CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2017-253814 filed on Dec. 28, 2017. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION
1. Field of the Invention

The present disclosure relates to a fan.

2. Description of the Related Art

A configuration and a manufacturing method of a conventional axial flow fan impeller will be described below. In manufacturing an impeller, a rotation shaft made of metal material is fixed to a rotor yoke. After the rotor yoke to which the rotation shaft is fixed is set in a metal mold for resin molding, insert molding is performed by injecting molding synthetic resin into the metal mold. An impeller hub is formed while an outer circumferential surface of a cylindrical unit of the cup-shaped rotor yoke is covered with the synthetic resin, and a plurality of blades are formed outside the impeller hub.

During the insert molding, the molding synthetic resin is extended along both axial ends of the cylindrical unit from the impeller hub toward a direction of an axial center in which the rotation shaft exists, whereby a bottom-side flange and an open end-side flange are formed at both axial ends of the cylindrical unit. The cylindrical unit is sandwiched using the bottom-side flange and the open end-side flange, which allows the impeller hub and the rotor yoke to be firmly fixed to each other (for example, see Japanese Patent Publication Laid-Open No. 2012-246806).

However, in the configuration and manufacturing method of the impeller of the conventional axial flow fan, in order to fix the impeller hub and the rotor yoke to each other by insert molding, there is a possibility that a fatigue fracture is generated in the resin impeller hub when an ambient temperature of the axial flow fan changes due to a difference between a linear expansion coefficient of the resin impeller hub and a linear expansion coefficient of the metal rotor yoke. That is, in the configuration and manufacturing method of the impeller of the conventional axial flow fan, the impeller hub and the rotor yoke are fixed by a method in which members are relatively susceptible to an influence of the change in ambient temperature.

SUMMARY OF THE INVENTION

According to one exemplary embodiment of the present disclosure, a fan includes an impeller and a motor. In the impeller, a plurality of blades are circumferentially arranged around a center axis. The motor rotates the impeller around the center axis. The impeller includes an impeller plate that extends in a radial direction. The motor includes a rotor. The rotor includes a rotor plate, which is axially opposed to at least a portion of the impeller plate and expands in the radial direction. The impeller plate includes a protrusion. The protrusion protrudes axially downward from a lower surface on a lower side in the axial direction toward the rotor plate. The rotor plate includes a plurality of plate springs and a hole. Each of the plurality of plate springs extends in a direction intersecting the axial direction and is capable of being axially bent. The hole is opposed to a leading end of the plate spring, and at least a portion of the protrusion is accommodated in the hole. The protrusion contacts with the leading end of the plate spring while being accommodated in the hole. The plate spring is axially bent while the projection contacts with the leading end of the plate spring.

The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a fan according to a first exemplary embodiment of the present disclosure.

FIG. 2 is a perspective view illustrating an impeller of the fan of the first exemplary embodiment of the present disclosure.

FIG. 3 is a sectional view illustrating the fan of the first exemplary embodiment of the present disclosure.

FIG. 4A is a perspective view illustrating the rotor of the fan of the first exemplary embodiment of the present disclosure.

FIG. 4B is a sectional view taken along line IVB-IVB in FIG. 4A.

FIG. 5 is an enlarged sectional view illustrating a part of the fan of the first exemplary embodiment of the present disclosure.

FIG. 6 is a plan view illustrating a rotor plate and a protrusion of the fan of the first exemplary embodiment of the present disclosure.

FIG. 7 is a plan view illustrating a rotor plate and a protrusion of a fan according to a first modification of the first exemplary embodiment of the present disclosure.

FIG. 8 is a plan view illustrating an impeller and a rotor plate of a fan according to a second modification of the first exemplary embodiment of the present disclosure.

FIG. 9 is an enlarged sectional view illustrating a portion of the fan of the second modification of the first exemplary embodiment of the present disclosure.

FIG. 10 is a plan view illustrating an impeller plate and an impeller tube of a fan according to a third modification of the first exemplary embodiment of the present disclosure.

FIG. 11 is a plan view illustrating a rotor plate and a protrusion of a fan according to a fourth modification of the first exemplary embodiment of the present disclosure.

FIG. 12 is a plan view illustrating a rotor plate and a protrusion of a fan according to a fifth modification of the first exemplary embodiment of the present disclosure.

FIG. 13 is an enlarged sectional view illustrating a portion of the fan of the fifth modification of the first exemplary embodiment of the present disclosure.

FIG. 14 is a plan view illustrating a rotor plate and a protrusion of a fan according to a sixth modification of the first exemplary embodiment of the present disclosure.

FIG. 15 is a plan view illustrating a rotor plate and a protrusion of a fan according to a seventh modification of the first exemplary embodiment of the present disclosure.

FIG. 16 is a sectional view illustrating a fan according to an eighth modification of the first exemplary embodiment of the present disclosure.

FIG. 17 is a sectional view illustrating a fan according to a ninth modification of the first exemplary embodiment of the present disclosure.

FIG. 18 is a sectional view illustrating a fan according to a second exemplary embodiment of the present disclosure.

FIG. 19A is a plan view illustrating a rotor plate of the fan of the second exemplary embodiment of the present disclosure.

FIG. 19B is a plan view illustrating the rotor plate and a protrusion of the fan of the second exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the identical or corresponding component is denoted by the identical reference numerals, and the overlapping description will be omitted.

