Centrifugal blower

Abstract

A centrifugal blower has a plurality of blades (60), a shroud (62), a main plate (64), and a cylinder portion (66). An air flow path (68) is provided between the cylinder portion and the main plate and the shroud and between two blades adjacent to each other. When the plurality of blades, the shroud, the cylinder portion, and the main plate rotate, air sucked into an air inlet (62a) is blown out through the air flow path. An arc-shaped covered area (62b) that projects toward the other side of the axis direction (DRa) is provided on the other side of the axis direction in the shroud. The shroud is formed so as to advance toward the one side of the axis direction as it goes from the outer end portion (62d) toward the inner end portion (621). An end surface (67) is provided on the one side of the axis direction in the cylinder portion. The covered area and the end surface are formed in such a manner that the end surface of the cylinder portion is parallel to the second imaginary line or the distance (ZL) of the axis direction between the end surface and the second imaginary line increases as it goes from the inner side of the radial direction toward the outer side.

Description

[0001] Cross-reference of related applications

[0002] This application is based on Japanese Patent Application No. 2021-163354, filed on October 4, 2021, the disclosure of which is incorporated herein by reference. Technical Field

[0003] This invention relates to centrifugal blowers. Background Technology

[0004] Conventionally, centrifugal fans have included a plurality of blades arranged in a circumferential direction centered on an axis, a shroud disposed on one side of the fan axis relative to the plurality of blades, and a main board disposed on the other side of the fan axis relative to the plurality of blades (for example, see Patent Document 1).

[0005] An air inlet is provided on the radially inner side of the shroud centered on the axis. The back side of the shroud on the opposite side of the fan axis is formed into a curved shape that faces the fan axis direction as it moves from the radially outer side to the radially inner side.

[0006] Here, on the opposite side of the main board in the direction of the fan axis, there is an impeller cup that supports the rotor of the electric motor radially outward. The radial dimension of the impeller cup centered on the axis is larger than the radial dimension centered on the axis of the air inlet.

[0007] The rotor of the electric motor rotates around its axis, causing the impeller cup to rotate around its axis as well. At this time, the main board, multiple blades, the shroud, and the impeller cup rotate together. Air flowing into the intake from one side of the fan axis is then blown radially outward through multiple airflow paths between adjacent blades.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2019-203481

[0011] Referring to the aforementioned patent document 1, the inventors studied how to suppress noise generation by ensuring that the airflow flowing into the air intake flows smoothly through multiple airflow paths between the shield and the main board.

[0012] According to the inventor's research, in a cross-sectional view of the shroud cut with a plane including the axis, it is necessary to form the area of ​​the shroud that overlaps with the impeller cup in the axial direction, i.e., the covered area, into an arc shape that protrudes toward the other side in the direction of the fan axis.

[0013] However, when using resin materials to integrally mold the shield, impeller cup, multiple blades, and main board, the shape of the shield is limited when using a sliding mold to form the impeller cup and multiple airflow paths between the main board and the shield.

[0014] For example, in order to allow the sliding mold to slide radially inward relative to the shield, impeller cup, multiple blades and main board and be pulled out, a shape with an inclination angle of 0 degrees or more is required between the shield and the main board.

[0015] However, depending on the shape of the motherboard, it is sometimes impossible to achieve a tilt angle greater than 0 degrees. Therefore, the inventors' detailed research revealed that when using a sliding mold integrally formed shield, impeller cup, multiple blades, and motherboard, it is sometimes impossible to form the shield's coverage area into the aforementioned cross-sectional arc shape.

[0016] Therefore, the inventors investigated the use of a sliding mold to integrally form a cover, multiple blades, and an impeller cup (i.e., a cylindrical portion) in addition to the main board. Summary of the Invention

[0017] The present invention was made in view of the above-mentioned problems, and its object is to provide a centrifugal blower that can suppress the generation of noise and can use a sliding mold to integrally form the cover, multiple blades and cylinder except for the main board.

[0018] To achieve the above objectives, according to one aspect of the present invention, the centrifugal blower comprises:

[0019] Multiple blades arranged in a circumferential direction centered on the axis;

[0020] A shield is formed such that when the direction of the axis extension is set as the axial direction, it covers multiple blades from one side of the axial direction and is arranged in a ring shape centered on the axis, and an air inlet that opens in the axial direction is formed on the radial inner side centered on the axis.

[0021] A motherboard, which is formed to cover multiple blades on the opposite side from the axial direction and is arranged in a ring shape centered on the axial direction, and has an opening in the axial direction formed on the radially inner side; and

[0022] The cylindrical portion is disposed within the opening and is formed into a cylindrical shape centered on an axis, and is configured to rotate centered on the axis by the rotational force of an electric motor.

[0023] Multiple blades, shields, and cylinders are integrated into a single, unified structure.

[0024] An airflow path is provided between the cylinder and the main plate and the protective cover, and between two adjacent blades among the multiple blades.

[0025] The cylindrical section is connected to the main board in a manner that prevents relative movement.

[0026] When the rotational force of the electric motor causes multiple blades, shrouds, cylinders, and main board to rotate to one side in the circumferential direction, the air drawn into the air inlet from one side in the axial direction is blown out radially outward through the airflow path.

[0027] A covering area is provided on the opposite side of the axial direction within the protective cover. The covering area is formed to cover the cylindrical portion from one side of the axial direction, and in a cross-sectional view of the protective cover cut with a plane including the axial direction, the covering area is formed in an arc shape protruding towards the opposite side of the axial direction.

[0028] The shield is formed such that it advances towards one side of the axial direction from the radially outer end in the covered area toward the radially inner end in the shield.

[0029] An end face is provided on one side of the cylindrical section in the axial direction.

[0030] When a line orthogonal to the axial direction and orthogonal to the radial direction is designated as the first imaginary line, and a tangent line orthogonal to the first imaginary line and tangent to the covered area is designated as the second imaginary line, the covered area and the end face are formed in such a way that the end face of the cylinder is parallel to the second imaginary line, or the distance between the end face and the second imaginary line in the axial direction increases from the radial inside to the outside.

[0031] Based on the above, the coverage area of ​​the shield is formed in an arc shape that bulges toward the opposite side of the axial direction in a cross-sectional view of the shield cut by a plane including the axis. The shield is formed to advance toward the side of the axial direction from the radially outer end in the coverage area toward the radially inner end in the shield.

[0032] Therefore, it allows the air drawn into the air intake to flow smoothly along the covered area. Therefore, it can suppress the noise generated when air flows in the airflow path.

[0033] Furthermore, the covering area and the end face are formed in such a way that the distance between the end face and the second imaginary line in the axial direction increases from the radially inner side to the outer side. Therefore, when the shroud, multiple blades, and cylinder are integrally formed, and the area between the covering area and the end face in the airflow path is formed using a sliding mold, the sliding mold can be pulled out radially outward from between the covering area and the inclined surface.

[0034] Based on the above, a centrifugal blower can be provided that can suppress noise generation and can use a sliding mold to integrally form the shroud, multiple blades, and cylinder.

[0035] Furthermore, the parenthesized reference numerals attached to each constituent element indicate an example of the correspondence between that constituent element and the specific constituent element described in the embodiments described later. Attached Figure Description

[0036] Figure 1 This is a cross-sectional view of the centrifugal blower cut along a plane including the fan axis in the first embodiment.

[0037] Figure 2 In the first embodiment Figure 1 Sectional view II-II in the figure omits the illustration of the electric motor and is used to illustrate the inclined surface of the main board, multiple blades, and impeller cup.

[0038] Figure 3 In the first embodiment, this is observed from one side along the fan axis. Figure 1 The diagram shows the protective cover and the air intake.

[0039] Figure 4 In the first embodiment Figure 3 The IV-IV sectional view is used to help illustrate the impeller cup and multiple blades.

[0040] Figure 5 In the first embodiment, Figure 1 The image shows a magnified view of a portion of the area covered by the protective cover and the inclined surface of the impeller cup.

[0041] Figure 6 It is schematically shown in the first embodiment. Figure 2 The image showing the two blades in the inclined plane of the impeller cup, with the periphery of the two blades magnified, is a partial magnified view used to help illustrate the impeller tilt angle of the inclined plane.

[0042] Figure 7 In the first embodiment Figure 6 Sectional view VII-VII in the figure is a sectional view used to help illustrate the impeller tilt angle of the part of the blade on the negative pressure side of the tilted surface of the impeller cup.

[0043] Figure 8 In the first embodiment Figure 6 Sectional view VIII-VIII in the figure is a sectional view used to help illustrate the impeller tilt angle of the part of the blade on the positive pressure side of the tilted surface of the impeller cup.

[0044] Figure 9 In the first embodiment, it is cut with a plane including the fan axis. Figure 1 A cross-sectional view of the motherboard unit.

[0045] Figure 10In the first embodiment, Figure 1 The enlarged sectional view, including the inclined surface of the impeller cup and the inner circumferential surface of the motherboard, is used to help illustrate the V-shaped recess formed by the inclined surface and the inner circumferential surface of the motherboard.

[0046] Figure 11 In the first embodiment Figure 6 The XI-XI sectional view is a sectional view used to help illustrate the impeller tilt angle of the part of the blade on the positive pressure side of the tilted surface of the impeller cup.

[0047] Figure 12 In the first embodiment Figure 6 The XII-XII sectional view in the figure is a sectional view used to help illustrate the impeller tilt angle of the part of the blade on the negative pressure side of the tilted surface of the impeller cup.

[0048] Figure 13 In the first embodiment, Figure 4 The enlarged partial view includes the blades and the inclined surface of the impeller cup, and is a view of the radially inner end of the fan in the inclined surface of the impeller cup.

