Propeller fan

Abstract

This propeller fan comprises a shaft part that is provided on a rotational axis and a plurality of blades that are provided to the outer peripheral side of the shaft part. The plurality of blades each have a leading edge that is positioned forward in the rotation direction and a trailing edge that is positioned rearward in the rotation direction. Ribs are formed in the plurality of blades. The ribs have a plurality of sides that are disposed in a polygonal shape centered in the shaft part in a view from the axial direction. The plurality of sides each connect the leading edges of two blades among the plurality of blades that are adjacent to each other in the rotation direction, or the trailing edges of said two blades.

Description

Propeller fan

[0001] The present disclosure relates to a propeller fan.

[0002] Patent Document 1 discloses a propeller fan. This propeller fan has a cylindrical portion formed on the rotation axis line and a plurality of blades provided on the outer peripheral side of the cylindrical portion. Each blade has a leading edge, a trailing edge, and an outer peripheral edge. The leading edge of each blade and the trailing edge of the blade adjacent to the said blade in the rotation direction are connected by a plate-like connecting portion. A reinforcing rib for reinforcing the strength of the blade is formed between the outer wall surface of the cylindrical portion and the pressure surface of each blade.

[0003] International Publication No. 2016 / 021555

[0004] However, even in the propeller fan as described above, at the time of rotation, stress concentrates on the leading edge or the trailing edge due to the centrifugal force applied to the outer peripheral edge side of the blade, and thus there is a problem that the strength of the blade may decrease.

[0005] The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a propeller fan capable of improving the strength of the blade.

[0006] The propeller fan according to the present disclosure includes a shaft portion provided on a rotation axis and a plurality of blades provided on the outer peripheral side of the shaft portion. Each of the plurality of blades has a leading edge positioned forward in the rotation direction and a trailing edge positioned rearward in the rotation direction. A rib is formed on the plurality of blades. The rib has a plurality of side portions arranged in a polygonal shape centered on the shaft portion when viewed in the axial direction. Each of the plurality of side portions connects the leading edges of two adjacent blades in the rotation direction among the plurality of blades or the trailing edges of the two blades.

[0007] According to the present disclosure, the strength of the blade can be improved.

[0008] This is a front view showing the configuration of a propeller fan according to Embodiment 1. This is an enlarged view showing the configuration of the first rib in the propeller fan according to Embodiment 1. This is an enlarged view showing the configuration of the first rib in a modified version of the propeller fan according to Embodiment 1. This is a diagram explaining the effects of the propeller fan according to Embodiment 1. This is an enlarged view showing the configuration of the first rib in the propeller fan according to Embodiment 2. This is an enlarged view showing the configuration of the first rib in a modified version of the propeller fan according to Embodiment 2. This is an enlarged view showing the configuration of the first and second ribs in the propeller fan according to Embodiment 3. This is an enlarged view showing the configuration of the first rib in the propeller fan according to Embodiment 4. This is an enlarged view showing the configuration of the first rib in the propeller fan according to Embodiment 5. This is an enlarged view showing the configuration of the first rib in the propeller fan according to Embodiment 6.

[0009] Embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to the embodiments described below, and can be modified in various ways without departing from the spirit of this disclosure. Furthermore, this disclosure includes all possible combinations of the configurations shown in each of the embodiments described below. In particular, the combinations of components are not limited to the combinations in each embodiment, and components described in one embodiment can be applied to another embodiment. In addition, in the following description, terms indicating direction (e.g., "up," "down," "right," "left," "front," "back," etc.) will be used as appropriate to facilitate understanding, but these are for illustrative purposes only and do not limit this disclosure. Also, in each drawing, components with the same reference numerals are the same or equivalent, and this is common throughout the entire specification. Note that the relative dimensions or shapes of each component in each drawing may differ from those of the actual components.

[0010] Embodiment 1. A propeller fan according to Embodiment 1 will be described. The propeller fan of this embodiment is used, for example, as a blower in an air conditioning system, a ventilation system, etc. Figure 1 is a front view showing the configuration of the propeller fan according to this embodiment. Figure 2 is an enlarged view showing the configuration of the first rib in the propeller fan according to this embodiment. Figures 1 and 2 show the configuration of the propeller fan as seen from the positive pressure side along the axial direction. Here, the axial direction is the direction along the rotation axis 10a of the propeller fan. The arrows in Figure 1 represent the rotation direction of the propeller fan.