In the following description, for convenience, a direction of a center axis AX of a motor may be set to an upper and lower direction (see FIG. 1). In the drawings, an X axis, a Y axis, and a Z axis of a three-dimensional orthogonal coordinate system are appropriately described for the purpose of easy understanding. A positive direction of the Z axis indicates an upper direction, and a negative direction of the Z axis indicates a lower direction. The upper and lower direction, the upward direction, and the downward direction are defined for convenience of description, but need not to be matched with a vertical direction. For example, the upper and lower direction may be matched with the vertical direction, a horizontal direction, or a direction crossing the horizontal direction. For example, the upper direction and the lower direction may be opposite directions. The upper and lower direction is defined only for convenience of description, but does not limit an orientation during use of a motor and a fan according to the present disclosure.

Hereinafter, as illustrated in FIG. 1, a direction parallel to the center axis AX of the motor is simply referred to as an “axial direction DA”, and a radial direction and a circumferential direction around the center axis AX of the motor are simply referred to as a “radial direction DR” and a “circumferential direction DC”. The term “in planar view” indicates that an object is viewed from the axial direction DA.

A fan FN according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 to 7. The fan FN will be described below with reference to FIG. 1. FIG. 1 is a perspective view illustrating the fan FN. In FIG. 1, the fan FN is viewed from above. As illustrated in FIG. 1, the fan FN includes an impeller PL, a motor MT, and a frame FR. The fan FN is an axial flow type fan that sends air toward the axial direction DA by rotation of the impeller PL. The frame FR accommodates the impeller PL and the motor MT. In the impeller PL, a plurality of blades 10 are arranged in the circumferential direction DC around the center axis AX. The motor MT rotates the impeller PL around the center axis AX. As a result, the impeller PL sends out air in the axial direction DA.

The impeller PL will be described below with reference to FIGS. 1 and 2. FIG. 2 is a perspective view illustrating the impeller PL. In FIG. 2, the impeller PL is viewed from below. As illustrated in FIGS. 1 and 2, the impeller PL includes the plurality of blades 10, an impeller plate 13, an impeller tube 15, and an impeller outer wall 17. In the first embodiment, the impeller PL includes five blades 10. The impeller PL is made of resin. Thus, the blade 10, the impeller plate 13, the impeller tube 15, and the impeller outer wall 17 are made of resin.

The impeller plate 13 spreads in the radial direction DR around the center axis AX. The impeller plate 13 has a substantially plate shape. The impeller plate 13 includes a hole 130 through which the center axis AX passes. Thus, the impeller plate 13 has a substantial annular shape. In addition, the impeller plate 13 covers a part of an upper side of the impeller tube 15 in the axial direction DA.

The impeller plate 13 includes a plurality of protrusions 19. Each of the plurality of protrusions 19 has a substantially quadrangular prism shape, and protrudes downward in the axial direction DA. The shape of the protrusion 19 is not particularly limited as long as the protrusion 19 protrudes from the impeller plate 13. For example, the protrusion 19 may have a substantially prismatic shape, a substantially columnar shape, a substantially pyramidal shape, or a substantially frustum shape. For example, the substantially pyramidal shape is a substantially conical shape or a substantially pyramid shape. For example, the substantially frustum shape is a substantially truncated cone shape or a substantially truncated pyramid shape. For example, the protrusion 19 may have a tapered shape.

The impeller tube 15 extends downward in the axial direction DA from the impeller plate 13, and is disposed around the center axis AX. The impeller tube 15 has a substantially tubular shape. In the first embodiment, the impeller tube 15 has a substantially cylindrical shape. The impeller tube 15 further includes a plurality of ribs 111. In the first embodiment, the impeller tube 15 has sixteen ribs 111. Each of the plurality of ribs 111 is arranged on an inner circumferential surface 15a on an inside of the impeller tube 15 in the radial direction DR. Each of the plurality of ribs 111 extends in the axial direction DA.

The impeller outer wall 17 is disposed around the center axis AX. The impeller outer wall 17 has a substantially tubular shape. In the first embodiment, the impeller outer wall 17 has a substantially cylindrical shape. The impeller outer wall 17 surrounds the impeller tube 15. On an outer wall surface of the impeller outer wall 17, the plurality of blades 10 are arranged in the circumferential direction DC. The impeller plate 13 and the impeller tube 15 constitute a cup-shaped structure body.

The motor MT will be described below with reference to FIG. 3. FIG. 3 is a sectional view illustrating the fan FN. As illustrated in FIG. 3, the motor MT of the fan FN includes a stator ST, a rotor RT, a rotation shaft SH, a bearing BR1, a bearing BR2, and a bearing housing HS.

The stator ST is disposed around the center axis AX. The stator ST has a substantially annular shape. The stator ST is disposed on the inside in the radial direction DR of the rotor RT. The stator ST is opposed to the rotor RT in the radial direction DR. The stator ST includes a stator core 91, a plurality of coils 93, and a binding pin 95. For example, the stator core 91 is constructed with a laminated steel plate in which electromagnetic steel plates are laminated in the axial direction DA.

