Fan unit

Abstract

To provide a fan device which efficiently dissipates heat generated on a coil, a circuit board or the like.SOLUTION: A fan device 1 has a plurality of through-holes 29 through which hubs 27 penetrate in an axis x direction. The fan device 1 is formed of an annular ventilating part G around an axis x formed by a gap which is formed between a lower end surface 273 in an axis x direction of the hub 27 and an upper end surface 129 in an axis x direction of an outer circumferential wall part 124. The fan device 1 has an operation point on an air amount area on which an air flow that flows-out to an outer part of the hub 27 through the plurality of through-holes 29 formed in the hub 27 becomes dominant. In the fan device 1, when an area of the ventilation part G is Sh and a net area of the plurality of through-holes 29 is Sa, Sa<Sh is satisfied and the value of Sh / Sa as the rate of area Sh of the ventilation part G and net area Sa of the plurality of through-holes 29 becomes less than 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fan device. [Background technology]

[0002] Axial flow fans are widely used as fan devices for cooling, ventilation, air conditioning, air blowing, etc. in electronic devices, home appliances, office equipment, industrial equipment, and vehicles. An example of an axial flow fan is an axial flow fan in which an impeller includes a cylindrical hub and a plurality of blades integrally formed with the cylindrical hub (see Patent Document 1). In the axial flow fan, ventilation through-holes are formed in an inclined surface formed on the outer peripheral edge of the hub. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-88772 Summary of the Invention [Problem to be solved by the invention]

[0004] In the axial flow fan of Patent Document 1, some of the air drawn into the main body case through the ventilation holes (intake port) is drawn into the hub through the ventilation through-holes. The air drawn into the hub flows out from a gap formed between the bottom end of the hub and the outer peripheral wall of the stator housing in which the bearing holder is disposed. The air that flows out from the gap is discharged to the outside of the main body case through a ventilation hole (exhaust port) provided on the bottom surface of the main body case.

[0005] However, the relationship between the area of the ventilation through-holes and the area of the above-mentioned gap is not clear in the axial flow fan of Patent Document 1. Therefore, it is expected that by clarifying the relationship between the area of the ventilation through-holes and the area of the above-mentioned gap in the fan device, the heat dissipation performance of the components of the motor mounted inside the hub will be improved.

[0006] The present invention takes the above problems as an example, and an object thereof is to provide a fan device capable of efficiently dissipating heat generated in components of a motor.

Means for Solving the Problems

[0007] In order to achieve the above object, a fan device according to the present invention includes a cup-shaped hub, an impeller having a plurality of blades provided on an outer peripheral surface of the hub, a motor that rotates the impeller, and a housing that houses the impeller. The housing has a motor base portion for disposing the motor on one end side in the axial direction. The motor base portion has a circular base portion, a bearing holder that is provided on the base portion and holds a bearing that rotatably supports a rotation shaft of the motor, and a cylindrical outer peripheral wall portion that extends in the axial direction from an outer peripheral edge of the base portion. The hub has a plurality of through holes penetrating in the axial direction, and an annular ventilation portion is formed around an axis formed by a gap between a lower end surface of the hub in the axial direction and an upper end surface of the outer peripheral wall portion in the axial direction. An operating point is provided in an air volume region where an air flow that flows out of the ventilation portion through the plurality of through holes formed in the hub and to the outside of the hub is dominant. When the area of the ventilation portion is Sh and the total area of the plurality of through holes is Sa, Sa < Sh, and a value of Sh / Sa, which is a ratio of the area Sh of the ventilation portion to the total area Sa of the plurality of through holes, is less than 10.

[0008] According to the fan device of the present invention, heat generated in a coil, a drive circuit board, or the like can be efficiently dissipated.

