Centrifugal fan and fixing method

Abstract

The centrifugal fan (1) is provided with a first portion (9) provided to the rotor (5) and a second portion provided to the fan part (3), and the second portion has a larger linear expansion coefficient than the first portion (9). The first portion (9) has a top surface portion (22) having a flat surface (22a) and a first cylindrical portion (23). The second portion has: a main surface portion (34) positioned closer to the first axial direction (C1) than the top surface portion (22); a second cylinder section (35) having an inner cylinder surface (35f) facing the outer cylinder surface (23f) of the first cylinder section (23) with a gap (S) therebetween; and an annular rib section (38) and a plurality of auxiliary rib sections (39) provided so as to protrude from the main surface section (34) in the second axial direction (C2). Adhesive sections (40) formed from an adhesive are provided between the flat surface (22a) and the annular end surface (38a) of the annular rib section (38) facing the flat surface (22a), and between the flat surface (22a) and each of the end surfaces (39a) of the plurality of auxiliary rib sections (39).

Description

Technical Field

[0001] The present invention relates to a centrifugal fan and a fixing method for fixing a fan unit to a rotor of the centrifugal fan. Background Art

[0002] A centrifugal fan includes a fan unit having a plurality of blades and a motor unit that is a drive source for the fan unit, and discharges a fluid sucked from near the rotation center as the fan unit rotates to the radial outside of the fan unit. Conventionally, for a centrifugal fan, a technique is known in which the fan unit is fixed to the rotor of the motor unit to integrally rotate the rotor and the fan unit. For example, Patent Document 1 discloses a centrifugal fan obtained by fixing the outer peripheral surface of a metal rotor holder (rotor) provided on a motor (motor unit) and the inner peripheral surface of a blade support portion of a resin impeller (fan unit) using an adhesive.

[0003] [Prior Art Documents]

[0004] [Patent Documents]

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-116848 Summary of the Invention

[0006] [Problems to be Solved by the Invention]

[0007] However, as in Patent Document 1, when the outer peripheral surface of the rotor holder and the inner peripheral surface of the blade support portion of the fan unit are adhesively fixed, a shift in the center of gravity position due to thermal deformation may occur depending on the usage environment of the centrifugal fan. The thermal deformation mentioned here means that the fan unit of the centrifugal fan and the fixing member (the rotor holder in Patent Document 1) for fixing the fan unit respectively change in size along with the temperature and temperature change around the centrifugal fan. The fan unit and the fixing member are mostly formed of different materials, and there is a case where, for example, in Patent Document 1, the fan unit is a resin product and the fixing member is a metal product. Thus, when the fan unit is formed of a material having a larger coefficient of linear expansion than the fixing member, the amount of thermal deformation of the fan unit becomes larger than that of the fixing member, and therefore the center of gravity position of the fan unit relative to the fixing member may shift from the position before thermal deformation (initially). When the center of gravity position of the fan unit shifts, it may have an adverse effect on the balance of the fan, and vibration and noise may occur during the operation of the centrifugal fan. Therefore, in order to avoid the shift of the center of gravity position of the fan unit relative to the fixing member, changing the bonding portion of the fan unit relative to the fixing member is considered, but in this case, ensuring the bonding strength becomes a problem.

[0008] The centrifugal fan and fixing method of the present invention are developed in view of such problems, and one of its purposes is to suppress the deviation of the center of gravity position accompanied by thermal deformation while ensuring the bonding strength of the fan part relative to the rotor. It should be noted that, not limited to this purpose, achieving the effects that can be derived from each structure shown in the following specific embodiments and cannot be obtained by the prior art is also another purpose of the present invention.

[0009]

Solution for Solving the Problem

[0010] The disclosed centrifugal fan and fixing method can be implemented as the following disclosed embodiments (application examples) to solve at least a part of the above problems.

[0011] The disclosed centrifugal fan includes: a first part provided on a rotor that rotates integrally with a shaft; and a second part provided on a fan part having a plurality of blade parts and fixed to the rotor, and having a larger linear expansion coefficient than the first part. The first part has: a top surface portion that extends from a first hole portion through which the shaft passes toward the radially outer side of the shaft and has a plane facing a first axial direction in the axial direction of the shaft; and a cylindrical first cylinder portion that extends from an end portion on the radially outer side of the top surface portion toward a second axial direction opposite to the first axial direction. The second part has: a main surface portion located at a position closer to the first axial direction than the top surface portion and extending from a second hole portion through which the shaft passes toward the radially outer side; an annular rib portion that protrudes from the main surface portion toward the second axial direction and has an annular end surface facing the plane; a plurality of auxiliary rib portions that protrude from the main surface portion toward the second axial direction and extend radially from the annular rib portion, and have end surfaces facing the plane; and a cylindrical second cylinder portion that extends from an end portion on the radially outer side of the main surface portion toward the second axial direction and has an inner cylinder surface facing the outer cylinder surface of the first cylinder portion with a gap therebetween. Bonding portions formed of an adhesive are provided between the annular end surface of the annular rib portion and the plane, and between the end surfaces of the plurality of auxiliary rib portions and the plane, respectively.

[0012] The disclosed fixing method fixes a second part to a first part. The first part is provided on the rotor of a motor unit having a rotor that rotates integrally with a shaft and a stator disposed opposite to the rotor, and the second part is provided on a fan unit having a plurality of blade parts and has a larger linear expansion coefficient than the first part. A top surface part and a first cylindrical part are provided on the first part. The top surface part extends radially outward from a first hole part through which the shaft passes and has a plane facing a first axial direction. The first cylindrical part extends from an end part on the radially outer side of the top surface part toward a second axial direction opposite to the first axial direction. A main surface part, an annular rib part, a plurality of auxiliary rib parts, and a second cylindrical part are provided on the second part. The main surface part extends radially outward from a second hole part through which the shaft passes. The annular rib part protrudes from the main surface part and has an annular end surface. The plurality of auxiliary rib parts protrude from the main surface part in the same direction as the annular rib part and extend radially in a radial direction from the annular rib part and have end surfaces facing the same direction as the annular end surface. The second cylindrical part extends from an end part on the radially outer side of the main surface part in the same direction as the annular rib part. The fixing method includes: a first step of applying an adhesive to the annular end surface or to a part of the plane that faces the annular end surface when the main surface part of the second part is disposed on the first axial side of the top surface part of the first part; a second step of disposing the main surface part of the second part on the first axial side of the top surface part of the first part and causing the annular end surface and the end surfaces to face the plane; and a third step of causing an inner cylindrical surface of the second cylindrical part to face an outer cylindrical surface of the first cylindrical part with a gap therebetween and causing the adhesive to spread between the annular end surface and the plane and between the end surfaces and the plane.