[0049] Figure 14 The diagram shows a planar cutaway view of the shroud, impeller cup, and main board in a centrifugal blower of the first embodiment, including the fan axis. It is used to illustrate the constraints of the integrally formed shroud, impeller cup, multiple blades, and main board.

[0050] Figure 15 In the first embodiment, Figure 1 The enlarged view of the right half of the shield, impeller cup, and motherboard with the fan axis as the center line is a cross-sectional view used to help illustrate the undercut area.

[0051] Figure 16 It is used to assist in explaining the first embodiment. Figure 15 The diagram showing the relationship between the imaginary tangent of the shroud's covered area and the inclined surface of the impeller cup is a diagram indicating that the imaginary tangent and the inclined surface are parallel.

[0052] Figure 17 It is used to assist in explaining the first embodiment. Figure 15 The diagram showing the relationship between the imaginary tangent of the shroud's coverage area and the inclined surface of the impeller cup is a diagram illustrating the state in which the distance between the imaginary tangent and the inclined surface decreases as the fan moves radially from the inner to the outer side.

[0053] Figure 18This is a diagram schematically showing two blades out of a plurality of blades in the first embodiment, viewed from one side of the fan axis direction. It is a diagram used to help illustrate the shape of the positive and negative pressure surfaces of the two blades.

[0054] Figure 19 It indicates that it is used for manufacturing in the first embodiment. Figure 1 A flowchart detailing the manufacturing process of the impeller.

[0055] Figure 20 It is used to assist in the explanation of the first embodiment and to explain Figure 18 A diagram of the manufacturing process in which multiple blades, impeller cups, and shrouds are integrally formed, and the mold used in this manufacturing process.

[0056] Figure 21 It is a cross-sectional view of the right half of the fan axis in the comparative example of the first embodiment, which is a cross-sectional view of multiple blades, impeller cups, shrouds and main board cut by a plane including the fan axis.

[0057] Figure 22 This is a diagram of the motherboard and multiple blades viewed from one side along the fan axis in the second embodiment.

[0058] Figure 23 In the second embodiment Figure 22 The XXIII-XXIII sectional views are used to help illustrate the motherboard tilt angle of the positive pressure side of the motherboard's inner peripheral surface, as well as the sectional views of the area between the shield and the motherboard.

[0059] Figure 24 In the second embodiment Figure 22 The XXIV-XXIV sectional view is used to help illustrate the motherboard tilt angle of the negative pressure side of the motherboard's inner peripheral surface, as well as the sectional view of the area between the shield and the motherboard.

[0060] Figure 25 This is a diagram of the motherboard and multiple blades viewed from one side of the fan axis direction in the third embodiment.

[0061] Figure 26 In the third embodiment Figure 25 The XXVI-XXVI sectional views are used to help illustrate the motherboard tilt angle of the negative pressure side portion of the motherboard's inner peripheral surface, as well as the sectional views of the area between the shield and the motherboard's outer peripheral surface.

[0062] Figure 27 In the third embodiment Figure 25The XXVII-XXVII sectional views are used to help illustrate the motherboard tilt angle of the positive pressure side portion of the motherboard's inner peripheral surface, as well as the sectional views of the area between the shield and the motherboard's outer peripheral surface.

[0063] Figure 28 In the third embodiment Figure 25 The XXVIII view is a cross-sectional view used to help illustrate the area between the outer peripheral surfaces of the motherboard.

[0064] Figure 29 This is a partially enlarged view of the impeller cup and part of the main board in another embodiment of the centrifugal blower, and a partial cross-sectional view of the inner peripheral surface of the main board used to help explain the main board.

[0065] Figure 30 This is a partially enlarged view of the impeller cup and part of the mainboard in another embodiment of the centrifugal blower, and a partial cross-sectional view of the outer peripheral surface of the mainboard used to help explain the mainboard.

[0066] Figure 31 This is a partially enlarged view of the impeller cup and part of the main board in other embodiments of the centrifugal blower, and a partial sectional view of the outer peripheral surface and inner peripheral surface of the main board used to help explain the main board.

[0067] Figure 32 This is a partial enlarged view, in other embodiments, showing an enlarged portion including the covered area of ​​the shield and the inclined surface of the impeller cup, which is equivalent to the first embodiment. Figure 5 Enlarged image.

[0068] Figure 33 This is a partially enlarged view, showing the inner radial side of the fan in the motherboard and the outer radial side of the fan in the impeller cup, in other embodiments. It is equivalent to the first embodiment. Figure 26 Enlarged image.

[0069] Figure 34 In other implementation methods Figure 32 A magnified view of part XXXIV in the image. Detailed Implementation

[0070] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. Furthermore, for the sake of simplicity, the same or equivalent parts are labeled with the same reference numerals in the drawings for each of the following embodiments.

[0071] (First Implementation)

[0072] The following is for reference Figure 1 , Figure 2 The centrifugal blower 10 of this embodiment will be described in detail. Figure 1 This is an axial sectional view of the centrifugal blower 10 in this embodiment, cut with a plane including the fan axis Sa.

[0073] Figure 1 The arrow DRa indicates the fan axis direction DRa of the fan axis Sa. The fan axis direction DRa is the direction of the fan axis extending from the fan axis Sa. Figure 1 The arrow DRr represents the fan radial direction DRr centered on the fan axis Sa. Figure 2 yes Figure 1 Sectional view II-II in Figure 2 In the diagram, the arrow Edr represents the circumferential direction Edr centered on the fan axis Sa. Figure 2 In order to make the illustration clearer, the cross-sectional lines of multiple blades 60 are omitted.

[0074] like Figure 1 as well as Figure 2 As shown, the centrifugal blower 10 is a turbine blower, which includes a housing 12, an electric motor 14, and an impeller 16.

[0075] The housing 12 protects the electric motor 14 and impeller 16 from external dust and dirt from the centrifugal fan 10. The housing 12 houses the electric motor 14 and impeller 16. The housing 12 is made of, for example, resin material. The housing 12 is formed in a generally disc-shaped manner, with the fan radial diameter (DRr) larger than that of the impeller 16.

[0076] The housing 12 includes a first cover 120 and a second cover 121. The first cover 120 is disposed on one side of the fan axis direction DRa relative to the impeller 16. The first cover 120 is formed to cover the impeller 16 from one side of the fan axis direction DRa.

[0077] The first cover 120 is formed in an annular shape centered on the fan axis Sa. An air intake 221a is formed inside the fan radial direction DRa in the first cover 120, extending through the fan axis DRa. The air intake 221a constitutes an air inlet for air to flow in from one side of the fan axis DRa.

[0078] A flared mouth portion 221b is provided around the air intake 221a in the first cover portion 120. The flared mouth portion 221b serves to smoothly guide the air flowing into the air intake 221a from the side of the centrifugal blower 10 in the direction of the fan axis DRa toward the air inlet 62a of the cover 62.

[0079] like Figure 1As shown, a first peripheral portion 222 is provided radially outward from the fan axis Sa in the first cover portion 120. The first peripheral portion 222 is formed circumferentially.

[0080] The second cover 121 is formed in a ring shape centered on the fan axis Sa. The second cover 121 is disposed on the opposite side of the fan axis direction DRa relative to the impeller 16, the plurality of blades 60, the shroud 62, and the main board 64. The second cover 121 is formed to cover the plurality of blades 60, the shroud 62, and the main board 64 from the opposite side of the fan axis direction DRa.

[0081] A second peripheral portion 242 is provided radially outward from the fan axis Sa in the second cover portion 121. The second peripheral portion 242 is formed circumferentially.

[0082] The second peripheral portion 242, together with the first peripheral portion 222, forms an air outlet 12a for blowing air out from the impeller 16. The air outlet 12a is formed around the entire circumference of the housing 12 centered on the fan axis Sa.

[0083] Furthermore, a plurality of supports (not shown) are provided between the first peripheral portion 222 and the second peripheral portion 242. These supports are arranged in the circumferential direction (Edr). The supports connect the first peripheral portion 222 and the second peripheral portion 242.

[0084] like Figure 1 As shown, the electric motor 14 is disposed radially inside the second cover 121 with the fan axis Sa as the center. The electric motor 14 is an external rotor type brushless DC motor. In this embodiment, the maximum dimension of the fan radial DRr in the electric motor 14 is larger than the maximum dimension of the fan radial DRr in the air inlet 62a of the cover 62.

[0085] The electric motor 14 includes a rotor 40, a rotating shaft 42, a stator housing 44, stator coils 46, and bearings 48a and 48b. The rotor 40 includes a rotor cup 140 and a plurality of permanent magnets 144. The rotor cup 140 is formed of a magnetic material such as iron and is generally cylindrical about the fan axis Sa.

[0086] Specifically, the rotor cup 140 includes a cylindrical portion 142 and a cover portion 143. The cylindrical portion 142 is formed into a cylinder centered on the fan axis Sa. The cover portion 143 is disposed on one side of the fan axis DRa relative to the cylindrical portion 142.

[0087] The cover portion 143 is formed to cover the cylindrical portion 142 on one side from the direction of the fan axis DRa. Specifically, the cover portion 143 includes: a boss portion 143a, which forms a recess 140a for fixing the rotation shaft 42; and an inclined portion 143b, which is disposed between the boss portion 143a and the cylindrical portion 142.

[0088] The inclined portion 143b is formed in an inclined shape such that it moves from the inside of the fan radial DRr to the outside of the fan radial DRr and toward the other side of the fan axis DRa. As will be described later, the inclined portion 143b guides the air flowing in through the air intake 221a and the air inlet 62a toward the outside of the fan radial DRr.

[0089] Multiple permanent magnets 144 are arranged along the circumferential direction Edr on the inner side of the fan radial DRr in the cylindrical portion 142. The multiple permanent magnets 144 are fixed to the inner circumferential surface of the cylindrical portion 142.

