HK1111273B - Brushless fan motor - Google Patents

Description

Brushless fan motor

Technical Field

The present invention relates to a brushless fan motor and a double counter-rotating axial-flow blower constituted by two brushless fan motors.

Background

A brushless fan motor shown in japanese patent laying-open No. 2003-230246 (patent document 1) or the like includes a rotor, a stator disposed inside the rotor, and an impeller disposed outside the rotor. The rotor includes a rotor cover having a cylindrical portion and an end plate portion integrally provided at one end of the cylindrical portion and fixed to the rotating shaft, and a plurality of permanent magnet magnetic pole portions provided at an inner peripheral portion of the cylindrical portion. The impeller includes a plurality of blades and a cover member to which the plurality of blades are attached. The cover member has: the cover member is fitted to the rotor cover. In such a brushless fan motor, there is a problem that heat generated in the stator is discharged to the outside, particularly when the rotation speed of the rotor is increased.

As a structure for solving the above problem, japanese unexamined patent application publication No. 10-210727 (patent document 2) discloses a motor in which an end plate portion of a metallic rotor cover is partially raised to form a plurality of blades. In the motor, when the rotor rotates, external air is introduced into the rotor cover via the plurality of wing portions. The introduced external air is heated by heat generated from the stator and discharged to the outside. As a result of which the temperature in the motor drops,

patent document 1: japanese patent laid-open No. 2003-230246.

Patent document 2: japanese patent laid-open No. Hei 10-210727.

However, in the brushless fan motor having the double structure in which the cover member is fitted to the rotor cover, there is a problem in that the temperature of the rotor cover itself is difficult to decrease. In addition, in the structure in which the wing portions are formed on the rotor cover, if the assembling accuracy of the rotor cover and the stator and the forming accuracy of the coil portion of the stator are not improved, there is a possibility that the wing portions and the coil portion come into contact with each other. Therefore, it is necessary to secure a sufficient interval between the end plate portion of the rotor cover and the stator, which causes an obstacle to downsizing in the axial direction of the brushless fan motor.

Disclosure of Invention

The invention provides a brushless fan motor and a double counter-rotating axial-flow blower which do not require high assembly accuracy, can reduce the axial dimension, and can improve the cooling effect of a stator.

A brushless fan motor, which is an improved object of the present invention, has a rotor, a stator, and an impeller. The rotor includes a rotor cover having a cylindrical portion and an end plate portion integrally provided at one end of the cylindrical portion and fixed to the rotating shaft, and a plurality of permanent magnet magnetic pole portions provided on an inner peripheral portion of the cylindrical portion. The stator is disposed inside the rotor. The impeller has a plurality of blades; and a cover member fitted to the rotor cover and having the plurality of blades attached thereto. Further, the cover member has: a cylindrical peripheral wall portion having a plurality of blades attached to an outer peripheral portion thereof, and a bottom wall portion provided at one end of the peripheral wall portion and facing the end plate portion. In the present invention, a central through hole penetrating in the axial direction of the rotating shaft is formed in the central portion of the bottom wall portion of the cover member. Further, a plurality of wing portions having a shape allowing outside air to be introduced through the central through hole are formed at intervals in the circumferential direction of the peripheral wall portion on the inner wall portion of the bottom wall portion facing the end plate portion. The end plate portion is formed with a plurality of through holes that pass through the end plate portion in the axial direction at intervals in the circumferential direction, and the plurality of through holes are used to introduce outside air introduced from the central through hole into the rotor cover.

