wound circumferentially in sequence. The glass fiber reinforcing layer 402 is wound circumferentially outside the transition layer 401.

[0087] As a preferred technical solution, the transition layer 401, the glass fiber reinforcing layer 402, and the high-strength fiber reinforcing layer 403 have the same length;

[0088] The length of the high-modulus fiber reinforcing layer 404 is greater than that of the high-strength fiber reinforcing layer 403, reserving space for subsequent adjustment of the dynamic balance state of the flywheel rotor.

[0089] Further, the flywheel shafting 100a further includes a motor, and the shafting support is connected to the motor.

[0090] As a preferred technical solution, the flywheel shafting 100a is a rotating component, and the flywheel shafting 100a forms a flywheel energy storage system after being combined with the stator assembly and the control device.

[0091] Embodiment 2

[0092] This embodiment provides a method for controlling the radial deformation amount. The calculation and analysis of the radial deformation amount are mainly completed based on finite element analysis (FEA) software in the actual design process. By means of the material model and loading conditions, the radial stress and deformation distribution under the condition of high-speed rotation are simulated, providing a basis for the ply design and process adjustment. The specific steps are as follows:

[0093] S1. Finite element calculation process:

[0094] (1) Input parameters:

[0095] Geometric parameters: the inner and outer radii of the flywheel, the thickness of different materials, etc.;

[0096] Material properties: the elastic modulus, density, and Poisson's ratio of each layer of material;

[0097] Working conditions: the design speed (ω).

[0098] (2) Set boundary conditions:

[0099] Assume that the hub and the rotor do not undergo out-of-plane detachment at the working speed, fix them on the shaft, and apply the design speed to the rotor.

[0100] (3) Result output:

[0101] The radial stress, circumferential stress and radial deformation distribution of each layer are obtained through analysis.

[0102] S2. Auxiliary of quantitative formula:

[0103] Based on the finite element calculation, the rationality of the results can be verified by combining the following formulas:

[0104]

[0105] Where Δγ is the radial deformation, ρ is the material density, ω is the rotational speed, r is the radius, and E is the modulus.

[0106] Each parameter is consistent with the actual design conditions and can be used to verify the deformation trend.

[0107] S3. Actual design adjustment:

[0108] According to the finite element analysis results, adjust the modulus gradient layup scheme of the hub and the rotor so that their radial deformations under high-speed rotation are as consistent as possible to avoid interface detachment.

[0109] The modulus of the hub gradually decreases from the inside to the outside, and the centrifugal stress is absorbed through the deformation buffer of the outer layer; the modulus of the rotor gradually increases from the inside to the outside to enhance the radial constraint ability of the outer layer.

[0110] For key positions (such as the maximum stress point and the contact interface), improve the local stress distribution by increasing the layup thickness or adjusting the helix angle.

[0111] S4. Process optimization:

[0112] Based on the finite element calculation results, improve the actual process adaptability by combining the following optimization means:

[0113] (1) Optimize the helix angle and thickness distribution of the fiber layup to control the deformation and stress distribution;

[0114] (2) Epoxy resin with a toughening formula can be selected to improve the interlayer bonding strength;

[0115] (3) Implement the integral curing process of the hub and the rotor to reduce the processing error.

[0116] Example 3

[0117] See Figure 1 , this example provides a preparation method for a flywheel shafting structure, and the specific steps are as follows:

[0118] S1. Determine the stiffness, strength and strain of the flywheel rotor and the hub according to the rotational speed of the flywheel shafting 100a, and determine the shape and layup scheme;

[0119] S1-1. Determine the design parameters

[0120] Target rotational speed ω: According to the requirements of the flywheel energy storage system, determine the rated operating rotational speed of the flywheel (such as 30000 rpm).

[0121] Material selection: Considering the properties of composite materials, determine the fiber and matrix materials for the rotor and the hub. High modulus carbon fiber (outer layer of the rotor) and glass fiber (inner layer of the rotor) are preferred, and the matrix material is epoxy resin.

[0122] Structural dimensions: Determine the outer diameter r 外 , inner diameter r 内 and thickness t of the flywheel shafting according to the energy storage requirements.

[0123] S1-2. Mechanical analysis and ply design

[0124] Modal analysis: Use finite element analysis to simulate the modal characteristics of the shafting to ensure no resonance phenomenon within the operating rotational speed range.