[0090] The rotating shaft 42 is formed as a cylinder centered on the fan axis Sa. One end of the rotating shaft 42 in the fan axis direction DRa is embedded in the recess 140a of the rotor cup 140. Thus, the rotating shaft 42 is fixed to the rotor cup 140. The rotating shaft 42 is made of a metal material such as iron, stainless steel, or brass.

[0091] The stator housing 44 is formed as a cylinder centered on the fan axis Sa. The stator housing 44 is positioned on the outer side of the fan radial direction DRr relative to the rotation axis 42.

[0092] Bearings 48a and 48b are disposed between the stator housing 44 and the rotating shaft 42. Bearings 48a and 48b are arranged along the fan axis DRa. Bearings 48a and 48b are supported by the stator housing 44, which supports the rotating shaft 42 so that it can rotate about the fan axis Sa.

[0093] The stator coil 46 has multiple windings wound with wires. The multiple windings are arranged in the circumferential direction Edr. As described later, the stator coil 46 applies a rotating magnetic field to the rotor 40, thereby applying a rotational force to the rotor 40 to rotate the rotor 40 about the fan axis Sa.

[0094] like Figure 1 As shown, impeller 16 is a centrifugal impeller used in centrifugal blower 10. Impeller 16 draws in air from one side of the fan axis direction DRa via air intake 221a, as indicated by arrow FLA, by rotating about the fan axis Sa in the fan rotation direction DRf.

[0095] In this embodiment, the fan rotation direction DRf refers to one side of the circumferential direction Edr. The impeller 16 blows the intake air outward radially outward relative to the fan axis Sa, as shown by arrow FLb.

[0096] Specifically, the impeller 16 of this embodiment includes multiple blades 60, a shroud 62, a main plate 64, and an impeller cup 66. Furthermore, for ease of explanation, as... Figure 2 As shown, multiple blades 60 are also denoted as blades 60a, 60b, 60c, 60d, 60e, 60f, 60g, 60h, 60i, 60j, 60k, 60l, and 60m.

[0097] like Figure 1 , Figure 2 as well as Figure 3 As shown, multiple blades 60 are arranged along the circumferential direction Edr. Figure 2 As shown, the multiple blades 60 each have a positive pressure surface 160a and a negative pressure surface 160b that form the shape of the blade.

[0098] The positive pressure surface 160a is formed in each of the plurality of blades 60 on one side of the circumferential direction Edr (i.e., the fan rotation direction DRf). The positive pressure surface 160a is the surface in each of the plurality of blades 60 that exerts positive pressure when the impeller 16 rotates in the fan rotation direction DRf.

[0099] The negative pressure surface 160b is formed on the opposite side of the circumferential direction Edr in each of the plurality of blades 60. The negative pressure surface 160b is the surface in each of the plurality of blades 60 that exerts negative pressure when the impeller 16 rotates in the fan rotation direction DRf.

[0100] Specifically, such as Figure 3 As shown, in each of the plurality of blades 60, the radially inner side centered on the fan axis Sa is located within the air intake 221a.

[0101] like Figure 2 As shown, an airflow path 68 is formed between the main board 64, the impeller cup 66, and the shroud 62, and between two adjacent blades 60 of the plurality of blades 60. Specifically, the airflow path 68 is formed between the positive pressure surface 160a of one blade 60 on the opposite side of the circumferential direction Edr among two adjacent blades 60, and the negative pressure surface 160b of one blade 60 on the side of the circumferential direction Edr among the two adjacent blades 60. The airflow path 68 is formed between the main board 64 and the shroud 62. The airflow path 68 is formed between the impeller cup 66 and the shroud 62.

[0102] In this embodiment, the positive pressure surface 160a of one blade 60 and the negative pressure surface 160b of the other blade 60 are formed along the fan radial DRr via the airflow path 68.

[0103] like Figure 1 As shown, multiple blades 60 are connected to the protective cover 62. Figure 4 , Figure 7 and Figure 8 As shown, multiple blades 60 are connected to an impeller cup 66. The multiple blades 60, the shroud 62, and the impeller cup 66 are made of resin material. As described later, the multiple blades 60, the shroud 62, and the impeller cup 66 constitute an integral component 94 formed by using a sliding mold 93.

[0104] Furthermore, in this embodiment, the constraints required for forming the plurality of blades 60, shields 62, and impeller cups 66 using the sliding mold 93 will be described later.

[0105] like Figure 1 As shown, the shroud 62 has a disc-shaped shape that extends radially toward the fan DRr. The shroud 62 is configured to cover a plurality of blades 60 on one side of the fan axis DRa. The shroud 62 supports the plurality of blades 60 on one side of the fan axis DRa.

[0106] An air intake hole 62a is formed on the inner side of the fan radially DRr in the shield 62, which draws in air from the air intake port 221a of the housing 12 as shown by arrow FLa. Therefore, the shield 62 is annular.

[0107] like Figure 1 and Figure 4 As shown, the shroud 62 has an inner circumferential end 621 and an outer circumferential end 622. The inner circumferential end 621 is the end of the shroud 62 located on the inner side of the fan radially DRr. The inner circumferential end 621 forms an air inlet 62a.

[0108] The outer peripheral end 622 is the outer end of the shroud 62 located on the radial direction DRr of the fan. The outer peripheral end 622, together with the multiple blades 60 and the main plate 64, forms the air outlet 68a of each of the multiple airflow paths 68.

[0109] like Figure 1 As shown, the shield 62 is formed in an inclined shape as it advances from the outer peripheral end 622 of the ring toward the inner peripheral end 621 of the ring toward one side of the fan axis direction DRa.

[0110] Specifically, a covering area 62b is provided on the opposite side of the fan axis DRa in the shroud 62. This covering area 62b is the area that overlaps with the impeller cup 66 in the fan axis DRa direction. Figure 1 as well as Figure 15 The cross-sectional view shown is formed as an arc shape that bulges out to the other side of DRa in the direction of the fan axis. Figure 15 It is Figure 1 The enlarged partial view includes the protective cover 62 and the impeller cup 66.

[0111] like Figure 15 As shown, the shield 62 is formed in an inclined manner as it advances from the outer end 62d of the fan radial DRr in the covered area 62b toward the inner circumferential end 621 toward one side of the fan axis direction DRa.

[0112] This prevents air flowing into the multiple airflow paths 68 from being stripped from the shield 62.

[0113] The shield 62 is covered by the first cover portion 120 of the housing 12 from one side of the fan axis DRa. For example... Figure 1 As shown, the protective cover 62 forms a path forming portion 62f that forms a maze-like gap 62c between itself and the path forming portion 120a of the first cover portion 120.

[0114] In this embodiment, a labyrinth mechanism is configured to suppress the flow of air in the gap 62c between the protective cover 62 and the first cover 120.

[0115] like Figure 1 As shown, the impeller cup 66 is formed into a cylindrical shape centered on the fan axis Sa. The impeller cup 66 is disposed inside the fan radial direction DRr relative to the second cover portion 121. The impeller cup 66 is a cylindrical portion disposed inside the fan radial direction DRr relative to the main board 64. That is, the impeller cup 66 is disposed within the opening 64a of the main board 64.

[0116] The impeller cup 66 is positioned outside the rotor cup 140 of the rotor 40 of the electric motor 14, radially DRr of the fan. The impeller cup 66 is supported by the rotor cup 140 of the rotor 40 of the electric motor 14. Therefore, the impeller cup 66 is configured to rotate about the fan axis Sa by the rotational force of the electric motor 14.

[0117] like Figure 1 and Figure 5 As shown, an inclined surface 67, serving as an end face, is formed on one side of the impeller cup 66 in the fan axis direction DRa. The inclined surface 67 is formed in an inclined shape such that it advances from the inside of the fan radial direction DRa toward the outside toward the other side of the fan axis direction DRa.

[0118] The inclined surface 67 is formed all the way around the circumference. The inclined surface 67 is arranged to overlap with the positive pressure surface 160a and negative pressure surface 160b of each of the plurality of blades 60 in the fan axial direction DRa.

[0119] In this embodiment, Figure 2 The outer end 67a of the fan radial DRr in the inclined surface 67 shown is located at the same position in the fan axial direction DRa, extending circumferentially along the circumferential direction Edr.

[0120] As will be described later, the position of the inner end 67b of the fan radial DRr in the inclined surface 67 in the fan axial direction DRa varies depending on the position of the circumferential direction Edr.

[0121] In this embodiment, such as Figure 7 , Figure 8 As shown, a connecting portion 70 is formed in the impeller cup 66 in the region overlapping with the plurality of blades 60 in the fan axis direction DRa, which is connected to the plurality of blades 60.

[0122] The connecting part 70 is disposed on the inner side of the fan radial DRr relative to the inclined surface 67 in the impeller cup 66.

[0123] Figure 7 yes Figure 6 Sectional view VII-VII in the figure. Figure 7 It is a cross-sectional view of the negative pressure surface 160b of blade 60c on the opposite side of blade 60c in the fan axis direction DRa in the inclined plane 67. Figure 8 yes Figure 6 Sectional view VIII-VIII in the middle. Figure 8 It is a cross-sectional view of the blade 60d near the positive pressure surface 160a on the opposite side of the blade 60d in the fan axis direction DRa in the inclined plane 67. Figure 6 yes Figure 2 A magnified view of a portion of the blades 60c and 60d in impeller 16. Figure 6 To clarify the illustration, the cross-sectional lines of the impeller cup 66 have been omitted. Figure 6 , Figure 7 , Figure 8 In order to make the illustration clearer, the cross-sectional lines of blades 60c and 60d are omitted.

