Centrifugal fan, impeller, and dryer

Abstract

To provide a highly efficient centrifugal fan or the like capable of further improving an air volume.SOLUTION: The centrifugal fan (12) includes an impeller (20) and a scroll casing (30). The impeller includes a main plate (21) and a plurality of first blades (22). The scroll casing houses the impeller and has a scroll part (31) provided with a suction opening (32) and a discharge part (33) provided with a blow-out opening (34). The first blade includes a first curved portion (22-1) that is located on an inner side in a radial direction of a rotation axis (0) and is convex in a rotation direction (R) when viewed in an axial direction of the rotation axis, and a second curved portion (22-2) that is located on an outer side in the radial direction with respect to the first curved portion and is concave in the rotation direction when viewed in the axial direction of the rotation axis.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to centrifugal fans, impellers, and dryers. [Background technology]

[0002] In recent years, attention has been focused on biomimetics, a technology that mimics and utilizes the diverse functions of living organisms. Nature Technology (registered trademark) is known as an example of a manufacturing company that uses biomimetic technology in electrical products and other products.

[0003] Conventionally, centrifugal fans have been known in which an impeller is disposed within a scroll casing and which blows air in a specific direction. The scroll casing has a cylindrical scroll section whose radius gradually increases, and the impeller is disposed within the scroll section. An intake port is formed in a wall surface of the scroll casing on one axial side of the impeller's rotating shaft, and an exhaust port is disposed on a radially outer side surface of the impeller's rotating shaft (for example, Patent Document 1).

[0004] Air drawn into the scroll casing through the suction port flows from the center of the impeller between the blades, and is ejected from the outer periphery of the impeller as high-speed, high-pressure air due to the centrifugal force generated by the rotation of the impeller. The air ejected from the impeller passes through the scroll section, becoming high-pressure air and being ejected from the discharge port. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-113399 Summary of the Invention [Problem to be solved by the invention]

[0006] The efficiency of a centrifugal fan is determined by the shape of the impeller and the shape of the scroll casing. If there is a large pressure loss in the scroll section, the air volume decreases and the efficiency drops. Therefore, although improvements have been proposed for the shape of the impeller and the scroll casing, they are still insufficient and there is still room for improvement.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a centrifugal fan or the like with higher efficiency that can further improve air volume. [Means for solving the problem]

[0008] In order to solve the above-described problems, a centrifugal fan according to one embodiment of the present disclosure includes: an impeller having a main plate rotatable about a rotation shaft and a plurality of first blades arranged on the main plate; and a scroll casing that houses the impeller and has a scroll section that has an inlet opening on one axial side of the rotation shaft; and a discharge section that protrudes in a predetermined direction from a circumferential surface of the scroll section and has an outlet opening through which air drawn in from the inlet opening is blown out, wherein the first blade has a first curved portion that is located radially inward of the rotation shaft and that is convex in the rotation direction of the rotation shaft when viewed axially of the rotation shaft, and a second curved portion that is located radially outward of the first curved portion and that is concave in the rotation direction when viewed axially of the rotation shaft.

[0009] In order to solve the above problem, a dryer according to one aspect of the present disclosure includes the centrifugal fan, a duct connected to the centrifugal fan, and a drying chamber connected to the duct.

[0010] In order to solve the above problems, an impeller according to one embodiment of the present disclosure is an impeller having a main plate that can rotate around a rotation axis, and a plurality of first blades arranged on the main plate, wherein the first blades have a first curved portion located radially inward of the rotation axis and that is convex in the rotation direction of the rotation axis when viewed from the axial direction of the rotation axis, and a second curved portion located radially outward of the first curved portion and that is concave in the rotation direction when viewed from the axial direction of the rotation axis, and the curvature of the first curved portion is smaller on the radially inner side than on the radially outer side. [Effects of the Invention]

[0011] According to one aspect of the present disclosure, it is possible to provide a centrifugal fan or the like that is more efficient and can further improve the air volume. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional side view of a washer-dryer as an example of a dryer, the washer-dryer including a blower device having a centrifugal fan according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram of the blower device as seen from the direction of the rotation axis of the impeller provided in the centrifugal fan. [Figure 3] 3 is a view of the blower with the upper cover removed, seen from the direction of the rotation shaft. FIG. [Figure 4] 3 is a view of the blower with the upper cover and shroud removed, viewed from the direction of the rotation shaft. FIG. [Figure 5] FIG. 2 is a perspective view of the impeller. [Figure 6] FIG. 6 is an enlarged view of a region B1 shown in FIG. [Figure 7] FIG. 2 is a view of the impeller as seen from the direction of the rotation axis. [Figure 8] FIG. 8 is an enlarged view of a region B2 shown in FIG. [Figure 9] FIG. 2 is a view of the impeller as seen from the radially outer side of the rotary shaft. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Embodiment] An embodiment of the present disclosure will be described in detail below.

