Electric air blower, and vacuum cleaner comprising the same

Abstract

To provide an electric air blower that improves cooling performance of a bearing and an electric motor.SOLUTION: An electric air blower 200 according to the present invention comprises: a rotor 16 comprised in a rotating shaft 5; an impeller 1 fixed to the rotating shaft 5; a stator 25 arranged so as to have a gap on an outer periphery of the rotor 16, and comprising a stator core 17 and a winding 23; a bearing 8 supporting the rotating shaft 5; and a bearing cover 9 containing the bearing 8. The stator core 17 comprises: a yoke 18; and a plurality of teeth 19 extending inward from the yoke 18, and around which the winding 23 is wound. An outer periphery of the bearing cover 9 comprises a cooling fin 14 extending along an axial direction. The cooling fin 14 is arranged between the teeth 19 adjacent to each other.SELECTED DRAWING: Figure 3B

Description

[Technical field]

[0001] The present invention relates to an electric blower and an electric vacuum cleaner equipped with the same. [Background technology]

[0002] In cordless stick vacuum cleaners and self-propelled vacuum cleaners, the demand for which has been rapidly increasing in recent years, electric blowers using DC brushless motors are used to obtain sufficient output even when driven by low-voltage batteries and to reduce vibration and noise. In addition, in order to achieve a compact electric vacuum cleaner, there is a demand for a compact electric blower. In order to achieve a compact electric blower, the outer diameter of the impeller can be reduced by increasing the speed of the electric blower. For this reason, some electric blowers have a brushless motor rotation speed of about 50,000 revolutions per minute or more. Examples of such electric blowers include those disclosed in Patent Document 1 and Patent Document 2.

[0003] Patent Document 1 states that "The rotating shaft is equipped with a rotor core and a centrifugal impeller, and the rotating shaft is supported by bearings. The bearings are contained in a bearing cover, and the bearing cover is integrally molded with a resin housing. The outer periphery of the centrifugal impeller is provided with guide vanes having diffuser vanes and return guide vanes on the back side of the diffuser vanes. A heat sink is provided on the outer periphery of the bearing cover, and a reference surface where no heat sink is provided is provided on the side of the bearing cover. The reference surface serves as the reference surface when the bearing cover and resin housing are insert molded together, and as a reference when cutting the inner diameter to fix the outer ring of the bearing."

[0004] Furthermore, Patent Document 2 describes that "a second axial diffuser vane is provided downstream of the first axial diffuser vane. An impeller-side motor housing is provided inside the first axial diffuser vane, and an anti-impeller-side motor housing is provided at an opposing position. The two motor housings have openings facing the radial direction on their outer circumferential surfaces. An inner wall of the impeller-side housing is provided with a flow path extending in the axial direction. The flow path extending in the axial direction extends to the axial end of the inner wall of the anti-impeller-side housing formed integrally with the second axial diffuser vane. The exhaust side end of the inner wall is located closer to the impeller than the anti-impeller side end of the outer circumferential surface of the anti-impeller-side motor housing. The opening is located closer to the anti-impeller side end of the outer circumferential surface of the anti-impeller-side motor housing than the exhaust side end of the inner wall." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-138510 A [Patent Document 2] Patent Publication No. 2022-81860 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional technology described in Patent Document 1, when an electric motor is driven to rotate a centrifugal impeller, air flows in through an air inlet of a fan casing and into the centrifugal impeller. The air is pressurized and accelerated in the centrifugal impeller, and is discharged from the centrifugal impeller. The airflow discharged from the centrifugal impeller is guided to a diffuser blade, where kinetic energy is converted into pressure energy and the pressure increases. The airflow discharged from the diffuser blade is redirected from a radially outward flow to an axial flow in a substantially triangular flow path formed between the inner surface of the fan casing and the trailing edge of the diffuser blade, and then redirected to a radially inward flow and flows into a return guide. It is shown that the airflow that has passed through the return guide blade flows into the inside of the housing from an opening of the housing, cools the cooling fins of the bearing cover, cools the bearings via the bearing cover, cools the rotor core, the stator core, and the conductors, and is discharged to the outside. It is also shown that a portion of the air flow that has passed through the return guide vanes is discharged to the outside through the exhaust port of the housing without flowing through the cooling fins.

