centrifugal fan

Abstract

In a centrifugal fan, since a blade rotates at high speed, it is desirable to further increase the joint strength of the blade and a plate. The centrifugal fan has a plate, a ring, and a plurality of blades (43) including a first blade (43a). A first joint surface (51) is a joint surface of the plate side of the first blade (43a). The first joint surface (51) has a second joint surface (52) and a third joint surface (53). The second joint surface (52) is a portion of the first joint surface (51) on the front end (91) side than the second straight line (L2). The third joint surface (53) is a portion of the first joint surface (51) on the rear end (92) side than the second straight line (L2). A first width dimension (D1) is largest in the width dimension of the second joint surface (52) along the second straight line (L2). A second width dimension (D2) is largest in the width dimension of the third joint surface (53) along the second straight line (L2). The first width dimension (D1) is 1.3 times or more of the second width dimension (D2).

Description

Technical Field

[0001] The present invention relates to a centrifugal fan. Background Art

[0002] As shown in Patent Document 1 (Japanese Patent Publication No. 2019-100209), a centrifugal fan is known, which comprises: a plate, which is arranged in a manner such that the thickness direction is along the direction of the rotation axis; a ring, which is arranged at a distance from the plate in the direction of the rotation axis and has a ring shape when viewed from the direction of the rotation axis; and a plurality of blades, which are arranged between the plate and the ring, one end of which is connected to the plate and the other end is connected to the ring. Summary of the Invention

[0003] Problems to be solved by the invention

[0004] In centrifugal fans, since the blades rotate at high speed, the centrifugal force acting on the blades is large. Therefore, it is desired to further improve the bonding strength between the blades and the plate.

[0005] Means for solving problems

[0006] A centrifugal fan according to a first aspect includes a plate, a ring, and a plurality of blades. The plate is arranged with its thickness direction along the direction of the rotation axis. The ring and the plate are spaced apart in the direction of the rotation axis. The ring has an annular shape when viewed from the direction of the rotation axis. The plurality of blades are arranged between the plate and the ring. One end of the plurality of blades is joined to the plate, and the other end is joined to the ring. The plurality of blades includes a first blade. The first joint surface is a joint surface on the plate side of the first blade. The first joint surface includes a second joint surface and a third joint surface. The second joint surface is a portion of the first joint surface that is closer to the front end than the second straight line. The second straight line passes through the center of the first straight line and is orthogonal to the first straight line. The first straight line connects the front end and rear end of the first blade in the rotation direction. The third joint surface is a portion of the first joint surface that is closer to the rear end than the second straight line. The first width dimension is the largest among the width dimensions of the second joint surface along the second straight line. The second width dimension is the largest among the width dimensions of the third joint surface along the second straight line. The first width dimension is at least 1.3 times the second width dimension.

[0007] By extending the second joint surface, which is the portion on the front end side of the first blade in the direction of rotation, toward the axis of rotation, the maximum vertical stress generated on the first joint surface by centrifugal force tends to decrease. In the centrifugal fan of the first aspect, the first width dimension is at least 1.3 times the second width dimension. The first width dimension is the largest among the width dimensions along the second straight line of the second joint surface. The second width dimension is the largest among the width dimensions along the second straight line of the third joint surface. As a result, the centrifugal fan can improve the joint strength between the first blade and the plate.

[0008] In the centrifugal fan according to a second aspect, in the centrifugal fan according to the first aspect, the first width dimension is equal to or less than three times the second width dimension.

[0009] Regarding the centrifugal fan according to a third aspect, in the centrifugal fan according to the first aspect or the second aspect, the first width dimension is 1.6 times or more the second width dimension.

[0010] Regarding the centrifugal fan of the fourth aspect, in the centrifugal fan of any one of the first to third aspects, in the second joint surface, the area of ​​the fourth joint surface, which is closer to the rotation axis side than the first straight line, is larger than the area of ​​the fifth joint surface, which is the part on the side opposite to the rotation axis side.

[0011] The first blade 43a has a tendency to separate from the fourth joint surface, which is the portion of the second joint surface on the rotation axis side, due to centrifugal force. In the centrifugal fan of the fourth aspect, the joint strength between the first blade and the plate can be increased by making the area of ​​the fourth joint surface larger than the area of ​​the fifth joint surface in the second joint surface.

[0012] Regarding the centrifugal fan of the fifth viewpoint, in the centrifugal fan of any one of the first viewpoints to the fourth viewpoints, the area of ​​the fourth joint surface, which is a portion of the second joint surface closer to the rotation axis than the first straight line, is larger than the area of ​​the sixth joint surface, which is a portion of the third joint surface closer to the rotation axis than the first straight line.