In the brushless fan motor of the present invention, when the rotor rotates, the outside air is introduced into the cover member through the central through hole of the cover member by the rotation of the plurality of wing members. The introduced outside air is introduced into the rotor cover through a plurality of through holes provided in the end plate portion of the rotor cover. The outside air introduced into the rotor cover is heated by heat generated by the stator, and then discharged to the outside, thereby cooling the stator. With this configuration, the outside air introduced into the cover member cools the end plate portion of the rotor cover and then cools the interior of the rotor cover, so that even when the cover member is fitted to the rotor cover, the interior of the rotor cover can be cooled after the rotor cover itself is partially cooled. Thus, according to the present invention, the double structure of the rotor cover and the cover member can solve the problem of the reduction of the cooling performance. Further, since only a plurality of through holes are formed in the rotor cover, high accuracy is not required for assembling the rotor and the stator. Thus, it is easy to manufacture. Further, since the wing portion does not protrude inside the rotor cover, there is no fear that the wing portion may damage the coil portion, and the size of the brushless fan motor in the axial direction can be reduced as much as possible.

When a plurality of blades are formed on the cover member of the impeller, the impeller may be formed by injection molding of synthetic resin or a cast product such as die casting of metal. Therefore, the plurality of fins can be formed in a desired shape that can exhibit a sufficient cooling effect, and the cooling effect of the stator can be improved.

The plurality of through holes are preferably provided at positions not opposed to the central through hole. This prevents dust and the like entering the impeller through the central through hole from directly entering the stator through the plurality of through holes.

The plurality of through holes are preferably provided at positions facing the coils of the stator. In this way, since the outside air introduced into the rotor cover through the plurality of through holes directly passes over the coils of the stator, the heat generated in the stator coils can be efficiently absorbed by the outside air, and the cooling performance can be improved.

The plurality of wing portions are formed at equal intervals in the circumferential direction of the peripheral wall portion, and the plurality of through holes are formed at equal intervals in the circumferential direction. In this case, the number of the plurality of wing portions is preferably larger than the number of the plurality of through holes so that the plurality of wing portions do not face the plurality of through holes. For example, the number of the plurality of wing portions may be one more than the number of the plurality of through holes, and the number of the plurality of wing portions is not a multiple of the number of the plurality of through holes. Thus, even if the cover member and the rotor cover are appropriately combined, the plurality of wing portions and the plurality of through holes do not all face (overlap) each other. As a result, the assembly is easy, and necessary external air can be reliably introduced into the rotor cover from the plurality of through holes.

The plurality of wing portions and the cover member are preferably integrally formed by injection molding or casting. In this way, the blades can be formed together when the impeller is formed, and in addition, the blades can be formed in a desired shape that can exhibit a sufficient cooling effect. Therefore, the cooling effect of the stator can be improved.

The double counter-rotating axial-flow blower, which is a modified object of the present invention, includes a 1 st single axial-flow blower and a 2 nd single axial-flow blower. The 1 st single axial flow blower includes: a 1 st brushless fan motor having an impeller; and a 1 st housing, the 1 st housing having an air tunnel with an intake-side opening portion on one side in an axial direction of a rotation shaft of the 1 st brushless fan motor and a discharge-side opening portion on the other side in the axial direction. The impeller rotates in the suction-side opening. The 2 nd single axial flow blower includes: a 2 nd brushless fan motor having an impeller; and a 2 nd housing, the 2 nd housing having an air tunnel having an intake-side opening portion on one side in an axial direction of a rotation shaft of the 2 nd brushless fan motor and a discharge-side opening portion on the other side in the axial direction. The impeller rotates in the discharge-side opening. Further, the 1 st casing of the 1 st axial-flow blower and the 2 nd casing of the 2 nd axial-flow blower may be combined by a coupling structure. The 1 st and 2 nd brushless fan motors have a rotor, a stator, and an impeller. The rotor includes a rotor cover having a cylindrical portion and an end plate portion integrally provided at one end of the cylindrical portion and fixed to the rotating shaft, and a plurality of permanent magnet magnetic pole portions provided on an inner peripheral portion of the cylindrical portion. The stator is disposed inside the rotor. The impeller has a plurality of blades; and a cover member fitted to the rotor cover and to which the plurality of blades are attached. The cover member has: a cylindrical peripheral wall portion having a plurality of blades attached to an outer peripheral portion thereof, and a bottom wall portion provided at one end of the peripheral wall portion and facing the end plate portion. The 1 st brushless fan motor is disposed so that the bottom wall portion of the cover member is positioned in the suction-side opening, and the 2 nd brushless fan motor is disposed so that the bottom wall portion of the cover member is positioned in the discharge-side opening. In the present invention, a central through hole penetrating in the axial direction of the rotating shaft is formed in the central portion of the bottom wall portion of the cover member of the 1 st brushless fan motor. Further, in the inner wall portion of the bottom wall portion of the 1 st brushless fan motor facing the end plate portion, a plurality of wing portions are formed at intervals in the circumferential direction of the peripheral wall portion, and the plurality of wing portions have a shape capable of introducing the outside air through the central through hole. Further, the end plate portion of the 1 st brushless fan motor has a plurality of through holes formed therein at intervals in the circumferential direction, the through holes penetrating the end plate portion in the axial direction, and the plurality of through holes are used for introducing the outside air introduced from the central through hole into the rotor cover.

