Energy-saving and environment-friendly electric fan

Abstract

The invention discloses an energy-saving and environment-friendly electric fan. The electric fan comprises a rotating shaft and a plurality of fan blades located on the periphery of the rotating shaft. The plurality of fan blades are uniformly distributed along the rotating shaft; the fan blade comprises a main body part, a rigid cylinder and a flexible cylinder. When the electric fan is in a working state, the other end of the flexible barrel can abut against the inner wall, close to the first side, of the main body part, and the other end of the flexible barrel moves relative to the inner wall of the main body part. According to the technical scheme, along with vibration of the fan blades, the other end of the flexible barrel slides relative to the inner wall of the main body part, a sliding friction pair is formed, vibration kinetic energy of the fan blades is converted into friction heat energy to be dissipated, and therefore self-adaptive friction damping is provided to restrain the amplitude of the fan blades.

Description

Technical Field

[0001] This invention relates to the field of large electric fan technology, and more specifically, to an energy-saving and environmentally friendly electric fan. Background Technology

[0002] Large electric fans are widely used in cooling towers, large factory ventilation, tunnel exhaust, and air coolers, with impeller diameters typically ranging from 5 to 20 meters. In these applications, the fan blades, as cantilevered long structures, continuously bear high-frequency cyclic loads generated by rotational centrifugal force and stable airflow during operation, as well as sudden impact loads caused by gusts, turbulence, or start-up and shutdown conditions. These alternating stresses easily induce fatigue cracks at the blade root and connection areas, significantly shortening the service life of the blades and connection system.

[0003] Currently, the conventional support structure for such electric fan blades typically uses solid rods or tubular support components (such as metal round tubes or fiber-reinforced composite tubes). One end of the support is embedded in the blade cavity and fixed to the blade shell by adhesive or mechanical connection, while the other end is rigidly connected to the fan hub via a flange or adapter to transmit torque and resist bending deformation. To improve structural strength to cope with severe loads, large-diameter or high-rigidity support components are usually required. This often necessitates a corresponding thickening of the blade root area to accommodate the support component, thereby increasing the overall weight of the blade and material consumption, and potentially compromising the aerodynamic shape of the blade, thus increasing operating energy consumption.

[0004] Furthermore, the aforementioned rigid connection method lacks an effective vibration energy dissipation mechanism. Large vibrations generated by the fan blades under impact loads are transmitted almost without attenuation to the hub, drive motor, and support tower through the rigid support, easily triggering resonance in the entire fan system. This leads to loosening of connecting bolts, premature bearing wear, and significant structural noise. Simultaneously, stress concentration easily occurs at the interface between the rigid support and the fan blade shell, further exacerbating the risk of fatigue damage in this area. Therefore, effectively suppressing fan blade vibration and reducing fatigue stress while maintaining a reasonable aerodynamic shape and weight has become a key technical challenge in the design of industrial large fan blades. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides an energy-saving and environmentally friendly electric fan to solve at least some of the technical problems mentioned in the background art.

[0006] To achieve the above objectives, a first aspect of the present invention provides an energy-saving and environmentally friendly electric fan, the fan comprising a rotating shaft and a plurality of fan blades located around the rotating shaft; the plurality of fan blades are evenly distributed along the rotating shaft; the fan blades include: The main body has a first side and a second side along the rotation direction of the rotation axis, the thickness of the second side being greater than the thickness of the first side; along the length direction of the main body, the main body has a first end near the rotation axis and a second end away from the rotation axis, the thickness of the first end being greater than the thickness of the second end; the main body has a mounting cavity extending along its length direction, the mounting cavity being near the second side of the main body. A rigid cylindrical body, one end of which is fixedly connected to the rotating shaft, and the other end of which extends from the first end of the main body into the mounting cavity and is fixed to the main body; A flexible cylinder is disposed within the mounting cavity, with one end of the flexible cylinder fixed to the rigid cylinder and the other end located near the second end of the main body. When the fan is in operation, the other end of the flexible cylinder can abut against the inner wall of the main body near the first side and move relative to the inner wall of the main body.