Brief Description of the Drawings

[0009] [Figure 1] It is a plan view schematically showing a configuration of a fan device according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view taken along line A-A schematically showing a configuration of the fan device shown in FIG. 1. [Figure 3]2 is a graph showing the relationship between the area ratio of the ventilation section area to the total area of the through holes and the temperature rise of the coil in the fan device shown in FIG. [Figure 4] 2 is a graph showing the relationship between air volume characteristics (PQ characteristics) and the temperature rise of the coil in the fan device shown in FIG. [Figure 5] 2 is a schematic diagram showing the airflow flowing through the hub of the fan device shown in FIG. 1 at maximum airflow. FIG. [Figure 6] FIG. 6 is an enlarged view of the vicinity of the through-hole in the schematic diagram shown in FIG. 5. [Figure 7] 2 is a schematic diagram showing the airflow flowing through the hub of the fan device shown in FIG. 1 at maximum static pressure. FIG. [Figure 8] FIG. 8 is an enlarged view of the vicinity of the through-hole in the schematic diagram shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fan device according to an embodiment of the present invention will now be described with reference to the drawings.

[0011] Fig. 1 is a plan view schematically showing the configuration of a fan device 1 according to an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line AA showing the configuration of the fan device 1.

[0012] In the following description, for convenience, the direction of arrow a in the direction of axis x will be referred to as the upper side a, and the direction of arrow b will be referred to as the lower side b. In addition, in the radial direction perpendicular to axis x, the direction away from axis x (the direction of arrow c in FIG. 2) will be referred to as the outer circumferential side c, and the direction toward axis x (the direction of arrow d in FIG. 2) will be referred to as the inner circumferential side d. In the following description, for convenience, the direction shown in FIG. 2 will be referred to as the side of the fan device 1. In addition, in the following description, for convenience, the direction in which the fan device 1 is viewed from the upper side a toward the lower side b will be referred to as the front, and the direction in which the fan device 1 is viewed from the lower side b toward the upper side a will be referred to as the bottom.

[0013] As shown in FIGS. 1 and 2, the fan device 1 according to the present embodiment includes a cup-shaped hub 27, an impeller 25 having a plurality of blades 28 provided on the outer peripheral surface of the hub 27, a motor 20 that rotates the impeller 25, and a housing 10 that houses the impeller 25. The housing 10 has a motor base portion 120 for arranging the motor 20 on one end side (lower side b) in the axial direction x. The motor base portion 120 includes a circular base main body portion 121 as a base portion, a bearing holder 17 provided on the base main body portion 121 and holding a bearing 22 that rotatably supports the rotation shaft (shaft 15) of the motor 20, and a cylindrical outer peripheral wall portion 124 extending in the axial direction x from the outer peripheral edge of the base main body portion 121. The hub 27 has a plurality of through holes 29 penetrating in the axial direction x. The fan device 1 forms an annular ventilation portion G centered on the axis x formed by a gap formed between the lower end surface 273 of the hub 27 in the axial direction x and the upper end surface 129 of the outer peripheral wall portion 124 in the axial direction x. The fan device 1 has an operating point in an air volume region where an air flow that flows out of the ventilation portion G through the plurality of through holes 29 formed in the hub 27 and out of the hub 27 is dominant. When the area of the ventilation portion G is Sh and the total area of the plurality of through holes 29 is Sa, the fan device 1 satisfies Sa < Sh. Hereinafter, the configuration and operation of the fan device 1 will be specifically described.

[0014] [Configuration of Fan Device] As described above, the fan device 1 includes a housing 10, a motor 20, and an impeller 25 as main components.