[0013] The first blade 43a tends to separate from the fourth joint surface, which is the portion of the second joint surface on the rotation axis side, due to centrifugal force. In the centrifugal fan of the fifth aspect, the joint strength between the first blade and the plate can be increased by making the area of ​​the fourth joint surface larger than the area of ​​the sixth joint surface.

[0014] Regarding the centrifugal fan of a sixth aspect, in the centrifugal fan of any one of the first to fifth aspects, when the first blade extending from the plate to the ring is viewed along the first straight line, the shape of the first blade includes the first recessed portion.

[0015] Regarding the centrifugal fan according to a seventh aspect, in the centrifugal fan according to the sixth aspect, the first recessed portion is formed at a position closer to the plate than to the ring.

[0016] The centrifugal fan according to the seventh aspect has such a structure, and can ensure the first width dimension without affecting the performance of the centrifugal fan.

[0017] Regarding the centrifugal fan according to an eighth aspect, in the centrifugal fan according to any of the first to seventh aspects, the plurality of blades includes a second blade adjacent to the first blade. The first joint surface is shaped such that a second recess is formed on the rotation axis side. The seventh joint surface is located outside the area enclosed by the second recess and a third straight line connecting the ends of the second recess. The seventh joint surface is a joint surface on the plate side of the second blade.

[0018] When the first blade and the second blade are deformed by the centrifugal force, the plate is also deformed accordingly. At this time, if the first blade is in close contact with the second blade, the plate cannot be deformed, and a large load is applied to the first joint surface and the seventh joint surface. In the centrifugal fan of the eighth aspect, the seventh joint surface is located outside the area surrounded by the second recess and the third straight line connecting the two ends of the second recess. Therefore, in the centrifugal fan, the plate can be deformed according to the deformation of the first blade and the second blade caused by the centrifugal force, so a large load is not applied to the first joint surface and the seventh joint surface. As a result, the centrifugal fan can improve the joining strength between the first blade and the second blade and the plate.

[0019] Regarding the centrifugal fan according to a ninth aspect, in the centrifugal fan according to any one of the first to eighth aspects, the first joining surface is located around a hollow portion formed on the plate side of the first blade.

[0020] In the centrifugal fan according to the ninth aspect, the first blades are made lighter by forming the hollow portion, thereby reducing the centrifugal force acting on the first blades.

[0021] Regarding the centrifugal fan according to a tenth aspect, in the centrifugal fan according to any one of the first to ninth aspects, the first blade is molded from resin.

[0022] In the centrifugal fan of the tenth aspect, the first blades are molded by injection molding or the like, thereby increasing the degree of freedom in the shape of the first blades.

[0023] Regarding the centrifugal fan according to an eleventh aspect, in the centrifugal fan according to any one of the first to tenth aspects, the plate and the ring are formed of aluminum or an aluminum alloy.

[0024] Regarding the centrifugal fan according to a twelfth aspect, in the centrifugal fan according to any one of the first to eleventh aspects, the plate and the first blade are joined by a method other than welding.

[0025] The centrifugal fan of the twelfth aspect does not require a space for accommodating a welding torch, and thus the number of blades can be increased, thereby eliminating Nz noise.

[0026] Regarding the centrifugal fan according to a thirteenth aspect, in the centrifugal fan according to any one of the first to twelfth aspects, the number of the plurality of blades is 7 to 11. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of the indoor unit.

[0028] Figure 2 This is a schematic cross-sectional view of a centrifugal fan.

[0029] Figure 3It is a three-dimensional diagram of the impeller.

[0030] Figure 4 This is a diagram of the impeller viewed from the plate side along the direction of the rotation axis.

[0031] Figure 5 This is a diagram showing a first joint surface that is a joint surface on the plate side of the first blade.

[0032] Figure 6 This is a diagram showing a first joint surface that is a joint surface on the plate side of the first blade.

[0033] Figure 7 This is a diagram showing a first joint surface that is a joint surface on the plate side of the first blade.

[0034] Figure 8 This is a diagram showing the eighth joint surface which is the joint surface on the ring side of the first blade.

[0035] Figure 9 is a diagram of a first blade extending from the plate to the ring viewed along a first straight line.

[0036] Figure 10 This is a diagram showing a first joint surface that is a joint surface on the plate side of a conventional blade.

[0037] Figure 11 This is a diagram showing a first joint surface that is a joint surface on the plate side of a conventional blade.

[0038] Figure 12 It is a diagram showing the fourth joint surface and the fifth joint surface.