[0014] (General configuration of a washer / dryer) FIG. 1 is a schematic cross-sectional side view of a washer / dryer 100, as an example of a dryer, including a blower device 11 having a centrifugal fan 12 according to this embodiment.

[0015] As shown in FIG. 1, the washer-dryer 100 of this embodiment includes an outer case 1, a washing tub 2 arranged in the outer case 1, a rotating drum (drying chamber) 3 rotatably arranged in the washing tub 2, and a rotating drum drive motor 4 that drives the rotating drum 3 to rotate around a central axis J.

[0016] Door 5 is provided on outer box 1, and washing tub 2 and rotating drum 3 open on the door 5 side. By closing door 5, washing tub 2 remains watertight and airtight. Washing tub 2 is provided with exhaust port 6 and air inlet 7. Exhaust port 6 and air inlet 7 are connected via air circulation duct (duct) 8.

[0017] Air circulation duct 8 forms a circulation path for circulating air inside washing tub 2. A filter device 9 for collecting lint and the like, a heat pump unit 10 as an example of a heating device, and a blower device 11 for circulating air are arranged along the way in air circulation duct 8. Blower device 11 is equipped with a centrifugal fan 12 of this embodiment.

[0018] That is, a washer-dryer 100 as an example of a dryer includes a centrifugal fan 12, an air circulation duct 8 which is a duct connected to the centrifugal fan 12, and a rotating drum 3 which is a drying chamber connected to the air circulation duct 8.

[0019] A plurality of through holes (not shown) are formed on the peripheral surface 3A of the rotating drum 3 to allow water and air to circulate between the rotating drum 3 and the inside of the washing tub 2. In addition, a plurality of air introduction holes (not shown) that communicate with the air supply port 7 of the washing tub 2 are formed on the bottom surface 3B of the rotating drum 3.

[0020] By driving blower device 11, air is sucked in from the heat pump unit 10 side. Dry, heated air supplied from heat pump unit 10 via blower device 11 passes through air circulation duct 8 and is introduced into rotary drum 3 from air inlet 7 as shown by arrow Y in FIG. 1. The introduced heated air removes moisture from items M to be dried, such as clothes, contained in rotary drum 3. The moist heated air escapes into washing tub 2 through through-holes in circumferential surface 3A of rotary drum 3, passes through exhaust port 6 of washing tub 2 through air circulation duct 8, enters filter device 9 as shown by arrow Z in FIG. 1, and is again introduced into heat pump unit 10.

[0021] (Configuration of the blower) Next, a blower 11 including a centrifugal fan 12 will be described. FIG. 2 is a view of the blower 11 as viewed from the direction of the rotation axis O of the impeller 20 included in the centrifugal fan 12. FIG. 3 is a view of the blower 11 as viewed from the direction of the rotation axis O with the upper cover 30A removed. FIG. 4 is a view of the blower 11 as viewed from the direction of the rotation axis O with the upper cover 30A and shroud 29 removed. FIG. 5 is a perspective view of the impeller 20. FIG. 6 is an enlarged view of region B1 shown in FIG. 5. FIG. 7 is a view of the impeller 20 as viewed from the direction of the rotation axis O. FIG. 8 is an enlarged view of region B2 shown in FIG. 7. FIG. 9 is a view of the impeller 20 as viewed from the radially outer side of the rotation axis O. Note that in FIGS. 5, 6, and 9, ridgelines are depicted for first blades 22 and second blades 23, which will be described later. Therefore, although it appears to be bent at the ridgeline, the faces on either side of the ridgeline are connected by a smooth curve.

[0022] 2 and 3, the blower 11 includes a centrifugal fan 12 and a fan motor 13. The centrifugal fan 12 includes an impeller 20 and a scroll casing 30 that houses the impeller 20.

[0023] The scroll casing 30 has a scroll portion 31 that houses the impeller 20, and a discharge portion 33 that protrudes from the circumferential surface of the scroll portion 31 in a predetermined direction.

