JP4106343B2 - Electric blower and electric device provided with the electric blower - Google Patents

Description

  The present invention relates to an electric blower and an electric device such as a vacuum cleaner provided with the electric blower.

  FIG. 1 of Patent Document 1 shows an example in which a switching element is provided in close contact with the outer periphery of a motor casing in a space formed by a step between the outer peripheral portion of the motor casing and the outer peripheral portion of the fan casing.

  According to FIG. 3 of Patent Document 2, there is shown an example in which a package including a control / drive integrated circuit board is attached to a casing in a region where air from a diffuser directly hits on the fan side of a partition plate.

JP-A-6-26494 (FIG. 1) JP-A-6-261847 (FIG. 3)

  In the electric blower shown in FIG. 1 of Patent Document 1, the switching element is provided on the outer periphery of the motor casing. However, since it is attached to the outer periphery of the motor casing close to the stator, it is greatly affected by the heat generated from the stator, so the cooling effect is low. Furthermore, the outer periphery of the motor casing has been subjected to various types of processing for various purposes, and since the outer peripheral surface shape is a curved surface, the degree of freedom of arrangement of the switching elements is small, It is difficult to bring the motor casing into close contact. Such a malfunction also causes an increase in cost. In particular, in a brushless motor having a plurality of power devices to be cooled, these problems become significant.

  On the other hand, in the electric blower shown in FIG. 3 of Patent Document 2, a package including a control / drive integrated circuit board is arranged in the air path between the fan and the motor. However, if the package is arranged in such an air passage, the air passage loss increases, and the efficiency of the electric blower decreases. In particular, in a brushless motor or the like provided with a plurality of power devices that are desired to be cooled, the internal air path becomes complicated and the air path loss increases.

  Accordingly, an object of the present invention is to enable efficient cooling of power devices such as switching elements without increasing air path loss.

The electric blower of the present invention is an electric blower comprising a motor, a centrifugal fan attached to a rotating shaft of the motor, and a case for housing the motor and the centrifugal fan, wherein the case houses the motor. Motor case, a fan cover that covers the centrifugal fan and has a larger outer periphery than the outer periphery of the motor case, and a connecting portion that connects the motor case and the fan cover, the connecting portion, Formed by a part of the connecting member which is a separate member from the motor case and the fan cover, which is a part of a partition wall forming a flow path between the discharge port of the centrifugal fan and the motor, wherein and the inside of the fan cover has a ventilation hole for communicating within said motor case, interval of forming the power device the connection member It was placed in surface contact with the outer surface.

  Therefore, by disposing the power device on the outer surface of the partition wall that forms the flow path between the discharge port of the centrifugal fan and the motor, the air flow loss in the flow path inside the case is not disturbed by the power device. In addition, the power device can be efficiently cooled without being affected by the heat of the motor part because it is located upstream of the motor part in the air flow by the centrifugal fan. Become.

  According to the present invention, power devices such as switching elements can be efficiently cooled without increasing the air path loss of the electric blower.

A configuration example underlying the implementation of the present invention will be described with reference to FIGS. 1 is a side view showing a part of the configuration of the electric blower of the present embodiment, FIG. 2 is a plan view showing a part of the internal configuration, FIG. 3 is a plan view and a bottom view showing a diffuser configuration example, FIG. 4 is a schematic circuit diagram showing a drive circuit of the electric blower.

The electric blower 1 of the present configuration example schematically includes a motor 2, a centrifugal fan 4 attached to a rotor shaft 3 that is a rotation shaft of the motor 2, and a case for housing the motor 2 and the centrifugal fan 4. 5.

Here, the motor 2 of this configuration example shows an example of a motor with a brush, and is housed in a motor case 6. The front end side of the motor case 6 is an opening 7, and a long plate-like bracket 8 is bridged in the diametrical direction of the motor case 6 so as to cover a part of the opening 7. Are attached by screws 9. Therefore, the opening 7 not covered by the bracket 8 becomes the ventilation hole 10. The bracket 8 protrudes in a substantially cylindrical shape toward the front (centrifugal fan 4 side), houses the bearing 11a on the inner peripheral side, and is formed with a through hole 12 for the rotor shaft 3 in the approximate center. A bearing storage portion 13a is provided.

