A cooling fan

Abstract

This utility model discloses a cooling fan, which includes a first blade structure and a second blade structure. The first blade structure includes a first circular frame, multiple first blades, and a body. The second blade structure includes a second circular frame and multiple second blades. The body is disposed within the first circular frame. The multiple first blades are arranged at intervals and circumferentially connected between the inner edge of the first circular frame and the body. The multiple second blades are arranged at intervals and circumferentially connected between the inner edge of the second circular frame. When the first and second blade structures are assembled together, the first and second circular frames are combined vertically to form a rectifier ring. The multiple first and second blades are alternately arranged between the body and the rectifier ring. The first blades and the adjacent second blades on the first side partially overlap to form air guide grooves. This cooling fan can effectively increase the number of fan blades to improve its heat dissipation efficiency. At the same time, its internal wiring is simple, its operation is stable, and it does not affect the internal space layout.

Description

Technical Field

[0001] This utility model relates to the field of heat dissipation equipment technology, specifically to a cooling fan. Background Technology

[0002] Cooling fans are essential for ventilation and heat dissipation in electronic heat-generating or cooling devices, and are crucial to the performance, normal operation, and reliability of these devices. Currently, with the increasing heat flux density of electronic products, high-frequency operation generates a large amount of heat. If this heat cannot be eliminated or transferred in time, it will lead to equipment malfunction and inability to function properly. To cope with the ever-increasing operating heat, multiple single fans are connected in series to form a multi-fan system for cooling. However, this method involves complex and messy internal wiring, which can easily lead to unstable operation and affect the internal space layout. Utility Model Content

[0003] In view of this, the present invention provides a cooling fan that can effectively increase the number of fan blades to improve its heat dissipation efficiency, while its internal wiring is simple, its operation is stable, and it will not affect the internal space layout.

[0004] This utility model embodiment provides a cooling fan, the cooling fan comprising:

[0005] The first fan blade structure includes a first circular frame, a plurality of first fan blades and a body. The body is disposed within the first circular frame, and the plurality of first fan blades are arranged at intervals and circumferentially connected between the inner edge of the first circular frame and the body.

[0006] The second fan blade structure includes a second circular frame and a plurality of second fan blades, wherein the plurality of second fan blades are arranged at intervals and are connected to the inner edge of the second circular frame in a ring.

[0007] When the first fan blade structure and the second fan blade structure are assembled together, the first circular frame and the second circular frame are combined vertically to form a rectifier ring. Multiple first fan blades and multiple second fan blades are alternately arranged between the body and the rectifier ring. The first fan blades partially overlap with the second fan blades adjacent to the first side to form an air guide groove. The first fan blades do not overlap with the second fan blades adjacent to the second side.

[0008] Optionally, some of the first fan blades extend from the upper surface of the first circular frame into the second circular frame, and some of the second fan blades extend from the lower surface of the second circular frame into the first circular frame.

[0009] Optionally, the first fan blade has an outwardly protruding locking block on its outer side away from the body, the locking block being located above the first circular frame, and the inner edge of the second circular frame having a locking hole that cooperates with the locking block.

[0010] Optionally, the inner edge of the second circular frame is further provided with a clearance groove, which is located below the card hole.

[0011] Optionally, the second fan blade has an outwardly protruding locking block near the outer side of the second circular frame. The locking block is located below the second circular frame, and the inner edge of the first circular frame has a locking hole that cooperates with the locking block.

[0012] Optionally, the inner edge of the second circular frame is further provided with a clearance groove, which is located above the card hole.

[0013] Optionally, the clearance groove has an inlet surface on the side near the card hole, and the card block has a guide surface on the side near the clearance groove.

[0014] Optionally, the length of the second blade is less than the length of the first blade.

[0015] Optionally, the upper surface of the first circular frame and the lower surface of the second circular frame are ultrasonically welded together.

[0016] Optionally, the cooling fan further includes an outer frame with a circular groove, and the first fan blade structure and the second fan blade structure are rotatably disposed in the circular groove after assembly.

