Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001]This application claims the priority benefit of Taiwan application serial no. 113145994, filed on Nov. 28, 2024. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.
BACKGROUND
Technical Field
[0002]The disclosure relates to a heat dissipation fan, and in particular to a centrifugal heat dissipation fan.
Description of Related Art
[0003]In the prior art, the operating principle of a centrifugal fan is to use a motor to drive an impeller to allow external air to enter the housing of the fan from an axial air inlet. The air entering the housing of the fan will change its flow direction to radial due to the centrifugal force generated by the impeller operation. Then, the pressure difference is generated through the gradually expanding flow channel in the housing of the fan to guide the airflow to an exhaust outlet. To put it simply, the flow channel in the housing needs to be designed in a volute-like gradually expanding manner to produce sufficient pressure difference changes when the working fluid enters and exits the fan, so that the working fluid enters the fan along the axial direction and is discharged out of the fan along the radial direction through the change in pressure difference.
[0004]However, as mentioned above, the method is prone to produce noise due to the high-speed steering (from axial to radial) of the working fluid at the gradually expanding flow channel. In addition, the gradually expanding flow channel becomes the main structure that allows the air in the housing to generate pressure differences and flow, which will inevitably impose restrictions on the design of the housing of the fan. That is to say, in order to form an gradually expanding flow channel that can cause a pressure difference, the internal space of the shell must maintain a specific shape and sufficient space. Therefore, it is not conducive to the design of the housing. Especially when it comes to conforming to a thin and light notebook computer, the shape of the fan and the space it occupies within the notebook computer cannot be easily adjusted.
SUMMARY
[0005]The application provides a centrifugal heat dissipation fan, which provides an optimized configuration for the housing and the impeller and thereby reduces the noise generated during operation.
[0006]The centrifugal heat dissipation fan of the application includes a housing and an impeller. The housing has at least one air inlet on an axial direction and at least one air outlet on a radial direction. The impeller has a hub and a plurality of blades surrounding the hub. Each of the blades extends from the hub. The hub is rotatably disposed in the housing along the axial direction. The hub drives the blades to rotate in the housing to generate an airflow. The airflow flows into the housing via the air inlet and out of the housing via the air outlet. The blades have at least two lengths, such that a variation of pressure change of the airflow is generated.
[0007]Based on above, since the blades in the housing of the centrifugal heat dissipation fan have at least two lengths, different degrees of spatial changes may be formed between the inner wall of the housing and the blades. In addition, when the airflow is driven by the blades in the housing, the above-mentioned spatial changes will cause the pressure difference of the airflow to change. Therefore, the cause of the pressure difference change is changed from the gradually expanding flow channel of the prior art to the blades of different lengths in the application.
[0008]Furthermore, the above-mentioned pressure difference changes can effectively reduce the noise generated when the impeller is running, and therefore allow the flow channel to be of equal width. In other words, it means that the rotation axis of the impeller and the central axis of the housing are essentially the same, allowing the housing to adjust (reduce) its volume accordingly, thereby improving the space it occupies in the electronic device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009]FIG. 1A is a schematic diagram of the centrifugal heat dissipation fan according to an embodiment of the present application.
[0010]FIG. 1B is an exploded view of the centrifugal heat dissipation fan of FIG. 1A.
[0011]FIG. 1C is a top view of the centrifugal heat dissipation fan of FIG. 1A.
[0012]FIG. 2A is a schematic diagram of the centrifugal heat dissipation fan according to another embodiment of the present application.
[0013]FIG. 2B is an exploded view of the centrifugal heat dissipation fan of FIG. 2A.
[0014]FIG. 3 is a schematic diagram of an existing centrifugal heat dissipation fan.
[0015]FIG. 4 is a top view of the centrifugal heat dissipation fan according to another embodiment of the present application.
[0016]FIG. 5 is a top view of the centrifugal heat dissipation fan.
[0017]FIG. 6 is a top view of the centrifugal heat dissipation fan.
[0018]FIG. 7A to FIG. 7E are top views of impellers of different embodiments of the present application.