  A diffuser 14 is fixed to the front side of the bracket 8. Further, a centrifugal fan 4 is disposed in front of the diffuser 14. A fan cover 15 is fitted (connected) to the outer peripheral portion of the motor case 6, and the centrifugal fan 4 and the diffuser 14 are covered by the fan cover 15. The fan cover 15 has a suction opening 16 opposed to the ventilation port 17 of the centrifugal fan 4 at the center of the front surface, and a rear opening (not shown) is formed on the entire rear surface. Is formed. The motor case 6 and the fan cover 15 constitute a case 5. Here, the fan cover 15 has a larger outer peripheral size in the centrifugal direction than the motor case 6 (large outer periphery). The upper end portion of the motor case 6 (when the fan cover 15 is in the upward direction when viewed from the motor case 6) and the lower end portion of the fan cover 15 are connected by a connecting portion 18.

  On the other hand, the motor 2 includes a stator 19 fixed to the motor case 6 and a rotor 20 arranged inside the stator 19. Then, both end portions of the rotor shaft 3 at the center of the rotor 20 are rotatably supported by bearings 11a and 11b. Further, an air outlet (not shown) as an exhaust port is formed in the peripheral surface near the rear surface of the motor case 6 so as to be positioned substantially in the radial direction. Further, the rear surface side in the axial direction of the motor case 6 is closed in a bottomed shape by the rear plate portion 21, and the central portion of the rear plate portion 21 protrudes in a substantially cylindrical shape toward the rear, and the inner peripheral surface side. A bearing housing portion 13b for housing the bearing 11b is provided.

  Here, a configuration example of the diffuser 14 will be described with reference to FIG. As shown in FIG. 3A, the diffuser 14 includes a substantially disc-shaped disc portion 81, a through-hole 82 formed substantially at the center of the disc portion 81 through which the rotor shaft 3 passes, and the bracket 8. Screw holes 83a and 83b for fixing to the outer periphery of the centrifugal fan 4, a plurality of arcuate blades 84 provided near the outer peripheral edge of the diffuser 14 so as to be positioned on the outer periphery of the centrifugal fan 4, and FIG. And a plurality of arcuate blades 85 provided in a spiral shape on the back surface, which is the other surface side of the disk portion 81. Then, the diffuser 14 is fitted into the connecting portion 18 of the case 5 and is fixed to the bracket 8 with a screw.

  In such a configuration, when the rotor shaft 3 rotates, the centrifugal fan 4 rotates together with the rotation, and suctioned air is sucked from the suction opening 16 formed on the front side of the fan cover 15 by this rotation. Through the discharge port 22. The air flows so as to spread in the axial direction between the arcuate blades 84 along the inner peripheral surface of the fan cover 15. Next, the air flows spirally between the arcuate blades 85 toward the center of the diffuser 14 on the back surface of the disc portion 81. In this way, the diffuser 14 uniformly rectifies the air blown from the discharge port 22 of the centrifugal fan 4 and guides it to the motor 2.

  On the other hand, as shown in FIG. 4, the electric blower 1 is connected to a commercial AC power supply 24 via a switching element 23 for power control. An electric blower control unit 26 composed of a microcomputer 25 or the like is connected to the gate of the switching element 23. The switching element 23 and the electric blower control unit 26 are mounted on a circuit board 27. Further, an operation unit 28 for selecting start, stop or electric power of the electric blower 1 is connected to the electric blower control unit 26. Thus, the drive circuit 27a is comprised by the switching element 23, the electric blower control part 26, etc.

In such a configuration, in this configuration example , the switching element 23 as a power device included in the drive circuit 27 a forms a flow path 29 between the discharge port 22 of the centrifugal fan 4 and the motor 2. The partition wall, specifically, is arranged on the outer surface of the connecting portion 18 formed by the flat portion, and is fixed by, for example, a screw 30.