[0015] As shown in FIG. 1, the housing 10 has a substantially square shape in a plan view. As shown in FIGS. 1 and 2, the housing 10 has an intake port 111, an exhaust port 122, an air channel 112, and bolt insertion holes 114. The air channel 112 is formed in a hollow cylindrical shape so as to accommodate the impeller 25. The inner peripheral surface d of the air channel 112 faces the impeller 25. The inner diameter of the air channel 112 is, for example, constant or substantially constant in the direction of the axis x. The inner diameter of the air channel 112 may vary in the axial direction and is not limited to the above dimensions. The intake port 111 is formed at an end of the housing 10 on an upper side a in the direction of the axis x. The exhaust port 122 is formed at an end of the housing 10 on a lower side b in the direction of the axis x. The fan device 1 is an axial fan that takes in air through the intake port 111 and expels air through the exhaust port 122. The bolt insertion holes 114 are provided at each corner of the housing 10. The bolt insertion holes 114 are holes for inserting bolts (not shown) for attaching the fan device 1 to a device or a housing (not shown). The exhaust port 122 includes a motor base 120 for arranging the motor 20 and a plurality of fixed blades 123.

[0016] The motor base portion 120 has a base main body portion 121, an outer peripheral wall portion 124, and a boss portion 125. The base main body portion 121 is formed on a lower side b of the motor base portion 120 in the direction of the axis x. The base main body portion 121 has a surface extending in the radial direction formed in a circular shape. The outer peripheral wall portion 124 is a cylindrical wall portion extending from an end of the outer peripheral side c of the base main body portion 121 to an upper side a in the direction of the axis x. A plurality of fixed vanes 123 are formed on the outer peripheral wall portion 124 of the motor base portion 120 on the exhaust port 122 side of the lower side b of the housing 10. The fixed vanes 123 connect the outer peripheral surface of the outer peripheral wall portion 124 to the inner peripheral surface of the air tunnel portion 112.

[0017] The boss portion 125 is a cylindrical portion that protrudes from the base main body portion 121 to the upper side a in the direction of the axis x at the center of the motor base portion 120. A hollow cylindrical bearing holder 17 made of metal (e.g., brass) is disposed in the boss portion 125. The bearing holder 17 is, for example, press-fitted into the boss portion 125. Note that in the fan device 1, the motor base portion 120 and the bearing holder 17 may be formed by integral molding, with the bearing holder 17 used as an insert material. The housing 10, including the motor base portion 120 and the fixed blades 123, is formed by integral molding using injection molding of synthetic resin (e.g., PBT resin).

[0018] The motor 20 and the impeller 25 are housed inside the air tunnel 112. The motor 20 is composed of a stator 13 and a rotor 24.

[0019] The stator 13 includes a circuit board 21, a stator core 18, an insulator 16, and a coil 19. The circuit board 21 is attached to a lower side b of the insulator 16 in the direction of the axis x.

[0020] Electronic components are mounted on a wiring pattern on the circuit board 21. The wiring pattern and the electronic components constitute a control circuit that controls the operation of the motor 20 in the fan device 1.

[0021] Stator core 18 is constructed by laminating multiple electromagnetic steel cores made of soft magnetic material. The core has an annular core back and multiple salient poles that radiate outward from the outer circumferential surface of the core back. Insulators 16 are attached to stator core 18 from both ends in the direction of axis x. A circular opening formed in the center of stator core 18 is fitted onto the outer circumferential surface of bearing holder 17. Stator core 18 may also be fixed to bearing holder 17 using an adhesive.

[0022] The coil 19 is wound around each salient pole of the stator core 18 via the insulator 16. End wires of the coil 19 are twisted and connected to terminal pins (not shown) embedded in the insulator 16. The terminal pins are electrically connected to the wiring pattern on the circuit board 21. The end wires of the coil 19 may also be electrically connected directly to the wiring pattern on the circuit board 21.

[0023] The rotor 24 includes a bushing 35 , a rotor yoke 40 , a magnet 26 , and a shaft 15 .