[0013]

Advantages of the Invention

[0014] According to the disclosed centrifugal fan and fixing method, it is possible to suppress the shift of the center of gravity position due to thermal deformation while ensuring the bonding strength of the fan unit to the rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is an axial sectional view of the centrifugal fan according to the embodiment.

[0016] Figure 2 is in Figure 1 a perspective view of a rotor yoke provided on the rotor of the motor unit of the centrifugal fan.

[0017] Figure 3 is in Figure 1 an axial half-sectional view of a main board with blades provided on the fan unit of the centrifugal fan.

[0018] Figure 4 is a perspective view obtained by observing the main board with blades from the second axial direction. Figure 3 of the main board with blades.

[0019] Figure 5 is Figure 1 an enlarged view of part X of

[0020] Figure 6 is a perspective view obtained by observing the intermediate plane portion and the inclined surface portion of the rotor yoke in the centrifugal fan, and the annular rib portion and the plurality of auxiliary rib portions of the main board with blades from the radially outer side and the first axial side ( Figure 5 the direction of arrow Y in Figure 1 ). Detailed Embodiment

[0021] The centrifugal fan and the fixing method as an embodiment will be described with reference to the accompanying drawings. The following embodiments are merely examples and are not intended to exclude various modifications and technical applications not explicitly shown in the following embodiments. Each structure of the present embodiment can be implemented with various modifications without departing from their gist.

[0022] [1. Structure]

[0023] Figure 1 is an axial sectional view of the centrifugal fan 1 of the present embodiment. As Figure 1 shown, the centrifugal fan 1 includes a motor part 2 as a driving source and a fan part 3 driven by the motor part 2. The centrifugal fan 1 is constituted, for example, by the motor part 2 and the fan part 3 being built in a housing 10 that forms the outer contour of the centrifugal fan 1. The motor part 2 has a shaft 4, a rotor 5 that rotates integrally with the shaft 4, and a stator 6 disposed opposite to the rotor 5. The fan part 3 is mounted on one axial side (the first axial C1 side described later) of the shaft 4 with respect to the rotor 5 of the motor part 2 and is fixed to the rotor 5 using an adhesive, and thus rotates integrally with the shaft 4 and the rotor 5. The centrifugal fan 1 can be used, for example, as a ventilation fan installed in a seat of a vehicle.

[0024] Hereinafter, the state in which the fan part 3 is mounted and fixed to the rotor 5 of the motor part 2 is referred to as the fixed state. In addition, the state before becoming the fixed state is referred to as the state before fixing. The state in which the fan part 3 is mounted on one axial side (the fan part 3 is placed on one axial side) of the rotor 5 in the state before fixing is referred to as the mounted state, and the state before the mounted state in the state before fixing (the state in which the fan part 3 is separated from the rotor 5) is referred to as the state before mounting. The centrifugal fan 1 becomes the fixed state by the adhesive applied to the fan part 3 in the state before mounting spreading (expanding) and curing between the fan part 3 and the rotor 5 when becoming the mounted state. The fan part 3 uses the adhesive part 40 formed by curing the adhesive (refer to Figure 5 andFigure 6 is adhesively fixed to the rotor 5, and thus rotates integrally with the shaft 4 and the rotor 5. In the following description, unless otherwise specified, it is assumed that the centrifugal fan 1 is in a fixed state.

[0025] In addition, hereinafter, the extending direction of the shaft 4 (the direction of the axis C of the shaft 4) is referred to as the axial direction. The direction in the axial direction in which the fan unit 3 is mounted with respect to the motor unit 2 is referred to as the first axial direction C1, and the direction opposite to the first axial direction C1 is referred to as the second axial direction C2. In addition, the direction orthogonal to the axial direction and away from the axis C of the shaft 4 is referred to as the radially outer side, the same direction and the direction toward the axis C is referred to as the radially inner side, and when not distinguishing between the inside and the outside, it is simply referred to as the radial direction. The direction orthogonal to the axial direction and rotating around the axis C is referred to as the circumferential direction.

[0026] The motor unit 2 has the shaft 4, the rotor 5, and the stator 6 as described above. The motor unit 2 of the present embodiment is an outer rotor type motor, and as Figure 1 shown, the stator 6 is arranged on the radially inner side of the rotor 5. The shaft 4 extends, for example, from a position on the second axial direction C2 side of the stator 6 to a position on the first axial direction C1 side of the fan unit 3. The end portion on the second axial direction C2 side and the axial intermediate portion of the shaft 4 can be supported by bearings 11 so as to be rotatable. The bearings 11 are held by a cylindrical bearing holder 12 fixed to the housing 10.

[0027] The stator 6 includes an annular stator core 7 formed by laminating a plurality of steel plates having the same shape. In the stator 6, a coil (not shown) wound around the stator core 7 with an insulator interposed therebetween can be provided. The stator core 7 is externally fitted to the bearing holder 12 and fixed in a state where the lamination direction of the steel plates coincides with the axial direction at its center, and thus is fixed to the housing 10 in a non-rotatable manner.

[0028] The rotor 5 includes magnets 8 and a rotor yoke 9 arranged to face each other in the radial direction with respect to the stator core 7. The magnets 8 are formed, for example, of long rectangular rubber magnets, and the ends of the rubber magnets are joined to form a ring having an inner diameter larger than the outer diameter of the stator core 7. The magnets 8 are fixed to the rotor yoke 9 and are arranged to face each other with a gap in the radial outer side of the stator core 7.

[0029] The rotor yoke 9 is a member that fixes the magnets 8 in a non-rotatable manner relative to the shaft 4 and suppresses the leakage of the magnetic force lines of the magnets 8, and is formed, for example, of a magnetic steel plate (metal). The rotor yoke 9 is, for example, in the shape of a bottomed cylinder (cup shape) opening toward the second axial direction C2, and covers the stator 6 from the first axial direction C1 side. In the rotor yoke 9, a first hole portion 21 for inserting the shaft 4, a cylindrical first cylindrical portion 23 located on the radially outer side of the stator core 7, and a top surface portion 22 connecting the first hole portion 21 and the first cylindrical portion 23 are provided.

[0030] The first hole portion 21 is a portion where a through hole 21h (see Figure 2 ) for the shaft 4 to pass through is formed, and for example, it has a cylindrical shape concentric with the axis C. The rotor yoke 9 is fixed so as not to rotate relative to the shaft 4 by inserting the shaft 4 into the through hole 21h and press-fitting and fixing the first hole portion 21 relative to the shaft 4.