Specifically, the stator core 91 includes a core back 91a and a plurality of teeth 91b. The core back 91a is disposed around the center axis AX. The core back 91a has a substantially annular shape. In the first embodiment, the core back 91a has a substantially annular shape. The plurality of teeth 91b are arranged at equal intervals along the circumferential direction DC. Each of the plurality of teeth 91b extends outward in the radial direction DR from the core back 91a. The plurality of coils 93 correspond to the plurality of teeth 91b. Each of the plurality of coils 93 is wound around the corresponding tooth 91b with an insulator (not illustrated) interposed therebetween. An end of a lead wire drawn out from the coil 93 is bound to the binding pin 95. The binding pin 95 extends in the axial direction DA. The binding pin 95 is disposed on the outside in the radial direction DR of the core back 91a.

The rotor RT is disposed around the center axis AX. The rotor RT is rotatable around the center axis AX. The impeller PL is fixed to the rotor RT. Thus, the impeller PL rotates around the center axis AX together with the rotor RT. The rotor RT is disposed on the outside in the radial direction DR of the stator ST. That is, the motor MT is an outer rotor type motor.

Specifically, the rotor RT includes a rotor plate 23, a rotor tube 21, and a magnet 25. The magnet 25 has a substantially annular shape. The rotor RT may include a plurality of magnets arranged in the circumferential direction DC instead of the substantially annular magnet 25. For example, the magnet 25 is a permanent magnet. The magnet 25 is opposed to the coil 93 in the radial direction DR.

The rotor tube 21 is disposed around the center axis AX. The rotor tube 21 has a substantially tubular shape. In the first embodiment, the rotor tube 21 has a substantially cylindrical shape. The rotor tube 21 extends downward in the axial direction DA from the rotor plate 23. The magnet 25 is fixed to the inner surface of the rotor tube 21 in the radial direction DR.

The rotor plate 23 spreads in the radial direction DR around the center axis AX. The rotor plate 23 has a substantially plate shape. The rotor plate 23 covers the upper side of the rotor tube 21 in the axial direction DA. The rotor plate 23 is opposed to at least a part of the impeller plate 13 in the axial direction DA.

In the first embodiment, the rotor plate 23 and the rotor tube 21 are made of metal. The rotor plate 23 and the rotor tube 21 constitute a substantially closed cylindrical rotor yoke. For example, the rotor yoke is made of a steel plate.

The rotation shaft SH is disposed around the center axis AX. The rotation shaft SH has a substantially columnar shape. The rotation shaft SH penetrates the rotor plate 23. The rotation shaft SH is fixed to the rotor plate 23. Thus, the rotation shaft SH rotates around the center axis AX together with the rotor RT. The rotation shaft SH is made of metal.

The bearing BR1 supports the upper side of the rotation shaft SH in the axial direction DA. On the other hand, the bearing BR2 supports the lower side of the rotation shaft SH in the axial direction DA. The bearings BR1 and BR2 are arranged side by side in the axial direction DA. The rotation shaft SH is rotatable while the bearing BR1 and the bearing BR2 support the rotation shaft SH. Each of the bearings BR1 and BR2 has a substantially annular shape. Each of the bearings BR1 and BR2 is made of metal.

The bearing housing HS accommodates the bearing BR1 and the bearing BR2. The bearing housing HS has a substantially cylindrical shape. The bearing housing HS extends in the axial direction DA. The bearing housing HS is disposed around the center axis AX. The bearing housing HS is inserted into the stator ST, and fixed to the stator ST.

The rotor plate 23 of the rotor RT will be described below with reference to FIGS. 4A and 4B. FIG. 4A is a perspective view illustrating the rotor RT. In FIG. 4A, the rotor RT is viewed from above. FIG. 4B is a sectional view taken along line IVB-IVB in FIG. 4A. Only the rotor plate 23 and the rotor tube 21 are illustrated in FIG. 4B.

As illustrated in FIG. 4A, the rotor plate 23 of the rotor RT includes a plurality of plate springs 231 and a plurality of holes 233. In the first embodiment, the rotor plate 23 includes eight plate springs 231 and eight holes 233. The number of the plate springs 231, the number of the holes 233, and the number of the protrusions 19 (FIG. 2) are equal to one another.

Each of the plurality of plate springs 231 has elasticity, and can be bent in the axial direction DA. Specifically, a leading end 231a of the plate spring 231 can swing in the axial direction DA with a base end 231b of the plate spring 231 as a spindle. The plate spring 231 has a substantially rectangular shape in planar view. Each of the plurality of plate springs 231 extends in the direction intersecting the axial direction DA.

As illustrated in FIG. 4B, each of the plurality of plate springs 231 has an inclined unit 232. The inclined unit 232 is inclined downward in the axial direction DA with respect to a direction D1 orthogonal to the center axis AX. The leading end 231a of the plate spring 231 corresponds to the leading end of the inclined unit 232. Thus, the leading end of the inclined unit 232 may be referred to as the “leading end 231a”.

As illustrated in FIG. 4A, each of the plurality of holes 233 includes a through-hole 235 penetrating the rotor plate 23. The hole 233 is opposed to the leading end 231a of the plate spring 231. That is, the leading end 231a of the plate spring 231 faces the through-hole 235 of the hole 233.