[0024] The bushing 35 is a circular member made of metal such as brass. The rotor yoke 40 is a cup-shaped member with a bottom connected to the bushing 35. The rotor yoke 40 is made of a soft magnetic material (e.g., a cold-rolled steel plate). The rotor yoke 40 has a circular bottom plate portion 411, a cylindrical side plate portion 412, and an inclined portion 413 formed between the bottom plate portion 411 and the side plate portion 412. A plurality of rotor yoke through holes 414 (for example, five in this embodiment) are formed in the inclined portion 413. The rotor yoke 40 is fixed to the bushing 35 by crimping the outer edge of the bushing 35, whereby the inner peripheral edge of a circular opening 415 formed in the center of the bottom plate portion 411 is fixed to the bushing 35.

[0025] Magnet 26 is an annular magnet arranged on the inner circumferential surface of side plate portion 412 of rotor yoke 40. Magnet 26 is arranged facing the outer circumferential surface of the salient pole of stator core 18 with a predetermined gap between them. Shaft 15 is arranged in the central portion of fan device 1 along axis x. Shaft 15 is coupled to bushing 35. Specifically, shaft 15 is press-fitted into shaft coupling hole 351, which is a circular through-hole formed in the center of bushing 35, and coupled to bushing 35.

[0026] The bearings 22 are mounted in pairs on the inner peripheral side d of the bearing holder 17. The bearings 22 rotatably support the shaft 15. A preload spring 221, which is a coil spring for applying a preload to the bearings 22, is interposed between the bushing 35 and one of the pair of bearings 22.

[0027] As described above, the impeller 25 includes the cup-shaped hub 27 with a bottom, and a plurality of blades 28 formed integrally with the hub 27 on the outer peripheral surface of the hub 27. The hub 27 and the blades 28 are integrally formed by injection molding of a synthetic resin (for example, PBT resin).

[0028] The hub 27 has an inclined portion 275 between the bottom wall 271 and the side wall 272. The side wall 272 is inclined so that the diameter gradually increases from the inclined portion 275 toward the lower end surface 273, allowing air to flow smoothly along the outer circumferential surface of the hub 27. The hub 27 is bonded to the outer circumferential surface of the rotor yoke 40 with an adhesive. The hub 27 may be integrally molded by inserting the rotor yoke 40. The hub 27 has multiple (five in this embodiment) hub through holes 274 formed in the inclined portion 275 between adjacent blades 28 in the circumferential direction. The hub through holes 274 communicate with rotor yoke through holes 414 formed in the inclined portion 413 of the rotor yoke 40. The hub through holes 274 and the rotor yoke through holes 414 have the same or substantially the same shape. That is, in the fan device 1, the hub through holes 274 and the rotor yoke through holes 414 function as an integrated through hole 29. An outer peripheral edge 291 of this through hole 29 is positioned so as to substantially coincide with the inner peripheral surface of the magnet 26 arranged on the inner peripheral surface of the rotor yoke 40 in the axial direction. In other words, an imaginary circle mo passing through the outer peripheral edge 291 of the through hole 29 is formed in a position overlapping with the inner peripheral surface 261 of the magnet 26 in the axial direction. Furthermore, an imaginary circle mi passing through the inner peripheral edge 292 of the through hole 29 is positioned so as to overlap with a portion of the coil 19 wound around each salient pole of the stator core 18 in the axial direction.

[0029] A lower end surface 273 of a side wall 272 of the hub 27 is located at a position a above the lower end surface of a side plate portion 412 of the rotor yoke 40 in the direction of the axis x. An upper end surface 129 of an outer peripheral wall portion 124 of the motor base portion 120 is located at a position a above the lower end surface 417 of the side plate portion 412 of the rotor yoke 40 in the direction of the axis x and faces the lower end surface 273 of the side wall 272 of the hub 27. In the cup-shaped hub 27, an annular gap is formed between the lower end surface 273 of the outermost periphery of the side wall 272 and the upper end surface 129 of the outer peripheral wall portion 124 of the motor base portion 120, the annular gap being centered on the axis x, in order to prevent interference between the hub 27 and the motor base portion 120. This gap functions as a ventilation portion G that connects the outer peripheral side c and the inner peripheral side d of the hub 27. In the fan device 1, the diameter D2 at the outermost edge of the side wall 272 of the hub 27 is set larger than the diameter D1 at the outermost edge of the outer wall portion 124 of the motor base portion 120, but the diameter D2 of the side wall 272 of the hub 27 may be approximately the same as the diameter D1 of the outer wall portion 124 of the motor base portion 120.