[0031] The first cylindrical portion 23 is a portion for fixing the magnet 8, and is provided so as to surround the stator core 7 from the radially outer side as Figure 1 shown. The first cylindrical portion 23 has, for example, a cylindrical shape concentric with the axis C and extends in the axial direction. The first cylindrical portion 23 has an inner cylindrical surface 23g (see Figure 2 and Figure 5 ) facing radially inward and an outer cylindrical surface 23f facing radially outward as Figure 5 shown. The diameter of the inner cylindrical surface 23g is set to be larger than the outer diameter of the stator core 7. The magnet 8 is fixed so as not to rotate relative to the shaft 4 by being fixed to the inner cylindrical surface 23g.

[0032] As Figure 1 shown, the top surface portion 22 is a portion that covers the magnet 8 and the stator 6 from the first axial C1 side. The top surface portion 22 extends from the end portion on the second axial C2 side of the first hole portion 21 toward the radially outer side and is connected to the end portion on the first axial C1 side of the first cylindrical portion 23, for example, as Figure 1 and Figure 2 shown. It should be noted that the "extending toward..." here does not limit to extending in a direction (e.g., radially) parallel to the reference direction, but includes extending in a direction inclined with respect to the reference direction. Hereinafter, the same applies to the case described as "extending toward...".

[0033] The top surface portion 22 can be constituted by combining a flat portion, a curved surface portion, a stepped portion, and a tapered surface portion (portion). Here, the exemplified top surface portion 22 includes an inner flat portion 24, a stepped portion 25, an intermediate flat portion 26, an inclined surface portion 27, and an outer flat portion 28, and these portions 24 to 28 are connected in this order from the radially inner side toward the radially outer side. The inner flat portion 24, the intermediate flat portion 26, the inclined surface portion 27, and the outer flat portion 28 are all in a circular ring shape concentric with the axis C when viewed axially as Figure 2 shown. The stepped portion 25 has a cylindrical shape concentric with the axis C and extends in the axial direction.

[0034] As Figure 1As shown, the inner planar portion 24 is connected to the second axial C2 side of the first hole portion 21 and extends radially outward. The stepped portion 25 is connected to the radially outer side of the inner planar portion 24 and extends in the second axial C2 direction. The intermediate planar portion 26 is connected to the second axial C2 side of the stepped portion 25 and extends radially outward. The inclined surface portion 27 is connected to the radially outer side of the intermediate planar portion 26 and extends radially outward and in the second axial C2 direction (obliquely). The outer planar portion 28 is connected to the radially outer side of the inclined surface portion 27 and extends radially outward. The end portion on the radially outer side of the outer planar portion 28 is connected to the end portion on the first axial C1 side of the first cylindrical portion 23. The top surface portion 22 extends as a whole from the first hole portion 21 toward the radially outer side and the second axial C2 side through these portions 24 to 28. It should be noted that the "connection" mentioned in this specification means that two portions are connected, not that two separately provided portions are connected (adjacent).

[0035] In this embodiment, the fan portion 3 is adhesively fixed to the rotor yoke 9. That is, the rotor yoke 9 corresponds to the "first part" described in the technical solution. The specific structure will be described later. Regarding the fan portion 3, the rib portion 36 provided on the fan portion 3 is adhesively fixed to the surface of the intermediate planar portion 26 of the top surface portion 22 facing the first axial C1 (see Figure 2 , Figure 5 , Figure 6 ). Hereinafter, this surface will be referred to as the adhesive surface 22a (plane).

[0036] The fan portion 3 is an impeller that sends the fluid sucked from the radially inner side to the radially outer side, and as Figure 3 shown, includes a plurality of blade portions 31 erected along the axial direction. The plurality of blade portions 31 are arranged at equal intervals in the circumferential direction around the axis C. A main board portion 32 that supports the end portions on the second axial C2 side of the plurality of blade portions 31 can be provided on the fan portion 3.

[0037] The fan portion 3 can include, as Figure 1 shown, a blade-integrated main board 13 in which a plurality of blade portions 31 and the main board portion 32 are integrally formed, and a shroud 14. The fan portion 3 is constituted, for example, by installing and fixing the shroud 14 to the blade-integrated main board 13 on the first axial C1 side. The blade-integrated main board 13 and the shroud 14 are, for example, separately formed of a resin having a larger linear expansion coefficient than the rotor yoke 9 and then combined.

[0038] The shroud 14 is a plate material fixed to the end portions on the first axial C1 side of the plurality of blade portions 31, and is formed in a circular ring shape having an air passage hole 14h for the suction air guide path formed therein on the radially inner side. The shroud 14 is fixed to the blade-integrated main board 13 by, for example, ultrasonic welding.

[0039] The main board 13 with blades has the above-mentioned blade part 31 and main board part 32. The main board part 32 of the present embodiment is provided at a position radially outside the first cylindrical part 23 of the rotor yoke 9. The main board part 32 is, for example, as shown in Figure 1 , Figure 3 , Figure 4 , in the shape of a flat plate with the same axial dimension (thickness, plate thickness), and forms an annular shape concentric with the axis C when viewed axially.

[0040] The main board 13 with blades further includes a second hole part 33, a main surface part 34, a second cylindrical part 35, and a rib part 36. These parts 33 to 36 are provided on the radially inner side of the main board part 32. In the present embodiment, these parts 33 to 36 correspond to the "second part" described in the technical solution.

[0041] The second hole part 33 is a hole part through which the shaft 4 passes. The second hole part 33 is a part that forms a through hole 33h (refer to Figure 3 and Figure 4 ) for the shaft 4 to pass through, and is, for example, in the shape of a cylinder concentric with the axis C. The inner diameter of the second hole part 33 is, for example, set to be equal to the outer diameter of the shaft 4 or slightly larger than the outer diameter of the shaft 4. It should be noted that the second hole part 33 may or may not be fixed to the shaft 4.

[0042] The main surface part 34 is a part that extends radially outward from the second hole part 33, is in the shape of a plate with substantially the same dimension (thickness, plate thickness) in the direction orthogonal to the extending direction, and forms an annular shape concentric with the axis C when viewed axially. The main surface part 34, for example, corresponds to the extending direction of the top surface part 22 of the rotor yoke 9, extends radially outward from the second hole part 33 and toward the second axial direction C2 side (tilted), and is connected to the radially inner side of the main board part 32. Thus, the main surface part 34 covers the rotor yoke 9 from the first axial direction C1 side. The main surface part 34 can also be described as extending obliquely with respect to the axial direction so as to form an arc-shaped protrusion toward the first axial direction C1 side when viewed radially. Through such a main surface part 34, the fluid inhaled from the first axial direction C1 side is easily guided along the extending direction of the main surface part 34 to the second axial direction C2 side and radially outward.