[0011] As shown in Figures 1 and 2, the propeller fan has a shaft portion 10 provided on a rotating shaft 10a and a plurality of blades 20 provided on the outer circumference of the shaft portion 10. The shaft portion 10 is a cylindrical boss. The shaft portion 10 protrudes both upstream and downstream in the airflow along the axial direction of the propeller fan. The drive shaft of a fan motor (not shown) is inserted into the shaft portion 10.

[0012] Each of the multiple blades 20 has a leading edge 21, a trailing edge 22, and an outer peripheral edge 23. The leading edge 21 is the edge located in front of the blade 20 in the direction of rotation of the propeller fan. The trailing edge 22 is the edge located behind the blade 20 in the direction of rotation of the propeller fan. The outer peripheral edge 23 is located on the outer circumference of the blade 20 and is provided between the outer peripheral end of the leading edge 21 and the outer peripheral end of the trailing edge 22. The inner circumference of each of the multiple blades 20 is connected to the outer peripheral surface of the shaft portion 10.

[0013] Two of the multiple blades 20 that are adjacent to each other in the direction of rotation are connected via a connecting portion 25. The connecting portion 25 is in contact with the base 26 of each blade 20. The connecting portion 25 connects the trailing edge 22 of a blade 20 to the leading edge 21 of a blade 20 located behind that blade 20 in the direction of rotation. The connecting portion 25 is in contact with the leading edge 21 of the blade 20 at the leading edge base 26a. The connecting portion 25 is in contact with the trailing edge 22 of the blade 20 at the trailing edge base 26b. The inner circumference of the connecting portion 25 is connected to the outer circumference of the shaft portion 10. The propeller fan of this embodiment is an integrated wing in which the shaft portion 10, the multiple blades 20, and the multiple connecting portions 25 are integrally formed.

[0014] Multiple blades 20 have a first rib 31 formed on them. The first rib 31 protrudes axially from the positive pressure side surface of the multiple blades 20. The first rib 31 has multiple edges 31a, 31b, and 31c. When viewed in the axial direction, the multiple edges 31a, 31b, and 31c are arranged in a polygonal shape centered on the shaft 10, for example, a regular polygonal shape centered on the shaft 10. The number of edges of the first rib 31 is the same as the number of blades 20. In this embodiment, since there are three blades 20, there are also three edges. That is, when viewed in the axial direction of the propeller fan, the multiple edges 31a, 31b, and 31c are arranged in a triangular shape centered on the shaft 10.

[0015] Furthermore, the first rib 31 has multiple vertices 31d, 31e, and 31f. When viewed in the axial direction of the propeller fan, these multiple vertices 31d, 31e, and 31f are located at the vertices of the polygonal shape. The number of vertices of the first rib 31 is the same as the number of blades 20. Each of the multiple vertices 31d, 31e, and 31f is positioned at the trailing edge root 26b of the corresponding blade 20. As a result, each of the edges 31a, 31b, and 31c of the first rib 31 connects the trailing edges 22 of two blades 20 that are adjacent to each other in the direction of rotation.

[0016] When viewed in the axial direction of the propeller fan, the edge portion 31a of the first rib 31 has an inner side surface 31a1, that is, the side closer to the rotation axis 10a, and an outer side surface 31a2, that is, the side further from the rotation axis 10a. When viewed in the axial direction of the propeller fan, the edge portion 31a of the first rib 31 is curved such that the side surface 31a2 is concave and the side surface 31a1 is convex. In other words, the edge portion 31a as a whole is curved so that it is convex toward the rotation axis 10a. For example, when viewed in the axial direction of the propeller fan, the edge portion 31a is curved such that the intermediate portion between the vertex portion 31d and the vertex portion 31e of the other end of the edge portion 31a approaches the rotation axis 10a with respect to the straight line connecting the vertex portion 31d at one end of the edge portion 31a and the vertex portion 31e at the other end of the edge portion 31a.

