FAN DEVICE

Abstract

A fan device (1) comprises a hub (10) and a plurality of fan blades (20). Each of the fan blades (20) includes a drive surface (21), and the drive surface (21) includes a first tooth column (30) and a second tooth column (40). The first tooth column (30) comprises a plurality of first gear units (31). Each of the first gear units (31) comprises a first body (32). A first central rib (35) and two first lateral ribs (36) project from a surface of the first body (32), and a groove (33) is formed between two adjacent first gear units (31). The second tooth column (40) comprises a plurality of second gear units (41). Each of the second gear units (41) comprises a second body (42) and an extension element (43).A second central rib (45) and two second lateral ribs (46) project from a surface of the second body (42), and the extension element (43) is located in the groove (33) and includes an extension rib (48). One end of the extension rib (48) is connected to the second central rib (45), and another end of the extension rib (48) extends to a position between two adjacent first lateral ribs (36) of two adjacent first gear units (31).

Description

BACKGROUND Technical area

[0001] The present invention relates to a heat dissipation device, and in particular a fan device. State of the art

[0002] Generally, the temperature of electronic components installed in electronic devices gradually increases with operating time. To prevent this high temperature from affecting the performance and lifespan of the electronic components, electronic devices are often equipped with cooling fans. The rotating fans circulate air, thus dissipating the heat from the electronic components.

[0003] With the rapid development of the electronics industry, ever-increasing demands are placed on the performance of electronic components, resulting in higher temperatures during operation. Therefore, the speed and airflow of the cooling fan must be increased simultaneously to improve cooling efficiency. However, increasing the fan speed and airflow also increases the noise generated by the device during operation, negatively impacting the user experience. Currently, most cooling fan blades have smooth surfaces, which does little to alleviate the noise problem.

[0004] Document CN 1 04 564 819 A discloses an axial flow wind turbine and an axial flow fan with such a wind turbine. The axial flow wind turbine comprises a hub and a plurality of fan blades, each fan blade comprising a driving surface covered with several rows of interlocking fish-scale-like scales.

[0005] Abigail Lynch, in her article "Placoid Denticles," published in Fishionary on September 25, 2015 (https: / / fishionary.fisheries.org / placoid-denticles / ), describes a type of scale found, for example, in sharks. In this particular species, all the scales are essentially identical in shape and structure, and they are stacked on top of each other in the same row, as well as in different rows. Consequently, the scales are at different heights, resulting in numerous gaps. Furthermore, the placoid denticles described are not true "scales" but rather modified teeth with an internal tissue component containing blood vessels and nerves, covered by a layer of dentin and an outer layer of enamel. These placoid denticles form a resilient protective layer for sharks, rays, and chimeras, reducing friction and resistance. SUMMARY

[0006] In light of the above, one embodiment provides a fan device comprising a hub and a plurality of fan blades. The hub includes a central shaft and an outer circumference. The outer circumference surrounds the central shaft. The plurality of fan blades are arranged at equal angles on the outer circumference. Each fan blade extends in one direction away from the central shaft. Each fan blade includes a drive surface, and the drive surface includes a first tooth column and a second tooth column. The first tooth column includes a plurality of first gear units. These are arranged side by side in the direction away from the central shaft. Each of the first gear units includes a first body. A first central rib and two first side ribs project from a surface of the first body.Between the first central rib and the first two side ribs, two flow guide channels are formed, and a groove is formed between two adjacent first gear units. The second gear column comprises a plurality of second gear units. These are arranged side by side in the direction away from the central shaft. Each of the second gear units comprises a second body and an extension element. A second central rib and two second side ribs project from a surface of the second body. Two second flow guide channels are formed between the second central rib and the two second side ribs. The extension element is located in the groove and comprises an extension rib.One end of the extension rib is connected to the second central rib, and another end of the extension rib extends to a position between two adjacent first side ribs of the two adjacent first gear units.