[0043] It should be noted that, as shown in Figure 1 and Figure 3 , the ends on the second axial direction C2 side of the plurality of blade parts 31 can be connected not only to the main board part 32 but also to the main surface part 34. That is, the main surface part 34 can also, together with the main board part 32, perform the function of the main board part 32 (the function of supporting the ends on the second axial direction C2 side of the plurality of blade parts 31). The thickness of the main surface part 34 is preferably the same as the thickness of the main board part 32.

[0044] The second cylindrical portion 35 is a cylindrical portion extending from the radially outer end of the main surface portion 34 (i.e., the boundary position between the main plate portion 32 and the main surface portion 34) in the second axial direction C2. For example, as Figure 4 shown, it is in the shape of a cylinder with an inner cylindrical surface 35f facing radially inward and an outer cylindrical surface facing radially outward, each having the same diameter in the axial direction and being concentric with the axis C. The second cylindrical portion 35, as Figure 1 shown, extends to a position overlapping the first cylindrical portion 23 of the rotor yoke 9 when viewed radially, and surrounds the first cylindrical portion 23 of the rotor yoke 9 from the radially outer side. The inner cylindrical surface 35f of the second cylindrical portion 35, as Figure 5 shown, faces the outer cylindrical surface 23f of the first cylindrical portion 23.

[0045] As Figure 1 , Figure 3 and Figure 4 shown, the radially inner portion of the main plate portion 32 of the main plate 13 with blades becomes a bottomed cylindrical shape (cup shape) opening toward the second axial direction C2 through such a second hole portion 33, the main surface portion 34, and the second cylindrical portion 35. Hereinafter, these portions 33 to 35 are also collectively referred to as the cup portion 37.

[0046] The rib portion 36 projects from the main surface portion 34 in the second axial direction C2 and is a portion for strengthening the main surface portion 34. In the present embodiment, as described above, the rib portion 36 is adhesively fixed to the adhesive surface 22a of the rotor yoke 9. Therefore, the rib portion 36 is disposed at a position where at least a part of it overlaps at least a part of the adhesive surface 22a when viewed axially. The rib portion 36 is preferably disposed, as Figure 1 shown, at a position separated radially inward from the second cylindrical portion 35 and separated radially outward from the second hole portion 33.

[0047] Here, when the main plate 13 with blades (fan portion 3) having the above-described cup portion 37 is made of a material having a larger linear expansion coefficient than the rotor yoke 9, which is its fixed destination, the fan portion 3 may thermally deform significantly more than the rotor yoke 9 when exposed to an environment with a drastic temperature change in its surroundings. The inventors of the present invention have found the following: in the thermal deformation of the above-described cup portion 37, there are characteristics of deforming in a manner of reducing the diameter with the boundary position between the main surface portion 34 and the second cylindrical portion 35 as a base point, and characteristics of deforming in a manner of the main surface portion 34 floating toward the first axial direction C1 side.

[0048] In addition, it was found that the latter characteristic among these deformation characteristics (i.e., the upward deformation of the main face portion 34) is caused by the shift of the center of gravity position of the fan portion 3. Moreover, the following insight was obtained: In a centrifugal fan in which an adhesive is provided between the cylindrical portion of the rotor and the cylindrical portion of the fan portion as in the past, even if the cylindrical portion of the fan portion is to be reduced in diameter due to temperature change, this deformation is hindered by the adhesive, and this deformation may be replaced by the upward deformation of the top face portion and the cylindrical portion of the fan portion corresponding to the amount by which the deformation is hindered (the amount of upward deformation increases compared to the case where the deformation of the cylindrical portion is not hindered).

[0049] Therefore, in the centrifugal fan 1 of the present invention, as Figure 5 shown, a gap S is provided between the first cylindrical portion 23 and the second cylindrical portion 35, and even if the second cylindrical portion 35 is reduced in diameter, it will not be hindered. Moreover, in order to leave this gap S as a space, the bonding portion is changed, and the top face portion 22 and the rib portion 36 are bonded and fixed. As a result, the reduction in diameter deformation of the second cylindrical portion 35 is permitted, so it will not be replaced by the upward deformation of the main face portion 34, and the situation where the force that causes the second cylindrical portion 35 to be reduced in diameter is transformed into the force that causes the main face portion 34 to deform is suppressed. Thus, the upward deformation of the main face portion 34 is suppressed, and the shift of the center of gravity position of the fan portion 3 is suppressed.

[0050] The gap S is a cylindrical space (gap) with a small radial dimension formed between the outer cylindrical surface 23f of the first cylindrical portion 23 and the inner cylindrical surface 35f of the second cylindrical portion 35. The radial dimension of the gap S is set to such a size that the second cylindrical portion 35 will not contact the first cylindrical portion 23 even when the second cylindrical portion 35 is reduced in diameter. The diameter of the inner cylindrical surface 35f of the second cylindrical portion 35 is set to a size that can form such a gap S between it and the outer cylindrical surface 23f of the first cylindrical portion 23.

[0051] In the present embodiment, the portion at the boundary position between the plate-shaped main face portion 34 and the second cylindrical portion 35 having the same diameter in the axial direction can have a relatively larger wall thickness as Figure 5 shown compared to other portions of the main board 13 with blades. It should be noted that the "large wall thickness" mentioned here means that the respective portions constituting the fan portion 3 converge, and thus the wall (resin) of the fan portion 3 converges. Hereinafter, this portion will be referred to as the "thick wall portion 35a".

[0052] In the present embodiment, as described above, the ends on the second axial direction C2 side of the plurality of blade portions 31 are connected to the main face portion 34, and the radially inner ends of the main board portion 32 are connected to the radially outer ends of the main face portion 34. Therefore, as Figure 3 shown, at the converging portion of the root portions of the blade portions 31 on the second axial direction C2 and the radially inner root portions of the main board portion 32 in the thick wall portion 35a, the wall thickness can be further increased.

[0053] By forming such a wall thickness portion 35a, the above-described characteristics of the thermal deformation of the cup portion 37 in the fan portion 3 are more likely to appear. However, due to the gap S, the diameter reduction deformation of the second cylindrical portion 35 starting from the wall thickness portion 35a is allowed, thus suppressing the deformation of the main surface portion 34. It should be noted that in the present embodiment, it can also be said that the above-described rib portion 36 is provided at a position separated from the second cylindrical portion 35, that is, a position separated from the wall thickness portion 35a.