DESCRIPTION OF THE EMBODIMENTS
[0019]FIG. 1A is a schematic diagram of a centrifugal heat dissipation fan according to an embodiment of the present application. FIG. 1B is an exploded view of the centrifugal heat dissipation fan of FIG. 1A. FIG. 1C is a top view of the centrifugal heat dissipation fan of FIG. 1A. Referring to FIG. 1A to FIG. 1C at the same time, in the embodiment, the centrifugal heat dissipation 100 includes a housing 110 and an impeller. The housing 110 has air inlets 111, 112 on an axial direction and a plurality of air outlets 113 located in different radial directions. Herein, the housing 110 has a component A1 and a component A2, where the component A1 has the air inlet 111 and the component A2 has the air inlet 112. And the outline of the housing 110 in the embodiment is circular, with a central axis C2. The impeller has a hub 120 and a plurality of blades 130 surrounding the hub 120. Each of the blades 130 extends from the hub 120. The hub 120 is rotatably disposed in the housing 110 along the axial direction. Here, the impeller has an rotation axis C1. The hub 120 drives the blades 130 to rotate in the housing 110 to generate an airflow. The airflow flows from the air inlets 111, 112 into the housing 110 and from the air outlets 113 out of the housing 110.
[0020]As shown in FIG. 1C, the impeller is provided with a dotted line at the outermost end of the blades 130 to form a circle. In the embodiment, the impeller and the housing 110 have concentric circular outlines, and the rotation axis C1 of the hub 120 coincides with the central axis C2 of the housing 110. As shown in FIG. 1B, the rotation axis C1 of the hub 120 is equidistant from at least a partial of inner wall W1 of the housing 110 (radial distance D1 as shown in FIG. 1B).
[0021]In the embodiment, the housing 110 has an outer diameter ψ1, such as 80 mm. The impeller has an outer diameter ψ2, such as 76 mm. Therefore, the ratio of the outer diameter ψ2 of the impeller to the outer diameter ψ1 of the housing 110 is greater than or equal to 80% (95% in the embodiment).
[0022]In the embodiment, the blades 130 have five different lengths, and when the ends of the blades 130 pass through the inner wall W1 of the housing 110 in sequence, an airflow compression area PA1 is formed. The airflow compression area PA1 is tapered toward the movement direction of the blades 130 (counterclockwise direction CCW as shown in FIG. 1C), and then when the impeller rotates, a pressure difference changes in the flow channel 114 in the housing 110. In other words, different from the fan casing of the prior art, the embodiment can achieve pressure difference changes through changes in the length of the blades 130. Since it is no longer necessary to provide the gradually expanding flow channel in the space within the housing 110, the housing 110 with the flow channels 114 of equal width can be used. Thereby, the space occupied by the housing 110 in the electronic device is effectively reduced.
[0023]In addition, in non-illustrated embodiment of the present application, for example, an additional wall structure (the structure is extended from the inner wall W1) can be added to the inner wall W1 to guide the airflow or extend the time when the airflow is compressed when the impeller rotates. And it can be appropriately adjusted according to the cooling requirements of the electronic device.
[0024]FIG. 2A is a schematic diagram of the centrifugal heat dissipation fan according to another embodiment of the present application. FIG. 2B is an exploded view of the centrifugal heat dissipation fan of FIG. 2A. referring to FIG. 2A and FIG. 2B at the same time, the difference between the centrifugal heat dissipation fan 200 and the previous embodiment is that the embodiment adopts a single air outlet 213 on the radial direction, which is a cooling fan commonly found in notebook computers. And the remaining part includes a housing 210 (composed of components A3 and A4, wherein the component A3 has an air inlet 211 and the component A4 has an air inlet 212). The housing 210 has a central axis C3. The hub 220 (having the rotation axis C1) and the blades 230 are generally the same or similar to the previous embodiments. In other words, the housing 210 of the embodiment has an outer diameter ψ3, such as 80 mm. The impeller has an outer diameter ψ4, such as 76 mm. Therefore, the ratio of the outer diameter ψ4 of the impeller to the outer diameter ψ3 of the housing 210 is 95%, which is the same as the previous embodiment. At the same time, the embodiment can also generate a similar airflow compression area PA2 in the flow channel 214 between the inner wall W2 and the blades 230.