[0030] Next, the relationship between the area of the through-holes 29 (hub through-hole 274 and rotor yoke through-hole 414) in the fan device 1 and the temperature rise Δt of the coil 19 will be described.

[0031] In the fan device 1, when the radius of the inner peripheral edge of the outer peripheral wall portion 124 of the motor base portion 120 is R1 and the length of the ventilation portion G in the direction of the axis x is L1, the area Sh of the ventilation portion G is expressed as follows: Sh=R1×2π×L1 …(1) It is expressed as:

[0032] The total area of the through holes 29 (the sum of the areas of the plurality of through holes 29) Sa is expressed as follows, where Aa is the area of one through hole 29 and N is the number of through holes 29: Sa = Aa × N …(2) It is expressed as:

[0033] 3 is a graph showing the relationship between the area ratio (Sh / Sa) of the area of the ventilation section G to the total area Sa of the through holes 29 in the fan device 1 and the temperature rise Δt of the coil 19. In FIG. 3, the horizontal axis represents the number (N) of the through holes 29, and the vertical axis (axis 1) on the left represents the temperature rise (Δt) indicating the difference between the temperature of the coil 19 and room temperature. Also, in FIG. 3, the vertical axis (axis 2) on the right represents the area ratio (Sh / Sa) of the area Sh of the ventilation section G to the total area Sa of the through holes 29, derived from (1) and (2). In the fan device 1, when the area of the air flow path in the stator 13 is Sm and the length L2 of one side of the housing 10 is 40 mm, Sh and Sm are constant.

[0034] [Table 1]

[0035] Table 1 shows the relationship between the temperature rise Δt of the coil 19 in each of the hubs 27 having different numbers N of through holes 29 when the number N of circular through holes 29 is changed from 0 to 5 (changing the total area Sa of the through holes 29) in the fan device 1. Note that the number N of through holes 29 was set to a maximum of 5, taking into consideration the strength of the hub 27.

[0036] In the fan device 1, the relationship between Sa, Sh, and Sm is as follows: Sa <Sh<Sm is.

[0037] 3, it can be seen that increasing the number of through holes 29 (increasing the total area Sa of the through holes 29) in the fan device 1 increases the amount of air blown out from the inside of the hub 27 to the outside. Therefore, it can be seen that the fan device 1 can reduce the temperature rise Δt of the coil 19.

[0038] In particular, it can be seen that if the number of through holes 29 in the fan device 1 is set to two or more, i.e., the area ratio Sh / Sa is set to 18.78 or less, the temperature rise Δt of the coil 19 is reduced by approximately half compared to when no through holes 29 are provided (zero through holes). Furthermore, if the number of through holes 29 in the fan device 1 is preferably set to four or more, i.e., the area ratio Sh / Sa is set to 9.39 or less, the temperature rise Δt of the coil 19 can be reduced to less than 60°C. Therefore, the fan device 1 can effectively cool the components of the motor 20, such as the coil 19. Furthermore, the fan device 1 can lower the heat resistance temperature of the insulating coating of the magnet wire that makes up the coil 19.

[0039] FIG. 4 is a graph showing the relationship between the airflow characteristics (PQ characteristics) and the temperature rise Δt of the coil 19 in the fan device 1. In FIG. 4, the horizontal axis represents airflow (A), and the left vertical axis (axis 1) represents static pressure (P). Also, in FIG. 4, the right vertical axis (axis 2) represents the temperature rise (Δt) of the coil 19. FIG. 4 is a plot of the temperature rise Δt of the coil 19 at each airflow. As in FIG. 3, the temperature rise Δt of the coil 19 is the difference between the temperature of the coil 19 and room temperature. Note that FIG. 4 also shows the temperature rise Δt of the coil in a fan device without through holes 29 as a comparative example. In FIG. 4, the number N of through holes 29 formed in the hub 27 was set to 5 based on the results of Table 1 and FIG. 3. When the number N of through holes 29 is 5, the area ratio Sh / Sa is 7.51.