[0017] The cooling fan of this embodiment includes a first blade structure and a second blade structure. The first blade structure includes a first circular frame, multiple first blades, and a body. The second blade structure includes a second circular frame and multiple second blades. The body is disposed within the first circular frame. The multiple first blades are arranged at intervals and circumferentially connected between the inner edge of the first circular frame and the body. The multiple second blades are arranged at intervals and circumferentially connected between the inner edge of the second circular frame. When the first and second blade structures are assembled together, the first and second circular frames are combined vertically to form a rectifier ring. The multiple first and second blades are alternately arranged between the body and the rectifier ring. The first blades and the adjacent second blades on the first side partially overlap to form air guide grooves. This cooling fan can effectively increase the number of fan blades to improve its heat dissipation efficiency. At the same time, its internal wiring is simple, its operation is stable, and it does not affect the internal space layout. Attached Figure Description

[0018] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:

[0019] Figure 1 This is a schematic diagram of the assembly of the first and second fan blade structures according to an embodiment of the present invention;

[0020] Figure 2This is a schematic diagram of the second fan blade structure according to an embodiment of the present invention;

[0021] Figure 3 yes Figure 2 Enlarged schematic diagram of the center card hole and clearance groove;

[0022] Figure 4 This is a schematic diagram of the first fan blade structure according to an embodiment of the present utility model;

[0023] Figure 5 yes Figure 4 Enlarged diagram of the middle card block;

[0024] Figure 6 This is a top view schematic diagram of the assembly of the first and second fan blade structures according to an embodiment of the present utility model;

[0025] Figure 7 This is an exploded structural diagram of the cooling fan according to an embodiment of the present invention.

[0026] Figure label:

[0027] 1-First fan blade structure; 11-First circular frame; 12-First fan blade; 13-Body; 2-Second fan blade structure; 21-Second circular frame; 22-Second fan blade; 3-Rectifying ring; 4-Clip block; 41-Guide surface; 5-Clip hole; 6-Avoiding groove; 61-Inlet surface; 7-Outer frame; 71-Circular groove; 72-Support plate; 73-Extension rod. Detailed Implementation

[0028] The present application is described below based on embodiments, but it is not limited to these embodiments. In the detailed description of the present application below, certain specific details are described in detail. Those skilled in the art can fully understand the present application without these details. To avoid obscuring the substance of the present application, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0029] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0030] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] Unless the context explicitly requires it, words such as "including" or "contains" throughout the application should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to".

[0032] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0033] like Figures 1-6 As shown, the cooling fan includes a first blade structure 1 and a second blade structure 2. Figure 4 As shown, the first fan blade structure 1 includes a first circular frame 11, a plurality of first fan blades 12, and a body 13. The body 13 is disposed within the first circular frame 11. The plurality of first fan blades 12 are arranged at intervals and are arranged in a ring between the inner edge of the first circular frame 11 and the body 13, and the two ends of the plurality of first fan blades 12 are respectively connected to the inner edge of the first circular frame 11 and the body 13. Figure 2 As shown, the second fan blade structure 2 includes a second circular frame 21 and a plurality of second fan blades 22, the plurality of second fan blades 22 being arranged at intervals and circumferentially connected to the inner edge of the second circular frame 21. Figure 1 As shown, when the first fan blade structure 1 and the second fan blade structure 2 are assembled together, the first circular frame 11 and the second circular frame 21 are combined to form a rectifier ring 3. Multiple first fan blades 12 and multiple second fan blades 22 are alternately arranged between the body 13 and the rectifier ring 3. This type of vertically spliced ​​cooling fan increases the number of fan blades and improves the cooling performance of the cooling fan.

[0034] Furthermore, after the first fan blade structure 1 and the second fan blade structure 2 are assembled together, the first fan blade 12 partially overlaps with the second fan blade 22 adjacent to the first side. Figure 5 The dotted line indicates the area where the air guide groove is formed, and the first fan blade 12 does not overlap with the adjacent second fan blade 22 on the second side. That is, there is an overlapping area between the first fan blade 12 and the adjacent second fan blade 22 on the first side. Figure 5 (As indicated by the dotted line), the overlapping area is smaller than the area of ​​the first blade 12 and the second blade 22. This overlapping area can form an air guide channel, which can increase the exhaust volume of the cooling fan and further improve the cooling efficiency of the cooling fan.

