AXIAL COOLING FAN

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 113145976, filed on Nov. 28, 2024. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The disclosure relates to a cooling fan, and in particular to an axial cooling fan.

Description of Related Art

Existing axial fans are widely used in computer chassis for cooling purposes. However, with the rapid development of personal computers and server performance, high-performance computer systems generate a significant amount of waste heat. In order to prevent the accumulation of waste heat, which could negatively affect the operation of the system, how to create fans that can achieve high airflow to achieve good cooling effect is an important goal at present.

The design trend of existing axial fans mostly focuses on optimizing the blades and adjusting the frame (or housing). However, the design trend is limited by the propeller-type blade design, so the fans are still confined to the domain of high air volume and low static pressure. At the same time, the blades may be regarded as sweeping the frame (or housing) at a fixed frequency, so the blades are prone to impact the frame (or housing) with the wake flow thereof and form the source of narrow band noise at the impact point. Also, according to the principle of wave superposition, the wake flow generates a large amplitude, fixed-frequency blade passing tone, which increases with the rotation speed.

In addition, when the existing axial fans rotate, the airflow moves along the surface of the fan blades. Due to the effects of viscosity, the airflow velocity on the blade surface gradually slows down, and eventually causing the airflow to separate from the blade surface and form vortices. The formation of the vortices reduces the airflow passing through the fan, leading to poor cooling performance, and the vortex phenomenon also generates noise issues.

SUMMARY

The disclosure provides an axial cooling fan, which generates a wind field like an axial fan through stacked conical blades, and reduces the noise generated by the axial fan.

The axial cooling fan of the disclosure includes a hub and multiple conical blades. The hub has a rotating axis. The conical blades are disposed around the hub and driven by the hub. The conical blades are stacked on top of each other and coaxial with the rotating axis, so as to form an air inlet and an air outlet, and a contour of each conical blade gradually expands from the air inlet toward the air outlet.

In an embodiment of the disclosure, the axial cooling fan further includes a housing, and the hub and the conical blades are rotatably disposed in the housing.

In an embodiment of the disclosure, a spacing of the conical blades is greater than or equal to 0.4 mm.

In an embodiment of the disclosure, the hub has a shaft portion and a plurality of rib portions, and the conical blades are combined with the rib portions and surround the shaft portion.

In an embodiment of the disclosure, among the conical blades, a length of at least one conical blade close to the hub is smaller than a length of at least one conical blade away from the hub.

In an embodiment of the disclosure, each conical blade is a continuous structure surrounding the hub.

In an embodiment of the disclosure, the conical blade has a conical portion and a guide portion, and the guide portion is connected to the end of the conical portion and located at the air outlet.

In an embodiment of the disclosure, the conical blade with the guide portion is away from the hub.

In an embodiment of the disclosure, the conical blade without the guide portion is close to the hub.

In an embodiment of the disclosure, a flow path is formed between two adjacent ones of the conical blades, and when the hub drives the conical blades to rotate around the rotating axis, a spiral airflow moving from the air inlet to the air outlet is generated in the flow path.

Based on the above, the axial cooling fan is surrounded by the multiple conical blades disposed around the periphery of the hub, in which the conical blades are stacked on top of each other and coaxial with the rotating axis of the hub, and thus can smoothly generate the airflow field similar to the conventional axial fans, while can effectively avoid the noise problem of existing axial fans, reduce the torque demand on the motor, and thereby the wind speed is increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an axial cooling fan according to an embodiment of the disclosure.

FIG. 2 shows the axial cooling fan of FIG. 1 from another perspective.

FIG. 3A is a perspective cross-sectional view of the axial cooling fan of FIG. 1.

FIG. 3B is a partial enlarged view of FIG. 3A.

FIG. 4 is a side view of the axial cooling fan according to another embodiment of the disclosure.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a schematic view of an axial cooling fan according to an embodiment of the disclosure. FIG. 2 shows the axial cooling fan of FIG. 1 from another perspective. Referring to FIG. 1 together with FIG. 2, in this embodiment, an axial cooling fan 100 includes a hub 110, a plurality of conical blades 120, and a housing 130. The hub 110 has a rotating axis CX. The conical blades 120 are disposed around the hub 110 and driven by the hub 110, and the hub 110 together with the conical blades 120 are rotatably disposed in the housing 130. By connecting to the hub 110 through a motor (not shown), the hub 110 and the conical blades 120 are driven to rotate around the rotating axis CX in the housing 130.

Here, the conical blades 120 are stacked on each other and coaxial with the rotating axis CX, thereby forming multiple air inlets FL1 and multiple air outlets FL2 between the hub 110 and the inner wall of the housing 130, and the contour of each conical blade 120 gradually expands from the air inlet FL1 toward the air outlet FL2. Since the conical blades 120 are a multi-layered structure, when the hub 110 drives the conical blades 120 to rotate around the rotating axis CX, the airflow may flow into the axial cooling fan 100 from the plurality of air inlets FL1 shown in FIG. 1 and flow out of the axial cooling fan 100 from the plurality of air outlets FL2 shown in FIG. 2.