[0025]FIG. 3 is a schematic diagram of an existing centrifugal heat dissipation fan. Referring to FIG. 3, the centrifugal heat dissipation fan 200A includes a housing 210A, a hub 220A and blades 230A. And as mentioned above, it uses a gradually expanding flow channel 214A. Herein, the outer diameter of the impeller is 62 mm, and the outer diameter of the housing 210A is 80 mm. Therefore, the ratio of the outer diameter of the impeller to the outer diameter of the housing 210A is 77.5%. FIG. 3 is used as the benchmark, and the performance produced by other embodiments is examined accordingly. After testing the embodiment shown in FIG. 2A (and FIG. 2B) and FIG. 3 with a pneumatic testing machine, when the dimension of the blades is the same and at the same rotation speed, it has been found that the heat dissipation performance of the embodiment of the FIG. 2A (and FIG. 2B) has been improved by 5% compared to the embodiment of FIG. 3 embodiment. In other words, the embodiment shown in FIG. 2A and FIG. 2B can bring about a pressure difference during operation, which is the reason for its performance improvement. Accordingly, FIG. 2A and FIG. 2B can further use larger-sized blades to amplify the above advantages. Correspondingly, when the size (outer diameter) of blade 230A shown in FIG. 3 increases, the outer diameter of the housing 210A must increase accordingly (equivalent to an increase in volume) in order to maintain the effect of the gradually expanding flow channels.
[0026]FIG. 4 is a top view of the centrifugal heat dissipation fan according to another embodiment of the present application. Referring to FIG. 4, the centrifugal heat dissipation fan 200B is similar to the previous embodiment and also includes a housing 210B, a hub 220B, and blades 230B, wherein the central axis of the housing 210B also coincides with the rotation axis of the hub 220B. And the impeller and the housing 210B both have a circular outline, so that the flow channel 214B maintains a constant width. The difference between the embodiment and the aforementioned embodiment of FIG. 2B is that, the outer diameter ψ6 of the impeller is 68 mm, and the outer diameter ψ5 of the housing 210B is 80 mm in the embodiment. Therefore, the ratio of the outer diameter ψ6 of the impeller to the outer diameter ψ5 of the housing 210B is 85%. Similarly, the efficiency of the centrifugal heat dissipation fan 200B of the embodiment is also tested here, and it is found that it has improved by 3% compared to the embodiment of FIG. 3.
[0027]FIG. 5 is a top view of the centrifugal heat dissipation fan. Referring to FIG. 5, the centrifugal heat dissipation fan 200C is similar to the previous embodiment and also includes a housing 210C, a hub 220C, and blades 230C. However, the central axis of the housing 210C in the embodiment is already non-coincident with the rotation axis of the impeller, because the two still have a circular outline. Therefore, the embodiment creates a gradually expanding flow channel 214C. In the embodiment, the outer diameter ψ8 of the impeller is 68 mm, and the outer diameter ψ7 of the housing 210C is 80 mm. Therefore, the ratio of the outer diameter ψ8 of the impeller to the outer diameter ψ7 of the housing 210C is 85%. At this time, it is also tested and found that its performance is improved by 4% compared with the embodiment of FIG. 3. It can be seen from this that the gradually expanding flow channel 214C does have an airflow compression effect. However, as mentioned above, the gradually expanding flow channel 214C of the embodiment may increase the volume of the housing 210C. Compared with the embodiment of FIG. 2A (i.e. FIG. 2B), it can be clearly seen that the efficiency gain of FIG. 5 is not as good as the airflow compression effect produced by directly increasing the outer diameter of the impeller and adopting blades of unequal lengths.
[0028]FIG. 6 is a top view of the centrifugal heat dissipation fan. Referring to FIG. 6, the centrifugal heat dissipation fan 200D is similar to the previous embodiment and also includes a housing 210D, a hub 220D, and blades 230D. However, the central axis of the housing 210D of this embodiment is already non-coincident with the rotation axis of the impeller, since both still have a circular outline. Therefore, the embodiment creates a gradually expanding flow channel 214D. The outer diameter ψ10 of the impeller of the embodiment is 62 mm, which is the same size as the impeller of FIG. 3. And the outer diameter ψ9 of the housing 210D is 80 mm,, so the ratio of the outer diameter ψ10 of the impeller to the outer diameter ψ9 of the housing 210D is 78%. At this time, it is also tested and found that its performance is reduced by 5% compared to the embodiment of FIG. 3. In other words, if the impeller only introduces a non-circular design, it is difficult to amplify the advantages shown in FIG. 2A and FIG. 2B, so it needs to be matched with an increase in the outer diameter of the impeller to achieve significant performance improvement.