In the double counter-rotating axial-flow fan according to the present invention, when the rotor rotates, the outside air introduced through the central through-hole of the cover member by the plurality of blades of the 1 st brushless fan motor is introduced into the rotor cover through the plurality of through-holes. Thereby, heat generated by the stator of the 1 st brushless fan motor is discharged to the outside, and the stator is cooled. In the dual counter-rotating axial-flow blower, since the rotational speed of the 1 st brushless fan motor is generally faster than the rotational speed of the 2 nd brushless fan motor, the stator of the 1 st brushless fan motor is likely to be at a high temperature. Therefore, in the present invention, the stator of the 1 st brushless fan motor of the double counter-rotating axial flow blower can be efficiently cooled, and the performance of the double counter-rotating axial flow blower can be improved.

Preferably, a central through hole penetrating in the axial direction of the rotary shaft is formed in the central portion of the bottom wall portion of the cover member of the 2 nd brushless fan motor, and a plurality of through holes penetrating in the axial direction are formed in the end plate portion of the 2 nd brushless fan motor at intervals in the circumferential direction. In this way, the outside air generated by the rotation of the 1 st brushless fan motor passes through the rotor cover of the 2 nd brushless fan motor, and then flows to the outside through the plurality of through holes. Therefore, the stator of the 2 nd brushless fan motor can be cooled. In this case, the plurality of through holes are preferably provided at positions not opposed to the central through hole. Thus, the stator coil cannot enter the stator from the outside through the central through hole, and therefore, the stator coil is not damaged by an external invasion object during the assembly of the blower into the device.

The 1 st and 2 nd brushless fan motors each have a bearing holder made of metal, and a bearing for supporting and freely rotating the rotary shaft is accommodated in the bearing holder, and the axial-flow blower of the 1 st and 2 nd units is preferably combined in a state where the bearing holder of the 1 st brushless fan motor and the bearing holder of the 2 nd brushless fan motor are in heat-transmittable contact with each other. In this way, heat generated by the stator of the 1 st brushless fan motor is transferred from the bearing holder of the 1 st brushless fan motor to the bearing holder of the 2 nd brushless fan motor. Therefore, the cooling effect of the stator of the 1 st brushless fan motor can be further improved.

Effects of the invention

According to the present invention, the outside air introduced into the cover member cools the end plate portion of the rotor cover, and then cools the inside of the rotor cover. Therefore, even if the cover member is fitted to the rotor cover, the inside of the rotor cover can be cooled after the rotor cover itself is locally cooled. Therefore, according to the present invention, the dual structure of the rotor cover and the cover member can solve the problem of the reduction of the cooling performance. Further, since the rotor cover is formed with only a plurality of through holes, high accuracy is not required in assembling the rotor and the stator, and manufacturing is easy. Further, since the wing portion does not protrude inside the rotor cover, there is no concern that the wing portion may damage the coil portion, and there is an advantage that the axial dimension of the brushless fan motor can be reduced to the extent possible.

Drawings

Fig. 1 is a sectional view of a brushless fan motor according to an embodiment of the present invention.