[0017] Similarly, the sides 31b and 31c are curved such that their outer peripheral surfaces are concave. In this embodiment, each of the sides 31a, 31b, and 31c is curved in an arc shape. Each of the sides 31a, 31b, and 31c does not come into contact with the outer peripheral surface of the shaft 10. A gap is formed between each of the sides 31a, 31b, and 31c and the outer peripheral surface of the shaft 10.

[0018] Figure 3 is an enlarged view showing the configuration of the first rib in a modified propeller fan according to this embodiment. As shown in Figure 3, in this modified example, the vertices 31d, 31e, and 31f of the first rib 31 are each positioned at the leading edge root 26a of the corresponding blade 20. As a result, the edges 31a, 31b, and 31c of the first rib 31 each connect the leading edges 21 of two blades 20 that are adjacent to each other in the direction of rotation. The other configurations are the same as those shown in Figures 1 and 2.

[0019] Figure 4 illustrates the effect of the propeller fan according to this embodiment. When the propeller fan rotates, stress concentrates on the leading edge 21 and trailing edge 22 of each blade 20. The peak of the stress distribution on the leading edge 21 is at the leading edge root 26a. The peak of the stress distribution on the trailing edge 22 is at the trailing edge root 26b. In this embodiment, the leading edge roots 26a of two adjacent blades 20, or the trailing edge roots 26b of two adjacent blades 20, are connected by the edge of the first rib 31. Therefore, as shown by the thick arrows in Figure 4, the stress concentrated at the leading edge root 26a or the trailing edge root 26b can be distributed in two directions.

[0020] Furthermore, since each of the edges 31a, 31b, and 31c of the first rib 31 is curved such that the outer surface is concave, airflow can be guided along each of the edges 31a, 31b, and 31c, as shown by the dashed arrows in Figure 4. This reduces airflow interference by the first rib 31 in the rotational direction, thereby improving the aerodynamic characteristics of the propeller fan.

[0021] In this embodiment, the first rib 31 is formed on the positive pressure side of the multiple blades 20, but the first rib 31 may also be formed on the negative pressure side of the multiple blades 20, or on both the positive pressure side and the negative pressure side. The same applies to the first rib 31 and the second rib 32 in each of the following embodiments.

[0022] As described above, the propeller fan according to this embodiment comprises a shaft portion 10 provided on a rotating shaft 10a, and a plurality of blades 20 provided on the outer circumference of the shaft portion 10. Each of the plurality of blades 20 has a leading edge 21 located forward in the direction of rotation and a trailing edge 22 located backward in the direction of rotation. A first rib 31 is formed on each of the plurality of blades 20. Here, the first rib 31 is an example of a rib. The first rib 31 has a plurality of sides 31a, 31b, and 31c arranged in a polygonal shape centered on the shaft portion 10 when viewed in the axial direction. Each of the plurality of sides 31a, 31b, and 31c connects the leading edges 21 of two adjacent blades 20 in the direction of rotation, or the trailing edges 22 of those two blades 20.

[0023] With this configuration, the stress concentrated on the leading edge 21 or trailing edge 22 of the blade 20 can be distributed in two directions by the first rib 31. Therefore, the strength of the blade 20 can be improved.

[0024] In the propeller fan according to this embodiment, when viewed in the axial direction, each of the multiple side portions 31a, 31b, and 31c is curved such that the outer peripheral side (for example, side 31a2) is concave.

[0025] With this configuration, airflow can be guided along each of the edges 31a, 31b, and 31c, thereby reducing airflow interference by the first rib 31 in the rotational direction, and thus improving the aerodynamic characteristics of the propeller fan.

[0026] In the propeller fan according to this embodiment, each of the multiple edges 31a, 31b, and 31c connects the leading edges 21 of two blades 20.

[0027] With this configuration, the stress concentrated on the leading edge 21 of the blade 20 can be distributed in two directions by the first rib 31, thereby improving the strength of the blade 20.

[0028] In the propeller fan according to this embodiment, each of the multiple edges 31a, 31b, and 31c connects the trailing edges 22 of two blades 20.

[0029] With this configuration, the stress concentrated on the trailing edge 22 of the blade 20 can be distributed in two directions by the first rib 31, thereby improving the strength of the blade 20.