[0029]From the comparison results of the above embodiments of FIG. 2A (i.e. FIG. 2B), FIG. 4 to FIG. 6, etc. and the centrifugal heat dissipation fan 200B of the prior art shown in FIG. 3, it can be clearly understood that as long as the blades of different lengths can be matched with the appropriate proportional relationship between the outer diameter of the impeller and the outer diameter of the housing (greater than or equal to 80%), that is, the flow channel can be designed with equal width, which can avoid the situation that the volume and space occupied by the housing cannot be reduced due to the gradually expanding flow channel.
[0030]FIG. 7A to FIG. 7E are top views of impellers of different embodiments of the present application. The hub Hub and the blades B1 shown in FIG. 7A is similar to the hub HUB and the blade B2 shown in FIG. 7B, both are designed with fixed frequency changes based on different blades of fixed size. FIG. 7A is used as an example for explanation. Under the premise of the aforementioned fixed frequency change, the blades B1 will form two annular areas RN1, RN2 relative to the hub Hub (or with the axial direction of its rotation axis as the center). And the distribution numbers of the blades B1 in the annular areas RN1 and RN2 are different from each other. In the embodiment, the number of the blades B1 located in the annular area RN1 is 80 pieces, and the number of the blades B1 located in the annular area RN2 is 40 pieces. That is, the number of the blades B1 located in the annular area RN2 far away from the center is smaller than the number of the blades B1 located in the annular area RN1 close to the center.
[0031]Furthermore, FIG. 7A shows a total of 80 long blades and short blades that are multiples of 40. Therefore, when the impeller rotates (one revolution), it can produce 40 pressure difference changes. When the blades B1 rotate once per second, the main frequency of airflow changes may change to 40 Hz. FIG. 7B shows the distribution of long, medium, short and medium blades B2 that are multiples of 20. Therefore, when the impeller rotates once per second, it can produce 20 pressure difference changes. And the main frequency of airflow changes generated by the blades B2 may change to 20Hz.
[0032]The blades B3 and B4 of the impeller shown in FIG. 7C and FIG. 7D are designed to change in periodic functions respectively. They also have 80 blades, but they have periodic frequency changes of 3 times and 5 times respectively. Therefore, the impeller rotates once per second can produce 3 and 5 airflow pressure differences, that is, the main frequencies of airflow changes generated by the blades B3, B4 may change to 3 Hz and 5 Hz. The length of the blades B5 shown in FIG. 7E changes randomly, so the airflow changes when the impeller rotates once per second without a fixed frequency. It can be clearly understood from the aforementioned FIG. 1A to FIG. 2B, FIG. 4 and FIG. 7A to FIG. 7E that the impeller of the application presents a non-circular profile due to the distribution of the blades of unequal lengths. In this way, the pressure difference between the blades and the inner wall of the housing can be changed. Furthermore, if the lengths of the aforementioned blades (outer diameter of the impeller) of FIG. 7A to FIG. 7E are the same and there is no change, it may obviously cause the 80 blades to produce airflow sound of the fan blades at a frequency of 80 Hz during operation. And the airflow sound is produced continuously, thus causing an unpleasant sound. Therefore, it is necessary to use different methods as shown in FIG. 7A to FIG. 7E (selecting the impeller appearance with different parameter changes) to avoid the resonance frequency band of the fan system.
[0033]In summary, in the above-mentioned embodiments of the application, since the blades in the housing of the centrifugal heat dissipation fan have at least two lengths, different degrees of spatial changes may be formed between the inner wall of the housing and the blades. Then, when the airflow is driven by the blades in the housing, the above-mentioned spatial changes may cause the pressure difference of the airflow to change. Therefore, the cause of the pressure difference change is changed from the gradually expanding flow channel of the prior art to the blades of different lengths in the application.
[0034]In different embodiments, the above-mentioned blades of different lengths, further matched with the outer diameter ratio of the impeller and the housing, can also determine the performance difference. In other words, only when the aforementioned outer diameter ratio reaches a certain value can the benefits of the gradually expanding flow channel be effectively replaced. Here, after staggered experiments and comparisons of multiple embodiments, it is believed that the aforementioned outer diameter ratio needs to be greater than or equal to 80% in order to achieve better performance for the blades of different lengths.
[0035]Furthermore, the above-mentioned pressure difference change can effectively reduce the noise generated by the impeller during operation and avoid noise concentration. And since the flow channels are of equal width, that is to say, the rotation axis of the impeller and the central axis of the housing are essentially the same, which allows the housing to adjust (reduce) its volume and improve the space it occupies within the electronic device.