Fig. 2 is a top view of the rotor cover as seen from the right side facing fig. 1.

Fig. 3 is a rear view of the impeller as seen from the left side facing fig. 1.

Fig. 4 is a cross-sectional view of a half of the double counter-rotating axial-flow blower according to the embodiment of the present invention.

Description of the symbols

1-cover part, 3-stator, 5-rotor, 7-impeller, 17-rotation axis, 19-rotor cover, 21-permanent magnet magnetic pole part, 23-cylindrical part, 25-end plate part, 25 a-through hole, 27-cover part, 29-blade, 31-peripheral wall part, 33-bottom wall part, 33 a-central through hole, 35-wing part, 151-1 st monomer axial flow blower, 153-2 nd monomer axial flow blower, 155-1 st shell, 157-1 st brushless fan motor, 181-2 nd shell, 183-2 nd brushless fan motor, 101a, 201 a-bearing holder.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a sectional view of a brushless fan motor according to an embodiment of the present invention. As shown in fig. 1, the brushless fan motor of this embodiment includes a cover member 1, a stator 3, a rotor 5, and an impeller 7. The cover member 1 has: a bearing holder 1a in which two bearings 8 for supporting and freely rotating a rotary shaft 17 of a rotor 5 described later are accommodated; a plate-like portion 1b connected to the bearing holder 1a and extending in the radial direction of the rotating shaft 17; and an outer tube portion 1c extending from the outer end of the plate-shaped portion 1b along the bearing holder 1a in the direction of the center line of the bearing holder 1 a. The bearing holder 1a is formed of brass. The plate-shaped portion 1b and the outer tube portion 1c are integrally formed by resin.

The stator 3 includes a core 9 formed by stacking a plurality of steel plates. The core 9 has a plurality of protruding pole portions 9a arranged in the circumferential direction. Further, a coil 11 is wound around each of the projecting pole portions 9 a. These projecting pole portions 9a function as stator poles by exciting the coils 11.

A circuit board 13 is fixed to the cover member 1 and the stator 3. A plurality of electronic components constituting a control circuit for controlling the current flowing through the coil 11 are mounted on the back surface of the circuit board 13 facing the plate-shaped portion 1b of the cover member 1. The control circuit on the circuit board 13 and the coil 11 are electrically connected by winding the lead wire of the coil 11 around a terminal pin 15 which is inserted through a through hole of the circuit board 13 and soldered to an electrode on the circuit board 13.

The rotor 5 includes a rotating shaft 17, a rotor cover 19, and a plurality of permanent magnet magnetic pole portions 21. As shown in fig. 1 and 2, the rotor cover 19 is integrally provided with a cylindrical portion 23 and an end plate portion 25, the end plate portion 25 is integrally provided at one end of the cylindrical portion 23 and fixed to the rotary shaft 17, and the rotor cover 19 is formed by press working a steel plate made of a magnetically permeable material. Fig. 2 is a plan view of the rotor cover 19 viewed from the right side in fig. 1. A plurality of permanent magnet magnetic pole portions 21 are provided on the inner peripheral portion of the cylindrical portion 23 of the rotor cover 19 so as to face the projecting pole portion 9 a. The end plate portion 25 of the rotor cover 19 is formed with 4 through holes 25a penetrating in the axial direction of the rotary shaft 17. The 4 through holes 25a are formed at equal intervals on a virtual circle concentric with the rotation shaft 17.

As shown in fig. 1 and 3, the impeller 7 is configured to integrally include a cover member 27 and 7 blades 29 attached to the cover member 27. In the present embodiment, the impeller 7 is formed by injection molding a synthetic resin material. Fig. 3 is a rear view of the impeller 7 as viewed from the left side in fig. 1. The cover member 27 has: a cylindrical peripheral wall portion 31 having 7 blades 29 attached to an outer peripheral portion thereof; and a bottom wall 33 provided at one end of the peripheral wall 31 and facing the end plate 25 of the rotor cover 19, wherein the cover member 27 is fitted to the rotor cover 19. A central through hole 33a penetrating in the axial direction of the rotary shaft 17 is formed in the central portion of the bottom wall portion 33. The 4 through holes 25a and the central through hole 33a of the rotor cover 19 are provided at positions not facing each other. In other words, 4 through holes 25a are formed at positions facing the bottom wall portion 33.