[0054] Moreover, a structure for improving the bonding strength of the fan portion 3 to the rotor yoke 9 is provided for the centrifugal fan 1 of the present invention. Specifically, as Figure 4 and Figure 5 shown, a ring-shaped rib portion 38 and a plurality of auxiliary rib portions 39 protruding from the main surface portion 34 toward the second axial direction C2 are provided as the rib portion 36. In the centrifugal fan 1, the adhesive applied to the ring-shaped end surface 38a on the second axial direction C2 side of the ring-shaped rib portion 38 expands when in the mounted state, so that the adhesive spreads not only between the ring-shaped end surface 38a and the bonding surface 22a, but also between the end surfaces 39a on the second axial direction C2 side of the plurality of auxiliary rib portions 39 and the bonding surface 22a. In other words, the adhesive applied to the ring-shaped end surface 38a of the ring-shaped rib portion 38 expands when in the mounted state, and thus it also shows that the adhesive is in close contact with the ring-shaped rib portion 38 and the plurality of auxiliary rib portions 39. The centrifugal fan 1 secures the rib portion 36 to the bonding surface 22a by using the bonding portion 40 (refer to Figure 5 ) formed by the curing of the adhesive, and ensures the bonding strength of the fan portion 3 to the rotor yoke 9.

[0055] The ring-shaped rib portion 38 is a portion protruding from the main surface portion 34 toward the second axial direction C2, and has a ring-shaped end surface 38a facing the second axial direction C2. The ring-shaped end surface 38a is a ring-shaped plane that surrounds the axis C when viewed from the second axial direction C2, and faces the bonding surface 22a. The ring-shaped rib portion 38 can be, for example, as Figure 4 shown, a cylindrical shape having a ring-shaped end surface 38a concentric with the axis C, an inner peripheral surface 38b facing the radial inner side, and an outer peripheral surface 38c facing the radial outer side.

[0056] The plurality of auxiliary rib portions 39 are portions protruding from the main surface portion 34 in the same direction as the ring-shaped rib portion 38 (i.e., the second axial direction C2) and extending radially from the ring-shaped rib portion 38. In the present embodiment, the plurality of auxiliary rib portions 39 are provided on the radial outer side of the ring-shaped rib portion 38 and extend radially outward from the ring-shaped rib portion 38 in a radial direction. The plurality of auxiliary rib portions 39 all have the same shape and can be separated from each other in the circumferential direction and arranged at equal intervals. Here, twelve auxiliary rib portions 39 having the same shape are separated from each other on the radial outer side of the ring-shaped rib portion 38 and arranged at equal intervals. It should be noted that in Figure 4In the figure, only one of the twelve auxiliary ribs 39 is marked with a reference numeral.

[0057] Each of the auxiliary ribs 39 has an end face 39a facing the second axial direction C2. Each end face 39a faces the bonding surface 22a. Each auxiliary rib 39 is, for example, a substantially triangular prism having a rectangular end face 39a and a pair of triangular side faces 39d that face in opposite directions in the circumferential direction. Hereinafter, the end face 39a will also be referred to as the rectangular end face 39a. Each auxiliary rib 39 extends axially as shown in Figure 4 and Figure 5 to the same position as the annular rib 38. The annular end face 38a of the annular rib 38 and the rectangular end face 39a of each auxiliary rib 39 thus become one continuous plane (a plane orthogonal to the axial direction).

[0058] It should be noted that the circumferential width of the auxiliary rib 39 is preferably set to be equal to the radial width of the annular rib 38. The radial width of the annular rib 38 and the circumferential width of the auxiliary rib 39 are further preferably widths that can ensure a bonding area that can obtain a bonding strength that satisfies the specifications of the centrifugal fan 1, and are preferably set to be slightly larger than the thicknesses of the main surface portion 34 and the main board portion 32. Thereby, deformation of the shape caused by the difference in curing time due to the difference in the amount of resin during the molding of the main board 13 with blades is suppressed.

[0059] Among the plurality of auxiliary ribs 39, some of the auxiliary ribs 39 may be provided with protrusions 50 that protrude from the rectangular end face 39a toward the second axial direction C2 as shown in Figure 3 and Figure 4 The protrusion 50 is a portion provided to form a space (gap) in which the bonding portion 40 is interposed between the annular end face 38a and the bonding surface 22a, and between the rectangular end face 39a and the bonding surface 22a, and abuts (rests) against the bonding surface 22a in the installed state as shown in Figure 6 The number of the protrusions 50 is preferably three or more. In this case, the three or more protrusions 50 are preferably separated from each other in the circumferential direction and arranged at equal intervals, and are preferably set so that the protruding amounts with respect to the rectangular end face 39a are all equal.

[0060] Here, as shown in Figure 4 protrusions 50 are provided on each of the three auxiliary ribs 39 that are provided at intervals of three among the twelve auxiliary ribs 39. By such protrusions 50 abutting against the bonding surface 22a of the rotor yoke 9, the annular end face 38a and the rectangular end face 39a are arranged in parallel with the bonding surface 22a. Therefore, the axial width of the gap (space) formed between the annular end face 38a and the bonding surface 22a, and between the rectangular end face 39a and the bonding surface 22a is uniform, and an improvement in the bonding balance of the fan unit 3 with respect to the rotor 5 is achieved.

[0061] It should be noted that the protruding amount of the convex portion 50 relative to the rectangular end face 39a is preferably set to be equal to the optimal film thickness of the adhesive. The optimal film thickness herein refers to the film thickness when the adhesive strength exhibited by the adhesive bonding can withstand the load assumed when the centrifugal fan 1 is used. For example, for an adhesive that meets the specifications of the centrifugal fan 1, the relationship between the film thickness and the adhesive strength can be verified through experimental simulations, etc., and the optimal film thickness can be determined based on the verification results.

[0062] As described above, the bonding portion 40 is a portion formed by the adhesive applied to the annular end face 38a in the pre-installation state expanding and curing when it becomes the installation state. The bonding portion 40 is provided at least between the annular end face 38a and the bonding surface 22a, and between the rectangular end face 39a and the bonding surface 22a.

[0063] In the present embodiment, the bonding portion 40 is Figure 5 and Figure 6 as shown, provided not only between the annular end face 38a and the bonding surface 22a, and between the rectangular end face 39a and the bonding surface 22a, but also on the radially inner side of the annular rib portion 38, the radially outer side of the annular rib portion 38, and both circumferential sides of the auxiliary rib portion 39. That is, the applied adhesive expands from the bonding surface 22a across the inner circumferential surface 38b of the annular rib portion 38, the outer circumferential surface 38c of the annular rib portion 38, and the pair of side surfaces 39d of the auxiliary rib portion 39, and the bonding portion 40 is also provided at these portions. Thereby, not only the annular end face 38a and the rectangular end face 39a are bonded and fixed to the bonding surface 22a, but also the inner circumferential surface 38b, the outer circumferential surface 38c, and the side surface 39d are bonded and fixed to the bonding surface 22a, so that the bonding strength of the fan portion 3 relative to the rotor 5 is further improved. In particular, the bonding strength along the circumferential direction (i.e., the rotation direction of the fan portion 3) is further improved.