[0124] like Figure 9 As shown, the main board 64 has an opening 64a extending through in the fan axial direction DRa, and is formed in an annular shape centered on the fan axis Sa. The main board 64 is disposed on the outer side of the fan radial direction DRa relative to the impeller cup 66. The main board 64 is formed to cover a plurality of blades 60 from the other side of the fan axial direction DRa.

[0125] Specifically, such as Figure 9As shown, the motherboard 64 includes: an outer peripheral surface 170 formed in an annular shape centered on the fan axis Sa; and an inner peripheral surface 171 disposed on the inner side of the fan radial direction DRR relative to the outer peripheral surface 170.

[0126] The outer peripheral surface 170 of the motherboard is an inclined surface 67 relative to the impeller cup 66, positioned on the outer side of the fan radial DRr as the motherboard flow path. For example... Figure 10 As shown, the outer peripheral surface 170 of the motherboard is positioned on one side of the fan radial direction DRa relative to the outer end 67a of the fan in the inclined surface 67. The outer peripheral surface 170 of the motherboard is formed circumferentially. The outer peripheral surface 170 of the motherboard is positioned on the other side of the fan axial direction DRa relative to the shroud 62. The outer peripheral surface 170 of the motherboard, together with the plurality of blades 60 and the shroud 62, forms a plurality of airflow paths 68.

[0127] The inner peripheral surface 171 of the motherboard is disposed between the outer peripheral surface 170 of the motherboard and the inclined surface 67 of the impeller cup 66. The inner peripheral surface 171 of the motherboard is formed as an inclined inner peripheral surface, moving from the inner side of the fan radial direction DRR to the outer side of the fan radial direction DRR, and facing one side towards the fan axis direction DRA. The inner peripheral surface 171 of the motherboard is formed circumferentially. The inner peripheral surface 171 of the motherboard and the inclined surface 67 of the impeller cup 66 together form a V-shaped recess that is recessed towards the other side of the fan axis direction DRA.

[0128] In this embodiment, the inner peripheral surface 171 of the main board serves to guide the air flowing along the inclined surface 67 of the impeller cup 66 to the outer peripheral surface 170 of the main board.

[0129] like Figure 10 As shown, the inner side of the radial DRr of the fan in the motherboard 64 is formed into a stepped shape with inner circumferential surfaces 180 and 181 and radial surface 182.

[0130] The inner circumferential surfaces 180 and 181 are offset from each other in the fan radial direction DRr and are formed throughout the fan axial direction Dra. The inner circumferential surfaces 180 and 181 are formed throughout the circumferential direction Edr. The inner circumferential surface 180 is disposed on the outer side of the fan radial direction DRr and on the side of the fan axial direction DRa relative to the inner circumferential surface 181.

[0131] Radial surface 182 is a second radial surface formed throughout the radial direction DRr of the fan. Radial surface 182 is formed throughout the circumferential direction Edr. Radial surface 182 is disposed between inner circumferential surfaces 180 and 181.

[0132] The outer side of the fan radial DRr in the impeller cup 66 is formed into a stepped shape with outer peripheral surfaces 190, 191 and radial surface 192.

[0133] The outer peripheral surfaces 190 and 191 are offset from each other in the fan radial direction DRr and are formed throughout the fan axial direction Dra. The outer peripheral surfaces 190 and 191 are formed throughout the circumferential direction Edr. The outer peripheral surface 190 is disposed on the outer side of the fan radial direction DRr and on the side of the fan axial direction DRa relative to the outer peripheral surface 191.

[0134] Radial surface 192 is a first radial surface formed throughout the radial direction DRr of the fan. Radial surface 192 is formed throughout the circumferential direction Edr. Radial surface 192 is disposed between outer circumferential surfaces 190 and 191.

[0135] In this embodiment, the inner side of the fan radial DRr in the main board 64 is engaged with the outer side of the fan radial DRr in the impeller cup 66. Thus, the impeller cup 66 is connected to the main board 64 in a manner that prevents relative movement.

[0136] The inner circumferential surface 180 and the outer circumferential surface 190 face each other with a gap 200 (i.e., the first gap). The inner circumferential surface 181 and the outer circumferential surface 191 face each other with a gap 201 (i.e., the first gap). The radial surfaces 182 and 192 face each other with a gap 202 (i.e., the second gap).

[0137] The gaps 200, 201, and 202 form a labyrinthine airflow path between the inner side of the fan radial DRr in the main board 64 and the outer side of the fan radial DRr in the impeller cup 66.

[0138] This creates a labyrinth structure that suppresses airflow between the inner side of the fan radial DRr in the main board 64 and the outer side of the fan radial DRr in the impeller cup 66.

[0139] Next, refer to Figure 2 , Figure 7 , Figure 8 , Figure 11 , Figure 12 , Figure 13 The details of the inclined surface 67 of the impeller cup 66 in this embodiment will be explained.

[0140] First, such as Figure 11 , Figure 12 As shown, in the cross section of the impeller cup 66 cut by a plane containing the fan axis Sa, the angle of the narrow angle formed between the imaginary surface 210 orthogonal to the fan axis Sa and the inclined surface 67 is set as the impeller tilt angle θ.

[0141] Here, as Figure 11 , Figure 12 As shown, a narrow angle refers to the angle θ that has the smaller angle among the two angles θ and β formed between the imaginary surface 210 and the inclined surface 67.

[0142] Figure 8It is a cross-sectional view of the area near the positive pressure surface 160a of blade 60d in the impeller cup 66, in the region overlapping with blade 60d in the fan axis direction DRa. Figure 7 This is a cross-sectional view of the negative pressure surface 160b of blade 60c in the region of impeller cup 66 that overlaps with blade 60c in the fan axial direction DRa.

[0143] Figure 11 This is a cross-sectional view near the positive pressure surface 160a of blade 60d at the intermediate inclined section 168 between the positive pressure surface 160a of blade 60d and the negative pressure surface 160b of blade 60c.

[0144] Figure 12 This is a cross-sectional view near the negative pressure surface 160b of blade 60c at the intermediate inclined portion 168 between the negative pressure surface 160b of blade 60c and the negative pressure surface 160b of blade 60d.

[0145] In this embodiment, the relay tilting portion 168 is a region formed in the tilting surface 67 between two adjacent blades 60. That is, the tilting surface 67 constitutes a plurality of relay tilting portions 168. For example, the relay tilting portion 168 between blades 60c and 60d is a region in the tilting surface 67 formed from blade 60d to blade 60c and toward the fan rotation direction DRf.

[0146] Figure 8 , Figure 11 The impeller tilt angle θ is the impeller tilt angle θ at the part of the blade 60d on the positive pressure surface 160a side of the inclined surface 67 in the circumferential direction Edr. Figure 7 , Figure 12 The impeller tilt angle θ is the impeller tilt angle θ at the part of the blade 60c on the negative pressure surface 160b side in the inclined surface 67 of the circumferential direction Edr.

[0147] Here, the outer end 67a of the fan radial DRr in the inclined surface 67 is arranged at the same position in the fan radial DRr throughout the circumferential direction Edr. The outer end 67a of the fan radial DRr in the inclined surface 67 is arranged at the same position in the fan axial direction DRa throughout the circumferential direction Edr.

[0148] In the plurality of relay inclined sections 168 of the inclined surface 67, the inner end 67b of the fan radial DRr of the inclined surface 67 is arranged at the same position on the fan radial DRr in a circumferential direction Edr.

[0149] like Figure 13As shown, compared with the negative pressure surface 160b side of the blade 60c in the inclined surface 67, the inner end 67b of the fan radial DRr of the inclined surface 67 is located on the other side of the fan axial direction DRa.

[0150] Here, the inner end 67b of the inclined surface 67 is formed to gradually advance towards the side of the fan axis direction DRa as it moves from the positive pressure surface 160a side of the blade 60d to the negative pressure surface 160b side of the blade 60c along the fan rotation direction DRf.

[0151] Figure 13 Reference numeral 167a in the figure refers to the end of the blade 60c on the negative pressure surface 160b side in the inner end 67b. Figure 13 Reference numeral 167b in the figure refers to the end of the blade 60d on the positive pressure surface 160a side in the inner end 67b.

[0152] Here, as Figure 15 As shown, the area of ​​the cross section obtained by cutting the undercut region 220 formed between the inclined surface 67 of the impeller cup 66 and the shroud 62 in the airflow path 68 with a plane including the fan axis Sa is defined as the flow path cross section area.

[0153] In the intermediate inclined section 168 between blades 60d and 60c, the impeller tilt angle θ gradually increases as it moves from the positive pressure surface 160a of blade 60d to the negative pressure surface 160b of blade 60c along the fan rotation direction DRf. Consequently, the flow path cross-sectional area gradually decreases as it moves from the positive pressure surface 160a of blade 60d to the negative pressure surface 160b of blade 60c along the fan rotation direction DRf.

[0154] Therefore, in the intermediate inclined section 168 between blades 60d and 60c, the air velocity flowing on the positive pressure surface 160a side of blade 60d can be reduced, while the air velocity flowing on the negative pressure surface 160b side of blade 60c can be increased. Thus, the velocity difference between the air velocity flowing on the positive pressure surface 160a side of blade 60d and the air velocity flowing on the negative pressure surface 160b side of blade 60c can be reduced. Therefore, noise generation caused by the velocity difference can be suppressed.

[0155] The tilting shape of the relay tilting portion 168 between blades 60d and 60c is similarly formed in other relay tilting portions 168 besides the relay tilting portion 168 between blades 60d and 60c.

[0156] Next, in this embodiment, refer to Figure 14 , Figure 15 , Figure 16 , Figure 17The constraints required when forming multiple blades 60, shields 62 and impeller cups 66 using a sliding mold 93 are explained.