[0007] Optionally, when the fan is not in operation, there is a gap between the other end of the flexible cylinder and the inner wall of the main body, the gap not exceeding 3mm.

[0008] Optionally, the rigid cylinder includes a first segment located outside the mounting cavity and a second segment located inside the mounting cavity along its length; the length of the second segment does not exceed one-half the length of the main body and is not less than one-third the length of the main body.

[0009] Optionally, the fan blade further includes a bolt and a nut, wherein the bolt passes sequentially through the upper side wall of the main body, the upper side wall of the rigid cylinder, the upper side wall of the flexible cylinder, the lower side wall of the flexible cylinder, the lower side wall of the rigid cylinder, and the lower side wall of the main body before engaging with the nut via a thread.

[0010] Optionally, the main body further includes a rigid liner located within the mounting cavity and at a second end of the main body; the other end of the flexible cylinder extends into the rigid liner. When the fan is in operation, the other end of the flexible cylinder can abut against the inner wall of the rigid liner and move relative to the inner wall of the rigid liner.

[0011] Optionally, the rigid cylinder is made of metal; and / or the flexible cylinder is made of glass fiber.

[0012] Optionally, the width of the rigid cylinder is D along the rotation direction of the rotation axis; the thickness of the rigid cylinder is d along the thickness direction of the main body, where d <D<2d。

[0013] Optionally, along the rotation direction of the rotation axis, the rigid cylinder includes a first cylinder and a second cylinder that are connected to each other, and the cross-sections of the first cylinder and the second cylinder cooperate to form a horizontal figure-eight shape.

[0014] Optionally, the main body further includes a reinforcing rib extending along its length and used to connect the upper sidewall and the lower sidewall of the main body. The reinforcing rib is located in the mounting cavity and divides the mounting cavity into a first cavity and a second cavity. The reinforcing rib is close to the first side, and the first cavity is close to the first side.

[0015] Optionally, the rigid cylinder extends into the second cavity, and the first cylinder is close to the reinforcing rib, while the flexible cylinder is located inside the first cylinder; when the fan is in operation, the other end of the flexible cylinder can abut against the reinforcing rib and move relative to the reinforcing rib.

[0016] The specific effects of this invention are as follows: The rigid cylinder serves as a high-rigidity support component, with one end fixed to the rotating shaft and the other end fixed to the main body, providing torque transmission and root structural support for the fan blades, while also serving as an anchoring base for the flexible cylinder. When the fan is working, the main body undergoes bending deformation under aerodynamic load and centrifugal force, causing the rigid cylinder to move synchronously. The flexible cylinder is fixed at one end to the rigid cylinder and free at the other end. During the bending process of the fan blades, it comes into contact with the inner wall of the main body due to inertial lag or poor elastic deformation. As the fan blades vibrate, the other end of the flexible cylinder slides relative to the inner wall of the main body, forming a sliding friction pair. This converts the vibration kinetic energy of the fan blades into frictional heat energy for dissipation, thereby providing adaptive frictional damping to suppress the fan blade amplitude, reduce the alternating stress at the root of the fan blades and the vibration energy transmitted to the rotating shaft, reduce structural fatigue and vibration loss, and achieve vibration reduction, noise reduction, and energy-saving operation of the fan. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an energy-saving and environmentally friendly electric fan according to the present invention; Figure 2 This is a partial structural diagram of an energy-saving and environmentally friendly electric fan according to the present invention; Figure 3 This is a schematic cross-sectional view of the main body of the present invention; Figure 4 This is a partial schematic diagram of a longitudinal cross-section of the main body of the present invention.

[0018] The reference numerals in the attached drawings are as follows: 1. Rotating shaft; 2. Fan blade; 21. Main body; 211. First side; 212. Second side; 213. First end; 214. Second end; 215. Mounting cavity; 22. Rigid cylinder; 23. Flexible cylinder; 24. Bolt; 25. Nut; 26. Rigid liner; 221. First cylinder; 222. Second cylinder; 216. Reinforcing rib; 217. First cavity; 218. Second cavity. Detailed Implementation

[0019] 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 a part of the embodiments of the present invention, and not all of them. 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.