[0030] Embodiment 2. A propeller fan according to Embodiment 2 will be described. Figure 5 is an enlarged view showing the configuration of the first rib in the propeller fan according to this embodiment. As shown in Figure 5, each of the edges 31a, 31b, and 31c of the first rib 31 connects the trailing edges 22 of two adjacent blades 20 in the direction of rotation. Each of the edges 31a, 31b, and 31c is in contact with the shaft portion 10 at the intermediate portion between the vertices.

[0031] According to this embodiment, similar to the first embodiment, the stress concentrated on the trailing edge 22 of the blade 20 can be distributed in two directions by the first rib 31. Since each side portion 31a, 31b, and 31c is in contact with the shaft portion 10, the stress distributed to each side portion can be supported by the shaft portion 10. Therefore, the strength of the blade 20 can be further improved.

[0032] Furthermore, in this embodiment, the hatched portion in Figure 5 can be used as the effective wing surface of each blade 20. In this embodiment, since each side portion 31a, 31b, and 31c is curved to be in contact with the shaft portion 10, the hatched portion in Figure 5 can be further enlarged. Therefore, the wing area of ​​each blade 20 can be increased, and thus the airflow of the propeller fan can be increased.

[0033] Figure 6 is an enlarged view showing the configuration of the first rib in a modified propeller fan according to this embodiment. As shown in Figure 6, each of the edges 31a, 31b, and 31c of the first rib 31 connects the leading edges 21 of two adjacent blades 20 in the direction of rotation. Each of the edges 31a, 31b, and 31c is in contact with the shaft portion 10 at the intermediate portion between the vertices. The same effects as described above can be obtained with this modified example.

[0034] As described above, in the propeller fan according to this embodiment, each of the multiple side portions 31a, 31b, and 31c is in contact with the shaft portion 10.

[0035] With this configuration, the stress distributed across each side portion 31a, 31b, and 31c can be supported by the shaft portion 10, thereby further improving the strength of the blade 20.

[0036] Furthermore, according to this embodiment, similar to Embodiment 1, interference of the airflow by the first rib 31 in the rotational direction can be reduced, thereby improving the aerodynamic characteristics of the propeller fan.

[0037] Embodiment 3. A propeller fan according to Embodiment 3 will be described. Figure 7 is an enlarged view showing the configuration of the first rib and the second rib in the propeller fan according to this embodiment. As shown in Figure 7, the first rib 31 and the second rib 32 are combined to form a plurality of blades 20.

[0038] The first rib 31 protrudes axially from, for example, the positive pressure side of the multiple blades 20. The first rib 31 has multiple edges 31a, 31b, and 31c. When viewed in the axial direction of the propeller fan, the multiple edges 31a, 31b, and 31c are arranged in a polygonal shape centered on the shaft 10. The number of edges of the first rib 31 is the same as the number of blades 20. In this embodiment, since there are three blades 20, the number of edges of the first rib 31 is also three. That is, when viewed in the axial direction of the propeller fan, the multiple edges 31a, 31b, and 31c are arranged in a triangular shape centered on the shaft 10.

[0039] Furthermore, the first rib 31 has multiple vertices 31d, 31e, and 31f. When viewed in the axial direction of the propeller fan, these multiple vertices 31d, 31e, and 31f are located at the vertices of the polygonal shape. The number of vertices of the first rib 31 is the same as the number of blades 20. Each of the multiple vertices 31d, 31e, and 31f is positioned at the trailing edge root 26b of the corresponding blade 20. As a result, each of the edges 31a, 31b, and 31c of the first rib 31 connects the trailing edges 22 of two adjacent blades 20 in the direction of rotation. Each of the edges 31a, 31b, and 31c of the first rib 31 is curved such that its outer peripheral side is concave, and it is in contact with the shaft portion 10.