[0157] First, consider using the sliding module 93x, such as Figure 14 As shown, multiple blades 60, a protective cover 62, an impeller cup 66, and a main board 64 are integrally formed. Figure 14 The illustration of the multiple blades 60 is omitted. In this case, for example, it is necessary to be able to slide the sliding mold 93x radially inward relative to the shield 62, the multiple blades 60, and the main board 64 to be pulled out.

[0158] In this case, such as Figure 14 As shown, the shape needs to have a tilt angle θd of 0deg or more between the shield 62 and the motherboard 64.

[0159] Figure 14 This is a sectional view of a centrifugal blower 10X, cut along a plane including the fan axis Sa, for comparison. Figure 14 The dotted line 64y is an imaginary surface that causes the surface 64x of the motherboard 64 to move parallel to one side of the fan axis DRa.

[0160] However, depending on the shape of the motherboard 64, it is sometimes impossible to achieve a tilt angle θd greater than 0deg.

[0161] In contrast, in this embodiment, in order to allow the air drawn in from the air inlet 62a to flow smoothly into the airflow path 68, the shield 62 is as follows: Figure 15 It is configured as shown. That is, the shield 62 is formed to advance toward one side of the fan axis direction DRa as it moves from the outer end 62d of the fan radial DRr in the covered area 62b toward the inner end 62e.

[0162] Here, in Figure 16 , Figure 17 In this context, a line orthogonal to the fan axis direction DRa and orthogonal to the fan radial direction DRR is designated as an imaginary line 230. Imaginary line 230 is... Figure 16 , Figure 17 The first imaginary line orthogonal to the paper.

[0163] Furthermore, the tangent line that is orthogonal to the imaginary line 230 and tangent to the coverage area 62b is designated as the imaginary tangent line 162b (i.e., the second imaginary line).

[0164] like Figure 16 As shown, the covered area 62b and the inclined surface 67 are formed such that the inclined surface 67 is parallel to the imaginary tangent 162b.

[0165] Or, such as Figure 17As shown, the coverage area 62b and the inclined surface 67 are formed such that the distance ZL between the inclined surface 67 and the imaginary tangent 162b in the fan axis direction DRa increases from the inner side of the fan radial DRa toward the outer side of the fan radial DRa.

[0166] like Figure 18 As shown, in each of the plurality of blades 60, the outer end of the fan radial DRr is designated as the outer end 61h. In each of the plurality of blades 60, the inner end of the fan radial DRr is designated as the inner end 61e. Figure 18 In order to make the illustration clearer, the cross-sectional lines of blades 60c and 60d are omitted.

[0167] The positive pressure surface 160a and the negative pressure surface 160b are formed such that the distance XR between the blades 60 increases as they advance from the inner end 61e to the outer end 61h. The distance XR between the blades 60 is the distance between the positive pressure surface 160a and the negative pressure surface 160b.

[0168] In this embodiment, such as Figure 18 As shown, the positive pressure surface 160a is formed into an arc shape that bulges out toward one side of the circumferential direction Edr when viewed from the direction of the fan axis DRa.

[0169] When viewed from the fan axis direction DRa, the negative pressure surface 160b forms an arc shape that bulges outward towards the circumferential direction Edr. Figure 18 In order to make the illustration clearer, the cross-sectional lines of blades 60c and 60d are omitted.

[0170] This constitutes multiple blades 60, shields 62, and impeller cups 66. Therefore, multiple blades 60, shields 62, and impeller cups 66 can be integrally formed using mold forming with sliding mold 93.

[0171] Next, according to Figure 19 The flowchart illustrates the manufacturing process of impeller 16. Figure 19 As shown, firstly, in step S01, multiple blades 60, a protective cover 62, and an impeller cup 66 are formed.

[0172] Specifically, such as Figure 20 As shown, multiple blades 60, shield 62 and impeller cup 66 are integrally formed by injection molding using a mold.

[0173] The mold comprises a cavity mold, a core mold, and multiple sliding molds 93. The cavity mold and the core mold are configured to open and close in the fan axis direction DRa. The core mold is a mold located on the opposite side of the cavity mold in the fan axis direction DRa.

[0174] Multiple sliding molds 93 are prepared to form an undercut region 220 between the impeller cup 66 and the shroud 62. The number of sliding molds 93 is arranged according to the number of airflow paths 68.

[0175] First, in the forming process of step S01, with multiple sliding molds 93 arranged between the cavity mold and the core mold, molten resin material is injected between the cavity mold and the core mold. Then, an integral component 94, formed by the cooling and solidification of the resin material, is formed between the cavity mold and the core mold.

[0176] Furthermore, the cavity mold and the core mold are separated along the fan axis DRa, and the integrated component 94 and multiple sliding molds 93 are removed from between the cavity mold and the core mold. At this time, the multiple sliding molds 93 slide outward along the positive pressure surface 160a and negative pressure surface 160b of two adjacent blades 60 in the fan radial direction DRa.

[0177] Then, as indicated by arrow Su, the multiple sliding molds 93 are slid out of the integrated structure 94 to the side opposite to the fan radial direction DRr and the fan axial direction DRa. Thus, the multiple sliding molds 93 are separated from the integrated structure 94.

[0178] Therefore, the forming of an integral component 94, which integrates multiple blades 60, a protective cover 62, and an impeller cup 66, is completed.

[0179] Next, in the molding process of step S02, the mainboard 64 is formed by resin molding using a mold.

[0180] Next, in the joining process of step S03, the inner side of the fan radial DRr in the main board 64 is fitted with the outer side of the fan radial DRr in the impeller cup 66, and the multiple blades 60 are joined to the main board 64 by bonding. Thus, the forming of the impeller 16 is completed.

[0181] Next, the operation of the centrifugal blower 10 in this embodiment will be explained.

[0182] First, in the electric motor 14, when a three-phase alternating current flows through the stator coil 46, a rotating magnetic field is generated in the stator coil 46. Accompanying this, the rotor 40 rotates due to the rotating magnetic field. At this time, the rotor 40 applies a rotational force to the impeller 16 via the impeller cup 66. Therefore, the impeller 16 rotates in the fan rotation direction DRf.

[0183] At this time, air flowing in from the side of the fan axis DRa through the air intake 221a of the housing 12 is drawn into the air intake 62a as shown by the arrow FLA.

[0184] A portion of the inhaled air flows into multiple airflow paths 68.

[0185] Here, the coverage area 62b in the shroud 62 is formed as an arc protruding to the opposite side of the fan axis DRa. Therefore, the air drawn into the intake port 62a is not stripped from the shroud 62, but flows along the shroud 62 to the outside of the fan radially DRa.

[0186] In addition, the air other than a portion of the air drawn into the intake port 62a flows along the shroud 62 along the inclined portion 143b of the rotor cup 140, the inclined surface 67 of the impeller cup 66, the inner peripheral surface 171 of the main plate, and the outer peripheral surface 170 of the main plate.

[0187] Thus, the air flowing in the multiple airflow paths 68 is directed outwards radially from the fan DRr due to centrifugal force. This flowing air is then blown out from the air outlet 12a through the air outlet 68a, as indicated by arrow FLb.

[0188] According to the above-described embodiment, in the centrifugal blower 10, a plurality of blades 60, a protective cover 62, and an impeller cup 66 are integrally formed into an integrated structure 94, and the impeller cup 66 is fitted relative to the main board 64.

[0189] The shroud 62 has a covering area 62b on the other side of the fan axis direction DRa, which is formed to cover one side of the impeller cup 66 in the fan axis direction DRa. The covering area 62b is formed as an arc protruding to the other side of the fan axis direction DRa in a cross-sectional view of the shroud 62 cut with a plane including the fan axis Sa.

[0190] Here, the shield 62 is formed to advance toward one side of the fan axis direction DRa as it moves from the outer end 62d of the fan radial DRr in the covered area 62b toward the inner circumferential end 621 of the fan radial DRr.

[0191] An inclined surface 67 is provided on one side of the fan axis direction DRa in the impeller cup 66. The inclined surface 67 is formed to advance towards one side of the fan axis direction DRa as it moves from the outside of the fan radial DRa toward the inside.

[0192] Based on the above, the coverage area 62b is formed in a cross-sectional view of the shield 62 cut with a plane including the fan axis Sa as an arc shape protruding toward the side opposite to the fan axis direction DRa. The shield 62 is formed to advance toward the side opposite to the fan axis direction DRa as it moves from the outer end 62d of the fan radial DRa in the coverage area 62b toward the inner circumferential end 621 of the fan radial DRa in the shield 62.

[0193] Therefore, air drawn in through the air inlet 62a can flow from the inner circumferential end 621 of the ring in the cover 62 along the outer end 62d of the covered area 62b. This suppresses the generation of noise when air flows in the airflow path 68.

[0194] Here, as Figure 21 As shown, in the case where the impeller cup 66a and the main board 64b in the comparative example are composed of an integrated main board 64A, there is a case where the distance XM between the integrated main board 64A and the shield 62 increases from the inside to the outside of the fan radial DRr.

[0195] In this situation, it is sometimes impossible to slide the sliding mold 93A between the integrated motherboard 64A and the shield 62 radially inward to pull it out.

[0196] In contrast, in this embodiment, the shield 62 is formed to advance toward one side of the fan axis direction DRa as it moves from the outer end 62d of the fan radial DRr in the covered area 62b toward the inner end 62e of the fan radial DRr.

[0197] Furthermore, the tangent line that is orthogonal to the imaginary line 230 and tangent to the coverage area 62b is designated as the imaginary tangent line 162b. The imaginary line 230 is orthogonal to the fan axis direction DRa and the fan radial direction DRR.