[0007] However, in the conventional technology described in Patent Document 1, the air discharged from the diffuser blades hits the inner surface of the fan casing, is redirected in the axial direction in a roughly triangular flow path, and is further redirected into a radially inward flow by the return guide blades. In Patent Document 1, the bearings can be cooled by having the discharge flow (cooling air) from the blower hit the cooling fins of the bearing cover, but the cooling air tends to flow into the exhaust port provided in the housing due to the redirected flow and pressure loss inside the motor, and there was a risk that the bearings and the stator core and conductors inside the motor could not be sufficiently cooled.

[0008] In the conventional technology described in Patent Document 2, the impeller-side motor housing and the anti-impeller-side motor housing that hold the bearings are installed so as to sandwich the stator core in the axial direction, and the outer periphery of the stator core and the inner wall of the motor housing are overlapped in the axial direction so that the exposed part of the stator core is exposed from the motor housing at approximately the center position, and assembled by bonding or press fitting. In addition, the motor housing is provided with openings in the axial and radial directions, and cooling air is taken into the electric motor from the openings in the anti-impeller-side motor housing by the Venturi effect caused by the main flow flowing through the impeller, the first axial diffuser vane, and the second axial diffuser vane. It is shown that this can improve the cooling performance and efficiency of the electric motor.

[0009] However, in the conventional technology described in Patent Document 2, when the motor is operated, the temperature of the stator core and windings, which are the heat source of the motor, becomes high. The temperature of the motor housing becomes high because the impeller side motor housing and the anti-impeller side motor housing are assembled to the stator core, which is the heat source, by bonding or press fitting. Since cooling air flows in from the opening of the anti-impeller side motor housing, the anti-impeller side motor housing and the bearing on the anti-impeller side are cooled, but the temperature of the impeller side motor housing is likely to become higher than that of the anti-impeller side motor housing.

[0010] In addition, because the opening of the impeller-side motor housing is located on the opposite side of the impeller from the bearing, the cooling air cannot reach the impeller-side bearing and is discharged from the opening of the motor housing, resulting in the problem that the impeller-side bearing cannot be sufficiently cooled.

[0011] Furthermore, the motor housing that holds the bearings is assembled by bonding or pressing onto both sides of the stator core, so the distance between the bearings is long and the fitting of the stator core and the motor housing reduces the precision of concentricity and can result in the shaft being installed at an angle, which can cause vibration and noise.

[0012] Furthermore, when the temperatures of the stator core and windings rise, the temperature of the motor housing, which is assembled to the stator core by bonding or press fitting, also rises, causing the motor housing to expand in the axial direction, which in turn causes the outer ring of the bearing fixed to the motor housing to expand in the axial direction, potentially generating vibrations and noise.

[0013] SUMMARY OF THE PRESENT EMBODIMENTS The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide an electric blower having improved cooling performance for the bearings and the electric motor, and an electric vacuum cleaner equipped with the same. [Means for solving the problem]

[0014] In order to solve the above problem, the present invention provides a motor comprising a rotor provided on a rotating shaft, an impeller fixed to the rotating shaft, a stator arranged with a gap on the outer periphery of the rotor and having a stator core and windings, a bearing supporting the rotating shaft, and a bearing cover containing the bearing, wherein the stator core comprises a yoke and a plurality of teeth extending inward from the yoke and around which the windings are wound, and the outer periphery of the bearing cover is provided with cooling fins extending along the axial direction, and the cooling fins are arranged between adjacent teeth. Effect of the Invention

[0015] According to the present invention, it is possible to provide an electric blower having improved cooling performance for a bearing and an electric motor, and an electric vacuum cleaner including the same.