[0035] The design of the first blade of the aforementioned cooling fan, with one side overlapping and the other side not overlapping, optimizes the airflow path, reduces blade tip turbine effect, lowers wind resistance and noise, and enhances the axial concentration of airflow, thereby improving heat dissipation efficiency. If both sides of the first blade overlap, it will disrupt the airflow path and affect heat dissipation efficiency.

[0036] Furthermore, the first circular frame 11 and the second circular frame 21 are combined to form a rectifier ring 3, so that the first fan blade 12 and the second fan blade 22 are both connected to the inner edge of the rectifier ring 3. The length of the second fan blade 22 is less than the length of the first fan blade 12, so that when the cooling fan rotates, the air force can be encircled in the fan blade to form a wind column, which concentrates the air force, increases the head, and reduces the noise during rotation.

[0037] Preferably, the first circular frame 11 and the second circular frame 21 are the same size, which facilitates the connection of the first fan blade structure 1 and the second fan blade structure 2 together, so that the upper and lower dimensions of the rectifier ring 3 are consistent, which can better improve the heat dissipation performance.

[0038] In this application, the number of first blades 12 and second blades 22 is the same, and they are evenly spaced, so that multiple first blades 12 and multiple second blades 22 are arranged alternately. This results in each first blade 12 having an overlapping area with a second blade 22 adjacent to one side, but not overlapping with a second blade 22 adjacent to the other side. This forms multiple evenly arranged air guide slots, which can increase the exhaust volume of the cooling fan and further improve the cooling efficiency of the cooling fan.

[0039] After the first blade structure 1 and the second blade structure 2 are connected, the body 13 forms the hub of the cooling fan. The hub has a simple circular shape, and its size can be precisely controlled, minimizing its impact on the airflow and allowing the fan to better perform its cooling function. The hub provides a mounting platform for the blades, ensuring that they are securely fixed in their position and will not fall off or loosen due to high-speed rotation. A motor or other drive device is installed inside the hub. The power generated by the motor or other drive device is transmitted to the first blade. The first blade drives the entire cooling fan to rotate and generate airflow through the first circular frame, enabling the cooling fan to operate at the speed and direction required by the design.

[0040] The concentric arrangement of the body 13 and the first circular frame 11 ensures optimal rotational balance for the entire cooling fan, resulting in smoother, more efficient, and more reliable operation. If the hub is off-center, it will cause an unbalanced force during fan rotation, leading to vibration and additional wear, reducing fan lifespan, and potentially causing mechanical failure.

[0041] In one embodiment, a portion of the first fan blade 12 extends from the upper surface of the first circular frame 11, and a portion of the second fan blade 22 extends from the lower surface of the second circular frame 21. When the first fan blade structure 1 and the second fan blade structure 2 are assembled, the second fan blade structure 2 is assembled with the first fan blade structure 1 from top to bottom, and the second circular frame 21 is connected directly above the first circular frame 11. At this time, the portion of the first fan blade 12 extending from the upper surface of the first circular frame 11 can extend into the second circular frame 21, and the portion of the second fan blade 22 extending from the lower surface of the second circular frame 21 can extend into the first circular frame 11. This increases the number of fan blades when the cooling fan rotates, and at the same time, the addition of a shorter second fan blade 22 between two longer first fan blades 12 does not affect the airflow and air pressure, thus improving the heat dissipation efficiency.

[0042] When the second fan blade structure 2 and the first fan blade structure 1 are assembled vertically, the second circular frame 21 and the first circular frame 11 can be fastened together. Specifically, the outer side of the first fan blade 12 away from the body 13 has an outwardly protruding locking block 4. The locking block 4 is located above the first circular frame 11, that is, the locking block 4 is set on the outer side of the portion of the first fan blade 12 that extends from the upper surface of the first circular frame 11, such as... Figure 4 and Figure 5 As shown. The inner edge of the second circular frame 21 has a locking hole 5 that mates with the locking block 4, as shown. Figure 2 and Figure 3 As shown. When the second fan blade structure 2 and the first fan blade structure 1 are assembled vertically, the locking block 4 can be snapped into the locking hole 5, thereby fixing the first fan blade structure 1 and the second fan blade structure 2 together. Preferably, each protruding part of the first fan blade 12 is provided with a locking block 4 on its outer side, and the inner edge of the second circular frame 21 is provided with multiple locking holes 5, each locking hole 5 can be connected to a locking block 4. The locking holes 5 are located at the inner edge of the second circular frame 21, so that after the locking block 4 is connected to the locking hole 5, multiple second fan blades 22 and multiple first fan blades 12 are arranged alternately, and the first fan blade 12 partially overlaps with the second fan blade 22 adjacent to one side, but does not overlap with the second fan blade 22 adjacent to the other side. At the same time, the lower surface of the second circular frame 21 is in contact with the upper surface of the first circular frame 11.