[0125] Stress analysis: Calculate the maximum centrifugal stress of the rotor under high-speed rotation using the following formula:

[0126]

[0127] where k = r 内 ^2 / r 外 ^2, which is used to describe the shape factor.

[0128] Ply design:

[0129] (1) Rotor part: From the inner layer to the outer layer, adopt a ply sequence from low modulus (glass fiber) to high modulus (carbon fiber), gradually increasing the modulus to control the radial and axial stress distributions. Meeting the specified thickness is sufficient.

[0130] (2) Hub part: From the inner layer to the outer layer, adopt a ply sequence from high modulus (carbon fiber) to low modulus (glass fiber) to ensure that the hub expands appropriately under the action of centrifugal force and remains tightly bonded to the rotor. Meeting the specified thickness is sufficient.

[0131] Ply angle: Combine circumferential (90°) and helical winding (±θ°), where the initial value of the helical angle is 15°, and adjust the angle range from 10° to 60° according to finite element analysis.

[0132] S2. Hub forming: Conduct circumferential and helical winding on the hub layer by layer, and use the wet winding process to complete the preparation of the composite material layer on the hub;

[0133] The metal layer 100 of the hub is a circular arched top with a hollow interior. The metal layer 100 (the inner layer of the hub) serves as a support, and on its outer surface, spiral and circumferential winding are alternately carried out layer by layer according to the laying scheme. During the winding process, a domed cover plate 100b is added to form a winding mold with the same size of winding holes at both ends. The spiral layer 200 is wound on the outer surface of the winding mold according to the laying scheme, and the end winding circumferential layer 300 is wound.

[0134] During the winding process, the hollow interior of the hub is filled with clay to prevent excessive changes in the mechanical dimensions of the hub during winding and curing, which may affect subsequent assembly.

[0135] As the winding thickness increases, the winding angle is modified according to the actual situation: the spiral angle of the first layer can be smaller than that of the second layer. By changing the winding angle, the axial stiffness of the hub is improved. The change of the winding angle is based on the mechanical performance requirements of the flywheel shafting and the optimization of the stress distribution between winding layers. The specific adjustment method and actual situation are as follows:

[0136] (1) Design principle of winding angle:

[0137] The winding angle affects the axial stiffness and circumferential strength of the composite material. A smaller spiral angle (such as ±10° to ±20°) tends to enhance the axial stiffness and is suitable for the initial several layers of the hub; a larger spiral angle (such as ±30° to ±45°) can provide better circumferential strength and is suitable for the outer layer of the hub.

[0138] By adjusting the winding angle, a balance can be achieved between the axial and circumferential stress distributions, so as to meet the deformation requirements of the hub during high-speed rotation.

[0139] The adjustment of the winding angle is based on the results of finite element analysis (FEA) and actual rotation experiment data. By analyzing the stress distribution corresponding to the spiral angle, the optimal angle range is selected to meet the requirements of dynamic stability and strength.

[0140] (2) Actual operation of adjusting the winding angle:

[0141] Initial layer angle (low angle): When winding the first layer, a spiral angle of ±10° to ±15° is selected to ensure the axial stiffness to adapt to the initial load transfer requirements.

[0142] Intermediate layer angle (gradually increasing): As the winding thickness increases, the spiral angle is gradually increased to ±20° to ±30° to gradually enhance the circumferential restraint ability and disperse the radial stress at the same time.

[0143] Outer layer angle (large angle): When winding the outermost layer, the spiral angle can reach ±30° to ±60° to provide a stronger circumferential restraint ability and control the radial expansion caused by centrifugal force.

[0144] (3) Modify the reference

[0145] "As the winding thickness increases, modify the winding angle according to the actual situation: the first-layer spiral angle can be set to ±10° to ±15°, providing a higher axial stiffness; the middle-layer angle gradually increases to ±20° to ±30°, enhancing the circumferential strength while controlling the axial stiffness; the outer-layer angle increases to ±30° to ±60°, providing a stronger circumferential constraint ability, so as to meet the deformation requirements of the hub during high-speed rotation."