An annular step portion 27a is formed between the bottom wall portion 33 and the peripheral wall portion 31. Further, 5 wing portions 35 are formed on an inner wall portion of the bottom wall portion 33 facing the end plate portion 25. These wing portions 35 are different in number (5) from the number (4) of the through holes 25 a. The 5 wing portions 35 have a shape that allows outside air to be introduced through the central through hole 33a, and are formed at equal intervals in the circumferential direction of the peripheral wall portion 31. Specifically, the 5 wing portions 35 are inclined and curved so as to be gradually separated from a radial virtual line extending from the axis of the rotary shaft 17 toward the peripheral wall portion 31. Further, the wing portions 35 extend from the step portions 27a toward the edge of the central through hole 33a, respectively.

In the brushless fan motor of this embodiment, when the rotor 5 rotates, the outside air introduced through the central through hole 33a of the cover member 27 by the rotation of the 5 wing portions 35 is introduced into the rotor cover 19 through the 4 through holes 25 a. Thereby, heat generated by the stator 3 is released by the outside air, and the stator 3 is cooled. In this example, since 5 fins 35 are formed on the cover member 27 of the impeller 7, when the impeller 7 is formed by injection molding using a synthetic resin material, the fins 35 can be formed together, and in addition, the 5 fins 35 can be formed in a desired shape that can exhibit a sufficient cooling effect. Therefore, the cooling effect of the stator 3 can be improved.

Fig. 4 is a cross-sectional view of a half of an embodiment of a double counter-rotating axial-flow blower according to the present invention using a brushless fan motor according to the present invention. The double counter-rotating axial-flow fan of the present embodiment is configured by combining the 1 st individual axial-flow fan 151 and the 2 nd individual axial-flow fan 153 with a coupling structure. The 1 st individual axial-flow blower 151 includes: the 1 st case 155; and a 1 st brushless fan motor 157 disposed in the 1 st housing 155. The 1 st housing 155 is provided with an annular suction-side flange 159 on one side in the direction in which the axis a extends (axial direction), and an annular discharge-side flange 161 on the other side in the axial direction. Further, the 1 st housing 155 is provided with a cylindrical portion 163 between the two flanges 159 and 161. The flange 159, the flange 161, and the internal space of the cylindrical portion 163 form an air tunnel. The suction-side flange 159 has a substantially square outline shape and has a suction-side opening 165 therein. The discharge-side flange 161 also has a substantially square outline shape, and has a discharge-side opening 167 therein. Further, 3 webs 169 are provided in the discharge-side opening 167, which are arranged at equal intervals in the circumferential direction and extend in the radial direction (radially). The 1 st brushless fan motor 157 is fixed to the 1 st housing 155 by the 3 webs 169. The 3 webs 169 are combined with 3 webs 193, which will be described later, of the 2 nd individual axial-flow fan 153, respectively, to form 3 stationary blades.

The number of blades of the 1 st brushless fan motor 157 is 7. The 1 st brushless fan motor 157 has the same configuration as the brushless fan motor shown in fig. 1 except for the number of blades. Therefore, the structure of the 1 st brushless fan motor 157 is indicated by the reference numeral 100 added to the reference numeral of the brushless fan motor shown in fig. 1, and the description thereof is omitted. Therefore, 4 through holes 125a penetrating in the axial direction of the rotary shaft 117 are formed in the end plate portion 125 of the 1 st brushless fan motor 157. A central through hole 133a penetrating in the axial direction of the rotary shaft 117 is formed in the central portion of the bottom wall portion 133. On an inner wall portion of the bottom wall portion 133 facing the end plate portion 125, 5 wing portions 135 are formed.