[0024] The scroll portion 31 has a suction opening 32 on one axial side of the rotation axis O of the impeller 20. The scroll portion 31 has a radius that spirally increases toward the front in the rotation direction R of the impeller 20.

[0025] The discharge section 33 extends from the outer circumferential end of the scroll section 31 while communicating with the interior of the scroll section 31. The discharge section 33 is provided with a blow-out opening 34 that blows out the air sucked in from the suction opening 32. The discharge section 33 is a part that forms a flow path between the scroll section 31 and the blow-out opening 34.

[0026] A tongue portion 35 protruding toward the inside of the scroll portion 31 is provided at a portion where the inner circumferential surface 31A of the scroll portion 31 and the discharge portion 33 are bent and connected. The tongue portion 35 is a member that guides the airflow swirling along the inner circumferential surface 31A inside the scroll portion 31 to the discharge portion 33.

[0027] As shown in Fig. 3, a shroud 29 is attached to the surface of the impeller 20 opposite to the main plate 21, which will be described later. A plurality of first blades 22 and a plurality of second blades 23 (see Fig. 5), which will be described later and are provided on the impeller 20, are crimped to the shroud 29. The shroud 29 is attached to the impeller 20 so that its center coincides with the rotation axis O.

[0028] An opening 29A is provided in the center of the shroud 29. The opening 29A has a larger opening area than the suction opening 32 of the scroll portion 31. When viewed in the axial direction of the rotation axis O, the opening 29A overlaps with the suction opening 32. When viewed in the axial direction of the rotation axis O, the opening 29A overlaps with an end portion 23A (see FIG. 8 ) of a second blade 23 of the impeller 20, which will be described later, on the inner side in the radial direction of the rotation axis O. When the shroud 29 is attached to the impeller 20, the distance between the shroud 29 and a main plate 21, which will be described later, in the axial direction of the rotation axis O decreases from the inner side in the radial direction of the rotation axis O to the outer side in the radial direction of the rotation axis O.

[0029] The distance between the shroud 29 and a main plate 21 (described later) may be constant between the inner side in the radial direction of the rotation axis O and the outer side in the radial direction of the rotation axis O.

[0030] 4, 5, and 7, the impeller 20 has a main plate 21 and a plurality of first blades 22 arranged on the main plate 21. The main plate 21 is a disk concentric with the rotation axis O, and is fixed to the rotation axis of the fan motor 13.

[0031] 7, the multiple first blades 22 have a plate shape extending from the main plate 21 in parallel to the axial direction of the rotation axis O. The multiple first blades 22 have the same shape and are arranged at equal intervals and tilted relative to the radial direction of the rotation axis O so that the outer end 22B in the radial direction of the rotation axis O is located in the opposite direction to the rotation direction R. The inner end 22A of each first blade 22 in the radial direction of the rotation axis O is located on an imaginary circle L1 centered on the rotation axis O, and the outer end 22B in the radial direction of the rotation axis O is located at the outer peripheral edge of the main plate 21.

[0032] As shown in Figures 7 and 8, the first blade 22 has a first curved portion 22-1 that is located radially inward of the rotation axis O and that is convex in the rotation direction R of the rotation axis O when viewed in the axial direction of the rotation axis O, and a second curved portion 22-2 that is located radially outward of the first curved portion 22-1 and that is concave in the rotation direction R when viewed in the axial direction of the rotation axis O.

[0033] In the above configuration, the first curved portion 22-1, which is convex in the rotation direction R, efficiently draws in air sucked in from the suction opening 32, and causes the air to adhere to the blades and flow toward the outer periphery of the impeller 20. The second curved portion 22-2, which is concave in the rotation direction R, pushes out air ejected from outside the outer periphery of the impeller 20 in the tangential direction X of the outer periphery of the impeller 20, creating a flow that follows the inner circumferential surface 31A of the scroll section 31 (see FIG. 4).

[0034] This allows for efficient air intake, while suppressing losses in pressure and velocity caused by air being ejected from the outer periphery of the impeller 20 and passing through the discharge section 33 toward the outlet opening 34 hitting the inner circumferential surface 31A of the scroll section 31. This makes it possible to further increase the air pressure difference between the suction opening 32 and the outlet opening 34. As a result, air volume and noise reduction are improved, resulting in high efficiency.