[0146] The types of composite materials for each layer of the hub are arranged in the order of decreasing modulus from the inside to the outside. For example, the first layer uses high-modulus fibers as the main reinforcing material, the second layer uses high-strength fibers as the main reinforcing material, and the outermost layer uses glass fibers as the main reinforcing material. In this way, during high-speed rotation, the hub will expand towards the inner wall of the rotor, and a more firm connection will be maintained between the two;

[0147] After winding is completed, put the hub into an oven. The curing heating rate of the winding process is 10°C / min, and the curing regime is to heat at 90°C for 2 hours, then heat at 110°C for 1.5 hours, and finally heat at 130°C for 2 hours.

[0148] S3. Rotor forming: After the hub winding is completed and cured, wind the rotor part with the hub as the base, mainly in the circumferential direction (90°), and spiral layers can be added as appropriate, and the angle can be selected as ±30°.

[0149] Carry out circumferential layered winding and curing forming of the flywheel rotor in sequence according to the flywheel rotor ply scheme. After the flywheel rotor is cured, a flywheel shafting structure is obtained; the winding methods of the transition layer 401, the glass fiber reinforced layer 402, the high-strength fiber reinforced layer 403, and the high-modulus fiber reinforced layer 404 are all circumferential winding, that is, the winding angle is 90°. The modulus of this rotor increases layer by layer from the inside to the outside. At high speeds, the inner layer is extruded towards the outermost layer, and high-modulus fiber reinforcing materials are used to offset the tendency of radial expansion and prevent the fibers between layers from loosening or breaking. The curing process is layered low-speed rotation heating, and the curing regime changes according to the type of resin matrix selected.

[0150] During the temperature rise of the liquid resin, its viscosity first decreases and then rises sharply. In the initial stage of curing heating, due to the decrease in the viscosity of the glue, the resin penetrates outward under the action of the pressure between the fiber layers. In order to prevent the influence of winding part deflection and uneven resin penetration on the mass imbalance of the composite flywheel, the composite flywheel curing adopts a rotating curing process.

[0151] The curing regime should be adjusted according to the physical and chemical properties of the formula. Now for reference and example: the curing heating rate of the winding process is 10°C / min, and the curing regime is to heat at 90°C for 2 hours, then heat at 110°C for 1.5 hours, and finally heat at 130°C for 2 hours.

[0152] S4. Curing conditions:

[0153] After winding, the hub and rotor as a whole are sent to an oven for rotational curing. The curing heating rate of the winding process is 10 °C / min. The curing regime is heating at 90 °C for 2 hours, then heating at 110 °C for 1.5 hours, and finally heating at 130 °C for 2 hours. The resin inside each layer can be evenly distributed, facilitating the subsequent dynamic balance treatment.

[0154] S5. Cut the hub part according to the height of the flywheel rotor, and then add a baffle 500 according to the thickness of the flywheel rotor;

[0155] According to Figure 5 As shown by the dotted line on, a cutting opening is reserved for the dome-shaped cover plate 100b added on the other side of the hub. After the spiral layer 200 and circumferential layer 300 of the hub are cured and formed, the cutting treatment is carried out according to the height of the flywheel rotor.

[0156] S6. Assembly and testing. After the flywheel rotor is completed with layered rotational curing, the mechanical dimensions and initial dynamic balance state of the product are detected.

[0157] Dynamic balance: Detect the dynamic balance state of the rotor and hub as a whole, and optimize the dynamic balance by adjusting the thickness of the outer carbon fiber layer.

[0158] Stability test: Conduct a long-term stability test at the rated speed to ensure no delamination or interface cracking.

[0159] Since there is a certain extrusion from the outer layer of the composite material hub to the inner layer of the rotor at high speeds, the outer layer of the composite material flywheel rotor is restricted by the high-modulus fiber reinforced layer. The deformation between the two components is relatively consistent, alleviating the tendency of the composite material to crack radially. In addition, compared with the metal hub, the strength is improved and the weight is reduced, and the overall axial stiffness of the shafting is increased.

[0160] Figure 2 The A ply layup scheme is that the total thickness of the high-strength glass fiber layer is 45 mm, the total thickness of the high-strength glass fiber - high-strength carbon fiber hybrid layer is 30 mm, and the total thickness of the high-modulus carbon fiber layer is 20 mm. The set operating speed is 30000 rpm. The curve in the figure is the change trend of the stress in the middle of the flywheel rotor in the radial direction under high-speed rotation. The positive value is the tensile stress and the negative value is the compressive stress. The radial stress of the flywheel rotor with this ply layup scheme is significantly less than the strength limit of the material at the above operating speed, and the safety factor reaches more than 2, proving that the rotor of this structure is safe and reliable.