The protrusion 19 of the impeller plate 13 and the plate spring 231 and the hole 233 of the rotor plate 23 will be described below with reference to FIG. 5. FIG. 5 is an enlarged sectional view illustrating a part of the fan FN. Vicinities of the protrusion 19, the plate spring 231, and the hole 233 in FIG. 3 are illustrated in FIG. 5.

As illustrated in FIG. 5, the protrusion 19 protrudes downward in the axial direction DA from a lower surface 13a on the lower side of the impeller plate 13 in the axial direction DA toward the rotor plate 23. At least a part of the protrusion 19 is accommodated in the hole 233. The protrusion 19 contacts with the leading end 231a of the plate spring 231 while the protrusion 19 is accommodated in the hole 233. Specifically, a wall surface 19a on the outside in the radial direction DR of the protrusion 19 contacts with the leading end 231a of the plate spring 231. Then, the plate spring 231 is bent in the axial direction DA while the protrusion 19 is in contact with the leading end 231a of the plate spring 231.

Thus, in the first embodiment, the leading end 231a of the plate spring 231 is relatively strongly caught on the protrusion 19 by elastic force of the bending of the plate spring 231. As a result, holding strength of the rotor RT with respect to the impeller PL can be improved.

For example, in the case where the motor MT is rotated at a high speed, there is a possibility that minute deformation is generated in the resin impeller PL due to centrifugal force, and there is a possibility that buoyancy of the impeller PL is relatively large. Thus, there is a possibility that force F acts on the impeller PL in the direction in which the impeller PL comes off from the rotor RT.

However, in the first embodiment, the leading end 231a of the plate spring 231 is relatively strongly caught on the protrusion 19 by the elastic force of the bending of the plate spring 231. For this reason, the impeller PL can be prevented from coming off from the rotor RT. In particular, because the fan FN is the axial flow type fan, the force F acting on the impeller PL is relatively large. Thus, the present disclosure is particularly effective for the axial flow type fan. The application of the present disclosure is not limited to the axial flow type fan, but the present disclosure can also be applied to a centrifugal type fan. The centrifugal type fan is a fan that sends air outward in the radial direction DR by centrifugal force.

Additionally, in the first embodiment, the holding strength of the rotor RT with respect to the impeller PL is improved using the elastic force of the plate spring 231. For this reason, the members constituting the fan FN can be prevented from being influenced by a change in ambient temperature. For example, the generation of fatigue fracture can be prevented in the resin impeller plate 13 when the ambient temperature of the fan FN changes due to a difference between a linear expansion coefficient of the resin impeller plate 13 and a linear expansion coefficient of the metal rotor plate 23. Additionally, stress loading caused by a difference in linear expansion coefficient between the impeller plate 13 and the rotor plate 23 can be reduced when the ambient temperature of the fan FN changes.

In the first embodiment, the holding strength of the rotor RT with respect to the impeller PL is improved using the elastic force of the plate spring 231 instead of an adhesive. For this reason, the holding strength is hardly affected by the change in ambient temperature. In the first embodiment, an adhesive applying and drying process for improving the holding strength can be omitted, so that the number of working steps and management steps can be reduced.

In the first embodiment, the holding strength of the rotor RT with respect to the impeller PL is improved using the elastic force of the plate spring 231 instead of a caulking pin. For this reason, a caulking process can be omitted, and the number of working steps and management steps can be reduced. Necessity of the caulking pin for improving the holding strength is eliminated, so that the number of components and component cost can be reduced.

In the first embodiment, the impeller PL and the rotor RT can be easily coupled together by inserting the protrusion 19 of the impeller plate 13 in the hole 233 of the rotor plate 23 in the axial direction DA.

In the first embodiment, the plate spring 231 of the rotor plate 23 is made of metal, so that the deformation due to stress, the deformation due to heat, and the deformation due to aging are small as compared with those of the plate spring made of resin. Thus, as compared with the plate spring made of resin, the holding strength of the rotor RT with respect to the impeller PL can be maintained for a long period of time.

In the first embodiment, the protrusion 19 of the impeller plate 13 is made of resin, so that the leading end 231a of the metal plate spring 231 is relatively easily engaged with the protrusion 19. As a result, the holding strength of the rotor RT with respect to the impeller PL can further be improved. The strength of the impeller plate 13 can be improved as compared with the case where snap-fit is formed in the impeller plate 13. In the first embodiment, necessity of a hole for forming the snap-fit in the impeller plate 13 is eliminated, and concentration of the stress on a periphery of the hole can be prevented.

In the first embodiment, irrespective of whether the protrusion 19 is accommodated in the hole 233, the inclined unit 232 of the plate spring 231 is inclined in the direction away from the lower surface 13a on the lower side of the impeller plate 13 in the axial direction DA with respect to a direction D1 orthogonal to the center axis AX. Thus, in the case where the force F acts in the direction in which the impeller PL comes off from the rotor RT, the leading end 231a of the inclined unit 232 is more strongly caught on the protrusion 19. As a result, the impeller PL can further be prevented from coming off from the rotor RT.

The disposition of the protrusion 19 of the impeller plate 13 and the plate spring 231 and the hole 233 of the rotor plate 23 will be described below with reference to FIG. 6. FIG. 6 is a plan view illustrating the protrusion 19 and the rotor plate 23. In FIG. 6, the rotor plate 23 is viewed from below.