[0035] Here, the first curved portion 22-1 is configured to be formed from the radially inner end 22A of the first blade 22, but the first curved portion 22-1 may be formed from a position radially outer than the end 22A of the first blade 22. Similarly, the second curved portion 22-2 is configured to be formed up to the radially outer end 22B of the first blade 22, but the second curved portion 22-2 does not have to reach the end 22B of the first blade 22.

[0036] Furthermore, although the first blade 22 is configured here to be formed in a shape parallel to the axial direction of the rotation axis O, it may be formed in a shape that is not parallel to the axial direction of the rotation axis O. For example, the first blade 22 may be formed in a shape that is recessed in the rotation direction R when viewed from the radial direction of the rotation axis O. If the direction along the rotation axis O is defined as the height direction of the blade based on the main surface of the main plate 21, the first blade 22 may be formed in a shape such that the central portion is recessed in the rotation direction R relative to the upper and lower portions in the height direction. Note that this type of shape also applies to the second blade 23 described below.

[0037] Furthermore, the first blade 22 is exemplified as a thin blade with uniform thickness, and the positive pressure surface and negative pressure surface have the same shape, but only the positive pressure surface may have a shape having the above-mentioned first curved portion 22-1 and second curved portion 22-2.

[0038] 7 and 8, the first curved portion 22-1 and the second curved portion 22-2 may be continuous across the first inflection point P1, and the distance from the first end 22-1A to the first inflection point P1 may be longer than the distance from the first inflection point P1 to the second end 22-2B.

[0039] The distance from the first end portion 22-1A to the first inflection point P1 corresponds to the length of the first curved portion 22-1. The distance from the first inflection point P1 to the second end portion 22-2B corresponds to the length of the second curved portion 22-2.

[0040] The first curved portion 22-1 can allow air to adhere to the blades more efficiently and flow to the outer peripheral side of the impeller 20 if it is longer rather than shorter. Even if the length of the second curved portion 22-2 is shorter than that of the first curved portion 22-1, it can push the air efficiently in the tangential direction of the outer periphery of the impeller 20.

[0041] Also, as shown in FIG. 8, the second end portion 22-2B in the second curved portion 22-2 may be configured to be located on the rotation direction R side with respect to the extension line L2 of the straight line passing through the first end portion 22-1A and the first inflection point P1 in the first curved portion 22-1.

[0042] The second curved portion 22-2 has a curved shape concave in the rotation direction R, so that it can push the air in the tangential direction X of the outer periphery of the impeller 20. With the above configuration, the effect of pushing out the air that has adhered to and flowed through the first curved portion 22-1 in the rotation direction R can be enhanced.

[0043] Also, the curvature of the first curved portion 22-1 may be configured such that the inner side in the radial direction is smaller than the outer side in the radial direction. In other words, the first curved portion 22-1 has a first region 22-11 on the inner side in the radial direction and a second region 22-12 on the outer side in the radial direction. If the curvature of the first region 22-11 is W1 and the curvature of the second region 22-12 is W2, then W1 < W2 may be satisfied. The first region 22-11 on the inner side in the radial direction is flatter than the second region 22-12 on the outer side in the radial direction.

[0044] Using the midpoint of the line connecting the first end 22-1A to the first inflection point P1 as a reference, the first region 22-11 may extend from the first end 22-1A to the midpoint at its maximum, and the second region 22-12 may extend from the midpoint to the first inflection point P1 at its minimum. In other words, in the straight-line distance connecting the first end 22-1A to the first inflection point P1, if the distance of the first region 22-11 is D1 and the distance of the second region 22-12 is D2, then D1≦D2.

[0045] The smaller the curvature (closer to flatness) of the first curved portion 22-1, which draws in air and causes it to adhere to the blades and flow toward the outer periphery of the impeller 20, the easier it is for air to adhere. With the above configuration, air can be efficiently taken in by the first region 22-11 of the first curved portion 22-1 on the suction opening 32 side. Furthermore, by providing the second region 22-12 with a larger curvature than the first region 22-11, the air that adheres to the first curved portion 22-1 and flows toward the outer periphery of the impeller 20 can be forcefully sent out to the concave second curved portion 22-2.

[0046] The curvature of the first curved portion 22-1 may be gradually increased from the radially inner side to the radially outer side, which allows the first curved portion 22-1 to more efficiently take in air and then forcefully send the air to the second curved portion 22-2.