[0007] Based on the above, according to the fan device of the embodiment of the present invention, by arranging a plurality of toothed columns on the drive surface of the fan blades, the airflow can be cut by each toothed unit in the toothed columns and flow into the flow guide channel of each toothed unit to form a vortex, thus achieving the effects of flow guidance and reducing wind resistance, and significantly reducing the noise of the fan device during operation. Furthermore, the airflow can be guided by the arrangement of the extension rib of every second toothed unit so that it enters the flow guide channels of different toothed columns uniformly, so that the airflow can be subjected to multiple resistance reductions and the noise of the fan device during operation can be further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The revelation is better understood with the help of the following detailed description, which serves only for illustration and thus does not limit the revelation, whereby: Fig. Figure 1 is a three-dimensional view of an embodiment of a fan device according to the present invention. Fig. Figure 2 is a side view of an embodiment of a fan device according to the present invention. Fig. Figure 3 is a three-dimensional partial view of an embodiment of a fan device according to the present invention. Fig. Figure 4 is a partial top view of a fan blade of an embodiment of a fan device according to the present invention. Fig. Figure 5 is another three-dimensional partial view of an embodiment of a fan device according to the present invention. Fig. Figure 6 is a schematic diagram of the flow guidance of an embodiment of a fan device according to the present invention. Fig. Figure 7 is another partial top view of a fan blade of an embodiment of a fan device according to the present invention. Fig. Figure 8 is another partial top view of a fan blade of an embodiment of a fan device according to the present invention. DETAILED DESCRIPTION

[0009] Fig. Figure 1 is a three-dimensional view of an embodiment of a fan device according to the present invention. Fig. Figure 2 is a side view of an embodiment of a fan device according to the present invention. As shown in Fig. 1 and Fig. As shown in Figure 2, the fan device 1 comprises a hub 10 and a plurality of fan blades 20. The fan device 1 can be installed on various electronic products. These electronic products can be, for example, computers, servers, or household appliances, in order to dissipate the heat from the heating elements installed in the electronic products.

[0010] As in Fig. 1 and Fig. As shown in Figure 2, the hub 10 comprises a central shaft 11 and an outer circumference 12. The outer circumference 12 surrounds the central shaft 11. The hub 10 is configured so that it can be connected to a drive element (such as a motor) to drive the hub 10 through the drive element to rotate about the central shaft 11.

[0011] As in Fig. 1 and Fig. As shown in Figure 2, the plurality of fan blades 20 are arranged at equal angles around the outer circumference 12 of the hub 10, and each fan blade 20 extends away from the central shaft 11. When the hub 10 is driven to rotate, the plurality of fan blades 20 can be driven to rotate synchronously to drive an airflow and to dissipate heat from the heating elements. The number of fan blades 20 can be more than two, depending on the actual product requirements. In this embodiment, for example, the number of fan blades 20 is 11, and the fan blades are arranged at equal angles (approximately 32.7° in this case) around the central shaft 11 of the hub 10.

[0012] In some embodiments, the individual fan blades 20 and the hub 10 can be formed in one piece (as in Fig. 1 and Fig. (2 shown). For example, the individual fan blades 20 and the hub 10 can be formed in one piece by injection molding or casting. Alternatively, the individual fan blades 20 and the hub 10 can also be pre-assembled. For example, each fan blade 20 can be mounted to the outer circumference 12 of the hub 10 by gluing, interlocking, or welding, which is not limited in the present invention.

[0013] Fig. Figure 3 is a partial three-dimensional view of an area 3 of Fig. 1. As in Fig. 1 to Fig. As shown in Figure 3, each fan blade 20 comprises a driving surface 21 and a lee surface 22. The driving surface 21 and the lee surface 22 are each two opposing surfaces of the individual fan blade 20. Furthermore, in this embodiment, each fan blade 20 is a long plate and comprises a first side edge 23, a second side edge 24, a third side edge 25, and a fourth side edge 26. The first side edge 23 and the second side edge 24 are two opposing longitudinal sides of the fan blade 20. The first side edge 23 and the second side edge 24 each extend away from the central shaft 11. The third side edge 25 and the fourth side edge 26 are two opposing short sides of the fan blade 20. The third side edge 25 is connected to the outer circumference 12 of the hub 10, and the fourth side edge 26 is located far from the outer circumference 12 relative to the third side edge 25.However, the above embodiments are only examples, and in some embodiments the fan blades 20 may also be plates with other shapes (such as square, oval or other irregular shapes).