[0016] Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0017] [Figure 1A] FIG. 1 is a perspective view of the appearance of an electric vacuum cleaner 400 equipped with electric blower 200 when used as a stick type. [Figure 1B] FIG. 4 is a side view of the vacuum cleaner 400 when used as a handheld type. [Diagram 2]4 is a vertical cross-sectional view of a vacuum cleaner body 410 of the vacuum cleaner 400. FIG. [Figure 3A] FIG. 1 is an external view of an electric blower 200 according to an embodiment of the present invention. [Figure 3B] FIG. 1 is a vertical cross-sectional view of an electric blower 200 according to an embodiment of the present invention. [Figure 4A] FIG. [Figure 4B] FIG. 2 is a cross-sectional view of the impeller 1 cut along the axial direction. [Figure 5A] 2 is a perspective view of an impeller-side housing 2 having a first axial-flow diffuser vane 29 and a bearing cover 9 integrated together. FIG. [Figure 5B] 1 is a cross-sectional view of an impeller-side housing 2 having a first axial-flow diffuser vane 29 and a bearing cover 9 integrated together. [Figure 5C] FIG. 2 is a rear perspective view of an impeller-side housing 2 having a first axial-flow diffuser vane 29 and a bearing cover 9 integrated together. [Figure 6A] 2 is a perspective view of the anti-impeller housing 3 having a second axial flow diffuser vane 30, as viewed from the impeller 1 side. FIG. [Figure 6B] 4 is a cross-sectional view of the anti-impeller housing 3 having a second axial flow diffuser vane 30. FIG. [Figure 7A] 2 is a perspective view of the external appearance of a stator 25 in which a winding frame 24 is fitted onto a stator core 17 of an electric motor section 202 and a winding 23 is wound around the stator 25. FIG. [Figure 7B] 2 is a cross-sectional view of a stator 25 in which a winding 23 is wound around a winding frame 24 fitted onto a stator core 17 of an electric motor section 202. FIG. [Figure 8A] 8 is a cross-sectional view of electric blower 200 taken along line VIIIA-VIIIA in FIG. 3A. [Figure 8B] FIG. 8B is a partially enlarged view of the dotted line VIIIB in FIG. 8A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings. Note that each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to only the illustrated examples. In addition, in each drawing, common or similar components are given the same reference numerals, and duplicated explanations thereof will be omitted.

[0019] Hereinafter, the configuration of an electric vacuum cleaner 400 equipped with electric blower 200 according to this embodiment will be described with reference to Figures 1A, 1B, and 2. Figure 1A is an external perspective view of electric vacuum cleaner 400 equipped with electric blower 200 according to this embodiment when used as a stick type. Figure 1B is a side view of electric vacuum cleaner 400 when used as a handheld type. Figure 2 is a vertical cross-sectional view of vacuum cleaner body 410 of vacuum cleaner 400.

[0020] In this embodiment, it is assumed that the electric blower 200 is mounted on a rechargeable electric vacuum cleaner 400 that can be switched between a stick type and a handheld type as appropriate. The electric blower 200 can be mounted on various types of electric vacuum cleaners 400, such as a stick type or a handheld type, a canister type, a self-propelled type, etc.

[0021] 1A, electric vacuum cleaner 400 includes cleaner body 410 forming an outer shell, telescopic pipe 402 provided so as to be extendable and retractable relative to cleaner body 410, grip section 403 provided at one end of telescopic pipe 402, and switch section 404 provided on grip section 403. Cleaner body 410 houses electric blower 200 (see FIG. 2) that generates a suction airflow required for dust collection, and dust collection chamber 401 that collects dust sucked in by the suction airflow generated by electric blower 200. Switch section 404 turns electric blower 200 (see FIG. 2) on and off.

[0022] 1A, the electric vacuum cleaner 400 is in a stick state, and the telescopic pipe 402 is extended. In the stick state, a suction body 405 is attached to the other end of the vacuum cleaner body 410, and the vacuum cleaner body 410 and the suction body 405 are connected by a connection part 406.

[0023] 1B, the vacuum cleaner 400 is in a handy state, with the telescopic pipe 402 stored in the vacuum cleaner body 410 and the grip part 403 adjacent to the telescopic pipe 402. In the handy state, a handy grip part 407 serving as a handle is provided on the upper surface side of the vacuum cleaner body 410, between the adjacent grip part 403 and the dust collection chamber 401. A suction body 408 (crevice nozzle) is attached to the other end of the vacuum cleaner body 410, and the vacuum cleaner body 410 and the suction body 408 are connected by a connection part 406.

[0024] In the above configuration, electric vacuum cleaner 400 operates electric blower 200 (see FIG. 2) housed in cleaner body 410 by operating switch 404 of grip 403, generating a suction airflow. Then, electric vacuum cleaner 400 sucks dust from suction body 405 (see FIG. 1A) or suction body 408 (see FIG. 1B), and collects the dust in dust collection chamber 401 of cleaner body 410 through connection 406.

[0025] As shown in Fig. 2, electric blower 200 that generates suction force, battery unit 420 that supplies power to electric blower 200, and drive circuit 430 are provided inside vacuum cleaner body 410. In the example shown in Fig. 2, electric vacuum cleaner 400 is in a handheld state, and suction mouth body 408 is removed from vacuum cleaner body 410.