[0039] Figure 13 It is a diagram showing the fourth joint surface and the sixth joint surface.

[0040] Figure 14 It is an enlarged view of the first joint surface of the first blade and the seventh joint surface of the second blade. DETAILED DESCRIPTION

[0041] (1) Air conditioning unit

[0042] The air conditioning apparatus 1 uses a vapor compression refrigeration cycle to perform air conditioning in a target space. In the present embodiment, the air conditioning apparatus 1 is a central air conditioning apparatus. The air conditioning apparatus 1 mainly includes an indoor unit 10 and a heat source unit 20.

[0043] (2) Indoor unit

[0044] Figure 1 FIG. 1 is a schematic structural diagram of the indoor unit 10. In this embodiment, the indoor unit 10 is an air handling unit. Figure 1As shown, the indoor unit 10 mainly includes a casing 11, a centrifugal fan 30, a heat exchanger 12, an electric heater 13, and a humidifier 14. The indoor unit 10 and the heat source unit 20 are connected via a pipe 94 through which a heating medium (eg, refrigerant, water, etc.) flows.

[0045] The casing 11 primarily houses the centrifugal fan 30, the heat exchanger 12, the electric heater 13, and the humidifier 14. The casing 11 is formed with a first opening 11a, a second opening 11b, and a third opening 11c. The first opening 11a is for drawing outdoor air OA from the outside into the casing 11. The second opening 11b is for drawing indoor air RA from the target space into the casing 11. The third opening 11c is for blowing conditioned supply air SA from the casing 11 toward the target space.

[0046] The centrifugal fan 30 draws outdoor air OA and indoor air RA into the casing 11 through the first opening 11a and the second opening 11b, and blows supply air SA into the target space through the third opening 11c. The centrifugal fan 30 generates an airflow AF within the casing 11 that flows from the first opening 11a and the second opening 11b toward the third opening 11c. The airflow AF passes through the heat exchanger 12, the electric heater 13, and the humidifier 14 in this order within the casing 11.

[0047] Heat exchanger 12, electric heater 13, and humidifier 14 are arranged on the flow path of airflow AF. Heat exchanger 12 exchanges heat between airflow AF and the heat medium in pipe 94 supplied from heat source unit 20. Electric heater 13 heats airflow AF after passing through heat exchanger 12. Humidifier 14 humidifies airflow AF by spraying water from a tank (not shown) located outside housing 11 through a nozzle.

[0048] (3) Centrifugal fan

[0049] Figure 2 : is a schematic cross-sectional view of the centrifugal fan 30. In this embodiment, the centrifugal fan 30 is a turbo fan. Figure 2 As shown, the centrifugal fan 30 mainly includes a fan motor 31 and an impeller 40. The impeller 40 is connected to the fan motor 31 via a hub member 44. The impeller 40 is driven by the fan motor 31 to rotate around the rotation axis A1. Figure 2 , the rotation direction of the impeller 40 is indicated as "A2".

[0050] Figure 3 4 is a perspective view of the impeller 40. Figure 3 As shown, the impeller 40 mainly comprises a plate 41, a ring 42 and a plurality of blades 43. Figure 3 In FIG, the ring 42 is depicted as semi-transparent.

[0051] (3-1) Board

[0052] like Figure 2 、 Figure 3 As shown in FIG. 4 , the plate 41 is configured such that its thickness direction is along the direction of the rotation axis A1. The plate 41 is formed of aluminum or an aluminum alloy. Figure 2 As shown, the plate 41 has a first plate surface 41 a facing the ring 42 and a second plate surface 41 b on the opposite side to the ring 42 . Figure 4 This is a diagram showing the impeller 40 as viewed from the plate 41 side along the direction of the rotation axis A1. Figure 4 As shown in FIG. 1 , the plate 41 has an annular shape when viewed from the direction of the rotation axis A1. An opening 41c for fixing the hub member 44 is formed in the center of the plate 41. Holes 41d for fixing the hub member 44 with bolts are formed around the opening 41c. Figure 4 As shown in FIG. 4 , six holes 41 d are formed in this embodiment. The plate 41 is connected to the fan motor 31 via a fixed boss member 44 .

[0053] (3-2) Ring

[0054] like Figure 2 、 Figure 3 As shown, the ring 42 and the plate 41 are spaced apart in the direction of the rotation axis A1. The ring 42 is formed of aluminum or an aluminum alloy. Figure 3 As shown, the ring 42 has an annular shape when viewed from the direction of the rotation axis A1. Figure 2 As shown, the ring 42 has a first ring surface 42 a facing the plate 41 and a second ring surface 42 b on the opposite side to the plate 41 .