[0014] Fig. 4 is a partial top view of a fan blade of an embodiment of a fan device according to the present invention. With reference to Fig. 3 and Fig. 4 The drive surface 21 of each fan blade 20 comprises at least two tooth columns. In this embodiment, the drive surface 21 of each fan blade 20 comprises, for example, three tooth columns (a first tooth column 30, a second tooth column 40, and a third tooth column 50), but is not limited to this. The drive surface 21 can also comprise two tooth columns or more than four tooth columns, depending on the size of the individual fan blades 20.

[0015] As in Fig. 2 to Fig. As shown in Figure 4, the first tooth column 30 on the drive surface 21 of the fan blade 20 contains a plurality of first tooth units 31, the second tooth column 40 contains a plurality of second tooth units 41, and the third tooth column 50 contains a plurality of third tooth units 51. The plurality of first tooth units 31, the plurality of second tooth units 41, and the plurality of third tooth units 51 are each arranged side by side in one direction away from the central shaft 11 of the hub 10 (that is, in one direction from the third side edge 25 to the fourth side edge 26).The first tooth column 30, the second tooth column 40 and the third tooth column 50 are further arranged in a plurality of columns from the first side edge 23 to the second side edge 24, such that the second tooth column 40 is arranged between the first tooth column 30 and the third tooth column 50, the first tooth column 30 is adjacent to the first side edge 23 relative to the second tooth column 40, and the third tooth column 50 is adjacent to the second side edge 24 relative to the second tooth column 40.

[0016] In some embodiments, the fan blades 20, the first tooth column 30, the second tooth column 40 and the third tooth column 50 can be formed in one piece (as in Fig. 1 and Fig. 2 shown). For example, the fan blades 20, the first tooth column 30, the second tooth column 40 and the third tooth column 50 can be formed in one piece by injection molding or casting.

[0017] Fig. 5 is a partial three-dimensional view of an area 5 of Fig. 1. As in Fig. 3 to Fig. As shown in Figure 5, each of the first gear units 31 in the first tooth column 30 comprises a first body 32, and a first central rib 35 and two first lateral ribs 36 project from a surface of the first body 32. The first central rib 35 and each of the first lateral ribs 36 extend from the first lateral rib 23 towards the second lateral rib 24, and the first central rib 35 is located between the two first lateral ribs 36 and is arranged parallel to each other, so that two concave first flow guide channels 37 are formed between the first central rib 35 and the two first lateral ribs 36, respectively.

[0018] As in Fig. 3 to Fig. As shown in Figure 5, in this embodiment the first body 32 is kite-shaped and has a long axis L1 and a short axis S1 that are perpendicular to each other. The long axes L1 of the first bodies 32 of the first gear units 31 are parallel to each other, so that a plurality of first gear units 31 are arranged side by side. The first central rib 35 on the first body 32 is arranged along the long axis L1, and the two first side ribs 36 are each arranged at two opposite ends of the short axis S1, with the length of the first central rib 35 being greater than the length of each of the first side ribs 36. The length of the first central rib 35 is twice the length of the first side rib 36, but this is not limited to this.

[0019] As in Fig. 3 to Fig. As shown in Figure 5, since the first body 32 of each first gear unit 31 is kite-shaped, a groove 33 is formed between two adjacent first gear units 31. In this embodiment, for example, a triangular groove 33 is formed between two adjacent inclined sides of the two adjacent first gear units 31 and two adjacent first side ribs 36.