[0026] Air sucked in through suction body 405 (see FIG. 1A) or suction body 408 (see FIG. 1B) is sent to dust collection chamber 401 arranged in front of electric blower 200 through flow path 440 provided in cleaner body 410, and is collected in dust collection chamber 401. Then, the air from which dust has been separated in dust collection chamber 401 passes through electric blower 200 and drive circuit 430, and is exhausted to the outside from an exhaust port (not shown) formed in cleaner body 410.

[0027] Next, the configuration of the electric blower 200 will be described with reference to Figs. 3 to 8. Fig. 3A is an external view of the electric blower 200 according to the embodiment of the present invention. Fig. 3B is a vertical cross-sectional view of the electric blower 200 according to the embodiment of the present invention. Fig. 4A is a perspective view of the impeller 1. Fig. 4B is a cross-sectional view of the impeller 1 cut along the axial direction. Fig. 5A is a perspective view of the impeller-side housing 2 having the first axial diffuser vane 29 and the bearing cover 9 integrated together. Fig. 5B is a cross-sectional view of the impeller-side housing 2 having the first axial diffuser vane 29 and the bearing cover 9 integrated together. Fig. 5C is a rear perspective view of the impeller-side housing 2 having the first axial diffuser vane 29 and the bearing cover 9 integrated together. Fig. 6A is a perspective view of the anti-impeller-side housing 3 having the second axial diffuser vane 30 as viewed from the impeller 1 side. Fig. 6B is a cross-sectional view of the anti-impeller-side housing 3 having the second axial diffuser vane 30. Fig. 7A is an external perspective view of stator 25 in which windings 23 are wound around stator core 17 of motor section 202 and winding frame 24 fitted thereon. Fig. 7B is a cross-sectional view of stator 25 in which windings 23 are wound around stator core 17 of motor section 202 and winding frame 24 fitted thereon. Fig. 8A is a cross-sectional view of electric blower 200 of Fig. 3A taken along line VIIIA-VIIIA. Fig. 8B is an enlarged view of a portion indicated by dotted line VIIIB in Fig. 8A. Note that Fig. 3B shows a typical air flow by solid arrows α1 and dotted arrows α2 only on the left side of Fig. 3B.

[0028] 2, electric blower 200 is attached inside electric vacuum cleaner 400. At that time, electric blower 200 is attached to electric vacuum cleaner 400 so that impeller 1 (see FIG. 3B) faces toward suction body 405 (see FIG. 1A) or suction body 408 (see FIG. 1B) on the lower side of vacuum cleaner 400.

[0029] As shown in Fig. 3B, electric blower 200 includes electric motor section 202 arranged radially inward of blower section 201. Blower section 201 includes, from upstream of the suction air flow, impeller 1 which is a rotor, first axial diffuser vane 29 on the impeller 1 side, and second axial diffuser vane 30. Fan casing 4 is arranged to cover impeller 1, and fan casing 4 is provided with suction port 6. Downstream of second axial diffuser vane 30, exhaust port 7 is provided to exhaust the air sucked in from suction port 6.

[0030] As shown in Figures 5A to 5C, the impeller side housing 2 is provided with a first axial diffuser vane 29. As shown in Figures 6A and 6B, the anti-impeller side housing 3 is provided with a second axial diffuser vane 30. In this embodiment, the impeller side housing 2 and the anti-impeller side housing 3 form a housing, and the first axial diffuser vane 29 and the second axial diffuser vane 30 form a diffuser vane.

[0031] As shown in FIGS. 5A to 5C and 3B, the impeller-side housing 2 (housing) is made of synthetic resin, and is integrated with a bearing cover 9 made of a non-magnetic metal material that houses a bearing 8 by insert molding.

[0032] The bearing cover 9 is provided with a support portion 10 having a substantially cylindrical shape that is molded integrally therewith, and the bearing cover 9 is integrated with the impeller-side housing 2 via the support portion 10 and fixed to the impeller-side housing 2 .

[0033] The support part 10, which has a substantially cylindrical shape, protrudes toward the impeller 1 beyond the position of the end part 2c on the impeller 1 side of the impeller-side housing 2. In other words, the support part 10 is disposed so as to overlap with the impeller 1 in a radial direction perpendicular to the axial direction. The support part 10 has a support post 11 for fixing the stator 25 with a fixing screw 15 on the side opposite the impeller, and has a screw hole 11a formed therein.