[0043] Furthermore, the inner edge of the second circular frame 21 is also provided with a clearance groove 6, which is located below the locking hole 5, such as... Figure 2 and Figure 3As shown. The clearance groove 6 has an opening at its bottom, which connects to the lower surface of the second circular frame 21. When the second fan blade structure 2 and the first fan blade structure 1 are assembled vertically, the clearance groove 6 provides clearance space for the locking block 4 to move upward relative to the locking hole 5, facilitating the locking block 4 to smoothly reach the locking hole 5 for connection and avoiding damage to the first fan blade structure 1 and the second fan blade structure 2. Preferably, the clearance groove 6 has a guide surface 61 on the side near the locking hole 5, and the locking block 4 has a guide surface 41 on the side near the clearance groove 6. When the locking block 4 moves upward relative to the locking hole 5, the guide surface 41 of the locking block 4 gradually contacts the guide surface 61 of the clearance groove 6, which makes the relative movement between the two smoother, thereby reducing the friction between them, reducing wear, making it easier for the locking block 4 to move and insert into the locking hole 5, and also preventing unnecessary movement or sliding, thus improving work efficiency. In this embodiment, the guide surface 61 and the guide surface 41 are inclined surfaces. The locking block 4, locking hole 5, and clearance groove 6 also provide positioning for the first fan blade structure 1 and the second fan blade structure 2 during assembly, so that the first fan blade 12 and the second fan blade 22 are arranged alternately after assembly, and that there is an overlapping area on one side and no overlap on the other side. The locking hole 5 can be a through hole or a blind hole, which can be used to insert and engage the locking block 4.

[0044] In this embodiment, the card hole 5 and the clearance groove 6 are located on the inner edge of the second circular frame 21, close to the side where the second fan blade 22 does not overlap with the first fan blade 12, which can prevent interference when the first fan blade structure 1 and the second fan blade structure 2 are installed vertically.

[0045] In another implementation, the positions of the locking block 4 and the locking hole 5 can be interchanged. That is, the locking block 4 is set on the outer surface of the second fan blade 22 near the second circular frame 21, and the locking block 4 is located below the second circular frame 21. In other words, the locking block 4 is set on the outer surface of the second fan blade 22 extending from the lower surface of the second circular frame 21. The inner edge of the first circular frame 11 has a locking hole 5 that cooperates with the locking block 4, which is not shown in the figure. The inner edge of the first circular frame 11 is also provided with a relief groove 6, which is located above the locking hole 5. The relief groove 6 has an opening above it, which connects to the upper surface of the first circular frame 11. Although the positions of the locking block 4, the locking hole 5, and the relief groove 6 change, the structure is the same as described above. The first fan blade structure 1 and the second fan blade structure 2 can also be fixedly connected together, so that after assembly, the first fan blade 12 and the second fan blade 22 are arranged alternately, and one side overlaps while the other side does not overlap.

[0046] In this embodiment of the application, after the first fan blade structure 1 and the second fan blade structure 2 are assembled together, the first circular frame 11 and the second circular frame 21 are not only connected by the snap-fit ​​of the snap-fit ​​block 4 and the snap-fit ​​hole 5, but the upper surface of the first circular frame 11 and the lower surface of the second circular frame 21 can also be welded together by ultrasonic welding.