  According to such a mounting structure of the switching element 23, a part of the case 5 (the connecting portion 18) is connected to the discharge port 22 of the centrifugal fan 4 and the upper end portion of the motor 2 (the centrifugal fan 4 of the electric blower 1 shown in FIG. 1). (I.e., the direction of the upper side), that is, a partition that forms a flow path between the end of the centrifugal fan 4 and the switching element 23 is not disposed in the flow path 29. Since it is arrange | positioned on the outer surface of such a partition which is a part of case 5, the airflow in the flow path inside case 5 is not disturbed. Therefore, the heat of the switching element 23 can be released to the case 5 without increasing the flow path loss of the electric blower 1 by the switching element 23. In addition, the connecting portion 18 (partition wall) in which the switching element 23 is disposed is located farther upstream than the motor 2 in the airflow generated by the centrifugal fan 4, so that the influence of heat generated from the motor 2 is small. Further, during the operation of the electric blower 1, the temperature of the air flowing through the flow path 29 of the connecting portion 18 in which the switching element 23 is disposed is on the downstream side of the motor 2 because the connecting portion 18 is upstream of the motor 2. Since the temperature is lower than the air temperature and the connecting portion 18 is a part of the case 5 that is in contact with the outside air, the heat from the switching element 23 is hardly trapped and the cooling effect is high. Further, such a connecting portion 18 is a step portion utilizing the difference in the outer peripheral size in the centrifugal direction between the fan cover 15 and the motor case 6, and can be easily formed structurally as a flat portion. Since the switching element 23 may be attached to a plane, the degree of freedom of attachment of the switching element 23 is higher than in the case where the switching element 23 is attached to the outer peripheral surface of the motor case 6.

Further, in the present configuration example , such a connecting portion 18 is also a portion facing the diffuser 14 that rectifies the airflow from the discharge port 22 of the centrifugal fan 4 toward the motor 2. Actually, the effectiveness of the cooling effect of the switching element 23 arranged in the part facing the diffuser 14 has been confirmed in the experiment results of the present inventors.

Incidentally, the connecting portion 18 in to case 5, be integral with the motor casing 6, it is bent in substantially L-shaped cross section so as to project toward the periphery of the opening 7 of the motor case 6 in the outer circumferential direction The flange portion 31 is used. Since it is easy to form such a flange portion 31 in a planar shape, the switching element 23 can be easily fixed.

Here, a modification is shown in FIGS. FIG. 5 is a side view showing a modification of the electric blower with a part cut away, and FIG. 6 is a plan view (top view) showing the electric blower. In the configuration example described above, the switching element 23 is arranged on the flat surface portion (flange portion 31) formed by the steps in consideration of the mounting property, the cooling efficiency, etc., but the influence of the heat generated from the stator 19 is affected. If attention is paid to the fact that the cooling can be efficiently performed without receiving, as the outer surface of the electric blower 1 on the suction side from the motor 2, a part facing the diffuser 14, for example, as shown in FIGS. 5 and 6 The fan cover 15 may be disposed on the outer peripheral surface portion.

A first embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in the above-described configuration example are denoted by the same reference numerals, and the description thereof is also omitted (the same applies to the embodiments described later).

  FIG. 7 is a side view showing a part of the configuration of the electric blower of the present embodiment, and FIG. 8 is a plan view showing a part of the internal configuration example.

Although the present embodiment basically conforms to the above-described configuration example , the motor case 32 is used instead of the motor case 6 in the present embodiment. The motor case 32 of the present embodiment has a bottomed structure with a rear plate portion 33 and the fan cover 15 side opens as an opening portion 34 to store the motor 2. A disk-shaped frame 35, which is a connecting member having an outer periphery larger than the outer periphery of the motor case 32, is attached to the motor case 32 with screws 36 or the like so as to close the opening 34 of the motor case 32. Further, the side wall portion 86 forming the side wall of the fan cover 15 is fitted into the outer peripheral edge portion 87 of the frame 35 by press fitting or the like. The motor case 32 and the fan cover 15 are fixed integrally. That is, the frame 35 is disposed between the motor case 32 and the fan cover 15. Further, the frame 35 is formed with a plurality of ventilation holes 37 for communicating the inside of the motor case 32 with the inside of the fan cover 15, for example, in a fan shape as shown in FIG. The ventilation hole 37 is designed so as to ensure an air volume necessary for cooling the motor 2 according to the performance of the centrifugal fan 4. In addition, a bearing housing portion 13a is provided at a substantially central portion of the frame 35. The bearing housing portion 13a projects in a substantially cylindrical shape toward the front, houses the bearing 11a on the inner peripheral side thereof, and has a through hole 12 for the rotor shaft 3 formed therein. ing.