[0064] It should be noted that in order to form such a bonding portion 40, it is preferable to apply an amount of adhesive to the annular end face 38a in the pre-installation state that is larger than the capacity of the gap formed between the bonding surface 22a and the annular end face 38a in the installation state. It is more preferable to apply an amount of adhesive (hereinafter referred to as "excessive amount") to the annular end face 38a in the pre-installation state that is larger than the capacity of the gaps formed between the bonding surface 22a and the annular end face 38a, and between the bonding surface 22a and the rectangular end face 39a in the installation state.

[0065] [2. Fixing method]

[0066] Hereinafter, the fixing method (fixing steps) of the fan portion 3 (main board 13 with blades) of the centrifugal fan 1 relative to the rotor 5 (rotor yoke 9) described above will be described. This fixing method includes three steps: a first step, a second step, and a third step.

[0067] First, in the first step, an adhesive is applied to the annular end face 38a of the main board 13 with blades in the state before installation. That is, the first step is the step of applying the adhesive to the annular end face 38a. In the first step, for example, an excessive amount of adhesive is uniformly applied to the entire area of the annular end face 38a of the ring.

[0068] Next, in the second step, the main board 13 with blades in the state before installation is arranged at a position on the first axial C1 side of the rotor yoke 9 in a concentric manner with the rotor yoke 9. That is, the main surface 34 is arranged at a position on the first axial C1 side of the top surface 22 in a concentric manner with the top surface 22. Thereby, the annular end face 38a and the rectangular end face 39a face the bonding surface 22a. That is, the second step is the step of arranging the main surface 34 of the main board 13 with blades at a position on the first axial C1 side of the top surface 22 of the rotor yoke 9 and making the annular end face 38a and the rectangular end face 39a face the bonding surface 22a.

[0069] In the second step, for example, the end portion on the first axial C1 side of the shaft 4 in the state where the rotor yoke 9 is press-fitted and fixed is inserted into the second hole portion 33 of the main board 13 with blades. Thereby, the rotor yoke 9 and the main board 13 with blades are coaxially (concentrically) arranged.

[0070] In the subsequent third step, the main board 13 with blades is placed on the first axial C1 side of the rotor yoke 9. The main board 13 with blades is, for example, press-fitted to the second axial C2 side until the convex portion 50 abuts against the bonding surface 22a, and thus is placed on the first axial C1 side of the rotor yoke 9. The centrifugal fan 1 thus becomes the installed state.

[0071] By placing the main board 13 with blades on the rotor yoke 9, the second cylindrical portion 35 is arranged at a position surrounding the first cylindrical portion 23 from the radially outer side. Thereby, as Figure 5 shown, the inner cylindrical surface 35f of the second cylindrical portion 35 and the outer cylindrical surface 23f of the first cylindrical portion 23 are arranged to face each other with a gap S therebetween. In addition, the adhesive applied to the annular end face 38a is not received in the gap between the annular end face 38a and the bonding surface 22a, and extends (spreads) not only between the annular end face 38a and the bonding surface 22a but also between the rectangular end face 39a and the bonding surface 22a. That is, the third step can also be said to be the step of arranging the inner cylindrical surface 35f of the second cylindrical portion 35 and the outer cylindrical surface 23f of the first cylindrical portion 23 to face each other with a gap S therebetween and spreading the adhesive between the annular end face 38a and the bonding surface 22a and between the rectangular end face 39a and the bonding surface 22a.

[0072] In the case where an excessive amount of adhesive is applied to the annular end face 38a, the adhesive also extends (spreads) radially inward of the annular rib 38, radially outward of the annular rib 38, and circumferentially on both sides of the auxiliary rib 39. The spread adhesive also contacts the inner peripheral surface 38b, the outer peripheral surface 38c, and the side surface 39d as shown in Figure 5 and Figure 6 . The adhesive spread on each surface cures over time and thus all become the above-described adhesive portions 40. In addition, as the adhesive cures, the centrifugal fan 1 becomes a fixed state.

[0073] It should be noted that the fixing of the shroud 14 to the main board 13 with blades can be performed before the first process, the second process, and the third process are implemented, or can be performed after these processes are implemented. The fixing of the stator 6 and the installation of the shaft 4 with respect to the bearing cage 12 can be performed before the first process, the second process, and the third process are implemented, or can be performed after these processes are implemented. The shaft 4 can also be inserted into the first hole portion 21 and the second hole portion 33 after the first process, the second process, and the third process are implemented.

[0074] [3. Function, Effect]

[0075] (1) In the above-described centrifugal fan 1, a gap S is formed between the outer cylindrical surface 23f of the first cylindrical portion 23 and the inner cylindrical surface 35f of the second cylindrical portion 35. Thus, even if the centrifugal fan 1 is used in an environment with a large temperature change, since the shrinkage deformation of the second cylindrical portion 35 caused by the temperature change is allowed, the upward floating deformation of the main surface portion 34 caused by the shrinkage deformation of the second cylindrical portion 35 being hindered can be suppressed. Therefore, the deviation of the center of gravity position of the fan portion 3 can be suppressed.

[0076] In addition, with respect to the centrifugal fan 1 described above, instead of the second cylindrical portion 35, a ring-shaped rib portion 38 and a plurality of auxiliary rib portions 39 are provided as rib portions that are adhesively fixed to the rotor yoke 9. In addition to this, in the centrifugal fan 1 described above, the adhesive portion 40 formed by an adhesive is interposed not only between the ring-shaped end face 38a and the adhesive surface 22a, but also between each of the rectangular end faces 39a of the plurality of auxiliary rib portions 39 and the adhesive surface 22a. As a result, the fan portion 3 can be fixed to the rotor yoke 9 with a higher adhesive strength compared to simply adhesively fixing only the ring-shaped end face 38a and the adhesive surface 22a. In addition, compared with a structure in which the radial width of the ring-shaped end face 38a is simply enlarged to expand the adhesive area, a plurality of auxiliary rib portions 39 that extend radially in a radial direction from the ring-shaped rib portion 38 are provided to ensure the adhesive area, which also helps to reduce material costs and weight. In addition, when the fan portion 3 is a resin product, it is also possible to suppress deformation of the shape caused by a difference in curing time due to a difference in the amount of resin. Therefore, according to the centrifugal fan 1 described above, it is possible to effectively suppress the shift of the center of gravity position caused by thermal deformation while ensuring the adhesive strength of the fan portion 3 with respect to the rotor 5. Moreover, the auxiliary rib portions 39 extend radially outward in a radial direction from the ring-shaped rib portion 38, so that the fluidity of the resin during molding becomes good, and the finishing accuracy such as the flatness and parallelism of the fan portion 3 can be improved.