As illustrated in FIG. 6, the plurality of protrusions 19 are arranged in the circumferential direction DC around the center axis AX. The plurality of holes 233 correspond to the plurality of protrusions 19. Each of the plurality of protrusions 19 is accommodated in each of the plurality of holes 233. Thus, in the first embodiment, the leading ends 231a of the plurality of plate springs 231 are relatively strongly caught on the plurality of protrusions 19. As a result, the holding strength of the rotor RT with respect to the impeller PL can further be improved. The plurality of plate springs 231 correspond to the plurality of protrusions 19.

Specifically, the plurality of protrusions 19 are arranged at equal intervals in the circumferential direction DC. The plurality of holes 233 and the plurality of plate springs 231 are arranged at equal intervals in the circumferential direction DC according to the interval of the plurality of protrusions 19. Thus, in the first embodiment, the plurality of protrusions 19 can be held by the plurality of plate springs 231 with substantially uniform force. As a result, the holding strength of the rotor RT with respect to the impeller PL can further be improved. A gap exists between the protrusion 19 and an edge 233a of the hole 233. That is, the hole 233 is larger than the protrusion 19 in planar view. Thus, in the first embodiment, the protrusion 19 can easily be inserted in the hole 233.

The plurality of protrusions 19 may not be arranged at equal intervals as long as the plurality of protrusions 19, the plurality of holes 233, and the plurality of plate springs 231 are disposed corresponding to one another. The plurality of holes 233 may not be arranged at equal intervals. The plurality of plate springs 231 may not be arranged at equal intervals.

The leading end 231a of the plate spring 231 faces the center axis AX. Thus, in the case where the motor MT rotates to generate the centrifugal force, the leading end 231a of the plate spring 231 is further strongly engaged with the protrusion 19 by the centrifugal force. As a result, the impeller PL can further be prevented from coming off from the rotor RT.

A width Wa in the circumferential direction DC of the base end 231b of the plate spring 231 is substantially equal to a width Wb in the circumferential direction DC of the leading end 231a of the plate spring 231. Thus, in the first embodiment, the plate spring 231 is easily bent as compared with the case where the width Wa is larger than the width Wb. As a result, even if the positions of the plurality of protrusions 19 vary in the radial direction DR, the plurality of plate springs 231 absorb the variation, which allows the plurality of protrusions 19 to be easily inserted in the plurality of holes 233.

Because the protrusion 19 has a substantially quadrangular prism shape, a contact area between the wall surface 19a of the protrusion 19 and the leading end 231a of the plate spring 231 is large as compared with the case where the protrusion 19 has a substantially columnar shape. As a result, the impeller PL can further be prevented from coming off from the rotor RT.

The protrusion 19 includes the wall surface 19a, a pair of wall surfaces 19b opposed to each other in the circumferential direction DC, and a wall surface 19c on the inside in the radial direction DR. The hole 233 includes the edge 233a. The edge 233a includes a first edge 2331 along the circumferential direction DC and a pair of second edges 2332 along the radial direction DR.

First to ninth modifications of the first embodiment of the present disclosure will be described below with reference to FIGS. 7 to 17. In FIGS. 7, 8, 10 to 12, 14, and 15, in order to clarify the drawing, the protrusion 19 and the protrusion 19A are indicated by dot hatching. In FIGS. 7, 8, 11, 12, 14, and 15, the rotor plate 23 and the rotor tube 21 are viewed from below.

A fan FN according to a first modification will be described with reference to FIG. 7. The first modification is different from the first embodiment in that a protrusion 19A of the first modification is in contact with the edge 233a of the hole 233. A different point between the first modification and the first embodiment will mainly be described below.

FIG. 7 is a plan view illustrating the protrusion 19A of the impeller plate 13 and the rotor plate 23 of the fan FN of the first modification.

As illustrated in FIG. 7, a width W1 in the circumferential direction DC of the plate spring 231 is smaller than a width W2 in the circumferential direction DC of the protrusion 19A. Thus, in the first modification, the leading end 231a of the plate spring 231 is easily engaged with the protrusion 19A as compared with the case where the width W1 is equal to the width W2. As a result, the holding strength of the rotor RT with respect to the impeller PL can further be improved.

The width W1 of the plate spring 231 is smaller than a width W3 in the circumferential direction DC of the hole 233. Thus, in the first modification, the plate spring 231 can easily be formed by punching.

The protrusion 19A and the edge 233a of the hole 233 contact with each other in a portion in which the protrusion 19A and the edge 233a are opposed to each other in the circumferential direction DC. Thus, in the first modification, the impeller PL can be positioned in the circumferential direction DC with respect to the rotor RT. Additionally, the protrusion 19A can be prevented from coming off from the hole 233.

Specifically, one of the pair of wall surfaces 19b of the protrusion 19A and one of the pair of second edges 2332 of the hole 233 contact with each other, and the other wall surface 19b and the other second edge 2332 contact with each other. A gap exists between the wall surface 19c of the protrusion 19A and the first edge 2331 of the hole 233.

A fan FN according to a second modification will be described with reference to FIG. 8. The second modification is different from the first embodiment in that the number of protrusions 19 of the second modification is an integral multiple of the number of blades 10. A different point between the second modification and the first embodiment will mainly be described below.

FIG. 8 is a plan view illustrating the rotor plate 23 and the impeller PL of the fan FN of the second modification.