[0020] As in Fig. 3 to Fig. As shown in Figure 5, each of the second gear units 41 in the second tooth column 40 comprises a second body 42 and an extension element 43. The structure of the second body 42 can be the same or a similar structure to that of the first body 32. In this embodiment, for example, a second central rib 45 and two second side ribs 46 also project from a surface of the second body 42. The second central rib 45 and each of the second side ribs 46 extend from the first side edge 23, which faces the second side edge 24, and the second central rib 45 is located between the two second side ribs 46 and is arranged parallel to each other, so that two concave second flow guide channels 47 are formed between the second central rib 45 and the two second side ribs 46, respectively.

[0021] As in Fig. 3 to Fig. As shown in Figure 5, in this embodiment the second body 42 is also kite-shaped and has a long axis L2 and a short axis S2, which are perpendicular to each other. The long axes L2 of the second bodies 42 of the second gear units 41 are parallel to each other, so that a plurality of second gear units 41 are arranged side by side. The second central rib 45 on the second body 42 is arranged along the long axis L2, and the two second side ribs 46 are each arranged at two opposite ends of the short axis S2, with one length of the second central rib 45 being greater than the length of each of the second side ribs 46. The length of the second central rib 45 is twice the length of the second side rib 46, but this is not the limit.

[0022] As in Fig. 3 to Fig. As shown in Figure 5, in this embodiment the plurality of first gear units 31 and the plurality of second gear units 41 are arranged offset, such that each of the second gear units 41 corresponds to the groove 33 formed between two adjacent first gear units 31, and the extension element 43 of each of the second gear units 41 is arranged in the groove 33. The extension element 43 comprises an extension rib 48. The extension rib 48 projects from the drive surface 21 of the fan blade 20. One end of the extension rib 48 is connected to the second central rib 45 of the second body 42, and another end of the extension rib 48 extends to a position between two adjacent first side ribs 36 of the two adjacent first gear units 31.

[0023] Therefore, with reference to Fig. 3, Fig. 4 and Fig. 6, in the fan device 1 according to the embodiment of the present invention, a plurality of toothed columns (such as the first toothed column 30 and the second toothed column 40) are mounted on the drive surface 21 of the fan blades 20. When the hub 10 rotates to set the plurality of fan blades 20 in rotation, an airflow A (as in Fig. (shown in Figure 6), which flows from the first side edge 23 of each of the fan blades 20, is cut through the first central rib 35 of each first toothed unit 31 and introduced into the two first flow guide channels 37 of each first toothed unit 31 to form a vortex W. In this way, the airflow A changes from a state of sliding friction to a state of rolling friction to reduce wind resistance and prevent outside air from re-entering the gaps of the fan blades 20, so that the gaps of the fan blades 20 are filled with a slow and quiet airflow, thereby greatly reducing the noise of the fan device 1 during operation.

[0024] Additionally, as in Fig. As shown in Figure 6, the airflow A1, which flows from the first flow guide channel 37 towards the second side edge 24, can be guided by the extension ribs 48 so that it gently enters the second flow guide channel 47 of the second gear unit 41 in the second tooth column 40, so that the airflow A1 can form a vortex W in the second flow guide channel 47, thereby reducing the wind resistance again and further reducing the noise of the fan device 1 during operation.

[0025] As in Fig. 3 to Fig. As shown again in Figure 5, each of the third gear units 51 in the third gear column 50 comprises a third body 52 and an extension element 53. The structure of the third body 52 can be the same or similar to the structure of the first body 32. In this embodiment, for example, a third central rib 55 and two third side ribs 56 also project from a surface of the third body 52. ​​The third central rib 55 and each of the third side ribs 56 extend from the first side edge 23 towards the second side edge 24, and the third central rib 55 is located between the two third side ribs 56 and is arranged parallel to each other, so that two concave third flow guide channels 57 are formed between the third central rib 55 and the two third side ribs 56, respectively.