[0034] A fixing screw 15 can be screwed into the screw hole 11 a , and the stator 25 is fixed to the impeller-side housing 2 by screwing the fixing screw 15 into the screw hole 11 a .

[0035] Heat sinks 12 are provided on both circumferential sides of support 11 so as to come into contact with protrusions 22 (see Figs. 7A and 7B) of stator core 17 and yoke 18 (see Figs. 7A and 7B).

[0036] The bearing cover 9 is formed in a cylindrical shape. A plurality of cooling fins 14 that protrude toward the outer periphery and extend along the axial direction are provided on the outer periphery of the bearing cover 9. The plurality of cooling fins 14 are arranged on the outer periphery of the bearing 8 and function as a heat sink that cools the bearing 8.

[0037] In this embodiment, the cooling fins 14 are disposed between the teeth 19 (see Figs. 7A and 7B) of the stator core 17, at axial positions (see Figs. 8A and 8B) on the impeller 1 side. In other words, the cooling fins 14 are disposed between adjacent teeth 19, in slots 20, which will be described later.

[0038] Moreover, the cooling fins 14 are arranged so as to overlap with the bearings 8 located on the upper side of the rotating shaft 5 in a radial direction perpendicular to the axial direction (see FIG. 3B). The bearings 8 located on the upper side of the rotating shaft 5 tend to have a higher temperature than the bearings 8 located on the lower side of the rotating shaft 5. Therefore, in this embodiment, the cooling fins 14 and the bearings 8 located on the upper side of the rotating shaft 5 are arranged so as to overlap with each other in a radial direction perpendicular to the axial direction, thereby improving the cooling performance of the bearings 8 located on the upper side of the rotating shaft 5.

[0039] 3B, bearings 8 and springs 13 are provided inside bearing cover 9. Springs 13 are arranged in a compressed state and abut against the outer rings of bearings 8 to apply preload.

[0040] In the impeller 1 shown in Figures 3B, 4A, and 4B, a metal sleeve 1b is covered with a hub plate 33 made of thermoplastic resin. The impeller 1 is fixed by a fixing nut 26 screwed onto a female thread that is threaded on the end of the rotating shaft 5. In this embodiment, the impeller 1, which is a rotor, is provided with a female thread on the end of the rotating shaft 5 and fixed using the fixing nut 26, but it may also be fixed to the rotating shaft 5 by press fitting.

[0041] As shown in Fig. 3B, the electric motor section 202 is located radially inward of the impeller side housing 2 and the anti-impeller side housing 3, and includes a rotor 16 fixed to the rotating shaft 5, and a stator 25 arranged on the outer periphery thereof with a gap therebetween. The stator 25 is configured by winding a winding 23 around a stator core 17 via a winding frame 24. On the outer diameter side of the stator core 17, a through hole 22a (see Fig. 7) is provided in a protrusion 22 (see Fig. 7) for fixing to the impeller side housing 2, and the stator core 17 is fixed to the impeller side housing 2 by a fixing screw 15.

[0042] 7A and 7B, a plurality of teeth 19 and slots 20 are arranged at equal intervals on the inner diameter side of stator core 17 around the entire circumference of stator core 17. Slots 20 are formed between adjacent teeth 19. The outer periphery of yoke 18 of stator core 17 has recessed portions 21 recessed toward the radial inner diameter side, and protruding portions 22 protruding toward the radial outer diameter side.

[0043] A slot 20 is formed by the space surrounded by the yoke 18 and the teeth 19, into which the winding 23 is inserted, and the winding 23 is wound around the teeth 19 via a winding frame 24.

[0044] The slots 20 have windings 23, but gaps are formed between the windings 23, through which cooling air (dotted arrow α2 shown in FIG. 3B) flows toward the impeller 1 side.

[0045] The protruding portion 22 on the outer diameter side of the yoke 18 is provided with a through hole 22a for fixing the stator 25 to the impeller-side housing 2. The through hole 22a and the screw hole 11a of the support 11 of the bearing cover 9 are formed at the axial position of the slot 20 of the stator core 17 on the impeller 1 side so that the cooling fin 14 of the bearing cover 9 is disposed. By providing the recessed portion 21 and the protruding portion 22 on the outer diameter side of the yoke 18, the surface area of ​​the outer peripheral surface of the stator core 17 is increased. This improves the cooling performance of the stator 25 by the cooling air (dotted arrow α2 in FIG. 3B) flowing between the stator core 17 and the anti-impeller-side housing 3. In addition, the heat sink 12 of the bearing cover 9 is fixed in contact with both sides of the protruding portion 22 of the stator core 17 in the circumferential direction, so that the cooling performance of the stator 25 can be improved. The yoke 18 of the stator core 17 may be substantially annular without the recessed portion 21.