In such a configuration, in the present embodiment, the outer peripheral portion 38 of the frame 35 at a position larger than the outer periphery of the motor case 32 forms a flow path 29 between the discharge port 22 of the centrifugal fan 4 and the motor 2. The connecting portion 18 (partition wall) is provided, and the switching element 23 is disposed and fixed by a screw 30 so as to be positioned on the outer surface of the outer peripheral portion 38. Therefore, also in the case of the present embodiment using the outer peripheral portion 38 of the frame 35, the same operation and effect as in the case of the above-described configuration example using the flange portion 31 can be achieved. In the present embodiment, the motor case 6, the fan cover 15, and the outer peripheral portion 38 of the frame 35 constitute the case 5.

  Further, in such a configuration, the frame 35 of the present embodiment constitutes a connecting portion 18 (partition wall) that forms a flow path between the discharge port 22 of the centrifugal fan 4 and the upper end portion of the motor 2, and A part thereof is disposed in the flow path on the upstream side (suction side) of the motor 2 that generates heat. As a result, the surface area of the frame 35 in contact with the air upstream of the motor 2 that generates heat is increased, and the cooling effect of the frame 35 is enhanced. Accordingly, the switching element 23 fixed integrally to the frame 35 is also efficiently cooled.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a side view showing the configuration of the electric blower of the present embodiment with a part cut away, FIG. 10 is a plan view showing a part of the internal configuration, and FIG. 11 is a schematic circuit diagram showing a drive circuit of the electric blower. It is.

The present embodiment basically conforms to the above-described configuration example , but in this embodiment, an application example to an electric blower 42 using a brushless motor 41 instead of the brushed motor 2 is described. Indicates.

  First, a configuration example of a drive control system including the drive circuit 27b when the brushless motor 41 is used will be described with reference to FIG. In the present embodiment, the electric blower 42 composed of the brushless motor 41 is rotationally driven by an alternating current generated from an inverter drive circuit 44 that is driven by using the direct current power supply unit 43 as a drive source. The electric blower control unit 45 that controls the driving of the electric blower 42 is connected to the drive circuits 46 a to 46 f and performs switching control of the switching elements 47 a to 47 f that are power devices such as power MOSFETs that constitute the inverter drive circuit 44. Details of each part will be described below.

  The DC power supply unit 43 is a battery pack obtained by combining a plurality of secondary batteries such as a nickel cadmium (NiCd) battery, a nickel hydride battery, or a lithium ion battery, or a rectified and smoothed commercial AC power supply. This DC voltage is supplied to the inverter drive circuit 44.

  The inverter drive circuit 44 has a configuration in which six switching elements 47a to 47f are connected in a three-phase bridge. These switching elements 47a to 47f are driven by the high voltage side drive circuits 46a to 46c and the low voltage side drive circuits 46d to 46f based on the pulse signal output from the electric blower control unit 45 mainly composed of the microcomputer 48. The AC current is supplied to the Y-connection windings 49 a to 49 c of the electric blower 42.

  The electric blower control unit 45 includes an operation unit 50 for selecting start, stop, or electric power of the electric blower 42, current detection means 51 for detecting a current flowing through the inverter drive circuit 44, and an input voltage. Input voltage detecting means 52 and the like are connected.

  Further, the electric blower control unit 45 is connected to a position detection means 55 for detecting the permanent magnet position of the rotor 54 surrounded by the stator 53. As such a position detection means 55, three magnetic sensors installed at an electrical angle interval of 120 ° are used. Examples of the magnetic sensor include a hall sensor and a hall IC. As other permanent magnet position detection methods, although not particularly shown, a method using an optical pulse encoder, a method of detecting voltages induced in the windings 49a to 49c by voltage phase detection means, and the like can be used. is there.

  In such a configuration, the plurality of switching elements 47a to 47f, which are power devices, are mounted on the circuit board 56 and further arranged on the outer surface of the connecting portion 18 (flange portion 30) of the motor case 6 by screws 30 or the like. Has been fixed. In this case, unlike a single switching element 23, a plurality of switching elements 47a to 47f are targeted. However, as shown in FIG. 10, these switching elements 47a to 47f are provided with a rotor shaft 3 of a brushless motor 41. They are arranged radially at equal intervals so as to be located on substantially the same circumference (not strictly on the same circumference) at the center.