[0020] like Figure 1 , Figure 2 and Figure 4 As shown, this embodiment of the invention discloses an energy-saving and environmentally friendly electric fan. The electric fan includes a rotating shaft 1 and multiple fan blades 2 located around the rotating shaft 1. The multiple fan blades 2 are evenly distributed along the rotating shaft 1. The fan blades 2 include a main body 21, a rigid cylinder 22 and a flexible cylinder 23.

[0021] Along the rotation direction of the rotation axis 1, the main body 21 has a first side 211 and a second side 212, the thickness of the second side 212 being greater than the thickness of the first side 211; along the length direction of the main body 21, the main body 21 has a first end 213 near the rotation axis 1 and a second end 214 away from the rotation axis 1, the thickness of the first end 213 being greater than the thickness of the second end 214; the main body 21 has a mounting cavity 215 extending along its length direction, the mounting cavity 215 being near the second side 212 of the main body 21; with this arrangement, the second side 212 of the main body 21 is thicker and the first side 211 is thinner, forming an airfoil-like aerodynamic cross section, which can reduce airflow resistance and improve fan efficiency; the first end 213 is thicker and the second end 214 is thinner along the length direction, which conforms to the bending moment distribution of a cantilever beam, achieving equal strength design, reducing blade tip weight, and reducing rotational inertia and material consumption while meeting structural strength requirements.

[0022] One end of the rigid cylinder 22 is fixedly connected to the rotating shaft 1, and the other end extends from the first end 213 of the main body 21 into the mounting cavity 215 and is fixed to the main body 21. The rigid cylinder 22, with one end fixed to the rotating shaft 1 and the other end extending into and fixed to the mounting cavity 215 of the main body 21, forms a rigid force transmission path from the rotor to the fan blade 2. Its high rigidity ensures efficient transmission of rotational torque to the main body 21, while resisting high bending stress and centrifugal force at the root of the fan blade 2, preventing excessive deformation or loosening of the root connection under alternating loads.

[0023] A flexible cylinder 23 is disposed within the mounting cavity 215, with one end fixed to the rigid cylinder 22 and the other end near the second end 214 of the main body 21. When the fan is in operation, the other end of the flexible cylinder 23 can abut against the inner wall of the main body 21 near the first side 211 and move relative to the inner wall of the main body 21. The other end of the flexible cylinder 23 is near the second end 214 of the main body 21, which is the area with the largest vibration amplitude. By providing local constraint at this location, the flexible cylinder 23 can effectively suppress the first bending mode vibration of the fan blade 2, specifically dissipate the vibration energy at the blade tip, and reduce fatigue stress concentration.

[0024] Specifically, when the fan is working, the main body 21 bends and deforms under the action of aerodynamic load and centrifugal force, causing the rigid cylinder 22 to move synchronously. One end of the flexible cylinder 23 is fixed inside the rigid cylinder 22, while the other end is free. During the bending process of the fan blade 2, it comes into contact with the inner wall of the main body 21 due to inertial lag or poor elastic deformation. As the fan blade 2 vibrates, the other end of the flexible cylinder 23 slides relative to the inner wall of the main body 21, forming a sliding friction pair. This converts the vibration kinetic energy of the fan blade 2 into frictional heat energy for dissipation, thereby providing adaptive frictional damping to suppress the amplitude of the fan blade 2, reduce the alternating stress at the root of the fan blade 2 and the vibration energy transmitted to the rotating shaft 1, reduce structural fatigue and vibration loss, and achieve vibration reduction, noise reduction and energy-saving operation of the fan.