[0198] The coverage area 62b and the inclined surface 67 are formed such that the inclined surface 67 is parallel to the imaginary tangent 162b. Alternatively, the coverage area 62b and the inclined surface 67 are formed such that the distance ZL between the inclined surface 67 and the imaginary tangent 162b in the fan axis direction DRa increases from the inner side of the fan radial DRa towards the outer side of the fan radial DRa. Therefore, when multiple blades 60, shroud 62, and impeller cup 66 are integrally formed, as described below.

[0199] That is, when forming the undercut region 220 between the covering region 62b and the inclined surface 67, the sliding mold 93 can be pulled out from between the covering region 62b and the inclined surface 67 toward the outside of the fan radial DRr.

[0200] Based on the above, noise generation can be suppressed, and the sliding mold 93 is used to integrally form the shield 62, multiple blades 60, and impeller cup 66, excluding the main board 64.

[0201] According to this embodiment, the effects of (1), (2), (3), (4), (5), and (6) can be obtained.

[0202] (1) The inclined surface 67 of the impeller cup 66 is formed to advance from the inner side of the fan radial direction DRr towards the outer side and towards the opposite side of the fan axis DRa. Therefore, the air drawn in through the air inlet 62a can flow smoothly radially outward between the coverage area 62b and the inclined surface 67. As a result, the generation of noise generated when air flows in the airflow path 68 can be suppressed.

[0203] (2) As the positive pressure surface 160a and the negative pressure surface 160b move from the inner end 61e to the outer end 61h, the distance XR between the blades 60 increases.

[0204] Therefore, the sliding mold 93 can be easily pulled out from between the covering area 62b and the inclined surface 67 toward the outside of the fan radial DRr.

[0205] (3) In this embodiment, the motherboard 64 has a motherboard outer peripheral surface 170, which is disposed on one side of the fan radial DRr relative to the outer end 67a of the inclined surface 67 on the fan axial direction DRa and is formed throughout the circumferential direction Edr.

[0206] Here, considering the constraints of using the sliding mold 93 and the goal of noise reduction based on airflow, such as Figure 15 As shown, it is possible to consider providing an air outlet 68a between an extension line 167c extending the inclined surface 67 inward toward the fan radial direction DRr and an imaginary tangent line 162b. In this case, the air outlet 68a is located on the opposite side of the fan axial direction DRa relative to the air inlet 62a.

[0207] That is, when the air outlet 68a is provided between the extension line 167c and the imaginary tangent line 162b, the distance between the air inlet 62a and the air outlet 68a is larger than in the present embodiment. Therefore, the volume of the centrifugal blower 10 is larger.

[0208] However, the position of the fan axis DRa at the air outlet 68a of the centrifugal blower 10 has a significant impact on its performance. Therefore, the performance of the centrifugal blower 10 varies depending on the position of the fan axis DRa at the air outlet 68a. The performance of the centrifugal blower 10 includes noise performance, efficiency, etc.

[0209] In contrast, in this embodiment, as described above, the outer peripheral surface 170 of the motherboard 64 is disposed on one side of the fan radial DRr relative to the outer end 67a of the fan in the inclined surface 67 in the fan axial direction DRa.

[0210] Therefore, it is not necessary to change the position of the fan axis DRa of the air outlet 68a, which contributes significantly to performance, with the same volume as the conventional centrifugal blower 10. That is, according to this embodiment, the constraint of using the sliding mold 93 can be satisfied, and the performance and volume can be the same as those of the conventional centrifugal blower.

[0211] (4) The motherboard 64 has an inner peripheral surface 171, which is disposed between the outer peripheral surface 170 and the inclined surface 67 and is formed throughout the circumferential direction Edr, and is formed to advance from the inner side of the fan radial DR to the outer side towards the fan axis DRa.

[0212] Therefore, the air flowing along the inclined surface 67 can be smoothly guided to the outer peripheral surface 170 of the motherboard.

[0213] (5) In the section through which the inclined surface 67 is cut by the plane containing the fan axis Sa, the angle of the narrow angle formed between the imaginary surface 210 orthogonal to the fan axis Sa and the inclined surface 67 is set as the impeller tilt angle θ.

[0214] The area of ​​the cross section obtained by cutting the undercut region 220 between the shroud 62 and the impeller cup 66 in the airflow path 68 with a plane containing the fan axis Sa is defined as the flow path cross section area.

[0215] Here, compared to the negative pressure surface 160b side of the inclined surface 67, the radial inner end 67b of the inclined surface 67 is disposed on the other side of the fan axis direction DRa.

[0216] The inner end 67b of the inclined surface 67 is formed to gradually advance towards the fan axis direction DRa as it moves from the positive pressure surface 160a side of the blade 60d to the negative pressure surface 160b side of the blade 60c along the fan rotation direction DRf.

[0217] Therefore, the impeller tilt angle θ gradually increases as it moves from the positive pressure surface 160a side toward the negative pressure surface 160b side toward the circumferential direction Edr. Consequently, the flow path cross-sectional area of ​​the undercut region 220 gradually decreases as it moves from the positive pressure surface 160a side toward the negative pressure surface 160b side toward the circumferential direction Edr.

[0218] Therefore, it is possible to reduce the velocity of the airflow flowing on the positive pressure surface 160a side in the undercut region 220 and increase the velocity of the airflow flowing on the negative pressure surface 160b side in the undercut region 220.

[0219] Therefore, it is possible to reduce the difference in velocity between the airflow flowing on the positive pressure side 160a and the airflow flowing on the negative pressure side 160b in the undercut region 220.

[0220] Here, when a velocity difference is generated between the airflow flowing on the positive pressure side 160a and the airflow flowing on the negative pressure side 160b in the undercut region 220, noise may be generated due to the friction between the two airflows.

[0221] In contrast, in this embodiment, as described above, the difference in airflow velocity between the two sides can be reduced. This reduces the generation of noise caused by this difference.

[0222] (6) In this embodiment, a labyrinthine gap 200, 201, 202 is formed between the inner side of the fan radial DRr in the main board 64 and the outer side of the fan radial DRr in the impeller cup 66. Therefore, the inner side of the fan radial DRr in the main board 64 and the outer side of the fan radial DRr in the impeller cup 66 form a labyrinth structure. As a result, airflow between the inner side of the fan radial DRr in the main board 64 and the outer side of the fan radial DRr in the impeller cup 66 can be suppressed.

[0223] (Second Implementation)

[0224] In the centrifugal blower 10 of this second embodiment, refer to Figure 22 , Figure 23 , Figure 24 An example of changing the tilt angle of the inner peripheral surface 171 of the main board in the centrifugal blower 10 of the first embodiment described above will be explained.

[0225] Figure 22 This is a diagram showing the motherboard 64 and multiple blades 60 viewed from the side of DRa along the fan axis. Figure 23 yes Figure 22 Sectional view XXIII-XXIII in the middle, Figure 24 yes Figure 22 Sectional view XXIV-XXIV. In Figure 22 In order to make the illustration clearer, the cross-sectional lines of multiple blades 60 are omitted.

[0226] In this embodiment, in a cross-section of the inner peripheral surface 171 of the motherboard 64 cut by a plane including the fan axis Sa, the angle of the narrow angle formed between the imaginary surface 240, which is orthogonal to the fan axis Sa, and the inner peripheral surface 171 of the motherboard is defined as the motherboard tilt angle θa. Here, the smaller of the two angles θa and βa formed between the imaginary surface 240 and the inner peripheral surface 171 of the motherboard is called the narrow angle θa.

[0227] like Figure 23 , Figure 24 As shown, the area of ​​the cross section obtained by cutting the region 174 between the shield 62 and the main board 64 in the airflow path 68 with a plane containing the fan axis Sa is set as the flow path cross section area.

[0228] Figure 23 The motherboard tilt angle θa is the motherboard tilt angle on the inner circumferential surface 171 of the motherboard 64 in the circumferential direction Edr, on the side of the positive pressure surface 160a of the blade 60l. Figure 24 The motherboard tilt angle θa is the motherboard tilt angle on the negative pressure surface 160b side of the motherboard 64 on the inner circumferential surface 171 of the motherboard 64 in the circumferential direction Edr.

[0229] In this embodiment, as described above, a plurality of blades 60 are arranged such that the positive pressure surface 160a and the negative pressure surface 160b overlap with the inner peripheral surface 171 of the motherboard 64 in the fan axial direction DRa.

[0230] The inner end 173 of the fan radial DRr in the inner peripheral surface 171 of the motherboard is configured such that the position of the fan radial DRr in the fan axis direction is the same in the entire circumferential direction Edr.

[0231] The outer end 172 of the fan radial DRr in the inner peripheral surface 171 of the motherboard is configured such that the position of the fan axis DRa is the same throughout the circumferential direction Edr. The outer end 172 of the fan radial DRr in the inner peripheral surface 171 of the motherboard is formed such that the position of the fan radial DRr faces outward as it moves from the negative pressure surface 160b toward the positive pressure surface 160a in the circumferential direction Edr.

[0232] Here, the main plate tilt angle θa gradually increases as it moves from the positive pressure surface 160a of blade 60l towards the negative pressure surface 160b of blade 60k in the circumferential direction (Edr). Consequently, the flow path cross-sectional area of ​​region 174 gradually decreases as it moves from the positive pressure surface 160a towards the negative pressure surface 160b in the circumferential direction (Edr). The main plate 64 with such a main plate tilt angle θa is also constructed similarly between adjacent blades 60 other than blades 60l and 60k among the plurality of blades 60.

[0233] According to the above-described embodiment, in the centrifugal blower 10, the mainboard tilt angle θa of the mainboard 64 gradually increases as it moves from the positive pressure surface 160a toward the negative pressure surface 160b in the circumferential direction Edr.

[0234] Therefore, the cross-sectional area of ​​the flow path in region 174 gradually decreases as it moves from the positive pressure surface 160a toward the negative pressure surface 160b in the circumferential direction (Edr). Thus, the velocity of the airflow flowing on the positive pressure surface 160a side in region 174 can be reduced, while the velocity of the airflow flowing on the negative pressure surface 160b side in region 174 can be increased.