By a mounting arrangement for such a switching element 47A～47f, the switching element 47A～47f, can be effectively cooled without increasing the air passage loss of the electric blower 42. In particular, when the brushless motor 41 as in the present embodiment is driven, a plurality of switching elements are required, and the plurality of switching elements 47a to 47f can be used without increasing the flow path loss of the electric blower 42. The present embodiment that can be effectively cooled is particularly effective. In addition, since the plurality of switching elements 47a to 47f are radially arranged with the rotor shaft 3 as a center on the same circumference, the variation in cooling of the switching elements 47a to 47f is reduced. Therefore, it is effective in cooling evenly, and the operation of the switching elements 47a to 47f, and hence the circuit operation can be stabilized.

Although the present embodiment has been described as an application example to the above-described configuration example scheme, the first embodiment scheme of the present invention using the frame 35 can be similarly applied.

  In these embodiments, the closed structure of the motor cases 6 and 31 has been described as a bottomed structure, but the rear plate portions 21 and 33 are configured to be closed by separate members. Also good.

  In these embodiments, the switching devices 23 and 47a to 47f such as a triac and a power MOSFET have been described as examples of power devices. However, the present invention is not limited to these devices. Switching elements such as Insurated Gate Bipolar Transistor) are also applicable, or are not limited to these elements alone, but are also applicable to a single chip packaged or deviced, and also applicable to resistive elements Can be.

A third embodiment of the present invention will be described with reference to FIG. The present embodiment is an application example to a vacuum cleaner as an electric device particularly suitable for mounting the electric blower 1 or 42 having the configuration as described above. FIG. 12 is a perspective view showing an external configuration of the electric vacuum cleaner of the present embodiment.

  The vacuum cleaner 61 according to the present embodiment includes a housing 62 that forms the base, a hose 63 that is detachably connected to the housing 62 at one end, a hand operation unit 64 that is provided at the other end of the hose 63, and one end that is A two-divided extension pipe 65 detachably connected to the hand operating section 64, a suction port body 66 detachably attached to the other end of the extension pipe 65, and the electric blower 1 housed and held in the housing 62 or 42, a dust collection chamber 67 formed in the housing 62, and the like.

  The hose 63 is connected to the housing 62 so that the base end thereof communicates with the suction side of the electric blower 1 or 42 via the dust collection chamber 67, and a hand operating part provided on the other end side of the hose 63. 64 is provided with a grip portion 68 extending rearward and an operation means 69 located in a range that can be operated by an operator's finger gripping the grip portion 68.

  The operation means 69 also serves as a power switch for the electric blower 1 or 42, and is configured to be able to select a plurality of types of operation modes in which the electric blower 1 or 42 is driven in different states. Specifically, from the grip 68 toward the extension pipe 65, a stop operation button 69a for setting the operation mode to the stop state, a weak operation button 69b for setting the operation mode to the weak operation state, and the operation mode to the strong operation state. The strong driving operation buttons 69c are arranged in a line sequentially. With such a configuration, for example, in a strong operation state, the electric blower 1 or 42 rotates at a high speed of 30,000 rpm and sucks dust.

  There are several factors that affect the vacuum suction power of vacuum cleaners. Among them are input power and wind path loss. When the input power is large, the dust suction force is improved, but the heat generation amount of the switching element for controlling the power tends to be large. When the heat generation amount is too large, the input power may be suppressed. Naturally, if the air path loss is large, the dust suction force decreases. Therefore, as in the present embodiment, it is possible to mount the electric blower 1 or 42 that can effectively realize the cooling of the power device without reducing the air path loss. It is particularly effective for improving

A fourth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a side view showing a part of the configuration of the electric blower of the present embodiment. In the present embodiment, a cooling air hole 70 is provided in the vicinity of the switching element 23 in the motor case 6 on the upstream side of the motor 2. That is, the cooling vent hole 70 is provided at a position where the blown air directly hits the switching element 23 or a position where the blown air causes (directly) forced convection around the switching element 23. FIG. 13 specifically shows an example in which a cooling air hole 70 is provided on the side surface of the motor case 6 parallel to the rotor shaft 3 in the vicinity where the switching element 23 is fixed. One or a plurality of cooling ventilation holes 70 may be provided.