[0077] (2) If the adhesive portion 40 is provided not only between the adhesive surface 22a and the ring-shaped end face 38a, and between the adhesive surface 22a and the rectangular end face 39a, but also across the inner peripheral surface 38b, the outer peripheral surface 38c of the ring-shaped rib portion 38, and the side surface 39d of the auxiliary rib portion 39, respectively, the adhesive strength of the fan portion 3 with respect to the rotor 5 can be further improved. In particular, the adhesive strength along the circumferential direction (i.e., the rotation direction of the fan portion 3) is further improved.

[0078] (3) When the main surface portion 34 extends from the second hole portion 33 toward the radially outer side and the second axial direction C2 side, the fluid sucked from the first axial direction C1 side can be smoothly pushed out along the main surface portion 34 to the outside in the second axial direction C2 and the radial direction. Therefore, the air supply efficiency of the fan portion 3 can be improved. In addition, it is possible to suppress the generation of vortices of the fluid on the radially inner side of the fan portion 3, so that noise suppression of the fan portion 3 is also achieved.

[0079] (4) When the main surface portion 34 extends from the second hole portion 33 toward the radially outer side and the second axial direction C2 side, if the auxiliary rib portion 39 is provided not on the radially inner side of the ring-shaped rib portion 38 but on the radially outer side of the ring-shaped rib portion 38, the amount of protrusion of the auxiliary rib portion 39 with respect to the main surface portion 34 can be suppressed. In addition, when the main board 13 with blades is a resin product, by suppressing the amount of protrusion of the auxiliary rib portion 39, it is possible to suppress deformation of the shape caused by a difference in curing time due to a difference in the amount of resin during molding.

[0080] (5) If the rib portion 36 formed by the annular rib portion 38 and the plurality of auxiliary rib portions 39 is disposed at a position radially separated from the second cylindrical portion 35, it is possible to suppress the situation where the diameter reduction deformation of the second cylindrical portion 35 is obstructed by the rib portion 36 fixed to the bonding surface 22a. Thus, the force that suppresses the diameter reduction deformation of the second cylindrical portion 35 is replaced by the upward floating deformation of the main surface portion 34, and therefore, the shift of the center of gravity position of the fan portion 3 can be effectively suppressed.

[0081] (6) If the rib portion 36 is disposed at a position radially separated from the second hole portion 33, it is possible to suppress the protruding amount of the rib portion 36 with respect to the main surface portion 34 that extends toward the radially outer side and the second axial direction C2 side. Therefore, the formability of the vane-equipped main board 13 having the second hole portion 33, the main surface portion 34, the second cylindrical portion 35, and the rib portion 36 can be improved. Moreover, when the annular rib portion 38 is disposed at a position separated from the second hole portion 33, the area of the annular end surface 38a of the annular rib portion 38 is enlarged. Thus, the bonding area is enlarged and the bonding strength can be improved.

[0082] (7) When the vane-equipped main board 13 is a resin product, the vane-equipped main board 13 having the second hole portion 33, the main surface portion 34, the second cylindrical portion 35, and the rib portion 36 can be easily formed by a resin having a higher formability than metal. In addition, since the rotor yoke 9 is a metal product that is less likely to undergo thermal deformation than the resin, the thermal deformation of the rotor yoke 9 due to temperature changes is suppressed. Therefore, the shift of the center of gravity position of the fan portion 3 can be more effectively suppressed.

[0083] (8) In the above fixing method, the fixing of the vane-equipped main board 13 to the rotor yoke 9 is completed only by applying an adhesive to the annular end surface 38a (first step), opposing the vane-equipped main board 13 to the rotor yoke 9 (second step), and placing the vane-equipped main board 13 on the rotor yoke 9 (third step). Therefore, the centrifugal fan 1 in which the center of gravity position of the fan portion 3 is not easily shifted and the bonding strength is maintained can be formed by a simple method.

[0084] [4. Others]

[0085] The structure of the above centrifugal fan 1 is an example and is not limited to the above structure. The above fixing method is also an example and is not limited to the above method. In the first step, an adhesive may also be applied to the rotor yoke 9. More specifically, in the first step, an adhesive may be applied to the portion of the bonding surface 22a of the rotor yoke 9 that opposes the annular end surface 38a when the main surface portion 34 is disposed at a position closer to the first axial direction C1 side than the top surface 22.

[0086] The top surface portion 22 of the rotor yoke 9 may not be a surface portion that extends toward the radially outer side and the second axial direction C2 side. For example, it may also be a surface portion that simply extends from the first hole portion 21 toward the radially outer side (perpendicular to the axial direction). The top surface portion 22 may not have a plurality of portions 24 to 28 with different extension directions.

[0087] The first cylindrical portion 23 only needs to extend from the radially outer end portion of the top surface portion 22 toward the second axial direction C2. It may not be a portion for fixing the magnet 8, nor a portion that surrounds the stator core 7 from the radially outer side. That is, in the centrifugal fan 1 described above, the rotor yoke 9 is provided as the "first part" described in the technical solution, but the "first part" described in the technical solution may not be the rotor yoke 9.

[0088] For the rotor 5, a portion (component) corresponding to the "first part" described in the technical solution may be provided separately from the rotor yoke 9. This portion may not be cup-shaped like the rotor yoke 9. In addition, the "first part" described in the technical solution only needs to be made of a material with a smaller linear expansion coefficient than the "second part" described in the technical solution, and it may not be a metal product. It should be noted that the motor portion 2 may also be an inner rotor type motor.

[0089] The annular end face 38a only needs to be annular and surround the axis C at least once. For example, it may also have a polygonal outer shape when viewed axially. The plurality of auxiliary rib portions 39 may not all have the same shape, and may also extend from the annular rib portion 38 toward the radially inner side. The number of the auxiliary rib portions 39 is not limited to twelve, as long as it is two or more (a plurality). The end face 39a of the auxiliary rib portion 39 may not be rectangular. The convex portion 50 provided on the auxiliary rib portion 39 may also be omitted.