As illustrated in FIG. 8, the number of protrusions 19 of the impeller plate 13 is an integral multiple of the number of blades 10 of the impeller PL. In the second modification, the impeller PL has four blades 10, and the impeller plate 13 has eight protrusions 19. Thus, the number of protrusions 19 of the impeller plate 13 is twice the number of blades 10 of the impeller PL.

According to the number of protrusions 19, the number of plate springs 231 of the rotor plate 23 is an integral multiple of the number of blades 10 of the impeller PL. According to the number of protrusions 19, the number of holes 233 of the rotor plate 23 is an integral multiple of the number of blades 10 of the impeller PL.

A transmission path of the force applied from the blades 10 of the impeller PL to the motor MT will be described below with reference to FIGS. 8 and 9. FIG. 9 is a view illustrating the transmission path of the force applied from the blade 10 to the motor MT. FIG. 9 illustrates a cross section similar to that of FIG. 5. For the sake of simplicity of the drawing, hatching representing the cross section is omitted in FIG. 9.

As illustrated in FIG. 9, force AW1 generated from the blade 10 by the rotation of the impeller PL is transmitted from the impeller plate 13 to the plate spring 231 of the rotor plate 23 through a position P1 of the protrusion 19. The position P1 indicates a position in the protrusion 19. As illustrated in FIGS. 8 and 9, the force AW1 reaches a position P2 of the rotor plate 23 from the plate spring 231. The position P2 indicates a position in the base end 231b of the plate spring 231.

At this point, as illustrated in FIG. 8, the plurality of blades 10 are arranged at equal intervals in the circumferential direction DC, the plurality of protrusions 19 are arranged at equal intervals in the circumferential direction DC, and the plurality of plate springs 231 are arranged at equal intervals in the circumferential direction DC. Thus, for example, the plurality of plate springs 231 are pushed to the outside in the radial direction DR by the force AW1 at the positions P2 of the plate springs 231. As a result, the radial and circumferential forces of the plurality of forces AW1 applied to the plurality of plate springs 231 are balanced with each other. For example, the plurality of protrusions 19 are pushed to the inside in the radial direction DR by the force AW1 at the positions P1 of the protrusions 19. Thus, the radial and circumferential forces of the plurality of forces AW1 applied to the plurality of protrusions 19 are balanced with each other. As a result, the deformation of the impeller PL can be prevented. The axial force of the force AW1 can be transmitted to the rotation shaft SH through the position P2. The axial force of the force AW1 can be transmitted from the rotation shaft SH to the bearing BR1 (FIG. 3), and absorbed by the bearing BR1.

In particular, in the second modification, the number of the protrusions 19 is the integral multiple of the number of blades 10, so that the force AW1 can be transmitted in a well-balanced manner from the plurality of blades 10 to the plurality of plate springs 231 through the plurality of protrusions 19. As a result, the plurality of forces AW1 applied to the plurality of plate springs 231 are further well-balanced with one another. The number of protrusions 19 is the integral multiple of the number of blades 10, so that the force AW1 can be transmitted from the plurality of blades 10 to the plurality of protrusions 19 in a well-balanced manner. Thus, the plurality of forces AW1 applied to the plurality of protrusions 19 are further well-balanced with one another. As a result, the deformation of the impeller PL can further be prevented.

A fan FN according to a third modification will be described with reference to FIG. 10. The third modification is different from the first embodiment in that the number of ribs 111 of the impeller tube 15 of the third modification is an integral multiple of the number of protrusions 19 of the impeller plate 13. A different point between the third modification and the first embodiment will mainly be described below.

FIG. 10 is a plan view illustrating the impeller plate 13 and the impeller tube 15 of the fan FN of the third modification. In FIG. 10, for convenience of description, the rotor tube 21, the hole 233, and the plate spring 231 are indicated by a two-dot chain line.

As illustrated in FIG. 10, the end on the inside in the radial direction DR of the plurality of ribs 111 of the impeller tube 15 contacts with the outer circumferential surface 21a on the outside in the radial direction DR of the rotor tube 21 while the rotor tube 21 is fitted in the impeller tube 15. The number of ribs 111 is an integral multiple of the number of protrusions 19. Thus, in the third modification, force Fa directed inward in the radial direction DR from the plurality of ribs 111 during press-fitting of the rotor RT in the impeller PL can be transmitted to the plurality of protrusions 19 in a well-balanced manner. As a result, the deformation of the impeller PL can be prevented. The force Fa can be transmitted to the plurality of plate springs 231 in a well-balanced manner through the plurality of protrusions 19. As a result, the deformation of the impeller PL can further be prevented.

In the third modification, the impeller tube 15 has sixteen ribs 111, and the impeller plate 13 has eight protrusions 19. Thus, the number of ribs 111 is twice the number of protrusions 19.

The plurality of ribs 111 are arranged at equal intervals in the circumferential direction DC. In the third modification, the plurality of ribs 111 include two or more ribs 111 opposed to the protrusion 19 in the radial direction DR and two or more ribs 111 that are not opposed to the protrusion 19 in the radial direction DR. The rib 111 that is not opposed to the protrusion 19 in the radial direction DR is a rib 111 that is displaced in the circumferential direction DC with respect to the protrusion 19.