  By adopting such a configuration, air with a small temperature rise before passing through the motor 2 can be flowed on or near the surface of the switching element 23. Therefore, the switching element 23 can be forcibly air-cooled, and the cooling effect of the switching element 23 is remarkably improved together with the heat radiation to the motor case 6 or the flange portion 31.

A fifth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a plan view showing an example of the internal configuration of a part of the electric blower of the present embodiment. This embodiment is basically the same as the second embodiment, but in this embodiment, the flange portion 31 on the upstream side of the brushless motor 41 is located near the switching elements 47a to 47f. A cooling ventilation hole 71 is provided. That is, the cooling vent hole 71 is provided at a position where the blown air causes (directly) forced convection around the switching elements 47a to 47f. FIG. 14 specifically shows an example in which a plurality of cooling air holes 71 are provided in the flange portion 31 perpendicular to the rotor shaft 3 in the vicinity where the switching elements 47a to 47f are fixed.

  By adopting such a configuration, it is possible to flow air with a small temperature rise before passing through the brushless motor 41 on or near the surfaces of the switching elements 47a to 47f. Therefore, the switching elements 47a to 47f can be forcibly air-cooled, and the cooling effect of the switching elements 47a to 47f is remarkably improved together with the heat radiation to the motor case 6 or the flange portion 31.

Is a side view showing lack some switching the configuration of an electric blower of a configuration example as a premise of the implementation of the embodiment of the present invention. It is a top view which shows the example of a part of internal structure. The structural example of a diffuser is shown, (a) is a top view, (b) is a bottom view. It is a schematic circuit diagram which shows the drive circuit of the said electric blower. It is a side view which cuts and shows a part of electric fan of a modification. It is a top view which shows an electric blower. It is a side view showing a part of the configuration of the electric blower of the first embodiment of the present invention. It is a top view which shows the example of a part of internal structure. It is a side view which partially cuts and shows the structure of the electric blower of the 2nd Embodiment of this invention. It is a top view which shows the example of a part of internal structure. It is a schematic circuit diagram which shows the drive circuit of the said electric blower. It is a perspective view which shows the external appearance structure of the vacuum cleaner of the 3rd Embodiment of this invention. It is a side view which partially cuts and shows the structure of the electric blower of the 4th Embodiment of this invention. It is a top view which shows the example of a part of internal structure of the electric blower of the 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric blower 2 Motor 3 Rotating shaft 4 Centrifugal fan 5 Case 6 Motor case 14 Diffuser 15 Fan cover 18 Connection part, partition 22 Discharge port 23 Power device (switching element)
27a, 27b Drive circuit 31 Flange, partition 32 Motor case 35 Connecting member (frame)
37 Ventilation hole 41 Brushless motor 42 Electric blower 47a-47f Power device (switching element)
70, 71 Cooling vent

Claims (5)

A motor, a drive circuit for driving the motor, a power device in the drive circuit, a centrifugal fan attached to a rotating shaft of the motor, and a case for housing the motor and the centrifugal fan. In the electric blower provided,
The case includes a motor case that houses the motor, a fan cover that covers the centrifugal fan and has an outer periphery larger than an outer periphery of the motor case, and a connecting portion that connects the motor case and the fan cover. And
The connecting portion is formed by a part of a connecting member that is a separate member from the motor case and the fan cover that are part of a partition wall that forms a flow path between the discharge port of the centrifugal fan and the motor. ,
The connecting member has a ventilation hole for communicating the fan cover with the motor case;
The power device is disposed in surface contact with the outer surface of the partition wall formed by the connecting member ,
An electric blower characterized by that.   2. The electric blower according to claim 1, further comprising a diffuser that rectifies an airflow directed from the discharge port of the centrifugal fan toward the motor, and wherein the power device is disposed at a portion facing the diffuser.   2. The electric blower according to claim 1, wherein a cooling ventilation hole is provided in the vicinity of the power device, the partition wall forming a flow path between the discharge port of the centrifugal fan and the motor. The motor is a brushless motor;
2. The electric blower according to claim 1, wherein the plurality of power devices for switching a current flowing through the brushless motor are arranged radially on substantially the same circumference around a rotation axis of the brushless motor. . An electric device comprising the electric blower according to any one of claims 1 to 4 .

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