[0055] (3-3)Leaf

[0056] like Figure 2 、 Figure 3 As shown, a plurality of blades 43 are arranged between the plate 41 and the ring 42. The number of the plurality of blades 43 is 7 to 11. Figure 3 、 Figure 4 As shown in FIG. 1 , in this embodiment, the number of blades 43 is 9. Figure 2 As shown, one end of the plurality of blades 43 is engaged with the first plate surface 41a of the plate 41, and the other end is engaged with the first ring surface 42a of the ring 42. Figure 3 、 Figure 4 As shown, the plurality of blades 43 are arranged at unequal pitches along the rotation direction A2 of the impeller 40 (the rotation direction A2 of the plurality of blades 43 ).

[0057] Hereinafter, any one of the plurality of blades 43 will be referred to as a first blade 43a. The first blade 43a is molded from resin.

[0058] Figures 5-7 4 is a diagram showing the first joining surface 51 on the plate 41 side of the first blade 43a (the joining surface between the first blade 43a and the first plate surface 41a). Figure 5 As shown, a hollow portion 71 is formed on the plate 41 side of the first blade 43a. The first joint surface 51 is located around the hollow portion 71. The first joint surface 51 is shaped so as to have a second recessed portion 74 formed on the rotation axis A1 side. Figure 5 In FIG, the first joint surface 51 is indicated by hatching. The first blade 43a has a pin 81 for determining the position of the first blade 43a and a hole 82 for passing a screw through the first blade 43a so that the first blade 43a is in close contact with the first plate surface 41a. Figure 5 As shown, in this embodiment, the first blade 43a has two pins 81 and three holes 82 on the first joint surface 51. The plate 41 and the first blade 43a are joined by a method other than welding. In this embodiment, the pins 81 determine the position of the first blade 43a, and screws are inserted to make the first blade 43a adhere to the first plate surface 41a. The plate 41 and the first blade 43a are joined by an adhesive.

[0059] The first joint surface 51 has a second joint surface 52 and a third joint surface 53. Here, in order to explain the second joint surface 52 and the third joint surface 53, a first straight line L1 and a second straight line L2 are defined. Figure 6 、 Figure 7 In order to easily see the first straight line L1 and the second straight line L2, the structure of the hollow portion 71 is omitted and the first joint surface 51 is depicted. Figure 6 As shown, the first straight line L1 is a straight line connecting the front end 91 and the rear end 92 of the first blade 43a in the rotation direction A2. The second straight line L2 is a straight line passing through the center 93 of the first straight line L1 and perpendicular to the first straight line L1. The second joint surface 52 is a portion of the first joint surface 51 that is closer to the front end 91 than the second straight line L2. The third joint surface 53 is a portion of the first joint surface 51 that is closer to the rear end 92 than the second straight line L2. Figure 6 In FIG, the second joint surface 52 and the third joint surface 53 are indicated by hatching. Figure 6 , the second joint surface 52 and the third joint surface 53 are distinguished by distinguishing the slopes of the hatched lines.

[0060] Furthermore, the first joint surface 51 has a first width dimension D1 and a second width dimension D2. Figure 7As shown, the first width dimension D1 is the largest dimension of the width dimensions of the second joint surface 52 along the second straight line L2. The second width dimension D2 is the largest dimension of the width dimensions of the third joint surface 53 along the second straight line L2. The first width dimension D1 is 1.3 times or more and 3 times or less of the second width dimension D2. The first width dimension D1 is preferably 1.6 times or more of the second width dimension D2.

[0061] Figure 8 4 is a diagram showing the connection surface of the first blade 43a on the ring 42 side (the bonding surface between the first blade 43a and the first ring surface 42a), that is, the eighth bonding surface 58. Figure 8 As shown in FIG. 4 , a hollow portion 72 is formed on the ring 42 side of the first blade 43a. The eighth joint surface 58 is located around the hollow portion 72. Figure 8 In FIG, the eighth joint surface 58 is indicated by hatching. The first blade 43a has a pin 83 for determining the position of the first blade 43a and a hole 84 for passing a screw through the first blade 43a so as to make the first blade 43a adhere to the first annular surface 42a. Figure 8 As shown, in this embodiment, the first blade 43a has a pin 83 and a hole 84 on the eighth joint surface 58. The plate 41 and the first blade 43a are joined by a method other than welding. In this embodiment, the pin 83 determines the position of the first blade 43a, a screw is passed through to make the first blade 43a adhere to the first annular surface 42a, and the ring 42 and the first blade 43a are joined using an adhesive.