[0026] As in Fig. 3 to Fig. As shown in Figure 5, in this embodiment the third body 52 is also kite-shaped and has a long axis L3 and a short axis S3 that are perpendicular to each other. The long axes L3 of the third bodies 52 of the third gear units 51 are parallel to each other, so that a plurality of third gear units 51 are arranged side by side. The third central rib 55 is arranged along the long axis L3, and the two third side ribs 56 are each arranged at two opposite ends of the short axis S3, with one length of the third central rib 55 being greater than the length of each of the third side ribs 56. The length of the third central rib 55 is twice the length of the third side rib 56, but this is not the limit.

[0027] As in Fig. 3 to Fig. As shown in Figure 5, since the second body 42 of each second gear unit 41 is kite-shaped, a groove 44 is formed between two adjacent second gear units 41. In this embodiment, for example, a triangular groove 44 is formed between two adjacent inclined sides of the two adjacent second gear units 41 and two adjacent second side ribs 46.

[0028] As in Fig. 3 to Fig. As shown in Figure 5, the plurality of third gear units 51 and the plurality of second gear units 41 are arranged offset such that each of the third gear units 51 corresponds to the groove 44 formed between two adjacent second gear units 41, and the extension element 53 of each of the third gear units 51 is arranged in the groove 44. The extension element 53 includes an extension rib 58. The extension rib 58 projects from the drive surface 21 of the fan blade 20. One end of the extension rib 58 is connected to the third central rib 55 of the third body 52, and another end of the extension rib 58 extends to a position between two adjacent second side ribs 46 of the two adjacent second gear units 41.

[0029] In this way, as in Fig. As shown in Figure 6, by the arrangement of the third tooth column 50 and the extension ribs 58, an airflow A2, which flows from every second flow guide channel 47 towards the second side edge 24, can be guided through the extension ribs 58 to gently enter the third flow guide channel 57 of every third tooth unit 51 in the third tooth column 50, so that the airflow A2 can form a vortex W in the third flow guide channel 57, thereby reducing the wind resistance several times over and further reducing the noise of the fan device 1 in use.

[0030] In some embodiments, the first body 32 of each first gear unit 31, the second body 42 of each second gear unit 41, and the third body 52 of each third gear unit 51 can also have the shape of other polygons, not limited to the kite shape. For example, the polygon can be a triangle, a rhombus, a pentagon, or the like.

[0031] As in Fig. 3 to Fig. As shown in Figure 5, in this embodiment the extension element 43 of each second gear unit 41 also includes two flow guide grooves 49. The two flow guide grooves 49 are located on opposite sides of the extension rib 48, and the two flow guide grooves 49 are connected to the two second flow guide channels 47 of the second gear unit 41 and the two adjacent first flow guide channels 37 of the two adjacent first gear units 31. That is, the flow guide grooves 49 of the extension element 43 are connected between the first flow guide channel 37 and the second flow guide channel 47, so that the airflow A1, which flows from the first flow guide channel 37 towards the second side edge 24, can enter the second flow guide channel 47 smoothly through the guidance of the flow guide grooves 49, thereby further reducing wind resistance.

[0032] As in Fig. 3 to Fig. As shown in Figure 5, in this embodiment the extension element 53 of each third gear unit 51 also includes two flow guide grooves 59. The two flow guide grooves 59 are located on opposite sides of the extension rib 58, and the two flow guide grooves 59 are connected to the two third flow guide channels 57 of the third gear unit 51 and the two adjacent second flow guide channels 47 of the two adjacent second gear units 41. That is, the flow guide grooves 59 of the extension element 53 are connected between the second flow guide channel 47 and the third flow guide channel 57, so that the airflow A2, which flows from the second flow guide channel 47 towards the second side edge 24, can enter the third flow guide channel 57 smoothly through the guidance of the flow guide grooves 59, thereby further reducing wind resistance.

[0033] As in Fig. As shown again in Figure 4, in this embodiment the first body 32 of each first gear unit 31 further has a projection 34, and the projection 34 extends from the first side edge 23 of the fan blade 20. Therefore, the airflow A entering from the first side edge 23 of each fan blade 20 can achieve a better cutting effect due to the projection 34, see Figure 4. Fig. 6. In addition, in this embodiment, an edge of the projection 34 extending from the first side edge 23 is a curved edge (here an arc-shaped curve) so that the airflow A can be guided through the curved edge after cutting to gently enter the two first flow guide channels 37 of each first gear unit 31, thereby further improving the flow guidance.