[0235] Therefore, the difference between the velocity of the airflow flowing on the positive pressure side 160a in region 174 and the velocity of the airflow flowing on the negative pressure side 160b in region 174 can be reduced. As a result, noise caused by this difference can be reduced.

[0236] (Third Implementation)

[0237] In the second embodiment described above, an example was given in which the flow path cross-sectional area of ​​the region 174 between the shield 62 and the motherboard 64 is configured to vary according to the circumferential direction Edr. However, referring to... Figure 24 , Figure 25 , Figure 26 , Figure 27 This embodiment will be described with respect to the flow path cross-sectional area of ​​the region 175 between the shield 62 and the outer peripheral surface 170 of the motherboard 64, which varies according to the circumferential direction Edr. Figure 25 In order to make the illustration clearer, the cross-sectional lines of multiple blades 60 are omitted.

[0238] Figure 25 This is a diagram showing the motherboard 64 and multiple blades 60 viewed from the side of DRa along the fan axis. Figure 26 yes Figure 25 Sectional view of XXVI-XXVI in the middle, Figure 27 yes Figure 25 Sectional views of XXVII-XXVII in the figure. Figure 28 yes Figure 25 XXVIII direction view in the middle.

[0239] In this embodiment, in the cross-section of the motherboard 64 cut by a plane including the fan axis Sa, the angle of the narrow angle formed between the imaginary surface 240 orthogonal to the fan axis Sa and the inner peripheral surface 171 of the motherboard is defined as the motherboard tilt angle θb. Here, the smaller of the two angles θb and βb formed between the imaginary surface 240 and the inner peripheral surface 171 of the motherboard is called the narrow angle.

[0240] like Figure 26 , Figure 27 As shown, the area of ​​the cross section obtained by cutting the region 175 between the shield 62 and the outer peripheral surface 170 of the motherboard 64 in the airflow path 68 with a plane containing the fan axis Sa is defined as the flow path cross section area.

[0241] Figure 26 The motherboard tilt angle θb is the motherboard tilt angle on the negative pressure surface 160b side of the motherboard 64 on the inner circumferential surface 171 of the motherboard 64 in the circumferential direction Edr. Figure 27The motherboard tilt angle θb is the motherboard tilt angle on the inner circumferential surface 171 of the motherboard 64 in the circumferential direction Edr, on the side of the positive pressure surface 160a of the blade 60l.

[0242] In this embodiment, as described above, a plurality of blades 60 are arranged such that the positive pressure surface 160a and the negative pressure surface 160b overlap with the inner peripheral surface 171 and the outer peripheral surface 170 of the motherboard 64 in the fan axial direction DRa.

[0243] The inner end 173b of the fan radial DRr in the inner peripheral surface 171 of the motherboard is configured such that the position of the fan radial DRr in the fan axis direction is the same in the entire circumferential direction Edr.

[0244] like Figure 28 As shown, the outer end 172 of the fan radial DRr in the inner circumferential surface 171 of the motherboard is formed such that it faces one side of the fan axis direction DRa from the positive pressure surface 160a toward the negative pressure surface 160b in the entire circumferential direction Edr. The outer end 172 of the fan radial DRr in the inner circumferential surface 171 of the motherboard is formed such that the position of the fan radial DRr is the same in the entire circumferential direction Edr. The motherboard tilt angle θb gradually decreases as it moves from the positive pressure surface 160a of the blade 60l toward the negative pressure surface 160b of the blade 60k toward one side of the circumferential direction Edr.

[0245] As the blade 60l moves from the positive pressure surface 160a toward the negative pressure surface 160b toward the circumferential direction Edr, the outer peripheral surface 170 of the main board gradually moves toward the fan axis direction DRa. Consequently, the flow path cross-sectional area of ​​region 175 gradually decreases as it moves from the positive pressure surface 160a toward the negative pressure surface 160b toward the circumferential direction Edr.

[0246] The main board 64, which has such a flow path cross-sectional area of ​​175, is constructed in the same way between two adjacent blades 60 other than blades 60l and 60k among the plurality of blades 60.

[0247] According to the embodiment described above, the main plate 64 of the centrifugal blower 10 is formed such that, as it moves from the positive pressure surface 160a toward the negative pressure surface 160b in the circumferential direction (Edr), the outer peripheral surface 170 of the main plate gradually moves toward the fan axis direction (DRa). As a result, the flow path cross-sectional area of ​​region 175 gradually decreases as it moves from the positive pressure surface 160a toward the negative pressure surface 160b in the circumferential direction (Edr).

[0248] Therefore, the velocity of the airflow flowing on the positive pressure surface 160a side in region 175 can be reduced, while the velocity of the airflow flowing on the negative pressure surface 160b side in region 175 can be increased. Thus, the difference between the velocity of the airflow flowing on the positive pressure surface 160a side and the velocity of the airflow flowing on the negative pressure surface 160b side in region 175 can be reduced. Consequently, noise generation caused by this difference can be reduced.

[0249] (Other implementation methods)

[0250] (1) In the first to third embodiments described above, an example was given in which the impeller cup 66 was connected to the main board 64 in a way that prevented relative movement, so that the main board 64 and the impeller cup 66 were fitted together. However, it is also possible to set it as in (a) and (b).

[0251] (a) In order to connect the impeller cup 66 to the main board 64 in a way that prevents relative movement, the main board 64 and the impeller cup 66 may also be bonded together by an adhesive.

[0252] (b) In order to connect the impeller cup 66 relative to the motherboard 64 in a manner that prevents relative movement, the motherboard 64 and the impeller cup 66 can also be configured as follows: Figure 32 , Figure 33 , Figure 34 It is welded as shown in the diagram.

[0253] exist Figure 32 In the specific example shown, the side of the fan in the motherboard 64 that is inside the radial direction DRr and in the fan axial direction DRa is fused to the impeller cup 66 through the joint 630. Figure 32 This is a magnified view of a portion including the inner circumferential surface 171 of the motherboard 64 and the inclined surface 67 of the impeller cup 66.

[0254] In this case, such as Figure 32 As shown by the dashed line, a protrusion 630a is formed on the inner side of the fan radial direction DRR in the motherboard 64 before fusion deposition, protruding towards the fan axis direction DRA.

[0255] On the other hand, before the welding process, in the combined state of the motherboard 64 and the impeller cup 66, such as Figure 32 As shown by the dotted line, the outer portion of the fan radial DRr in the impeller cup 66 is formed to interfere with the protrusion 630a of the main board 64. Furthermore, the outer portion of the fan radial DRr in the impeller cup 66 is fused to the protrusion 630a of the main board 64 to form a joint 630.

[0256] exist Figure 33 , Figure 34In the specific example shown, the fan radially inside DRr and on the other side of the fan axis direction DRa in the motherboard 64 is fused to the impeller cup 66 through the joint 631. Figure 33 It is a magnified view of a portion including the inner side of the fan radial DRr in the motherboard 64 and the outer side of the fan radial DRr in the impeller cup 66. Figure 34 yes Figure 33 A magnified view of part XXXV in the image.

[0257] In this case, such as Figure 32 As shown by the dotted line, a protrusion 631a is formed on the outer side of the fan radial DRr in the impeller cup 66 before fusion, protruding to the other side of the fan axis DRa.

[0258] Before the welding process, with the motherboard 64 and impeller cup 66 combined, as follows: Figure 33 , Figure 34 As shown by the single-dotted line, the portion inside the radial DRr of the fan in the motherboard 64 is formed to interfere with the protrusion 631a of the impeller cup 66.

[0259] Furthermore, the protrusion 631a of the impeller cup 66 is fused to the main plate 64 to form a joint 631.

[0260] (2) In the first to third embodiments described above, an example of a motherboard 64 including an outer peripheral surface 170 and an inner peripheral surface 171 was described. However, the motherboard 64 may be configured in other ways, such as in (c), (d), and (e).

[0261] (c) such as Figure 29 As shown, the motherboard 64 includes an outer peripheral surface 170 and an inner peripheral surface 171. The inner peripheral surface 171 has a motherboard inclined surface 171a and a motherboard orthogonal surface 171b.

[0262] The motherboard tilt surface 171a is formed such that it advances from the inside of the fan radial direction DRr towards the outside towards one side of the fan axis DRa. The motherboard tilt surface 171a is formed throughout the circumferential direction Edr.

[0263] The motherboard orthogonal surface 171b is positioned on the opposite side of the motherboard inclined surface 171a in the fan axis direction DRa. The motherboard orthogonal surface 171b is formed throughout the fan axis direction DRa. The motherboard orthogonal surface 171b is formed throughout the circumferential direction Edr.

[0264] (d) such as Figure 30As shown, the motherboard 64 includes an outer peripheral surface 170 and an inner peripheral surface 171. The outer peripheral surface 170 is formed to extend from the inside of the fan radial direction DRR towards the outside towards one side of the fan axis direction DRA. The inner peripheral surface 171 is formed along the fan axis direction DRA.

[0265] (e) such as Figure 31 As shown, the motherboard 64 includes an outer peripheral surface 170 and an inner peripheral surface 171. The outer peripheral surface 170 is formed to smoothly advance from the inside of the fan radial direction DRr towards the outside towards one side of the fan axial direction DRa. The inner peripheral surface 171 is formed to smoothly advance from the inside of the fan radial direction DRr towards the outside towards one side of the fan axial direction DRa.

[0266] (3) In the first, second and third embodiments described above, an example of integrally forming multiple blades 60, shields 62 and impeller cups 66 from resin material was described. However, in addition to resin material, multiple blades 60, shields 62 and impeller cups 66 may also be integrally formed from metal material, for example.