[0025] As an optional implementation, when the fan is not in operation, there is a gap of no more than 3 mm between the other end of the flexible cylinder 23 and the inner wall of the main body 21. When the fan is not in operation, due to the existence of the gap, the flexible cylinder 23 does not contact the inner wall of the fan blade 2, resulting in no static friction torque and avoiding continuous wear and fretting fatigue. When the fan is in operation, the main body 21 is subjected to bending moment and undergoes bending deformation, while the flexible cylinder 23 bends outward under the action of centrifugal force and inertial force. Since one end is fixed inside the rigid cylinder 22 and the other end is free, the flexible cylinder 23 actively abuts against the inner wall of the fan blade 2 near the first side 211 after bending, establishing contact pressure. At this time, the vibration of the fan blade 2 causes the flexible cylinder 23 to slide relative to each other, converting the vibration kinetic energy into frictional heat energy for dissipation. This "gap-contact-sliding" mechanism is adaptive. When the main body 21 vibrates slightly, there is no contact, that is, there is zero damping between the flexible cylinder 23 and the main body 21, resulting in low energy consumption. When the main body 21 vibrates significantly, contact is established between the flexible cylinder 23 and the main body 21, and the contact pressure increases with the increase of the amplitude, thereby achieving adaptive elimination of the vibration of the main body 21. At the same time, the gap is limited to within 3mm to ensure that the flexible cylinder 23 can contact the inner wall in time to generate damping under normal working load, avoiding contact lag and damping failure due to excessive gap; at the same time, it prevents unexpected contact caused by thermal expansion and contraction or manufacturing errors due to excessive gap.

[0026] As an optional implementation, the rigid cylinder 22 includes a first segment outside the mounting cavity 215 and a second segment inside the mounting cavity 215 along its length. The length of the second segment is no more than half the length of the main body 21 and no less than one-third the length of the main body 21. The fact that the length of the second segment is no less than one-third of the length of the main body 21 ensures that the rigid cylinder 22 and the main body 21 have sufficient overlap length, providing reliable torque transmission and bending stiffness support, and avoiding excessive stress concentration at the connection point under alternating loads. The fact that the length of the second segment is no more than half the length of the main body 21 prevents the rigid cylinder 22 from being too long and encroaching on the working area of ​​the flexible cylinder 23, ensuring that the flexible cylinder 23 has sufficient length to generate elastic bending deformation to contact the inner wall of the fan blade 2. This also reduces the amount of rigid metal material used, lowers the overall weight, meets energy-saving and environmental protection requirements, and prevents the distal end of the fan blade 2 from becoming too rigid and losing its flexible damping effect.

[0027] As an optional implementation manner, the fan blade 2 further includes a bolt 24 and a nut 25. The bolt 24 sequentially passes through the upper side wall of the main body portion 21, the upper side wall of the rigid cylinder 22, the upper side wall of the flexible cylinder 23, the lower side wall of the flexible cylinder 23, the lower side wall of the rigid cylinder 22, and the lower side wall of the main body portion 21, and then is in threaded cooperation with the nut 25. The bolt 24 sequentially passes through the upper and lower side walls of the main body portion 21, the rigid cylinder 22, and the flexible cylinder 23 and is in cooperation with the nut 25, realizing the one-time clamping and fastening of the three-layer structure. This not only simplifies the assembly process and ensures the accurate relative positioning of each layer in the thickness direction, but also provides a reliable interlayer connection stiffness through mechanical pre-tightening, preventing interlayer slip or loosening caused by centrifugal force or vibration under rotational conditions, and facilitating later disassembly and maintenance.

[0028] As an optional implementation manner, the main body portion 21 further includes a rigid lining 26. The rigid lining 26 is located in the installation cavity 215 and at the second end 214 of the main body portion 21. The other end of the flexible cylinder 23 extends into the rigid lining 26. When the electric fan is in the working state, the other end of the flexible cylinder 23 can abut against the inner wall of the rigid lining 26 and generate relative movement with the inner wall of the rigid lining 26. By providing the rigid lining 26 at the second end 214 of the main body portion 21 and having the other end of the flexible cylinder 23 extend into and slide in contact with the rigid lining 26, a local rigid support and wear-resistant contact surface are provided in the relatively thin tip region of the main body portion 21, avoiding the aerodynamic surface damage or structural weakening caused by the direct friction between the flexible cylinder 23 and the soft main body portion 21, ensuring the stability of the damping effect and extending the service life of the fan blade 2.