[0040] The second rib 32 protrudes axially from the same plane on which the first rib 31 is formed. The second rib 32 has multiple edges 32a, 32b, and 32c. When viewed in the axial direction of the propeller fan, the multiple edges 32a, 32b, and 32c are arranged in a polygonal shape centered on the shaft 10. The number of edges of the second rib 32 is the same as the number of edges of the first rib 31, which is three. That is, when viewed in the axial direction of the propeller fan, the multiple edges 32a, 32b, and 32c are arranged in a triangular shape centered on the shaft 10. Each edge 32a, 32b, and 32c of the second rib 32 intersects with two edges of the first rib 31.

[0041] Furthermore, the second rib 32 has multiple vertices 32d, 32e, and 32f. When viewed in the axial direction of the propeller fan, these multiple vertices 32d, 32e, and 32f are located at the vertices of the polygonal shape described above. The number of vertices of the second rib 32 is the same as the number of vertices of the first rib 31, which is three. Each of the multiple vertices 32d, 32e, and 32f is positioned at the leading edge base 26a of the corresponding blade 20. As a result, each of the edges 32a, 32b, and 32c of the second rib 32 connects the leading edges 21 of two blades 20 that are adjacent to each other in the direction of rotation. Each of the edges 32a, 32b, and 32c of the second rib 32 is curved so that its outer peripheral side is concave and is in contact with the shaft portion 10.

[0042] As described above, in the propeller fan according to this embodiment, the ribs include a first rib 31 and a second rib 32. Each of the multiple sides 31a, 31b, and 31c of the first rib 31 connects the trailing edges 22 of the two blades 20. Each of the multiple sides 32a, 32b, and 32c of the second rib 32 connects the leading edges 21 of the two blades 20.

[0043] With this configuration, the stress concentrated on the trailing edge 22 of the blade 20 can be distributed in two directions by the first rib 31, and the stress concentrated on the leading edge 21 of the blade 20 can be distributed in two directions by the second rib 32. Therefore, the strength of the blade 20 can be further improved.

[0044] Also, according to the present embodiment, similar to Embodiments 1 and 2, interference of the airflow by the first rib 31 and the second rib 32 in the rotational direction can be reduced, so that the aerodynamic characteristics of the propeller fan can be improved.

[0045] Embodiment 4. A propeller fan according to Embodiment 4 will be described. FIG. 8 is a diagram showing an enlarged configuration of the first rib in the propeller fan according to the present embodiment. As shown in FIG. 8, the first rib 31 further has a plurality of extending portions 31g, 31h, and 31i. Each of the plurality of extending portions 31g, 31h, and 31i is a portion extending from the corresponding vertex portion 31d, 31e, or 31f to the outer peripheral side. The extending portion 31g extends from the vertex portion 31d along the trailing edge 22 of the blade 20 to the outer peripheral side. The extending portion 31h extends from the vertex portion 31e along the trailing edge 22 of the blade 20 to the outer peripheral side. The extending portion 31i extends from the vertex portion 31f along the trailing edge 22 of the blade 20 to the outer peripheral side.

[0046] In the present embodiment, since each side portion 31a, 31b, and 31c connects the trailing edges 22 of two blades 20, each of the plurality of extending portions 31g, 31h, and 31i extends along the trailing edge 22 of the blade 20. On the other hand, when each side portion 31a, 31b, and 31c connects the leading edges 21 of two blades 20, each of the plurality of extending portions 31g, 31h, and 31i may extend along the leading edge 21 of the blade 20.

[0047] In the present embodiment, a part of the stress from the outer peripheral side at the trailing edge 22 or the leading edge 21 can be supported by each of the extending portions 31g, 31h, and 31i. Moreover, the stress of each of the extending portions 31g, 31h, and 31i can be dispersed in two directions along two side portions as indicated by the solid arrows in FIG. 8. Therefore, the stress distribution on the trailing edge 22 side or the leading edge 21 side can be made more uniform. Also, as indicated by the broken arrows in FIG. 8, the airflow on the inner peripheral side can flow along the first rib 31, so that the aerodynamic characteristics can be improved.

[0048] As described above, in the propeller fan according to the present embodiment, the first rib 31 has a plurality of vertex portions 31d, 31e, 31f and a plurality of extending portions 31g, 31h, 31i. The plurality of vertex portions 31d, 31e, 31f are located at vertices having a polygonal shape when viewed in the axial direction. The plurality of extending portions 31g, 31h, 31i extend from each of the plurality of vertex portions 31d, 31e, 31f toward the outer peripheral side. Each of the plurality of extending portions 31g, 31h, 31i extends along the edge of the blade 20.