[0040] As shown in Figure 4, the temperature rise Δt of coil 19 in fan device 1 is low at the maximum static pressure and the maximum airflow, and there is a region in the airflow characteristics between the midstream region (approximately half the maximum airflow) and the maximum airflow where the temperature rise Δt of coil 19 is the highest. As shown in Figure 4, in fan device 1, the airflow region between the airflow when the temperature rise Δt of coil 19 reaches the highest temperature (maximum temperature) and the maximum airflow is referred to as region 1 for convenience. In addition, in fan device 1, the airflow region between the airflow when the temperature rise Δt of coil 19 reaches the highest temperature (maximum temperature) and the maximum static pressure is referred to as region 2 for convenience.

[0041] The operating point of the fan device 1 will now be explained. The intersection of the fan's airflow characteristics (PQ characteristic curve) and the pressure loss curve (system impedance) of the device that uses the fan is called the operating point. The operating point is generally an airflow range of several tens of percent around half the fan's maximum airflow. The fan is used to avoid the airflow range where surging occurs. In other words, the operating point of the fan device 1 is used within the second region in Figure 4.

[0042] FIG. 5 is a schematic diagram showing the airflow flowing inside the hub 27 when the fan device 1 has a maximum airflow rate. FIG. 6 is an enlarged view of the vicinity of the through-hole 29 in the schematic diagram shown in FIG. 5. FIGS. 5 and 6 are the results of a computer simulation using a simple model to schematically show the airflow flowing inside the hub 27 when the fan device 1 has a maximum airflow rate. In FIGS. 5 to 8, small arrows drawn around the hub 27 schematically show the airflow around the hub 27.

[0043] According to computer simulations shown in FIGS. 5 and 6, when the fan device 1 has a maximum airflow rate (static pressure is 0), airflow is drawn into the hub 27 of the impeller 25 through the through-hole 29 (at a location with an area Sa). The airflow then passes through an airflow passage inside the motor 20 and passes through a ventilation section G (see FIG. 2, at a location with an area Sh) formed by a gap between the lower end surface 273 of the hub 27 and the upper end surface 129 of the outer peripheral wall 124 of the base main body 121. The airflow that has passed through the ventilation section G is discharged to the outside of the housing 10 through the exhaust port 122 of the housing 10. Therefore, in the first region of the fan device 1, the airflow predominantly follows a path in which it is drawn into the hub 27 through the through-hole 29, passes through the airflow passage inside the motor 20, passes through the ventilation section G, and flows to the outside, as indicated by arrow Af1 in FIG. 5. In the first region of the fan device 1, the airflow Af1 has the fastest flow velocity at the maximum air volume.

[0044] Fig. 7 is a schematic diagram showing the airflow flowing inside hub 27 when the static pressure of fan device 1 is at its maximum. Fig. 8 is an enlarged view of the vicinity of through-hole 29 in the schematic diagram shown in Fig. 7. Figs. 7 and 8 are the results of a computer simulation using a simple model, similar to Figs. 5 and 6, in order to schematically show the airflow flowing inside hub 27 when the static pressure of fan device 1 is at its maximum.