In addition, the 1 st housing 155 is integrated with the cover member 101 of the 1 st brushless fan motor 157 in a state where the 3 webs 169 of the 1 st housing 155 are coupled to the outer cylindrical portion 101c of the 1 st brushless fan motor 157. The 1 st brushless fan motor 157 is disposed such that the bottom wall 133 of the cover member 127 is positioned in the suction-side opening 165.

The 1 st brushless fan motor 157 rotates counterclockwise at a speed higher than the rotational speed of the 2 nd brushless fan motor 183 described later in a state viewed from the 1 st single axial flow fan 151 side (a state viewed from the left side in fig. 4).

The 2 nd individual axial-flow blower 153 includes: a 2 nd case 181; and a 2 nd brushless fan motor 183 disposed in the 2 nd case 181. The 2 nd casing 181 has a suction-side flange 185 provided on one side in the direction in which the axis a extends (axial direction), and a discharge-side flange 187 provided on the other side in the axial direction a. Further, the 2 nd housing 181 has a cylindrical portion 189 between the two flanges 185 and 187. Further, an air tunnel is formed by the inner spaces of flange 185, flange 187, and cylindrical portion 189. The suction-side flange 185 has a substantially square outline and has a suction-side opening 191 therein. The discharge-side flange 187 also has a substantially square outline shape and has a discharge-side opening 195 therein. In the suction-side opening 191, 3 webs 193 are provided, which are arranged at equal intervals in the circumferential direction and extend in the radial direction. The 2 nd brushless fan motor 183 is fixed to the 2 nd housing 181 by the 3 webs 193. The 3 webs 193 are combined with the 3 webs 169 of the 1 st individual axial flow fan 151, respectively, to form 3 stationary blades.

In the double counter-rotating axial-flow fan of this embodiment, the 1 st axial-flow fan 151 and the 2 nd axial-flow fan 153 can be combined by fitting the hooks 181a of the 2 nd casing 181 of the 2 nd axial-flow fan 153 into the fitting grooves 151a of the 1 st axial-flow fan 151. The structure of such a combination can be obtained by a known method as shown in Japanese patent laid-open No. 2004-278371 and the like.

The 2 nd brushless fan motor 183 rotates in a clockwise direction, in other words, in a direction opposite to the rotation direction of the 1 st brushless fan motor 157 in a state viewed from the 1 st single axial flow blower 151 side (a state viewed from the left side facing fig. 4). As described above, the 2 nd brushless fan motor 183 rotates at a speed slower than the rotation speed of the 1 st brushless fan motor 157.

The 2 nd brushless fan motor 183 has the same structure as the brushless fan motor shown in fig. 1 except for the impeller. Therefore, the 2 nd brushless fan motor 183 is indicated by the reference numeral 200 added to the reference numeral of the brushless fan motor shown in fig. 1, and its description is omitted.

The impeller 207 of the 2 nd brushless fan motor 183 is integrally provided with a cover member 227 and 5 blades 229 attached to the cover member 227, and is formed by injection molding a synthetic resin made of ABS/PBT. The 5 blades 229 have a shape that allows air to flow from left to right in fig. 4 when rotated in a clockwise direction when viewed from the 1 st individual axial-flow fan 151 (when viewed from the left in fig. 4). The cover member 227 has: a cylindrical peripheral wall 231 having 5 blades 229 attached to the outer peripheral portion thereof; and a bottom wall 233 provided at one end of the peripheral wall 231 and facing the end plate 225 of the rotor cover 219, and the cover member 227 is fitted to the rotor cover 219. A central through hole 233a penetrating in the axial direction of the rotary shaft 217 is formed in the central portion of the bottom wall 233. The 4 through holes 225a and the central through hole 233a of the rotor cover 219 are provided at positions not facing each other. The bottom wall 233 is not formed with a wing. The 2 nd brushless fan motor 183 is disposed such that the bottom wall 233 of the cover member 227 is positioned in the suction-side opening 195.