[0049] According to this configuration, a part of the stress from the outer peripheral side at the trailing edge 22 or the leading edge 21 can be supported by each of the extending portions 31g, 31h, 31i, and the stress of each of the extending portions 31g, 31h, 31i can be dispersed in two directions. Therefore, the stress distribution on the trailing edge 22 side or the leading edge 21 side can be made more uniform.

[0050] Embodiment 5. The propeller fan according to Embodiment 5 will be described. FIG. 9 is a diagram showing an enlarged configuration of the first rib in the propeller fan according to the present embodiment. As shown in FIG. 9, each of the side portions 31a, 31b, 31c of the first rib 31 is curved in an arc shape.

[0051] The first rib 31 further has a plurality of extending portions 31g, 31h, 31i. The extending portion 31g extends from the vertex portion 31d toward the outer peripheral side in an arc shape continuous with the side portion 31a. Here, the side portion 31a is a side portion located in front of the vertex portion 31d in the rotational direction of the propeller fan. For example, the extending portion 31g and the side portion 31a form one arc. Similarly, the extending portion 31h extends from the vertex portion 31e toward the outer peripheral side in an arc shape continuous with the side portion 31b. The extending portion 31i extends from the vertex portion 31f toward the outer peripheral side in an arc shape continuous with the side portion 31c.

[0052] In this embodiment, a portion of the stress from the outer circumference of the blade 20 can be supported by the extended portions 31g, 31h, and 31i. Furthermore, the stress in each extended portion 31g, 31h, and 31i can be distributed in two directions along the two edges, as shown by the solid arrows in Figure 9. Therefore, the stress distribution of the blade 20 can be made more uniform. In addition, as shown by the dashed arrows in Figure 9, the airflow on the inner circumference can be smoothly directed along the first rib 31 (for example, the edge portion 31a and the extended portion 31g), thus further improving the aerodynamic characteristics.

[0053] As described above, in the propeller fan according to this embodiment, the first rib 31 has a plurality of vertex portions 31d, 31e, 31f and a plurality of extension portions 31g, 31h, 31i. The plurality of vertex portions 31d, 31e, 31f are located at the vertices of a polygonal shape when viewed in the axial direction. The plurality of extension portions 31g, 31h, 31i extend outward from each of the plurality of vertex portions 31d, 31e, 31f. When viewed in the axial direction, each of the plurality of edges 31a, 31b, 31c is curved in an arc shape such that the outer surface is concave. When viewed in the axial direction, each of the plurality of extension portions 31g, 31h, 31i extends in an arc shape continuous with the corresponding edge.

[0054] With this configuration, a portion of the stress from the outer periphery at the trailing edge 22 or leading edge 21 can be supported by each of the extended portions 31g, 31h, and 31i, and the stress at each of the extended portions 31g, 31h, and 31i can be distributed in two directions. Therefore, the stress distribution of the blade 20 can be made more uniform.

[0055] Furthermore, this configuration allows the airflow on the inner circumference to flow smoothly along the first rib 31 (for example, the edge portion 31a and the extended portion 31g), thereby further improving the aerodynamic characteristics.

[0056] Embodiment 6. A propeller fan according to Embodiment 6 will be described. Figure 10 is an enlarged view showing the configuration of the first rib in the propeller fan according to this embodiment. As shown in Figure 10, the first rib 31 further has a plurality of extended portions 31g, 31h, and 31i. The extended portion 31g extends from the apex portion 31d toward the outer circumference along the radial direction centered on the rotation axis 10a. Similarly, the extended portion 31h extends from the apex portion 31e toward the outer circumference along the radial direction centered on the rotation axis 10a. The extended portion 31i extends from the apex portion 31f toward the outer circumference along the radial direction of the propeller fan centered on the rotation axis 10a.