The impeller tube 15 may only include two or more ribs 111 opposed to the protrusion 19 in the radial direction DR, or may only include two or more ribs 111 that are not opposed to the protrusion 19 in the radial direction DR.

A fan FN according to a fourth modification will be described with reference to FIG. 11. The fourth modification differs from the first embodiment in that a plate spring 231A of the fourth modification is longer than the plate spring 231 of the first embodiment in the radial direction DR. A different point between the fourth modification and the first embodiment will mainly be described below.

FIG. 11 is a plan view illustrating the protrusion 19 of the impeller plate 13 and the rotor plate 23 of the fan FN of the fourth modification. As illustrated in FIG. 11, an outer edge 23b on the outside in the radial direction DR of the rotor plate 23 has a substantially circular shape. The leading end 231a of the plate spring 231A is located closer to the center axis AX with respect to a midpoint M of a shortest distance between the outer edge 23b of the rotor plate 23 and the center axis AX. Thus, in the fourth modification, the plate spring 231A is longer in the radial direction DR as compared with the case where the leading end 231a is located on the outside in the radial direction DR with respect to the midpoint M. As a result, the force AW1 (FIG. 9) from the blade 10 is transmitted from the protrusion 19 to the position P2 through the relatively long plate spring 231A, so that the force AW1 applied to the protrusion 19 can be reduced.

A fan FN according to a fifth modification will be described with reference to FIGS. 12 and 13. The fifth modification is different from the first embodiment in that a plate spring 231B of the fifth modification faces the outside in the radial direction DR. A different point between the fifth modification and the first embodiment will mainly be described below.

FIG. 12 is a plan view illustrating the protrusion 19 of the impeller plate 13 and the rotor plate 23 of the fan FN of the fifth modification. FIG. 13 is a sectional view illustrating a part of the fan FN. For the sake of simplicity of the drawing, hatching representing the cross section is omitted in FIG. 13.

As illustrated in FIG. 12, the leading end 231a of the plate spring 231B of the rotor plate 23 faces the outside in the radial direction DR. Thus, in the fifth modification, the protrusion 19 can be disposed on the further outside in the radial direction DR as compared with the case where the leading end 231a faces the inside in the radial direction DR. As a result, as illustrated in FIG. 13, a hole 130A of the impeller plate 13 can be enlarged, and a weight of the impeller PL can be reduced.

The transmission path of the force applied from the blade 10 of the impeller PL to the motor MT will be described below with reference to FIGS. 12 and 13. As illustrated in FIG. 13, force AW2 generated from the blade 10 by the rotation of the impeller PL is transmitted from the impeller plate 13 to the plate spring 231B of the rotor plate 23 through a position P3 of the protrusion 19. The position P3 indicates a position in the protrusion 19.

At this point, as illustrated in FIG. 12, the plurality of protrusions 19 are arranged at equal intervals in the circumferential direction DC, and the plurality of plate springs 231B are arranged at equal intervals in the circumferential direction DC. Thus, for example, the plurality of plate springs 231B are pushed inward in the radial direction DR by the force AW2. As a result, the radial and circumferential forces of the plurality of forces AW2 applied to the plurality of plate springs 231B are balanced with each other. For example, the plurality of protrusions 19 are pushed inward in the radial direction DR by the force AW2 at the positions P3 of the protrusions 19. Thus, the radial and circumferential forces of the plurality of forces AW2 applied to the plurality of protrusions 19 are balanced with each other. As a result, the deformation of the impeller PL can be prevented. The axial force of the force AW2 can be transmitted from the plate spring 231B to the rotation shaft SH through the rotor plate 23. The axial force of the force AW2 can be transmitted from the rotation shaft SH to the bearing BR1 (FIG. 3), and absorbed by the bearing BR1.

In particular, in the fifth modification, the leading end 231a of the plate spring 231B faces the outside in the radial direction DR, so that the protrusion 19 can be disposed on the further outside in the radial direction DR compared to the case where the leading end 231a faces the inside in the radial direction DR.

At least a part of the protrusion 19 of the impeller plate 13 is opposed to the magnet 25 in the axial direction DA. Thus, in the fifth modification, the protrusion 19 can easily be prevented from interfering with the end in the axial direction DA of the coil 93. Additionally, the protrusion 19 is prevented from interfering with the coil 93, so that the lengths of the impeller tube 15 and the rotor tube 21 can be reduced in the axial direction DA.

A fan FN according to a sixth modification will be described with reference to FIG. 14. The sixth modification is different from the first embodiment in that a plate spring 231C of the sixth modification has a substantially trapezoidal shape in planar view. A different point between the sixth modification and the first embodiment will mainly be described below.

FIG. 14 is a plan view illustrating the protrusion 19 of the impeller plate 13 and the rotor plate 23 of the fan FN of the sixth modification. As illustrated in FIG. 14, the plate spring 231C has the substantially trapezoidal shape in planar view. Specifically, a width WL in the circumferential direction DC of the base end 231b of the plate spring 231C is larger than a width WU in the circumferential direction DC of the leading end 231a of the plate spring 231C. Thus, in the sixth modification, the elastic force of the plate spring 231C can be strengthened as compared with the case where the width WL is equal to the width WU. Further, since the width WL is wider, the strength around the base end 231b can be increased. As a result, the leading end 231a of the plate spring 231C is more easily engaged with the protrusion 19, and the holding strength of the rotor RT with respect to the impeller PL can further be improved.