[0062] Figure 9 4 is a diagram showing the first blade 43a extending from the plate 41 to the ring 42 along the first straight line L1. Figure 9 As shown, when the first blade 43a extending from the plate 41 to the ring 42 is viewed along the first straight line L1, the shape of the first blade 43a includes a first recess 73. The first recess 73 is formed closer to the plate 41 than to the ring 42.

[0063] (4) Verification

[0064] Here, the rotation speed (destruction speed) at which the blades are broken by centrifugal force was verified using the first blade 43a of this embodiment and the blade 43' used in a conventional turbofan. ANSYS, a simulation software, was used for this verification.

[0065] The specifications of the first blade 43a and the blade 43' in this verification are shown in Table 1 below.

[0066] [Table 1]

[0067]

[0068] As shown in Table 1, in this verification, the diameter of the impeller 40 having the first blades 43a and the diameter of the conventional impeller having the blades 43' were both set to 500 mm. Furthermore, the number of first blades 43a and the number of blades 43' were both set to 9. Furthermore, the arrangement of the first blades 43a in the impeller 40 was substantially the same as the arrangement of the blades 43' in the conventional impeller.

[0069] The mass of the first blade 43a is 1200 g, and the mass of the blade 43' is 1324 g.

[0070] Figure 10 、 Figure 11 1 is a diagram showing a first joint surface 51' which is a joint surface on the plate side of a conventional blade 43'. Figure 10 As shown, on the plate side of the blade 43', unlike the first blade 43a, no hollow portion is formed. Figure 10 In FIG, the rotation direction of the blade 43' is represented as "A2'". Figure 10 In FIG, the first joint surface 51' is indicated by hatching. Similar to the first blade 43a, the blade 43' is molded from resin, and the plate and the blade 43' are bonded by an adhesive. Figure 11 In FIG, the first straight line L1', the second straight line L2', the first width dimension D1' and the second width dimension D2' of the first joint surface 51' are shown. Figure 11 The second joint surface 52' is indicated by hatching. The area of ​​the first joint surface 51 of the first blade 43a is 9250.63 mm 2 The area of ​​the first joint surface 51' of the blade 43' is 9341.27 mm 2 The first width dimension D1 of the first blade 43a is 82.29 mm, and the first width dimension D1' of the blade 43' is 57 mm. The second width dimension D2 of the first blade 43a is 49.99 mm, and the second width dimension D2' of the blade 43' is 53.06 mm. In the first blade 43a, the first width dimension D1 is 1.65 times the second width dimension D2, and in the blade 43', the first width dimension D1' is 1.07 times the second width dimension D2'.

[0071] The verification results are shown in Table 2 below.

[0072] [Table 2]

[0073]

[0074] As shown in Table 2, the breaking rotation speed of the first blade 43 a is 3500 rpm, and the breaking rotation speed of the blade 43 ′ is 2300 rpm.

[0075] At a rotational speed of 2300 rpm, the maximum stress generated on the surface of the first blade 43a (excluding the surface joining the plate 41 and the ring 42) was 25 MPa, and the maximum stress generated on the surface of the blade 43' (excluding the surface joining the plate and the ring) was 28 MPa. At a rotational speed of 3100 rpm, the maximum stress generated on the surface of the first blade 43a (excluding the surface joining the plate 41 and the ring 42) was 44 MPa.

[0076] When the rotation speed is 2300 rpm, the maximum vertical stress generated on the first joint surface 51 of the first blade 43a is 8.25 MPa, and the maximum vertical stress generated on the first joint surface 51' of the blade 43' is 17.8 MPa. When the rotation speed is 3100 rpm, the maximum vertical stress generated on the first joint surface 51 of the first blade 43a is 15 MPa. Figure 7 In FIG. 4 , the portion where the maximum vertical stress is generated in the first joint surface 51 of the first blade 43 a is indicated as “P”. Figure 11 In FIG. 4 , a portion where the maximum vertical stress is generated in the first joint surface 51 ′ of the blade 43 ′ is indicated as “P′”.

[0077] like Figure 7 、 Figure 11 As shown, in the first joint surfaces 51 , 51 ′, the locations P, P′ generating the maximum vertical stress are both located on the rotation axis A1 , A1 ′ side of the second joint surfaces 52 , 52 ′.