[0045] According to a computer simulation of the simplified model shown in FIGS. 7 and 8, when the fan device 1 is at maximum static pressure (air volume is zero), airflow is drawn from the ventilation section G into the hub 27. The airflow then passes through the airflow path inside the motor 20 and is discharged to the outside through the through-holes 29. Therefore, in the second region of the fan device 1, the airflow predominantly follows a path indicated by the arrow Af2 in FIG. 7, in which the airflow is drawn from the ventilation section G into the hub 27, passes through the airflow path inside the motor 20, and flows to the outside through the through-holes 29. In the second region of the fan device 1, the airflow Af2 has the fastest flow velocity at maximum static pressure.

[0046] Therefore, in the fan device 1, at the airflow rate at which the temperature rise Δt of the coil 19 reaches the highest temperature (maximum temperature), there is essentially no airflow flowing inside the hub 27. In this state, heat is trapped inside the hub 27 of the fan device 1. As a result, in this state, it is thought that the temperature rise Δt of the coil 19 reaches the highest temperature in the fan device 1.

[0047] As shown in Figure 4, the fan device of the comparative example, which does not have through holes 29, consumes the most power and generates the most heat at maximum static pressure. On the other hand, according to the curve of the temperature rise Δt of coil 19 shown in Figure 4, fan device 1 is able to suppress the rise in temperature of coil 19 at maximum static pressure. As described above, in fan device 1, at maximum static pressure, airflow Af2 from ventilation section G on the lower end surface of hub 27 passes through through holes 29 and flows to the outside, and the airflow flowing inside hub 27 has the fastest flow velocity, which is thought to be why the inside of hub 27 is efficiently cooled by dissipating heat.

[0048] In fan device 1, the airflow Af2 flowing inside hub 27 in the second region is mainly drawn into hub 27 from ventilation section G, passes through an air flow path inside motor 20, and flows to the outside through through-holes 29. Since fan device 1 has a plurality of through-holes 29 (for example, five) formed in hub 27, it is possible to increase the amount of air blown out of hub 27. Furthermore, with fan device 1, it is possible to increase the amount of air blown out of hub 27, so that it is possible to efficiently dissipate heat from coil 19 and reduce the temperature inside hub 27.

[0049] Furthermore, the outer peripheral edge 291 of the through hole 29 is positioned so as to substantially coincide with the inner peripheral surface 261 of the magnet 26 disposed on the inner peripheral surface of the rotor yoke 40. Therefore, the airflow drawn into the hub 27 from the ventilation section G flows through the gap formed between the outer peripheral surfaces of the salient poles of the stator core 18 and the magnet 26, and is then smoothly guided to the through hole 29 and blown out of the hub 27. Furthermore, because the coil 19 is wound around the stator core 18 via the insulator 16, only the outer peripheral surfaces of the salient poles of the stator core 18 are exposed. Therefore, only the outer peripheral surfaces of the salient poles of the stator core 18 are the locations from which heat is dissipated to the outside. Because the airflow drawn into the hub 27 flows smoothly through the gap and is guided to the through hole 29, the outer peripheral surfaces of the salient poles of the stator core 18 are cooled, and the stator core 18 is efficiently cooled.

[0050] Furthermore, if the outer peripheral edge 291 of the through hole 29 is formed so as to be positioned inside (on the inner peripheral side) of the inner peripheral surface 261 of the magnet 26, when the air flow sucked into the hub 27 is guided into the through hole 29, part of the air flow sucked into the hub 27 will enter the corner portion 416 formed between the inclined portion 413 and the side plate portion 412 of the rotor yoke 40, making it easier for a circulating flow to occur, which may become a factor that hinders the air flow sucked into the hub 27 from being smoothly guided into the through hole 29.

[0051] If outer peripheral edge 291 of through hole 29 were formed so as to be positioned outside (toward the outer periphery) of the inner peripheral surface of magnet 26, this would not hinder the airflow sucked into hub 27 from being guided into through hole 29, but would come close to corner portion 416 formed between inclined portion 413 and side plate portion 412, making it difficult to form through hole 29. For this reason, outer peripheral edge 291 of through hole 29 is preferably positioned so as to substantially coincide with inner peripheral surface 261 of magnet 26 arranged on the inner peripheral surface of rotor yoke 40 in the axial direction.