[0047] The curvature of the second curved portion 22-2 may be larger than the curvature of the first curved portion 22-1. If the curvature of the first curved portion 22-1 is not constant, the curvature of the second curved portion 22-2 is larger than the curvature of any portion of the first curved portion 22-1.

[0048] The smaller the curvature of the first curved portion 22-1, which draws in air, attaches it to the blades, and flows it toward the outer periphery of the impeller 20, the easier it is for air to attach to it. In contrast, the larger the curvature of the second curved portion 22-2, which pushes air out in the tangential direction X of the outer periphery of the impeller 20, the easier it is to capture air and push it out effectively. With the above configuration, the first curved portion 22-1 can efficiently take in air, and the second curved portion 22-2 can efficiently push the air out in the tangential direction of the outer periphery of the impeller 20.

[0049] 5 to 8, the impeller 20 may have a plurality of second blades 23 arranged between adjacent first blades 22. Radially inner ends 23A of the second blades 23 are positioned radially outward of radially inner ends 22A of the first blades 22.

[0050] Similar to the first blades 22, the second blades 23 have a plate shape extending parallel to the axial direction of the rotation axis O from the main plate 21. The second blades 23 have the same shape and are arranged at equal intervals in a state inclined relative to the radial direction of the rotation axis O so that the outer ends 23B in the radial direction of the rotation axis O are positioned in the opposite direction to the rotation direction R.

[0051] 7, an inner end 23A of each second blade 23 in the radial direction of the rotation axis O is located on an imaginary circle L4 centered on the rotation axis O. An outer end 23B of each second blade 23 in the radial direction of the rotation axis O is located at the outer peripheral edge of the main plate 21.

[0052] The second blade 23 overlaps with the shroud 29 when viewed in the axial direction of the rotation axis O. In this embodiment, the imaginary circle L4 coincides with the opening 29A of the shroud 29 when viewed in the axial direction of the rotation axis O.

[0053] By providing the second blades 23 between adjacent first blades 22, the air passing through the spaces between the adjacent first blades 22 can be taken in by adhering to the second blades 23. This further improves the air volume and makes the fan more efficient.

[0054] In this case, as shown in Figure 8, the second blade 23 may have a third curved portion 23-1 located radially inward of the rotation axis O and convex in the rotation direction of the rotation axis O, and a fourth curved portion 23-2 located radially outward of the third curved portion 23-1 and concave in the rotation direction R.

[0055] Similarly to the first blade 22, the second blade 23 is configured to have a third curved portion 23-1 that draws in air and a fourth curved portion 23-2 that pushes out air in the tangential direction X of the outer periphery of the impeller 20, thereby further improving the air volume and achieving even higher efficiency.

[0056] Here, although the radially inner third end 23-1A of the third curved portion 23-1 is the same as the inner end 23A of the second blade 23, this is not necessarily the case. Similarly, the radially outer fourth end 23-2B of the fourth curved portion 23-2 is the same as the outer end 23B of the second blade 23, but this is not necessarily the case.

[0057] Furthermore, the second blade 23 is exemplified as a thin blade with uniform thickness, and the positive pressure surface and negative pressure surface have the same shape, but only the positive pressure surface may have a shape having the above-mentioned third curved portion 23-1 and fourth curved portion 23-2.

[0058] 7 and 8, in the second blade 23, the third curved portion 23-1 and the fourth curved portion 23-2 may be continuous with the second inflection point P2 in between. The first inflection point P1 and the second inflection point P2 may be located on an imaginary circle (the same circle) L3 centered on the rotation axis O, and the second curved portion 22-2 and the fourth curved portion 23-2 may have the same shape.

[0059] 5, the surface (end surface) of the first region 22-11 of the first blade 22 opposite to the main plate 21 may be inclined so as to approach the main plate 21 (the main surface of the main plate 21) as it approaches the rotation axis O. In other words, if the dimension in the direction along the rotation axis O is defined as the height of the blade with the main plate 21 as the reference, the first region 22-11 of the first blade 22 may have a shape that becomes lower as it approaches the rotation axis O.

[0060] Furthermore, second blade 23 may have a shape obtained by removing first region 22-11 from first blade 22. In other words, second blade 23 may be configured to have the same shape as second region 22-12 and second curved portion 22-2 of first blade 22.