[0047] In another embodiment, a portion of the first fan blade 12 extends from the lower surface of the first circular frame 11, and a portion of the second fan blade 22 extends from the upper surface of the second circular frame 21. When the first fan blade structure 1 and the second fan blade structure 2 are assembled, the first fan blade structure 1 is assembled with the second fan blade structure 2 from top to bottom, and the first circular frame 11 is connected directly above the second circular frame 21. At this time, the portion of the first fan blade 12 extending from the lower surface of the first circular frame 11 can extend into the second circular frame 21, and the portion of the second fan blade 22 extending from the upper surface of the second circular frame 21 can extend into the first circular frame 11. This increases the number of fan blades when the cooling fan rotates, and at the same time, the addition of a shorter second fan blade 22 between two longer first fan blades 12 does not affect the airflow and air pressure, thus improving the heat dissipation efficiency. When the first fan blade structure 1 and the second fan blade structure 2 are assembled vertically, the first circular frame 11 and the second circular frame 21 can be fastened together. The fastening connection method is the same as the two fastening connection methods in the above embodiments, that is, the fastening connection method between the locking block 4 and the locking hole 5 is the same, and will not be described in detail again. In addition, the lower surface of the first circular frame 11 and the upper surface of the second circular frame 21 can be welded together by ultrasonic welding.

[0048] The first fan blade structure 1 and the second fan blade structure 2 are joined together using an interlocking and ultrasonic welding technique. This allows for rapid assembly while preserving the original physical properties of the materials, enhancing the overall strength and durability of the fan blades. After ultrasonic welding, the seams at the joints are virtually invisible, resulting in an aesthetically pleasing finish and further reducing airflow resistance, thus improving the cooling efficiency of the fan. The principle of ultrasonic welding technology is to generate instantaneous frictional heat at the material contact surfaces through high-frequency vibration (20kHz–40kHz), achieving seamless splicing with micron-level precision. This process avoids the stress concentration problems associated with traditional gluing or screw fixing, while ensuring the dynamic balance accuracy of the fan blades (ISO 1940 G2.5 standard) and reducing vibration noise during high-speed rotation.

[0049] The cooling fan also includes an outer frame 7, which has a circular slot 71, such as... Figure 7As shown. The first fan blade structure 1 and the second fan blade structure 2 are rotatably mounted within the circular groove 71 after assembly. The first fan blade 12 and the second fan blade 22 are located between the rectifying ring 3 formed by the first circular frame 11 and the second circular frame 21 and the main body 13. The second fan blade 22 is a shorter fan blade, located between the first fan blades 12, so that when the cooling fan rotates, the airflow is encircled within the first fan blades 12 and the second fan blades 22 to form an air column, reducing turbulence to lower noise, and concentrating the airflow direction to increase head and improve heat dissipation efficiency. A support plate 72 is provided on one side of the circular groove 71, and the support plate is connected to the extension position of the center line of the circular groove 71 by multiple spaced extension rods 73. After the first fan blade structure 1 and the second fan blade structure 2 are mounted within the circular groove 71, the main body 13 can be rotatably connected to the support plate 72. Meanwhile, the support plate 72 is used to fix the motor or other drive devices. The body 13 is covered on the outside of the motor, and the drive shaft of the motor is fixedly connected to the inside of the body 13. Thus, the motor can drive the first fan blade structure 1 and the second fan blade structure 2 by driving the body 13, which also improves safety and aesthetics.

[0050] In other embodiments, the first blade 12 and the second blade 22 can also be arranged in opposite directions, which can also achieve the effect of concentrating air force and reducing noise.

[0051] The first blade 12 and the second blade 22 are inspired by fluid dynamics in nature (such as the wings of birds or the swimming trajectory of fish). Through streamlined curved surfaces and annular air guides, they achieve laminar flow guidance, reduce turbulent energy loss, and improve heat dissipation efficiency. The shapes of the first blade 12 and the second blade 22 can be airfoil, curved, inclined, arc-shaped, or planar structures.

[0052] The number of the first blade 12 and the second blade 22 may be equal or unequal. The first blade 12 and the second blade 22 are made of high-performance engineering plastics (such as PBT-GF30 or carbon fiber reinforced nylon), which have the characteristics of being lightweight, high temperature resistant (can withstand environments of 80℃~120℃), creep resistant and fatigue resistant, and are suitable for long-term high-speed operation.

[0053] In the first fan blade structure 1 and the second fan blade structure 2, the first fan blade 12 and the second fan blade 22 can be simulated in three dimensions using mechanical analysis software to optimize the fan blade tilt angle, radius of curvature, and annular opening ratio, ensuring a balance between maximum airflow and air pressure at different speeds. Then, the first fan blade structure 1 and the second fan blade structure 2 can be manufactured using high-precision five-axis CNC injection molds, ensuring that the fan blade surface tolerance is controlled within ±0.02mm. Combined with in-mold injection molding, flow guide textures or markings can be integrally formed on the fan blade surface, avoiding structural damage during later processing.