[0034] As in Fig. 4 and Fig. As shown in Figure 5, in this embodiment the third body 52 of the third gear unit 51 further has a projection 54, and the projection 54 extends from the second side edge 24 of the fan blade 20. The projection 54 is tapered to a point in order to avoid obstructing the airflow. Furthermore, as shown in Fig. As shown in Figure 6, an airflow A3 is also guided through the pointed projection 54 when it flows from the third flow guide channel 57 of the third gear unit 51 to avoid the generation of an uneven wake flow and to further reduce noise.

[0035] Fig. Figure 7 is another partial top view of a fan blade of an embodiment of a fan device according to the present invention. As in Fig. As shown in Figure 7, in this embodiment, the height H1 of a first side rib 36 of each first gear unit 31 is lower than the height H2 of a first center rib 35. The height H1 of the first side rib 36 and the height H2 of the first center rib 35 can be heights by which the first side rib 36 and the first center rib 35 project from the surface of the first body 32. As shown in Fig. 5 to Fig. As shown in Figure 7, the first central rib 35, with its relatively large height, can therefore effectively isolate and direct the airflow. Furthermore, the first side rib 36, with its relatively small height, allows the vortex W formed in the first flow guide channel 37 to generate a better turbine rotation effect, thereby achieving improved drag and noise reduction. In some embodiments, the height of the second side rib 46 of each second gear unit 41 can also be less than the height of the second central rib 45, and the height of the third side rib 56 of each third gear unit 51 can also be less than the height of the third central rib 55. The details are not described again here.

[0036] Fig. Figure 8 is another partial top view of a fan blade of an embodiment of a fan device according to the present invention. As in Fig.As shown in Figure 8, in this embodiment, a first central rib 35 of each first toothed unit 31 comprises a top edge 38. The top edge 38 has a leading edge 381, a middle section 382, ​​and a trailing edge 383. The middle section 382 is connected between the leading edge 381 and the trailing edge 383, and the leading edge 381 abuts a first side edge 23 of the fan blade 20 with respect to the trailing edge 383. The leading edge 381 and the trailing edge 383 are each inclined edges, and the height of the middle section 382 is greater than both the height of the leading edge 381 and the height of the trailing edge 383. That is, the top edge 38 of the first central rib 35 has a height variation (i.e., the center is high and two sides are low) and not a uniform height, in order to improve the flow-guiding effect of the first central rib 35.

[0037] In some embodiments, the upper edge of a second intermediate rib 45 of each second gear unit 41 and the upper edge of a third intermediate rib 55 of each third gear unit 51 may also have a height variation with the first intermediate rib 35 instead of a uniform height, in order to improve the flow-guiding effect of the second intermediate rib 45 and the third intermediate rib 55. The details are not described here.

[0038] Based on the above, according to the fan device of the embodiment of the present invention, by arranging a plurality of toothed columns on the drive surface of the fan blades, the airflow can be cut by each toothed unit in the toothed columns and flows into the flow guide channel of each toothed unit to form a vortex. This achieves the effects of flow guidance and the reduction of wind resistance, as well as a significant reduction in the noise of the fan device during operation. Furthermore, the airflow can be guided by the arrangement of the extension rib of every second toothed unit so that it enters the flow guide channels of different toothed unit columns uniformly, thus allowing the airflow to be subjected to multiple resistance reductions and further reducing the noise of the fan device during operation.