[0061] 9, the first blade 22 may be inclined so that the boundary between the first region 22-11 and the second region 22-12 is farthest from the main plate 21, and the first blade 22 approaches the main plate 21 (the main surface of the main plate 21) from the boundary with the second region 22-12 toward the outer periphery of the impeller 20. In other words, the first blade 22 may be shaped so that the boundary between the first region 22-11 and the second region 22-12 is the highest and becomes lower as the boundary approaches the outer periphery of the impeller 20.

[0062] In addition, in the present embodiment, the impeller 20 provided in the centrifugal fan 12 of the blower 11 has been exemplified, but the impeller 20 may be used in a fan other than the centrifugal fan 12. In that case, the impeller 20 may have at least the following configuration.

[0063] That is, referring to Figure 7, the impeller has a main plate 21 that can rotate around a rotation axis O, and a plurality of first blades 22 arranged on the main plate 21, and each first blade 22 has a first curved portion 22-1 that is located radially inward of the rotation axis O and is convex in the rotation direction R of the rotation axis O, and a second curved portion 22-2 that is located radially outward of the first curved portion 22-1 and is concave in the rotation direction R, and the curvature of the first curved portion 22-1 is smaller on the radially inner side than on the radially outer side.

[0064] By using the impeller having the above configuration, the rotation of the impeller allows the fluid sucked in from the center portion to adhere to the blades and flow efficiently toward the outer periphery of the impeller, and the fluid guided to the outer periphery can be effectively pushed out in the tangential direction X of the outer periphery of the impeller.

[0065] 〔summary〕 A centrifugal fan according to a first aspect of the present disclosure comprises: a main plate rotatable around a rotation axis; an impeller having a plurality of first blades arranged on the main plate; and a scroll casing that houses the impeller and has a scroll section that has an intake opening on one axial side of the rotation axis; and a discharge section that protrudes in a predetermined direction from the circumferential surface of the scroll section and has an outlet opening for blowing out air drawn in from the intake opening, wherein the first blade has a first curved portion located radially inward of the rotation axis and that is convex in the rotation direction of the rotation axis when viewed from the axial direction of the rotation axis; and a second curved portion located radially outward of the first curved portion and that is concave in the rotation direction when viewed from the axial direction of the rotation axis.

[0066] A centrifugal fan according to a second aspect of the present disclosure may be such that, in the first aspect, the first curved portion and the second curved portion are continuous across a first inflection point, and the distance from a first end portion on the inner side of the front radial direction of the first curved portion to the first inflection point is longer than the distance from the first inflection point to a second end portion on the outer side of the radial direction of the second curved portion.

[0067] A centrifugal fan according to a third aspect of the present disclosure may be configured such that, in the second aspect, the second end is located on the rotation direction side of an extension of a straight line passing through the first end and the first inflection point.

[0068] A centrifugal fan according to a fourth aspect of the present disclosure is any one of the first, second, and third aspects, wherein the curvature of the first curved portion is smaller on the inside in the radial direction than on the outside in the radial direction.

[0069] A centrifugal fan according to a fifth aspect of the present disclosure is any one of the first to fourth aspects, wherein the curvature of the second curved portion may be greater than the curvature of the first curved portion.

[0070] A centrifugal fan according to aspect 6 of the present disclosure is any one of aspects 1 to 5 above, wherein the impeller has a plurality of second blades arranged between adjacent ones of the plurality of first blades, and the radially inner ends of the plurality of second blades may be located radially outward of the radially inner ends of the plurality of first blades.

[0071] A centrifugal fan according to a seventh aspect of the present disclosure is any one of the first to fifth aspects, wherein the impeller has a plurality of second blades arranged between adjacent first blades, and the radially inner ends of the second blades are located radially outward of the rotating shaft relative to the radially inner ends of the first blades, and the second blades have a third curved portion located radially inward of the rotating shaft and convex in the rotational direction of the rotating shaft, and a fourth curved portion located radially outward of the third curved portion and concave in the rotational direction.

[0072] A centrifugal fan according to aspect 8 of the present disclosure may be configured as in aspect 7 above, wherein the third curved portion and the fourth curved portion are continuous across a second inflection point, the first inflection point and the second inflection point are located on the same circle, and the second curved portion and the fourth curved portion have the same shape.

[0073] A dryer according to a ninth aspect of the present disclosure includes the centrifugal fan according to any one of the first to eighth aspects, a duct connected to the centrifugal fan, and a drying chamber connected to the duct.