[0029] As an optional implementation manner, the material of the rigid cylinder 22 is metal; and / or the material of the flexible cylinder 23 is glass fiber. The rigid cylinder 22 is made of metal material to ensure high stiffness, high strength, and reliable torque transmission at the root, and the flexible cylinder 23 is made of glass fiber to provide appropriate elastic deformation ability and lightweight characteristics. The combination of the two materials not only meets the structural bearing requirements but also realizes the vibration damping function, while avoiding the possible electrochemical corrosion caused by the direct contact between metal and composite materials.

[0030] As Figure 3 shown, as an optional implementation manner, along the rotation direction of the rotating shaft 1, the width of the rigid cylinder 22 is D; along the thickness direction of the main body portion 21, the thickness of the rigid cylinder 22 is d, where d < D < 2d. By defining the aspect ratio of the flat cross-section of the rigid cylinder 22, while keeping the support structure compact in the thickness direction of the fan blade 2, a significantly increased cross-sectional moment of inertia is provided along the rotation direction. Thus, without increasing the external dimensions of the fan blade 2, the bending strength and natural frequency of the fan blade 2 system are greatly improved, enabling the electric fan to operate far from the resonance condition and ensuring the integrity of the aerodynamic profile on the thin side of the fan blade 2.

[0031] As an optional implementation, along the rotation direction of the rotation axis 1, the rigid cylinder 22 includes a first cylinder 221 and a second cylinder 222 that are connected to each other. The cross-sections of the first cylinder 221 and the second cylinder 222 cooperate to form a horizontal figure-eight shape. By designing the rigid cylinder 22 as an integrated double-connected circular tube structure in a horizontal figure-eight shape, not only can the sectional moment of inertia of the parallel double circular tubes be maximized in the width direction to significantly improve the bending stiffness and natural frequency, keeping the fan away from resonance, but also the closed torsional section is formed through the middle connecting waist, which greatly enhances the overall torsional performance and shear bearing capacity of the structure. At the same time, this integrated connecting design also realizes the dual-cavity functional partitioning—the first cylinder 221 and the second cylinder 222 can independently accommodate the flexible cylinder 23 and the rigid support components, respectively, completing the reuse of structural support and functional integration in a compact space, while avoiding the risk of relative slippage or connection failure, ensuring the reliability and structural integrity of the cooperative deformation of the two tubes at high speeds.

[0032] As an optional implementation, the main body 21 further includes a reinforcing rib 216 extending along its length and used to connect the upper and lower sidewalls of the main body 21. The reinforcing rib 216 is located within the mounting cavity 215 and divides the mounting cavity 215 into a first cavity 217 and a second cavity 218. The reinforcing rib 216 is close to the first side 211, and the first cavity 217 is also close to the first side 211. The reinforcing rib 216 connects the upper and lower sidewalls of the main body 21, not only serving as a structural reinforcement to improve the overall torsional stiffness and structural integrity of the fan blade 2 and prevent local buckling, but also dividing the mounting cavity 215 into two independent cavities, achieving physical isolation between the rigid support area and the flexible damping area, and optimizing the internal space layout.

[0033] As an optional implementation, the rigid cylinder 22 extends into the second cavity 218, and the first cylinder 221 is close to the reinforcing rib 216, with the flexible cylinder 23 located inside the first cylinder 221. When the fan is in operation, the other end of the flexible cylinder 23 can abut against the reinforcing rib 216 and move relative to it. By arranging the first cylinder 221 of the rigid cylinder 22 adjacent to the reinforcing rib 216, the movable end of the flexible cylinder 23 slides against the reinforcing rib 216. The high stiffness of the reinforcing rib 216 provides a stable contact reaction surface, forming an effective bending moment countermeasure near the stiffness center of the fan blade 2, thereby specifically suppressing the bending deformation of the fan blade 2 and providing distributed constraints along the length of the reinforcing rib 216, effectively managing the stress distribution and vibration transmission inside the fan blade 2.