Claims

[1] Fan device (1), comprising: a hub (10) with a central shaft (11) and an outer circumference (12), wherein the outer circumference (12) surrounds the central shaft (11), and a plurality of fan blades (20) arranged on the outer circumference (12) at equal angles, each of the fan blades (20) extending in one direction away from the central shaft (11), each of the fan blades (20) comprising a drive surface (21) and the drive surface (21) comprising: a first tooth column (30) comprising a plurality of first tooth units (31), wherein the first tooth units (31) are arranged side by side in the direction away from the central shaft (11), each of the first tooth units (31) comprising a first body (32), a first central rib (35) and two first side ribs (36) projecting from a surface of the first body (32), two first flow guide channels (37) formed between the first central rib (35) and the two first side ribs (36), and a groove (33) formed between two adjacent first tooth units (31), and a second tooth column (40) comprising a plurality of second tooth units (41), wherein the second tooth units (41) are arranged side by side in the direction away from the central shaft (11), each of the second tooth units (41) comprising a second body (42) and an extension element (43), a second central rib (45) and two second side ribs (46) projecting from a surface of the second body (42), two second flow guide channels (47) formed between the second central rib (45) and the two second side ribs (46), the extension element (43) being arranged in the groove (33) and having an extension rib (48), one end of the extension rib (48) being connected to the second central rib (45) and another end of the extension rib (48) extends to a position between the two adjacent first side ribs (36) of the two adjacent first gear units (31). [2] Fan device (1) according to claim 1, wherein the height of each of the first side ribs (36) is lower than the height of the first central rib (35). [3] Fan device (1) according to claim 1, wherein the first body (32) is kite-shaped and has a long axis (L1) and a short axis (S1) perpendicular to each other, the first central rib (35) is arranged along the long axis (L1) and the two first side ribs (36) are arranged at two opposite ends of the short axis (S1). [4] Fan device (1) according to claim 1, wherein the first central rib (35) has an upper edge (38), the upper edge (38) has a front edge (381), a middle section (382) and a rear edge (383), the middle section (382) is connected between the front edge (381) and the rear edge (383) and a height of the middle section (382) is greater than a height of the front edge (381) and a height of the rear edge (383). [5] Fan device (1) according to claim 1, wherein the extension element (43) further comprises two flow guide grooves (49), the two flow guide grooves (49) being arranged on two opposite sides of the extension rib (48) and the two flow guide grooves (49) being connected to the two second flow guide channels (47) and the two adjacent first flow guide channels (37) of the two adjacent first gear units (31). [6] Fan device (1) according to claim 1, wherein each of the fan blades (20) has a first side edge (23) and a second side edge (24), the drive surface (21) is arranged between the first side edge (23) and the second side edge (24), the first tooth column (30) adjoins the first side edge (23) relative to the second tooth column (40), the first body (32) of each of the first tooth units (31) has a projection (34) and the projection (34) extends from the first side edge (23). [7] Fan device (1) according to claim 6, wherein the projection (34) has a curved edge. [8] Fan device (1) according to claim 1, wherein the drive surface (21) further comprises a third tooth column (50), the second tooth column (40) is arranged between the first tooth column (30) and the third tooth column (50), the third tooth column (50) comprises a plurality of third tooth units (51), the third tooth units (51) are arranged side by side in the direction away from the central shaft (11), each of the third tooth units (51) comprises a third body (52) and an extension element (53), a third central rib (55) and two third side ribs (56) project from a surface of the third body (52), two third flow guide channels (57) are formed between the third central rib (55) and the two third side ribs (56), a groove (44) is formed between two ends of two adjacent second tooth units (41) near the third tooth column (50),the other extension element (53) is arranged in the groove (44) and has an extension rib (58), one end of the extension rib (58) is connected to the third central rib (55), and another end of the extension rib (58) extends to a position between the two adjacent second side ribs (46) of the two adjacent second gear units (41). [9] Fan device (1) according to claim 8, wherein each of the fan blades (20) has a first side edge (23) and a second side edge (24), the drive surface (21) is arranged between the first side edge (23) and the second side edge (24), the third tooth column (50) adjoins the second side edge (24) with respect to the second tooth column (40), the third body (52) of each of the third tooth units (51) has a projection (54) and the projection (54) extends from the second side edge (24). [10] Fan device (1) according to claim 9, wherein the projection (54) is pointed.

Images