[0057] In this embodiment, a portion of the stress from the outer circumference of the blade 20 can be supported by the extended portions 31g, 31h, and 31i. Furthermore, the stress in each extended portion 31g, 31h, and 31i can be distributed in two directions along the two edges, as shown by the solid arrows in Figure 10. Therefore, the stress distribution of the blade 20 can be made more uniform. In addition, the airflow on the inner circumference can be directed along the first rib 31, thereby improving the aerodynamic characteristics.

[0058] As described above, in the propeller fan according to this embodiment, the first rib 31 has a plurality of vertex portions 31d, 31e, and 31f, and a plurality of extension portions 31g, 31h, and 31i. The plurality of vertex portions 31d, 31e, and 31f are located at the vertices of a polygonal shape when viewed in the axial direction. The plurality of extension portions 31g, 31h, and 31i extend outward from each of the plurality of vertex portions 31d, 31e, and 31f. Each of the plurality of extension portions 31g, 31h, and 31i extends along the radial direction centered on the rotation axis 10a when viewed in the axial direction.

[0059] With this configuration, a portion of the stress from the outer periphery at the trailing edge 22 or leading edge 21 can be supported by each of the extended portions 31g, 31h, and 31i, and the stress at each of the extended portions 31g, 31h, and 31i can be distributed in two directions. Therefore, the stress distribution of the blade 20 can be made more uniform.

[0060] 10 Shaft portion, 10a Rotation axis, 20 Blade, 21 Front edge, 22 Rear edge, 23 Outer edge, 25 Connecting portion, 26 Root, 26a Root on front edge side, 26b Root on rear edge side, 31 First rib, 31a Edge portion, 31a1 Side, 31a2 Side, 31b Edge portion, 31c Edge portion, 31d Vertex portion, 31e Vertex portion, 31f Vertex portion, 31g Extended portion, 31h Extended portion, 31i Extended portion, 32 Second rib, 32a Edge portion, 32b Edge portion, 32c Edge portion, 32d Vertex portion, 32e Vertex portion, 32f Vertex portion.

Claims

1. A propeller fan comprising: a shaft portion provided on a rotating axis; and a plurality of blades provided on the outer circumference of the shaft portion, wherein each of the plurality of blades has a leading edge located forward in the direction of rotation and a trailing edge located backward in the direction of rotation, and ribs are formed on the plurality of blades, the ribs having a plurality of edges arranged in a polygonal shape centered on the shaft portion when viewed in the axial direction, and each of the plurality of edges connecting the leading edges of two adjacent blades in the direction of rotation, or the trailing edges of two blades.

2. The propeller fan according to claim 1, wherein, when viewed in the axial direction, each of the plurality of edges is curved such that the outer peripheral side surface is concave.

3. The propeller fan according to claim 1 or claim 2, wherein each of the plurality of sides is in contact with the shaft.

4. The propeller fan according to any one of claims 1 to 3, wherein each of the plurality of edges connects the leading edges of the two blades.

5. The propeller fan according to any one of claims 1 to 3, wherein each of the plurality of edges connects the trailing edges of the two blades.

6. The propeller fan according to any one of claims 1 to 5, wherein the rib has a first rib and a second rib, each of the plurality of sides of the first rib connects the trailing edges of the two blades, and each of the plurality of sides of the second rib connects the leading edges of the two blades.

7. The propeller fan according to any one of claims 1 to 6, wherein the rib has a plurality of vertex portions located at the vertices of the polygonal shape when viewed in the axial direction, and a plurality of extension portions extending outward from each of the plurality of vertex portions, and each of the plurality of extension portions extends along the edge of the blade.

8. The propeller fan according to any one of claims 1 to 6, wherein the rib has a plurality of vertices located at the vertices of the polygonal shape when viewed in the axial direction, and a plurality of extensions extending outward from each of the plurality of vertices, and when viewed in the axial direction, each of the plurality of sides is curved in an arc shape such that the outer surface is concave, and each of the plurality of extensions extends in an arc shape continuous with the corresponding side when viewed in the axial direction.

9. The propeller fan according to any one of claims 1 to 6, wherein the rib has a plurality of vertex portions located at the vertices of the polygonal shape when viewed in the axial direction, and a plurality of extension portions extending outward from each of the plurality of vertex portions, and each of the plurality of extension portions extends radially along the axis of rotation when viewed in the axial direction.

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