[0078] On the other hand, the value of the "maximum vertical stress generated at the first joint surface (Table 2)" is smaller for first blade 43a than for blade 43' (even the value of the maximum vertical stress generated at first joint surface 51 at a rotational speed of 3100 rpm is smaller than the value of the maximum vertical stress generated at first joint surface 51' at a rotational speed of 2300 rpm). Since the location P on first joint surface 51 where the maximum vertical stress is generated is closer to the rotation axis than the location P' on first joint surface 51' where the maximum vertical stress is generated, it can be inferred that the closer the location is to the rotation axis, the smaller the maximum vertical stress value.

[0079] Therefore, it is speculated that: although the blade is peeled off from the rotation axis side of the second joint surface due to centrifugal force, by expanding the second joint surface toward the rotation axis side, the location where the maximum vertical stress is generated becomes close to the rotation axis, and the value of the maximum vertical stress also becomes smaller, so the blade becomes difficult to peel off.

[0080] As a result, it is speculated that one of the main reasons why the value of the "destruction rotation speed (Table 2)" of the first blade 43a is greater than the value of the "destruction rotation speed" of the blade 43' is that the value of the "first width dimension / second width dimension (Table 1)" of the first blade 43a is greater than the value of the "first width dimension / second width dimension" of the blade 43'.

[0081] (5) Characteristics

[0082] (5-1)

[0083] In the past, a centrifugal fan as follows is known, which includes: a plate, which is arranged in a manner such that the thickness direction is along the direction of the rotation axis; a ring, which is arranged at a distance from the plate in the direction of the rotation axis and has a ring shape when viewed from the direction of the rotation axis; and a plurality of blades, which are arranged between the plate and the ring, and one end of which is connected to the plate and the other end of which is connected to the ring.

[0084] In a centrifugal fan, the blades rotate at high speed, and thus the centrifugal force acting on the blades is large. Therefore, it is desired to further improve the bonding strength between the blades and the plate.

[0085] The centrifugal fan 30 of this embodiment includes a plate 41, a ring 42, and a plurality of blades 43. The plate 41 is arranged so that its thickness direction is along the direction of the rotation axis A1. The ring 42 is arranged at a distance from the plate 41 in the direction of the rotation axis A1. The ring 42 has an annular shape when viewed from the direction of the rotation axis A1. The plurality of blades 43 are arranged between the plate 41 and the ring 42. One end of the plurality of blades 43 is joined to the plate 41, and the other end is joined to the ring 42. The plurality of blades 43 include a first blade 43a. The first joining surface 51 is the joining surface of the first blade 43a on the plate 41 side. The first joining surface 51 includes a second joining surface 52 and a third joining surface 53. The second joining surface 52 is a portion of the first joining surface 51 that is closer to the front end 91 than the second straight line L2. The second straight line L2 passes through the center 93 of the first straight line L1 and is orthogonal to the first straight line L1. The first straight line L1 connects the front end 91 and the rear end 92 of the first blade 43a in the rotation direction A2. The third joint surface 53 is a portion of the first joint surface 51 that is closer to the rear end 92 than the second straight line L2. The first width D1 is the largest width dimension of the second joint surface 52 along the second straight line L2. The second width D2 is the largest width dimension of the third joint surface 53 along the second straight line L2. The first width D1 is at least 1.3 times the second width D2.

[0086] By extending the second joint surface 52, the portion of the first blade 43a on the front end 91 side in the rotational direction A2, toward the rotational axis A1, the maximum vertical stress generated on the first joint surface 51 by centrifugal force tends to decrease. In the centrifugal fan 30 of this embodiment, the first width dimension D1 is at least 1.3 times the second width dimension D2. The first width dimension D1 is the largest along the second straight line L2 of the second joint surface 52. The second width dimension D2 is the largest along the second straight line L2 of the third joint surface 53. As a result, the centrifugal fan 30 can improve the joint strength between the first blade 43a and the plate 41.

[0087] (5-2)

[0088] In the centrifugal fan 30 of the present embodiment, the first width dimension D1 is equal to or less than three times the second width dimension D2.

[0089] (5-3)

[0090] In the centrifugal fan 30 of the present embodiment, the first width dimension D1 is 1.6 times or more of the second width dimension D2.

[0091] (5-4)

[0092] In the centrifugal fan 30 of the present embodiment, when the first blade 43 a extending from the plate 41 to the ring 42 is viewed along the first straight line L1 , the shape of the first blade 43 a includes the first recess 73 .

[0093] (5-5)

[0094] In the centrifugal fan 30 of the present embodiment, the first recess 73 is formed closer to the plate 41 than the ring 42. As a result, the centrifugal fan 30 can ensure the first width D1 without affecting the performance of the centrifugal fan 30.