A fan FN according to a seventh modification will be described with reference to FIG. 15. The seventh modification is different from the sixth modification in that the plate spring 231C of the seventh modification faces the rotation direction of the rotor RT. A different point between the seventh modification and the sixth modification will mainly be described below.

FIG. 15 is a plan view illustrating the protrusion 19 of the impeller plate 13 and the rotor plate 23 of the fan FN of the seventh modification. As illustrated in FIG. 15, the leading end 231a of the plate spring 231C faces the rotation direction D2 of the rotor RT. Thus, in the seventh modification, the protrusion 19 is positioned in the direction toward which the leading end 231a of the plate spring 231C is directed. As a result, as compared with the case where the leading end 231a faces the direction opposite to the rotation direction D2 of the rotor RT, the leading end 231a of the plate spring 231C is more easily engaged with the protrusion 19, and the holding strength of the rotor RT with respect to the impeller PL can further be improved.

The width WL and the width WU may be equal to each other as long as the leading end 231a of the plate spring 231C faces the rotation direction D2 (FIG. 14).

A fan FN according to an eighth modification will be described with reference to FIG. 16. The eighth modification is different from the first embodiment in that the protrusion 19 of the eighth modification is opposed to the core back 91a. A different point between the eighth modification and the first embodiment will mainly be described below.

FIG. 16 is a sectional view illustrating the fan FN of the eighth modification. As illustrated in FIG. 16, at least a part of the protrusion 19 of the impeller plate 13 is opposed to the core back 91a in the axial direction DA. Thus, in the eighth modification, the protrusion 19 can easily be prevented from interfering with the end in the axial direction DA of the coil 93 and the end in the axial direction DA of the binding pin 95. Additionally, the protrusion 19 is prevented from interfering with the coil 93 and the binding pin 95, so that the lengths of the impeller tube 15 and the rotor tube 21 can be reduced in the axial direction DA.

A fan FN according to a ninth modification will be described with reference to FIG. 17. The ninth modification is different from the first embodiment in that the protrusion 19 of the ninth modification is opposed to the bearing housing HS. A different point between the ninth modification and the first embodiment will mainly be described below.

FIG. 17 is a sectional view illustrating the fan FN of the ninth modification. As illustrated in FIG. 17, at least a part of the protrusion 19 of the impeller plate 13 is opposed to the bearing housing HS in the axial direction DA. Thus, in the ninth modification, the length of the protrusion 19 can relatively be increased in the radial direction DR. As a result, the strength of the protrusion 19 can be improved.

A fan FNA according to a second embodiment of the present disclosure will be described with reference to FIGS. 18 to 19B. The second embodiment is different from the first embodiment in that the fan FNA of the second embodiment has one protrusion 19A and one hole 233A. A different point between the second embodiment and the first embodiment will mainly be described below. In FIGS. 19A and 19B, the protrusion 19A and the rotor plate 23A are viewed from below. Also, the protrusion 19A is indicated by dot hatching in order to clarify the drawing.

The fan FNA will be described with reference to FIGS. 18 and 19A. FIG. 18 is a sectional view illustrating the fan FNA of the second embodiment. As illustrated in FIG. 18, an impeller PLA of the fan FNA includes an impeller plate 13A. The rotation shaft SH is fixed to the impeller plate 13A. The rotor RT of the motor MT of the fan FNA includes a rotor plate 23A.

FIG. 19A is a plan view illustrating the rotor plate 23A. As illustrated in FIGS. 18 and 19A, the rotor plate 23A has the substantially circular hole 233A. The hole 233A includes a through-hole 235A penetrating the rotor plate 23A. The hole 233A is opposed to a leading end 231a of the plate spring 231. That is, the leading end 231a of the plate spring 231 faces the through-hole 235A of the hole 233A. The leading end 231a of the plate spring 231 protrudes toward the center axis AX with respect to an edge 2333 of the hole 233A.

The protrusion 19A and the plate spring 231 will be described below with reference to FIGS. 18 to 19B. FIG. 19B is a plan view illustrating the rotor plate 23A and the protrusion 19A. As illustrated in FIGS. 18 to 19B, at least a part of the protrusion 19A is accommodated in the hole 233A. The protrusion 19A contacts with the leading end 231a of the plate spring 231 while being accommodated in the hole 233A. Specifically, a wall surface 19d on the outside in the radial direction DR of the protrusion 19A contacts with the leading end 231a of the plate spring 231. The plate spring 231 is bent in the axial direction DA while the protrusion 19A contacts with the leading end 231a of the plate spring 231.

Thus, in the second embodiment, similarly to the first embodiment, the leading end 231a of the plate spring 231 is relatively strongly caught on the protrusion 19A by the elastic force of the bending of the plate spring 231. As a result, holding strength of the rotor RT with respect to the impeller PL can be improved. Additionally, in the second embodiment, similarly to the first embodiment, the holding strength of the rotor RT with respect to the impeller PL is improved using the elastic force of the plate spring 231, so that the members constituting the fan FNA can be prevented from being affected by the change in ambient temperature. The second embodiment has the same effect as the first embodiment.

For example, the present disclosure can be used for a fan.

Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.

While preferred embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.