[0161] Figure 3 The B ply layup scheme and the rotational speed are the same as Figure 2Consistent, this example incorporates the internal effects of the assembled hub at operating speed into the rotor analysis. The radial tensile stress levels (positive values) of the composite rotor in the previous section are basically the same, and there will be no separation between the composite material and the interior.

[0162] Figure 2 and Figure 3 is the curve of the change of the stress in the middle part of the flywheel rotor with different ply schemes under high-speed rotation in the radial direction. Positive values are tensile stresses, and negative values are compressive stresses, indicating that cracking can be avoided by adjusting the rotor layers.

[0163] When the above shafting and flywheel rotor are both at high speeds, the tendency of the composite hub to deform radially is consistent with that of the rotor, and because similar types of reinforcing fibers and resins are used, the tendency of the composite layer to crack is alleviated.

[0164] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A flywheel shafting structure, characterized in that, The flywheel shafting (100a) includes a shafting support, a flywheel rotor, and a hub. One end of the hub is connected to the shafting support, and the other end of the hub is provided with a flywheel rotor for storing and releasing energy. The hub includes a metal layer (100), a helical layer (200), and a circumferential layer (300). The metal layer (100) is provided outside the shafting support, the helical layer (200) is provided outside the metal layer (100), and the circumferential layer (300) is provided at one end where the helical layer (200) is connected to the shafting support. The flywheel rotor includes a transition layer (401) and a reinforcement layer. One end of the transition layer (401) is connected to the helical layer (200), and the other end of the transition layer (401) is provided with a reinforcement layer.

2. The flywheel shafting structure according to claim 1, characterized in that The metal layer (100) is a circular arch top with a hollow interior, and the material of the helical layer (200) is fiber.

3. The flywheel shafting structure according to claim 1, wherein, The material of the metal layer (100) includes steel, aluminum alloy, titanium alloy, magnesium alloy, and cast iron.

4. A flywheel shafting structure according to claim 1, characterized in that, The helical layer (200) has multiple layers, which are, from the inside to the outside, a high-modulus fiber layer, a high-strength fiber layer, and a glass fiber layer.

5. A flywheel shafting structure according to claim 1, characterized in that The material of the transition layer (401) is a resin matrix.

6. A flywheel shafting structure according to claim 1, characterized in that, The reinforcement layer includes a glass fiber reinforcement layer (402), a high-strength fiber reinforcement layer (403), and a high-modulus fiber reinforcement layer (404) that are wound circumferentially in sequence. The glass fiber reinforcement layer (402) is wound circumferentially outside the transition layer (401).

7. A flywheel shafting structure according to claim 1, characterized in that, The flywheel shafting (100a) further includes a motor, and the shafting support is connected to the motor.

8. A preparation method of a flywheel shafting structure as described in any one of claims 1 - 7, characterized in that, The specific steps are as follows: S1. Determine the stiffness, strength, and strain of the flywheel rotor and the hub according to the rotational speed of the flywheel shafting (100a) and the types of composite materials, and determine the shape and ply layup scheme. S2. Perform circumferential and helical winding on the hub layer by layer to complete the preparation of the composite material layer on the hub. S3. Cut the hub part according to the height of the flywheel rotor, and then add a baffle (500) according to the thickness of the flywheel rotor. S4. Perform circumferential layer-by-layer winding and curing molding of the flywheel rotor in sequence according to the ply layup scheme of the flywheel rotor. After the flywheel rotor is cured, the flywheel shafting structure is obtained.

9. The preparation method of a flywheel shafting structure according to claim 8, characterized in that The metal layer (100) of the hub is a circular arch top with a hollow interior. During the winding process, a domed cover plate (100b) is added to form a winding mold with the same size of winding holes at both ends. The helical layer (200) is wound on the outer surface of the winding mold according to the ply layup scheme, and the circumferential layer (300) is wound at the end.

10. The preparation method of a flywheel shafting structure according to claim 8, characterized in that In step S2, the modulus of the hub decreases from the inside to the outside; in step S4, the modulus of the flywheel rotor increases from the inside to the outside.

Images