[0052] Furthermore, the imaginary circle mi passing through the inner circumferential edge of the through hole 29 is positioned so as to overlap, in the axial direction, a portion of the coil 19 wound around each salient pole of the stator core 18. This promotes efficient heat dissipation from the coil 19.

[0053] In addition, those skilled in the art can appropriately modify the fan device of the present invention in accordance with conventionally known knowledge. As long as such modifications still include the configuration of the present invention, they are of course included in the scope of the present invention. [Explanation of symbols]

[0054] 1...fan device, 10...housing, 13...stator, 15...shaft, 16...insulator, 17...bearing holder, 18...stator core, 19...coil, 20...motor, 21...circuit board, 22...bearing, 24...rotor, 25...impeller, 26...magnet, 27...hub, 28...blade, 29...through hole, 35...bush, 40...rotor yoke, 111...intake port, 112...wind tunnel portion, 114...bolt insertion hole, 120...motor base portion, 121...base main body portion, 122...exhaust port, 123...fixed blade, 124...outer wall portion, 125...boss portion, 129...upper end surface, 221...preload spring, 261...inner circumferential surface, 271...bottom wall, 272...side wall, 273...lower end surface, 274... Hub through-hole, 275...inclined portion, 291...outer peripheral edge, 292...inner peripheral edge, 351...shaft coupling hole, 411...bottom plate portion, 412...side plate portion, 413...inclined portion, 414...rotor yoke through-hole, 415...opening, 416...corner portion, 417...lower end surface, G...ventilation portion, Sa...total area of multiple through-holes, Sh...area of ventilation portion, Sm...area of air flow path inside the motor, L1...axial length of ventilation portion, L2...length of one side of the housing, Af1, Af2...air flow, D1...diameter of the outermost peripheral edge of the outer wall portion of the motor base portion, D2...diameter at the outermost peripheral edge of the hub, R1...radius at the innermost peripheral edge of the outer wall portion of the motor base portion, Δt...temperature rise of the coil, mi, mo...imaginary circle

Claims

1. A cup-shaped hub and an impeller having a plurality of blades provided on the outer peripheral surface of the hub; a motor that rotates the impeller; a housing that accommodates the impeller; A fan device comprising: the housing has a motor base portion for disposing the motor on one end side in the axial direction, the motor base portion has a circular base portion, a bearing holder provided on the base portion for holding a bearing that rotatably supports a rotation shaft of the motor, and a cylindrical outer peripheral wall portion extending in an axial direction from an outer peripheral edge of the base portion, The hub has a plurality of through holes extending therethrough in the axial direction, a gap formed between a lower end surface of the hub in the axial direction and an upper end surface of the outer peripheral wall portion in the axial direction forms an annular ventilation portion around an axis defined by the gap; an operating point in an air volume region where airflow passing from the ventilation section through the plurality of through holes formed in the hub and flowing out to the outside of the hub is dominant; The area of ​​the ventilation section is Sh, The total area of ​​the plurality of through holes is Sa, When Sa<Sh and the value of Sh / Sa, which is the ratio of the area of ​​the ventilation portion to the total area of ​​the plurality of through holes, is less than 10; Fan device.

2. a rotor yoke having a bottomed cup shape, the rotor yoke having a circular bottom plate portion, a cylindrical side plate portion, and an inclined portion formed between the bottom plate portion and the side plate portion, and having an annular magnet on the inner peripheral surface of the side plate portion; the hub includes a bottom wall, a side wall, and an inclined portion between the bottom wall and the side wall, and is disposed on an outer peripheral surface of the rotor yoke; the through-hole is formed in the inclined portion of the hub and the inclined portion of the rotor yoke, An imaginary circle passing through the outer periphery of the through hole substantially coincides with the inner periphery of the magnet in the axial direction. The fan device according to claim 1 .

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