[0090] The main surface portion 34 of the fan portion 3 may not be a surface portion that extends from the second hole portion 33 toward the radially outer side and the second axial direction C2 side. For example, it may also be a surface portion that simply extends from the second hole portion 33 toward the radially outer side (perpendicular to the axial direction). The second cylindrical portion 35 only needs to be a cylindrical shape that extends from the radially outer end portion of the main surface portion 34 toward the second axial direction C2 and has an inner cylindrical surface 35f that faces the outer cylindrical surface 23f of the first cylindrical portion 23 with a gap S therebetween, and it may not be a cylindrical shape. For example, the second cylindrical portion 35 may also be a cylindrical shape with a polygonal outer shape when viewed axially. Similarly, the first cylindrical portion 23 may also be a cylindrical shape with a polygonal outer shape when viewed axially.

[0091] The second hole portion 33, the main surface portion 34, the second cylindrical portion 35, and the rib portion 36 only need to be provided at least in the fan portion 3 having a plurality of blade portions 31, and may also be portions (components) provided separately from the blade-equipped main board 13. That is, the "second portion" described in the technical solution may not be a part of the blade-equipped main board 13. In addition, the shroud 14 of the fan portion 3 may be omitted, and the blade portion 31 and the main board portion 32 may not be integrally formed as the blade-equipped main board 13.

[0092] The "second portion" described in the technical solution only needs to be made of a material having a larger linear expansion coefficient than the "first portion" described in the technical solution, and may not be a resin product. If the "first portion" and the "second portion" described in the technical solution satisfy the relationship of the linear expansion coefficient, they may both be resin products or metal products.

[0093]

Explanation of Reference Numerals

[0094] 1 Centrifugal fan

[0095] 2 Motor portion

[0096] 3 Fan portion

[0097] 4 Shaft

[0098] 5 Rotor

[0099] 21 First hole portion

[0100] 22 Top surface portion

[0101] 22a Bonding surface (flat surface)

[0102] 23 First cylindrical portion

[0103] 23f Outer cylindrical surface

[0104] 31 Blade portion

[0105] 33 Second hole portion

[0106] 34 Main surface portion

[0107] 35 Second cylindrical portion

[0108] 35f Inner cylindrical surface

[0109] 38 Annular rib portion

[0110] 38a Annular end surface

[0111] 38b Inner peripheral surface

[0112] 38c Outer peripheral surface

[0113] 39 Auxiliary rib portion

[0114] 39a Rectangular end face (end face)

[0115] 39d Side face

[0116] 40 Bonding part

[0117] C1 First axial direction

[0118] C2 Second axial direction

[0119] S Gap.

Claims

1. A centrifugal fan, characterized in that: The centrifugal fan has: A first part is provided on a rotor that rotates integrally with the shaft; and a second portion, which is provided in a fan portion having a plurality of blade portions and fixed to the rotor and has a larger linear expansion coefficient than the first portion, The first part has: a top surface portion extending from a first hole portion through which the shaft passes toward a radially outer side of the shaft and having a flat surface facing a first axial direction in an axial direction of the shaft; and a cylindrical first cylindrical portion extending from the radially outer end of the top surface portion in a second axial direction opposite to the first axial direction, The second part has: a main surface portion, which is located closer to the first axial direction than the top surface portion and extends from a second hole portion through which the shaft passes toward the radially outer side; an annular rib portion, which is arranged to protrude from the main surface portion toward the second axial direction and has an annular end surface that is annular and faces the plane; a plurality of auxiliary ribs protruding from the main surface portion toward the second axial direction and extending radially from the annular rib portion in the radial direction and having end surfaces facing the plane; and a cylindrical second cylindrical portion extending from the radially outer end of the main surface portion toward the second axial direction and having an inner cylindrical surface opposed to the outer cylindrical surface of the first cylindrical portion with a gap therebetween, Adhesive portions formed of an adhesive are provided between the annular end surface of the annular rib and the flat surface, and between each of the end surfaces of the plurality of auxiliary ribs and the flat surface.

2. The centrifugal fan according to claim 1, characterized in that: The bonding portion is provided across the inner peripheral surface of the annular rib portion, the outer peripheral surface of the annular rib portion, and the side surfaces of each of the auxiliary rib portions that face the circumferential direction of the shaft.

3. The centrifugal fan according to claim 1, characterized in that: The main surface portion extends from the second hole portion toward the radially outer side and the second axial direction side.

4. The centrifugal fan according to claim 3, characterized in that: The plurality of auxiliary ribs are radially extended from the annular rib toward the radially outer side.

5. The centrifugal fan according to claim 3 or 4, characterized in that: The annular rib and the plurality of auxiliary ribs are provided at positions separated from the second cylinder portion in the radial direction.

6. The centrifugal fan according to claim 5, characterized in that: The annular rib and the plurality of auxiliary ribs are provided at positions separated from the second hole portion in the radial direction.

7. The centrifugal fan according to claim 1, characterized in that: The first part is a metal product, The second part is a resin product.

8. A fixing method, wherein a second part is fixed to a first part, wherein the first part is provided in a rotor of a motor part having a rotor rotating integrally with a shaft and a stator arranged opposite to the rotor, and the second part is provided in a fan part having a plurality of blades and having a larger linear expansion coefficient than the first part, characterized in that: The first portion is provided with a top face portion and a first barrel portion, wherein the top face portion extends radially outward from the first hole portion through which the shaft passes and has a plane facing a first axial direction, and the first barrel portion extends from a radially outer end portion of the top face portion toward a second axial direction opposite to the first axial direction. The second portion is provided with a main surface portion, an annular rib portion, a plurality of auxiliary rib portions, and a second barrel portion, the main surface portion extending radially outward from the second hole portion for the shaft to pass through, the annular rib portion protruding from the main surface portion and having an annular annular end face, the plurality of auxiliary rib portions protruding from the main surface portion in the same direction as the annular rib portion and extending radially from the annular rib portion in a radial direction and having an end face facing the same direction as the annular end face, and the second barrel portion extending from the radially outer end portion of the main surface portion in the same direction as the annular rib portion, The fixing method comprises: A first step of applying an adhesive to the annular end surface, or applying an adhesive to the following portion in the plane, the portion being a portion in the plane that faces the annular end surface when the main surface portion of the second portion is arranged at a position closer to the first axial side than the top surface portion of the first portion; a second step of arranging the main surface portion of the second portion at a position closer to the first axial side than the top surface portion of the first portion, and making the annular end surface and the end surface face the plane; as well as In the third step, the inner cylindrical surface of the second cylindrical portion and the outer cylindrical surface of the first cylindrical portion are placed opposite to each other with a gap therebetween, and the adhesive is spread between the annular end surface and the flat surface and between the end surface and the flat surface.

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