FIG. 3A is a perspective cross-sectional view of the axial cooling fan of FIG. 1. FIG. 3B is a partial enlarged view of FIG. 3A. Please refer to FIG. 2, FIG. 3A, and FIG. 3B at the same time. Further, the hub 110 has a shaft portion 111 and a plurality of rib portions 112. The rib portions 112 extend radially from the shaft portion 111 and with respect to the shaft portion 111. The multiple conical blades 120 are combined with the rib portions 112 and surround the shaft portion 111 to facilitate being driven by the hub 110. Furthermore, as shown in FIG. 3A and FIG. 3B, among the conical blades 120, the length of at least one conical blade 120 close to the hub 110 (the shaft portion 111) is smaller than the length of at least one conical blade 120 away from the hub 110 (the shaft portion 111). At the same time, for each conical blade 120, it is essentially a continuous structure surrounding the hub 110 (the shaft portion 111). In other words, unlike the existing axial fans, the axial cooling fan 100 of this embodiment adopts the conical blades 120 with the continuous structure, and thus can avoid the fixed-frequency blade passing tone generated by the propeller blades passing through the inner wall of the housing.

In addition, as shown in FIG. 3B, if the hub 110 (the shaft portion 111) and the inner wall of the housing 130 are used as the structural orientation reference, the area adjacent to the hub 110 (the shaft portion 111) and away from the housing 130 is regarded as the inside, and the area adjacent to the housing 130 and away from the hub 110 (the shaft portion 111) is regarded as the outside, then as shown in FIG. 3B, the conical blade 120 close to the outside may be further divided into a conical portion 121 and a guide portion 122. The guide portion 122 is connected to the end of the conical portion 121 and located at the air outlet FL2 (marked in FIG. 3A), and the conical blade 120 close to the inside is equivalent to having only the conical portion 121 without the guide portion. This configuration to provide airflow guidance effect for the axial cooling fan 100 in the disclosure, that is, by keeping the conical blade 120 with the guide portion 122 away from the hub 110 (the shaft portion 111), and keeping the conical blade 120 without the guide portion 122 close to the hub 110 (the shaft portion 111), the airflow field of the axial cooling fan 100 can be similar to the existing axial fans.

In addition, as shown in FIG. 3B, the slopes of the conical blades 120 in this embodiment (based on the rotating axis CX) are consistent with each other, that is, the conical portions 121 of the conical blades 120 are parallel to each other to facilitate layer-by-layer stacking. Furthermore, the flow path is formed between two parallel and adjacent conical blades 120. Also, when the hub 110 drives the conical blades 120 to rotate around the rotating axis CX, the gas (or air) between the two adjacent conical blades 120 is driven by the rotating conical blades 120 due to the friction with the conical blades 120, while at the same time, the rotating conical blades 120 generate a centrifugal force F3, which is equivalent to the centrifugal force F3 generating two component forces F1 and F2 acting on the gas respectively, in which the component force F1 acts on the gas between the conical blades 120 along the wall surfaces, while the component force F2 is equivalent to the normal force of the wall surfaces of the conical blades 120 acting on the gas. In this way, the gas between the conical blades 120 exhibits a spiral motion, and a spiral airflow (as shown by the dashed arrow in FIG. 3A) moving from the air inlet FL1 toward the air outlet FL2 is generated in the flow path. In particular, when the rotational speed of the conical blades 120 increases, the centrifugal force F3 becomes larger, and the spiral motion of the gas (or air) becomes more significant. Therefore, the axial cooling fan 100 in the disclosure can generate the airflow field similar to the axial fans.

In addition, the spacing of the conical blades 120 in this embodiment is greater than or equal to 0.4 mm, which means when the spacing is 0.4 mm, the boundary layers formed by the airflow in the flow path between the wall surfaces of the conical blades 120 are overlapped. As a result, the friction force of the boundary layer smoothly drives the gas (or air) in the flow path, and at this point, the static pressure of the axial cooling fan 100 reaches the maximum thereof. This operational condition allows the airflow speed at the air outlet FL2 to reach the maximum, so the axial cooling fan 100 no longer needs to rely on the torque of the motor to increase the airflow speed (that is, the demand on the motor is reduced).

FIG. 4 is a side view of an axial cooling fan according to another embodiment of the disclosure. Referring to FIG. 4, compared with the previous embodiment, the difference is that an axial cooling fan 200 of this embodiment merely includes a hub 210 and the conical blades 120, but does not have the housing 130. The reason is that the conical blades 120 in the embodiment already form the inlet and outlet of the airflow (the air inlet FL1 and the air outlet FL2), and at least part of the conical blades 120 further has a guide portion 122 at the end close to the air outlet FL2, which can be used to achieve desired airflow guiding effect. In this embodiment, the type or quantity of the guide portion 122 is not limited. In this embodiment, spaces C1 and C2 located at the side of the air outlet FL2 may be used for extending the conical blades 120 or adding a new guide portion 122.

In summary, in the embodiments of the disclosure, in the axial cooling fan, the plurality of conical blades are disposed around the periphery of the hub, in which the conical blades are stacked on top of each other and coaxial with the rotating axis of the hub, and thus can smoothly generate the airflow field similar to the conventional axial fans, while can effectively avoid the noise problem of the existing axial fans, reduce the torque demand on the motor, and thereby the wind speed is increased.

Furthermore, when the conical blades rotate in the flow path formed by the multiple conical blades, the component force of the centrifugal force further drives the airflow to travel in the spiral path on the conical blades, causing the axial cooling fan to generate the airflow field similar to the existing axial fans, thereby meeting the existing demands for axial fans. In the embodiment, the spacing of the conical blades may be adjusted according to needs, in which the minimum spacing may reach 0.4 mm to maximize the fan static pressure at that point, so as to increase the airflow speed flowing from the air outlet, and thus reduce the demand level on the torque of the motor of the axial cooling fan. In addition, the multiple conical blades of the axial cooling fan form the air inlet and the air outlet, so the housing may be removed according to needs, and the guide portion of the conical blade may be added or extended according to needs.