[0095] (5-6)

[0096] In the centrifugal fan 30 of this embodiment, the first joint surface 51 is located around the hollow portion 71 formed on the plate 41 side of the first blade 43a. As a result, the centrifugal fan 30 can reduce the weight of the first blade 43a by forming the hollow portion 71, thereby reducing the centrifugal force acting on the first blade 43a.

[0097] (5-7)

[0098] In the centrifugal fan 30 of this embodiment, the first blades 43a are molded from resin. As a result, the centrifugal fan 30 can improve the degree of freedom in the shape of the first blades 43a by molding the first blades 43a by injection molding or the like.

[0099] (5-8)

[0100] In the centrifugal fan 30 of the present embodiment, the plate 41 and the ring 42 are formed of aluminum or an aluminum alloy.

[0101] (5-9)

[0102] In the centrifugal fan 30 of this embodiment, the plate 41 and the first blades 43a are joined by a method other than welding. As a result, the centrifugal fan 30 does not require space for a welding torch, thereby increasing the number of blades 43 and eliminating Nz noise.

[0103] (5-10)

[0104] In the centrifugal fan 30 of the present embodiment, the number of the plurality of blades 43 is 7 to 11.

[0105] (6) Modification

[0106] (6-1) Modification 1A

[0107] In the second joint surface 52 , the fourth joint surface 54 , which is a portion closer to the rotation axis A1 than the first straight line L1 , may have a larger area than the fifth joint surface 55 , which is a portion opposite to the rotation axis A1 .

[0108] Figure 12 : is a diagram showing the fourth joint surface 54 and the fifth joint surface 55. Figure 12 In FIG, the fourth joint surface 54 and the fifth joint surface 55 are indicated by hatching. Figure 12 , the fourth joint surface 54 and the fifth joint surface 55 are distinguished by distinguishing the slopes of the hatched lines.

[0109] The first blade 43a tends to separate from the fourth joint surface 54, which is the portion of the second joint surface 52 on the rotation axis A1 side, due to centrifugal force. Therefore, in the centrifugal fan 30, the area of ​​the fourth joint surface 54 is larger than the area of ​​the fifth joint surface 55 in the second joint surface 52, thereby increasing the joint strength between the first blade 43a and the plate 41.

[0110] (6-2) Modification 1B

[0111] The area of ​​the fourth joint surface 54 , which is a portion of the second joint surface 52 closer to the rotation axis A1 than the first straight line L1 , may be larger than the area of ​​the sixth joint surface 56 , which is a portion of the third joint surface 53 closer to the rotation axis A1 than the first straight line L1 .

[0112] Figure 13 : is a diagram showing the fourth joint surface 54 and the sixth joint surface 56. Figure 13 In FIG, the fourth joint surface 54 and the sixth joint surface 56 are indicated by hatching. Figure 13, the fourth joint surface 54 and the sixth joint surface 56 are distinguished by distinguishing the slopes of the hatched lines.

[0113] The first blade 43a tends to separate from the fourth joint surface, which is the portion of the second joint surface 52 on the rotation axis A1 side, due to centrifugal force. Therefore, the centrifugal fan 30 can improve the joint strength between the first blade 43a and the plate 41 by making the fourth joint surface 54 larger than the sixth joint surface 56.

[0114] (6-3) Modification 1C

[0115] Hereinafter, any blade adjacent to the first blade 43a among the plurality of blades 43 is referred to as the second blade 43b. Also, the joining surface of the second blade 43b on the plate 41 side (the joining surface between the second blade 43b and the first plate surface 41a) is referred to as the seventh joining surface 57. Figure 14 It is an enlarged view of the first joint surface 51 of the first blade 43a and the seventh joint surface 57 of the second blade 43b.

[0116] At this time, if Figure 14 As shown, the seventh joint surface 57 may be located outside the region surrounded by the second recessed portion 74 of the first joint surface 51 and the third straight line L3 connecting both ends of the second recessed portion 74 .

[0117] When the first and second blades 43a, 43b deform due to centrifugal force, the plate 41 also tends to deform accordingly. At this time, if the first and second blades 43a, 43b are in close contact, the plate 41 cannot deform, and a significant load is applied to the first and seventh joint surfaces 51, 57. In the centrifugal fan 30 of this embodiment, the seventh joint surface 57 is located outside the area enclosed by the second recess 74 and the third straight line L3 connecting the two ends of the second recess 74. Therefore, in the centrifugal fan 30, the plate 41 can deform in response to the deformation of the first and second blades 43a, 43b caused by centrifugal force, thereby preventing significant loads from being applied to the first and seventh joint surfaces 51, 57. As a result, the centrifugal fan 30 can improve the joint strength between the first and second blades 43a, 43b and the plate 41.