[0034] The vibration reduction and fatigue performance testing process of the sliding damping system of rigid cylinder 22 and flexible cylinder 23 is as follows: The full-size wind turbine blade 2 disclosed in the present invention is selected. It is 5.2m long, 0.23m in root diameter, and 0.08m in tip chord length. The main body 21 is made of glass fiber / carbon fiber hybrid composite material. A high-strength steel rigid cylinder 22 is set inside. The rigid cylinder 22 has an outer diameter of 200mm, a wall thickness of 2mm, and a length of 2m, accounting for 38.5% of the total length of the blade 2. It extends from the root into the mounting cavity 215 and is fixed to the main body 21 by a through bolt 24. A glass fiber flexible cylinder 23 is set inside the rigid cylinder 22. The flexible cylinder 23 has an outer diameter of 180mm and a length of 3m. In the non-working state, the initial gap between the end of the flexible cylinder 23 and the inner wall of the main body 21 is 2.5mm. An aluminum alloy rigid liner 26 is embedded inside the second end 214 of the main body 21.

[0035] Distributed fiber optic strain sensors and triaxial MEMS accelerometers were installed at the root flange of fan blade 2 and at distances of 1.5m, 3m, and 5.2m from the root. Fan blade 2 was fixed to a full-size fan blade 2 fatigue test rig via the root flange of rigid cylinder 22. First, a static limit test was conducted: a limit bending moment of 15 MN·m was applied at a distance of 1m from the root. After unloading, fan blade 2 showed no permanent deformation, and the flexible cylinder 23 showed obvious contact marks with the inner wall of the rigid liner 26, but no structural damage. Subsequently, a fatigue load equivalent to a 20-year lifespan was applied: bending moment amplitude in the flaring direction ±12 MN·m, oscillation direction ±4 MN·m, frequency 0.5-2.0 Hz, and number of cycles 2×10⁻⁶. 6 Secondly, the impact load of simulated extreme gusts is superimposed.

[0036] Test results show that under a single impact bending moment of 10 MN·m, the initial amplitude at the blade tip is 0.12m. Through sliding friction damping between the flexible cylinder 23 and the inner wall of the blade 2, as well as the rigid liner 26, the amplitude decays to 10% of its initial value in 4.2 seconds. During the decay process, the root bending moment transmission coefficient is measured to be stable at 0.68, indicating that 32% of the vibration energy is dissipated through the friction pair and not transmitted to the hub. (Complete all 2×10...) 6 After several fatigue cycles, no visible cracks were found at the root of fan blade 2, and the maximum strain amplitude at the root was reduced by 35% compared to the design value. Disassembly and inspection revealed only uniform wear marks in the contact area between the flexible cylinder 23 and the rigid liner 26, with no fretting corrosion or material tearing. The total weight of fan blade 2 was 0.42 tons, which is 0.09 tons lighter than the traditional structure using a full-length steel box girder. While maintaining the same aerodynamic shape, the material cost was reduced by approximately 15%.

[0037] The stiffness and aerodynamic performance testing process for the flat "8"-shaped cross-section structure is as follows: The rigid cylinder 22 in this embodiment is used for fabrication. The rigid cylinder 22 is a horizontally placed figure-eight shaped integrated double-connected circular tube: it is formed by two high-strength steel circular tubes with an outer diameter of 160mm connected by an 80mm wide waist section, resulting in a total width of 280mm and a wall thickness of 3mm. The material is Q345E steel. T-shaped reinforcing ribs 216 are arranged along the length of the main body 21, dividing the mounting cavity 215 into a first cavity 217 and a second cavity 218. The rigid cylinder 22 is embedded in the second cavity 218, and the first cylinder 221 is arranged close to the reinforcing ribs 216. A flexible cylinder 23 is disposed within the first cylinder 221, with its free end slidingly contacting the inner wall of the reinforcing ribs 216.

[0038] A full-scale structural loading test was conducted: Under cantilever beam conditions, the moment of inertia of the figure-eight section in the swing direction was measured to be 8.9 × 10⁻⁶. 6 mm 4 The mass per unit length is 285 kg / m. Under the ultimate bending moment test (applying 1.5 times the design bending moment, 18 MN·m), the two roots of the fan blade showed no permanent deformation after unloading, with a yield safety factor of 1.8. Torsional stiffness tests showed that the torsional constant J of this section reached 4.8 × 10⁻⁶. 6 N·m 2 Under a torque of 500 kN·m, the root torsion angle is only 0.6°, effectively resisting aerodynamic torsional loads.