In a state where the 1 st unit axial flow blower 151 and the 2 nd unit axial flow blower 153 are combined, the plate-shaped portion 101b of the 1 st brushless fan motor 157 is in contact with the plate-shaped portion 201b of the 2 nd brushless fan motor 183. Thus, the end of the bearing holder 101a of the 1 st brushless fan motor 157 and the end of the bearing holder 201a of the 2 nd brushless fan motor 183 are in heat-transferable contact.

In the double counter-rotating axial-flow fan of this embodiment, when the rotor 105 of the 1 st brushless fan motor 157 rotates, the outside air introduced through the central through-hole 133a of the cover member 121 via the wing 135 of the 1 st brushless fan motor 157 is introduced into the rotor cover 119 through the through-hole 125 a. Thereby, heat generated by stator 103 of 1 st brushless fan motor 157 is discharged to the outside, and stator 103 is cooled. In the double-counter-rotating axial-flow blower, since the rotation speed of the 1 st brushless fan motor 157 is generally faster than the rotation speed of the 2 nd brushless fan motor 183, the stator 103 of the 1 st brushless fan motor 157 is likely to be at a high temperature. For this reason, in the present invention, the stator 103 of the 1 st brushless fan motor 157 of the dual counter-rotating axial-flow blower can be efficiently cooled. In particular, in the present invention, since the fins 135 are formed on the cover member 127 of the impeller 107, and the impeller 107 can be formed by a casting product such as injection molding of synthetic resin or die casting of metal, the fins 135 can be formed in a desired shape that can exhibit a sufficient cooling effect. Thus, the cooling effect of the stator 103 can be improved.

Further, since the center through-hole 233a is formed in the center portion of the bottom wall portion 233 of the cover member 227 of the 2 nd brushless fan motor 183 and the through-hole 225a is formed in the end plate portion 225 of the 2 nd brushless fan motor 183, the external air generated by the rotation of the 1 st brushless fan motor 157 passes through the rotor cover 219 of the 2 nd brushless fan motor 183 and then flows to the outside through the through-hole 225 a. Therefore, stator 203 of 2 nd brushless fan motor 183 can be cooled.

Further, since the end of the bearing holder 101a of the 1 st brushless fan motor 157 is in heat-transmittable contact with the end of the bearing holder 201a of the 2 nd brushless fan motor 183, heat generated in the stator 103 of the 1 st brushless fan motor 157 is transmitted from the bearing holder 101a of the 1 st brushless fan motor 157 to the bearing holder 201a of the 2 nd brushless fan motor 183. Accordingly, the cooling effect of the stator 103 of the 1 st brushless fan motor 157 can be further improved.

Claims (8)

1. A brushless fan motor, comprising:

a rotor including a rotor cover having a cylindrical portion and an end plate portion integrally provided at one end of the cylindrical portion and fixed to a rotating shaft, and a plurality of permanent magnet magnetic pole portions provided on an inner peripheral portion of the cylindrical portion;

a stator disposed inside the rotor; and

an impeller having a plurality of blades and a cover member fitted to the rotor cover and having the plurality of blades attached thereto,

the cover member has: a cylindrical peripheral wall portion having the plurality of blades attached to an outer peripheral portion thereof, and a bottom wall portion provided at one end of the peripheral wall portion and opposed to the end plate portion,

a central through hole penetrating in an axial direction of the rotary shaft is formed in a central portion of the bottom wall portion of the cover member,

a plurality of wing portions having a shape allowing outside air to be introduced through the central through hole are formed at equal intervals in a circumferential direction of the peripheral wall portion on an inner wall portion of the bottom wall portion facing the end plate portion,

a plurality of through holes penetrating the end plate portion in the axial direction are formed in the end plate portion at equal intervals in the circumferential direction, the plurality of through holes being configured to introduce outside air introduced from the central through hole into the rotor cover,

the number of the plurality of wing portions is larger than the number of the plurality of through holes so that the plurality of wing portions do not face the plurality of through holes.