[0118] (6-4) Modification 1D

[0119] In this embodiment, the plate 41 and the ring 42 are molded from aluminum or an aluminum alloy. However, the plate 41 and the ring 42 may be molded from resin like the blades 43 .

[0120] (6-5) Modification 1E

[0121] In this embodiment, the centrifugal fan 30 is a turbofan for an air handling unit. However, the centrifugal fan 30 may also be used in any device as a turbofan, such as a turbofan used in a fan coil unit, a turbofan used as a ventilation fan or a humidifying fan in a household outdoor unit, or the like.

[0122] (6-6)

[0123] While the embodiments of the present disclosure have been described above, it should be understood that various changes in form and detailed configuration can be made without departing from the spirit and scope of the present disclosure as described in the claims.

[0124] Description of labels

[0125] 30: centrifugal fan;

[0126] 41: board;

[0127] 42: Ring;

[0128] 43: leaves;

[0129] 43a: first leaf;

[0130] 43b: second blade;

[0131] 51-57: first to seventh joint surfaces;

[0132] 71: hollow part;

[0133] 73: First concave part;

[0134] 74: second concave part;

[0135] 91: front end;

[0136] 92: backend;

[0137] 93: Center of the first straight line;

[0138] A1: rotation axis;

[0139] A2: rotation direction;

[0140] D1: first width dimension;

[0141] D2: second width dimension;

[0142] L1~L3: First straight line~third straight line.

[0143] Prior art literature

[0144] Patent Literature

[0145] Patent Document 1: Japanese Patent Application Publication No. 2019-100209

Claims

1. A centrifugal fan (30), wherein: The centrifugal fan (30) has: a plate (41) configured such that its thickness direction is along the direction of the rotation axis (A1); a ring (42) arranged at a distance from the plate in the direction of the rotation axis and having an annular shape when viewed from the direction of the rotation axis; as well as A plurality of blades (43) including a first blade (43a) are arranged between the plate and the ring, one end of the blade (43) is engaged with the plate, and the other end of the blade (43) is engaged with the ring. The first joint surface (51) serving as the joint surface of the first blade on the plate side has: a second joint surface (52) which is a portion of the first joint surface that is closer to the front end (91) of the first blade in the rotation direction (A2) than a second straight line (L2), the second straight line (L2) passing through the center (93) of the first straight line (L1) and being orthogonal to the first straight line, the first straight line (L1) connecting the front end (91) and the rear end (92) of the first blade in the rotation direction (A2); and A third joint surface (53) is a portion of the first joint surface that is closer to the rear end than the second straight line. A maximum first width dimension (D1) of the second joint surface along the second straight line is 1.3 times or more the maximum second width dimension (D2) of the third joint surface along the second straight line.

2. The centrifugal fan (30) according to claim 1, wherein: The first width dimension is less than or equal to three times the second width dimension.

3. The centrifugal fan (30) according to claim 2, wherein: The first width dimension is greater than or equal to 1.6 times the second width dimension.

4. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: In the second joint surface, the area of ​​the fourth joint surface (54) which is a portion closer to the rotation axis than the first straight line is larger than the area of ​​the fifth joint surface (55) which is a portion on the opposite side to the rotation axis.

5. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: The area of ​​the fourth joint surface (54), which is a portion of the second joint surface closer to the rotation axis than the first straight line, is larger than the area of ​​the sixth joint surface (56), which is a portion of the third joint surface closer to the rotation axis than the first straight line.

6. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: When viewing the first blade extending from the plate to the ring along the first straight line, the shape of the first blade includes a first recess (73).

7. The centrifugal fan (30) according to claim 6, wherein: The first recess is formed at a position closer to the plate than to the ring.

8. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: The plurality of blades include a second blade (43b) adjacent to the first blade, The first joint surface is shaped so as to form a second recess (74) on the rotation axis side. A seventh joint surface (57) serving as a joint surface of the second blade on the plate side is located outside a region surrounded by the second recess and a third straight line (L3) connecting both ends of the second recess.

9. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: The first joint surface is located around a hollow portion (71) formed on the plate side of the first blade.

10. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: The first blade is molded from resin.

11. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: The plate and the ring are formed from aluminum or an aluminum alloy.

12. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: The plate and the first blade are joined by a method other than welding.

13. The centrifugal fan (30) according to any one of claims 1 to 3, wherein: The number of the plurality of blades is 7 to 11.

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