[0074] An impeller according to aspect 10 of the present disclosure is an impeller having a main plate rotatable around a rotation axis, and a plurality of first blades arranged on the main plate, wherein the first blades have a first curved portion located radially inward of the rotation axis and convex in the rotation direction of the rotation axis when viewed from the axial direction of the rotation axis, and a second curved portion located radially outward of the first curved portion and concave in the rotation direction when viewed from the axial direction of the rotation axis, and the curvature of the first curved portion is smaller on the radially inner side than on the radially outer side.

[0075] This disclosure includes a technical idea that focuses on the flying squirrel's gliding flight posture and tail direction. In other words, this disclosure relates to biomimetics.

[0076] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of symbols]

[0077] 3 Rotating drum (drying chamber) 6 exhaust port 7 Air supply port 8 Air circulation duct (duct) 100 Washer / Dryer (Dryer) 11. Blower 22-11 1st area 22-12 Second area 12 Centrifugal fan 20 impeller 21 Main plate 22 First Feather 22-1 1st curve section 22-2 Second curve part 22-1A 1st end 22-2B 2nd end 22A Inner end of first blade 22B Outer end of first blade 23 Second Feather 23-1 Third curve section 23-2 4th curve section 23A Inner end of second blade 23B Outer end of second blade 23-1A 3rd end 23-2B 4th end 30 Scroll casing 31 Scroll section 31A Inner surface 32 Intake opening 33 Discharge part 34 Air outlet L2 extension line P1 1st inflection point P2 2nd inflection point

Claims

1. an impeller having a main plate rotatable around a rotation axis and a plurality of first blades arranged on the main plate; a scroll casing that houses the impeller and has a scroll section that has an inlet opening on one axial side of the rotary shaft, and a discharge section that protrudes in a predetermined direction from a circumferential surface of the scroll section and has an outlet opening that blows out air that has been sucked in through the inlet opening; Equipped with The first blade is a first curved portion located radially inside the rotation shaft and protruding in a rotation direction of the rotation shaft when viewed from the axial direction of the rotation shaft; a second curved portion that is positioned radially outward of the first curved portion and that is recessed in the rotation direction when viewed from the axial direction of the rotation shaft.

2. the first curved line portion and the second curved line portion are continuous with each other across a first inflection point, 2. The centrifugal fan according to claim 1, wherein a distance from a first end portion on a front radially inner side of the first curved portion to the first inflection point is longer than a distance from the first inflection point to a second end portion on a radially outer side of the second curved portion.

3. The centrifugal fan according to claim 2 , wherein the second end is located on a side of an extension of a straight line passing through the first end and the first inflection point, in the rotation direction.

4. The centrifugal fan according to claim 1 , wherein a curvature of the first curved portion is smaller on an inner side in the radial direction than on an outer side in the radial direction.

5. The centrifugal fan according to claim 1 , wherein the second curved portion has a curvature greater than the curvature of the first curved portion.

6. The impeller has a plurality of second blades arranged between adjacent ones of the plurality of first blades, 2. The centrifugal fan according to claim 1, wherein radially inner ends of the second blades are located radially outward of radially inner ends of the first blades.

7. The impeller has a plurality of second blades arranged between adjacent ones of the plurality of first blades, an inner end portion of the second blade in the radial direction of the rotary shaft is located more outer in the radial direction of the rotary shaft than an inner end portion of the first blade in the radial direction of the rotary shaft, The second blade is a third curved portion located radially inside the rotation shaft and protruding in a rotation direction of the rotation shaft; 3. The centrifugal fan according to claim 2, further comprising: a fourth curved portion located radially outward of the third curved portion and recessed in the rotational direction.

8. the third curved line portion and the fourth curved line portion are continuous with each other across a second inflection point, the first inflection point and the second inflection point are located on the same circle, The centrifugal fan according to claim 7 , wherein the second curved portion and the fourth curved portion have the same shape.

9. A centrifugal fan according to any one of claims 1 to 8; a duct connected to the centrifugal fan; a drying chamber connected to the duct.

10. An impeller having a main plate rotatable around a rotation axis and a plurality of first blades arranged on the main plate, The first blade is a first curved portion located radially inside the rotation shaft and protruding in a rotation direction of the rotation shaft when viewed from the axial direction of the rotation shaft; a second curved portion that is positioned radially outward of the first curved portion and that is recessed in the rotation direction when viewed from the axial direction of the rotation shaft, The curvature of the first curved portion is smaller on the inside in the radial direction than on the outside in the radial direction.

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