[0039] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An energy-saving and environmentally friendly electric fan, the electric fan comprising a rotating shaft and a plurality of fan blades located around the rotating shaft; The plurality of fan blades are evenly distributed along the rotation axis; characterized in that... The fan blades include: The main body has a first side and a second side along the rotation direction of the rotation axis, the thickness of the second side being greater than the thickness of the first side; along the length direction of the main body, the main body has a first end near the rotation axis and a second end away from the rotation axis, the thickness of the first end being greater than the thickness of the second end; the main body has a mounting cavity extending along its length direction, the mounting cavity being near the second side of the main body. A rigid cylindrical body, one end of which is fixedly connected to the rotating shaft, and the other end of which extends from the first end of the main body into the mounting cavity and is fixed to the main body; A flexible cylinder is disposed within the mounting cavity, with one end of the flexible cylinder fixed to the rigid cylinder and the other end located near the second end of the main body. When the fan is in operation, the other end of the flexible cylinder can abut against the inner wall of the main body near the first side and move relative to the inner wall of the main body.

2. The energy-saving and environmentally friendly electric fan according to claim 1, characterized in that, When the fan is not in operation, there is a gap between the other end of the flexible cylinder and the inner wall of the main body, and the gap does not exceed 3mm.

3. The energy-saving and environmentally friendly electric fan according to claim 1, characterized in that, The rigid cylinder comprises a first segment located outside the mounting cavity and a second segment located inside the mounting cavity along its length direction; the length of the second segment does not exceed one-half the length of the main body and is not less than one-third the length of the main body.

4. The energy-saving and environmentally friendly electric fan according to claim 1, characterized in that, The fan blade also includes a bolt and a nut. The bolt passes through the upper side wall of the main body, the upper side wall of the rigid cylinder, the upper side wall of the flexible cylinder, the lower side wall of the flexible cylinder, the lower side wall of the rigid cylinder, and the lower side wall of the main body in sequence, and then engages with the nut through a thread.

5. The energy-saving and environmentally friendly electric fan according to claim 1, characterized in that, The main body also includes a rigid liner, which is located within the mounting cavity and at the second end of the main body; the other end of the flexible cylinder extends into the rigid liner. When the fan is in operation, the other end of the flexible cylinder can abut against the inner wall of the rigid liner and move relative to the inner wall of the rigid liner.

6. The energy-saving and environmentally friendly electric fan according to claim 1, characterized in that, The rigid cylinder is made of metal; and / or the flexible cylinder is made of glass fiber.

7. The energy-saving and environmentally friendly electric fan according to claim 1, characterized in that, Along the rotation direction of the rotation axis, the width of the rigid cylinder is D; along the thickness direction of the main body, the thickness of the rigid cylinder is d, where d <D<2d。 8. The energy-saving and environmentally friendly electric fan according to claim 7, characterized in that, Along the rotation direction of the rotation axis, the rigid cylinder includes a first cylinder and a second cylinder that are connected to each other, and the cross-sections of the first cylinder and the second cylinder cooperate to form a horizontal figure-eight shape.

9. An energy-saving and environmentally friendly electric fan according to claim 8, characterized in that, The main body also includes a reinforcing rib extending along its length and used to connect the upper sidewall and the lower sidewall of the main body. The reinforcing rib is located in the mounting cavity and divides the mounting cavity into a first cavity and a second cavity. The reinforcing rib is close to the first side, and the first cavity is close to the first side.

10. An energy-saving and environmentally friendly electric fan according to claim 9, characterized in that, The rigid cylinder extends into the second cavity, and the first cylinder is close to the reinforcing rib. The flexible cylinder is located inside the first cylinder. When the fan is in operation, the other end of the flexible cylinder can abut against the reinforcing rib and move relative to the reinforcing rib.

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