2. The brushless fan motor of claim 1,

the plurality of through holes are provided at positions not opposed to the central through hole.

3. The brushless fan motor of claim 2,

the plurality of through holes are provided at positions facing the coils of the stator.

4. The brushless fan motor of claim 1,

the plurality of wing portions and the cover member are integrally formed by injection molding or casting.

5. A dual counter-rotating axial flow blower comprising:

a 1 st single axial flow fan including a 1 st brushless fan motor having an impeller and a 1 st casing, the 1 st casing having an air tunnel having a suction-side opening portion on one side in an axial direction of a rotation shaft of the 1 st brushless fan motor and a discharge-side opening portion on the other side in the axial direction, the impeller rotating in the suction-side opening portion; and

a 2 nd single axial-flow fan including a 2 nd brushless fan motor having an impeller and a 2 nd casing, the 2 nd casing having an air tunnel having a suction-side opening portion on one side in the axial direction of a rotation shaft of the 2 nd brushless fan motor and a discharge-side opening portion on the other side in the axial direction, the impeller rotating in the discharge-side opening portion,

the 1 st shell of the 1 st single axial flow blower and the 2 nd shell of the 2 nd single axial flow blower are combined together through a combination structure,

the 1 st and 2 nd brushless fan motors include:

a rotor including a rotor cover having a cylindrical portion and an end plate portion integrally provided at one end of the cylindrical portion and fixed to a rotating shaft, and a plurality of permanent magnet magnetic pole portions provided on an inner peripheral portion of the cylindrical portion;

a stator disposed inside the rotor; and

an impeller having a plurality of blades and a cover member fitted to the rotor cover and having the plurality of blades attached thereto,

the cover member has: a cylindrical peripheral wall portion having the plurality of blades attached to an outer peripheral portion thereof, and a bottom wall portion provided at one end of the peripheral wall portion and opposed to the end plate portion,

the 1 st brushless fan motor is disposed so that the bottom wall portion of the cover member is positioned at the suction-side opening portion, the 2 nd brushless fan motor is disposed so that the bottom wall portion of the cover member is positioned at the discharge-side opening portion,

the double counter-rotating axial-flow blower is characterized in that,

a central through hole penetrating in an axial direction of the rotating shaft is formed in a central portion of the bottom wall portion of the cover member of the 1 st brushless fan motor,

a plurality of wing portions having a shape allowing external air to be introduced through the central through hole are formed at equal intervals in a circumferential direction of the peripheral wall portion on an inner wall portion of the bottom wall portion of the 1 st brushless fan motor facing the end plate portion,

a plurality of through holes penetrating the end plate portion in the axial direction are formed in the end plate portion of the 1 st brushless fan motor at equal intervals in the circumferential direction, the plurality of through holes being configured to introduce outside air introduced from the central through hole into the rotor cover,

the number of the plurality of wing portions is larger than the number of the plurality of through holes so that the plurality of wing portions do not face the plurality of through holes.

6. The double counter-rotating axial-flow blower according to claim 5,

a central through hole penetrating in an axial direction of the rotating shaft is formed in a central portion of the bottom wall portion of the cover member of the 2 nd brushless fan motor,

a plurality of through holes penetrating the end plate portion in the axial direction are formed in the end plate portion of the 2 nd brushless fan motor at intervals along the circumferential direction.

7. The double counter-rotating axial-flow blower according to claim 6,

the plurality of through holes of the 2 nd brushless fan motor are provided at positions not opposed to the central through hole of the 2 nd brushless fan motor.

8. The double counter-rotating axial-flow blower according to claim 5,

the 1 st and 2 nd brushless fan motors each have a bearing holder made of metal, the bearing holder accommodating therein a bearing that supports the rotary shaft and allows it to freely rotate,

the 1 st and 2 nd single axial flow fans are combined in a state where the bearing holder of the 1 st brushless fan motor and the bearing holder of the 2 nd brushless fan motor are in heat-transferable contact with each other.