[0054] The cooling fan can be linked with a smart drive chip to adjust its speed according to temperature, maintaining quiet operation under low load and delivering maximum airflow under high load, thus extending equipment lifespan. The cooling fan interface can be standardized, supporting quick installation and removal and multi-platform compatibility (such as PCs, servers, industrial equipment, etc.), reducing user maintenance costs.

[0055] The cooling fan in this embodiment features a vertically integrated annular cooling fan blade design. By connecting the first and second circular frames vertically in a closed configuration, the airflow path is optimized, effectively reducing the tip vortex phenomenon common in traditional fan blades, lowering wind resistance and noise, while simultaneously enhancing the axial concentration of airflow and improving heat dissipation efficiency. This cooling fan is suitable for high-density electronic devices, servers, new energy vehicles, and other applications with stringent requirements for heat dissipation efficiency, noise control, and structural reliability. The vertically integrated annular cooling fan blade design allows two fan blade structures to rotate simultaneously from a single main body. The internal wiring of the main body is simple, the operation is stable, and it does not affect the internal spatial layout of the cooling fan.

[0056] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cooling fan, characterized in that, The cooling fan includes: The first fan blade structure (1) includes a first circular frame (11), a plurality of first fan blades (12) and a body (13). The body (13) is disposed inside the first circular frame (11). The plurality of first fan blades (12) are arranged at intervals and are connected in a ring between the inner edge of the first circular frame (11) and the body (13). The second fan blade structure (2) includes a second circular frame (21) and a plurality of second fan blades (22), wherein the plurality of second fan blades (22) are arranged at intervals and are connected to the inner edge of the second circular frame (21); When the first fan blade structure (1) and the second fan blade structure (2) are assembled together, the first circular frame (11) and the second circular frame (21) are combined to form a rectifier ring (3). Multiple first fan blades (12) and multiple second fan blades (22) are alternately arranged between the body (13) and the rectifier ring (3). The first fan blade (12) and the second fan blade (22) adjacent to the first side partially overlap to form an air guide groove. The first fan blade (12) and the second fan blade (22) adjacent to the second side do not overlap.

2. The cooling fan according to claim 1, characterized in that, Part of the first fan blade (12) extends from the upper surface of the first circular frame (11) into the second circular frame (21), and part of the second fan blade (22) extends from the lower surface of the second circular frame (21) into the first circular frame (11).

3. The cooling fan according to claim 2, characterized in that, The first fan blade (12) has an outwardly protruding locking block (4) on the outer side away from the body (13). The locking block (4) is located above the first circular frame (11). The inner edge of the second circular frame (21) has a locking hole (5) that cooperates with the locking block (4).

4. The cooling fan according to claim 3, characterized in that, The inner edge of the second circular frame (21) is also provided with a clearance groove (6), which is located below the card hole (5).

5. The cooling fan according to claim 2, characterized in that, The second fan blade (22) has an outwardly protruding locking block (4) near the outer side of the second circular frame (21). The locking block (4) is located below the second circular frame (21). The inner edge of the first circular frame (11) has a locking hole (5) that cooperates with the locking block (4).

6. The cooling fan according to claim 5, characterized in that, The inner edge of the second circular frame (21) is also provided with a clearance groove (6), which is located above the card hole (5).

7. The cooling fan according to claim 4 or 6, characterized in that, The clearance groove (6) has an inlet surface (61) on the side near the card hole (5), and the card block (4) has a guide surface (41) on the side near the clearance groove (6).

8. The cooling fan according to any one of claims 1-6, characterized in that, The length of the second blade (22) is less than the length of the first blade (12).

9. The cooling fan according to claim 1, characterized in that, The upper surface of the first circular frame (11) and the lower surface of the second circular frame (21) are welded together by ultrasonic welding.

10. The cooling fan according to claim 1, characterized in that, The cooling fan also includes an outer frame (7) with a circular groove (71), and the first fan blade structure (1) and the second fan blade structure (2) are rotatably disposed in the circular groove (71) after assembly.

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