[0267] (4) In the first to third embodiments described above, an example in which two outer peripheral surfaces 190 and 191 are provided on the outer side of the fan radial DRr in the impeller cup 66 is described.

[0268] Not limited to this, as long as a maze structure is formed between the inner side of the fan radial DRr in the motherboard 64 and the outer side of the fan radial DRr in the impeller cup 66, more than three outer peripheral surfaces can also be provided on the outer side of the fan radial DRr in the impeller cup 66.

[0269] In this case, more than three inner circumferential surfaces are formed inside the radial DRr of the fan in the motherboard 64.

[0270] (5) In the first to third embodiments described above, an example was described in which the end face of the impeller cup 66 formed on one side of the fan axis direction DRa is set as an inclined surface 67. The inclined surface 67 is an end face formed to advance from the inside of the fan radial direction DRa toward the outside towards the other side of the fan axis direction DRa.

[0271] However, it is also possible to instead designate the end face of the impeller cup 66 formed on one side of the fan axis direction DRa as a plane orthogonal to the fan axis direction DRa.

[0272] (6) In the first to third embodiments described above, an example of forming the covering area 62b into an arc shape that protrudes to the other side of the fan axis DRa has been described, but it is not limited thereto. The shape of the covering area 62b is not limited to an arc shape, as long as it is an arc shape.

[0273] (7) Furthermore, the present invention is not limited to the embodiments described above, and appropriate modifications can be made within the scope of the invention's intended protection. Additionally, the above embodiments are not unrelated to each other, and can be appropriately combined except where explicitly stated they cannot be combined. Furthermore, in the above embodiments, the elements constituting the embodiments are not essential elements, except where specifically stated as necessary or considered theoretically necessary.

[0274] In this embodiment with such a configuration, the following protection scope can also be formed: the electric motor of the centrifugal blower has a rotor that is arranged radially inside the opening relative to the impeller cylinder, supported on the impeller cylinder, and applies rotational force to the impeller cylinder.

[0275] The rotor has a cylindrical part and a cover part. The cylindrical part is formed in a cylindrical shape with the axis as the center. The cover part is formed to cover the hollow part of the cylindrical part from one side in the direction of the fan axis. Furthermore, the cover part is formed to face the other side in the direction of the fan axis as it moves from the radial inside to the outside, and guides the air drawn into the air intake to the air flow path.

Claims

1. A centrifugal blower, characterized in that, have: Multiple blades arranged in a circumferential direction centered on the axis; A shield, which is formed to cover the plurality of blades from one side of the axial direction when the direction in which the axis extends is set as the axial direction, and is arranged in an annular shape centered on the axis, with an air inlet that opens in the axial direction formed on the radially inner side centered on the axis. A motherboard is formed to cover the plurality of blades from the other side of the axial direction and is arranged in a ring shape centered on the axial direction, and an opening is formed on the inner side of the radial direction that opens in the axial direction; as well as The cylindrical portion is disposed within the opening and is formed into a cylindrical shape centered on the axis, and is configured to rotate around the axis by the rotational force of an electric motor. The multiple blades, the protective cover, and the cylindrical section constitute an integral part. An airflow path is provided between the cylindrical section, the main board, and the protective cover, and between two adjacent blades among the plurality of blades. The cylindrical portion is connected to the main board in a manner that prevents relative movement. When the plurality of blades, the shroud, the cylinder, and the main plate are rotated in one direction in the circumferential direction by the rotational force of the electric motor, the air drawn into the air inlet from one direction in the axial direction is blown out radially outward through the airflow path. A covering area is provided on the other side of the axial direction within the protective cover. This covering area is formed to cover one side of the cylindrical portion along the axial direction. In a cross-sectional view of the protective cover cut with a plane including the axial direction, the covering area is formed in an arc shape protruding towards the other side of the axial direction. The shield is configured to advance toward one side of the axial direction from the radially outer end in the covered area toward the radially inner end in the shield. An end face is provided on one side of the cylindrical portion in the axial direction. When a line orthogonal to the axial direction and orthogonal to the radial direction is designated as a first imaginary line, and a tangent line orthogonal to the first imaginary line and tangent to the covered area is designated as a second imaginary line, the covered area and the end face are formed in such a way that the end face of the cylinder is parallel to the second imaginary line, or the distance between the end face and the second imaginary line in the axial direction increases from the inner side to the outer side of the radial direction.

2. The centrifugal blower according to claim 1, characterized in that, The end face of the cylindrical portion is formed as an inclined surface that advances towards one side of the axial direction as it moves from the radially outer side toward the radially inner side.

3. The centrifugal blower according to claim 2, characterized in that, The motherboard has a motherboard flow surface, which is disposed on one side of the axial direction relative to the radially outer end of the inclined surface and is formed throughout the circumferential direction.

4. The centrifugal blower according to claim 3, characterized in that, The main board has an inner circumferential inclined surface disposed between the main board flow surface and the inclined surface of the cylindrical portion and formed throughout the circumferential direction, and is formed to advance towards one side of the axial direction as it moves from the radial inner side to the outer side.

5. The centrifugal blower according to claim 2, characterized in that, One of two adjacent blades among the plurality of blades, the blade positioned on the opposite side of the circumferential direction, has a positive pressure surface formed on one side of the circumferential direction, and applies positive pressure when the rotation is performed towards that side of the circumferential direction. One of the two adjacent blades, located on one side of the circumferential direction, has a negative pressure surface, which is formed on the other side of the circumferential direction, and applies negative pressure when the rotation is performed towards the side of the circumferential direction. When the narrow angle formed between the imaginary surface orthogonal to the axis and the inclined surface is defined as the impeller tilt angle, and the area of ​​the cross-section obtained by cutting the region between the shroud and the cylinder in the airflow path with a plane including the axis is defined as the flow path cross-sectional area, The impeller tilt angle gradually increases as it moves from the positive pressure side toward the negative pressure side toward the circumferential direction, and thus the flow path cross-sectional area gradually decreases as it moves from the positive pressure side toward the negative pressure side toward the circumferential direction.

6. The centrifugal blower according to claim 5, characterized in that, Compared to the negative pressure side of the inclined surface, the radially inner end of the inclined surface is located on the opposite side of the axial direction. The radial inner end of the inclined surface is formed to gradually advance towards the axial direction as it moves from the positive pressure surface side toward the negative pressure surface side toward the circumferential direction.

7. The centrifugal blower according to claim 4, characterized in that, One of two adjacent blades among the plurality of blades, the blade positioned on the opposite side of the circumferential direction, has a positive pressure surface formed on one side of the circumferential direction, and applies positive pressure when the rotation is performed towards that side of the circumferential direction. One of the two adjacent blades, located on one side of the circumferential direction, has a negative pressure surface, which is formed on the other side of the circumferential direction, and applies negative pressure when the rotation is performed towards the side of the circumferential direction. The positive pressure surface and the negative pressure surface are configured to overlap with the inner peripheral inclined surface of the motherboard in the axial direction. The angle of the narrow angle formed between the imaginary surface orthogonal to the axis and the inner circumferential inclined surface is defined as the motherboard tilt angle, and the area of ​​the cross-section obtained by cutting the region between the shield and the motherboard in the airflow path with a plane containing the axis is defined as the flow path cross-sectional area. The motherboard tilt angle gradually increases as it moves from the positive pressure surface toward the negative pressure surface toward the circumferential direction, thereby the flow path cross-sectional area gradually decreases as it moves from the positive pressure surface toward the negative pressure surface toward the circumferential direction.

8. The centrifugal blower according to claim 4, characterized in that, One of two adjacent blades among the plurality of blades, the blade positioned on the opposite side of the circumferential direction, has a positive pressure surface formed on one side of the circumferential direction, and applies positive pressure when the rotation is performed towards that side of the circumferential direction. One of the two adjacent blades, located on one side of the circumferential direction, has a negative pressure surface, which is formed on the other side of the circumferential direction, and applies negative pressure when the rotation is performed towards the side of the circumferential direction. The positive pressure surface and the negative pressure surface are configured to overlap with the motherboard flow surface of the motherboard in the axial direction. When the area of ​​the cross-section obtained by cutting the region between the shield and the mainboard flow surface in the airflow path with a plane containing the axis is defined as the flow path cross-sectional area, The mainboard flow path is formed such that as it moves from the positive pressure surface toward the negative pressure surface toward the circumferential direction, it gradually moves toward the axial direction, thereby the flow path cross-sectional area gradually decreases as it moves from the positive pressure surface toward the negative pressure surface toward the circumferential direction.

9. The centrifugal blower according to any one of claims 2 to 8, characterized in that, The radially outer side of the cylindrical portion forms a stepped shape, which has two or more outer peripheral surfaces that are staggered in the radial direction and extend throughout the axial direction. The radial inner side of the motherboard forms a stepped shape, which has two or more inner peripheral surfaces that are offset radially and extend throughout the axial direction. With the radial outer side of the cylindrical portion and the radial inner side of the main plate interlocked, the two or more outer peripheral surfaces are respectively separated by gaps and face the corresponding inner peripheral surfaces of the two or more inner peripheral surfaces, thereby forming a labyrinth structure that suppresses the flow of air between the radial outer side of the cylindrical portion and the radial inner side of the main plate.

10. The centrifugal blower according to claim 9, characterized in that, The outer radial side of the cylindrical portion has a first radial surface, which is disposed between the two outer peripheral surfaces and is formed radially throughout the cylindrical portion. The motherboard has a second radial surface on its radially inner side, which is disposed between the two inner peripheral surfaces and is formed radially throughout the motherboard. When the gap is set as the first gap, the first radial surface and the second radial surface are opposite each other through the second gap, thereby forming the maze structure.

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