[0046] Stator core 17 is produced by laminating multiple electromagnetic steel sheets that have been pressed using a die, but by making yoke 18 into a roughly circular ring shape, the die structure of stator core 17 can be simplified.

[0047] Winding 23 is electrically connected to drive circuit 430 (see FIG. 2) provided in electric blower 200. Although copper wire is used for winding 23, a smaller and lighter electric blower can be provided by using aluminum wire or a composite wire material using copper material around the aluminum wire. Winding 23 shown in FIGS. 7A and 7B is a wire material, but is shown as an integrated unit.

[0048] 3B, an end bracket 27 for mounting a circuit (not shown) is attached to the stator 25 on the side opposite the impeller with fixing screws 15. End bracket 27 is provided with screw holes 27a for fixing the circuit, and the circuit (not shown) is fixed to end bracket 27.

[0049] A winding frame 24 is disposed around stator core 17. Winding frame 24 is made of an insulating synthetic resin material, and is fitted to stator core 17 in a manner that prevents windings 23 from coming into direct contact with stator core 17. Note that stator core 17 shown in Figures 7A and 7B is shown as an integrated unit of laminated electromagnetic steel sheets. Any material may be used for winding frame 24 as long as it is easy to mold and has electrical insulation properties and a certain degree of heat resistance and rigidity. For example, polybutylene terephthalate resin (PBT), polyethylene terephthalate resin (PET), or resins containing glass fiber are desirable.

[0050] The rotor 16 of the electric motor unit 202 is provided at the end of the rotating shaft 5 opposite to the end where the impeller 1 is fixed, and is made of a rare earth bonded magnet. The rare earth bonded magnet is made by mixing a rare earth magnetic powder with an organic binder. For example, a samarium iron nitrogen magnet or a neodymium magnet can be used as the rare earth bonded magnet. The rotor 16 is molded integrally with the rotating shaft 5. Note that, although a permanent magnet is used for the rotor 16 in this embodiment, the present invention is not limited thereto, and a reluctance motor, which is a type of commutatorless motor capable of high-speed rotation of about 50,000 to 200,000 revolutions per minute, may also be used.

[0051] A bearing cover 9 containing a bearing 8 is disposed between the impeller 1 and the rotor 16, and the bearing 8 rotatably supports the rotating shaft 5. A ring 28 for balance adjustment is attached to the end of the rotating shaft 5 on the rotor 16 side. Two-sided balance correction can be performed by rotating the rotor and cutting the back surface of the impeller 1 and the ring 28. The ring 28 for balance adjustment is made of a metal material with a higher specific gravity than the rotor 16, and is made, for example, from a sintered product such as copper or by machining.

[0052] A first flow path 31 is provided on the side of electric blower 200, passing through impeller 1, first axial diffuser vane 29 on the impeller 1 side, and second axial diffuser vane 30. First flow path 31 is a flow path through which air flows due to the suction force at suction port body 405 (see FIG. 1A) or suction port body 408 (see FIG. 1B) on the lower side of vacuum cleaner 400, and air flows from suction port 6 to exhaust port 7 as indicated by solid arrow α1 in FIG. 3B.

[0053] The second flow path 32 is a flow path 32 in which air flows into the inside of the motor from between the windings 23 of the slots 20 of the motor section 202, flows inside the motor section 202 towards the impeller 1 side, hits the cooling fins 14 of the bearing cover 9, and flows towards the exhaust port 7 of the anti-impeller side housing 3 through a gap formed between the inner wall 2a of the impeller side housing 2, the inner wall 3a of the anti-impeller side housing 3, and the stator 25, and the air flows towards the exhaust port 7 of the anti-impeller side housing 3 as indicated by the dotted arrow α2 shown in Figure 3B.

[0054] The first flow passage 31 and the second flow passage 32 join at a lower end 3c (axial end) of the inner wall 3a of the housing 3 on the opposite side to the impeller. The lower end 3c of the inner wall 3a of the housing 3 on the opposite side to the impeller is located at a position approximately half the axial dimension of the second axial diffuser vane 30. By joining the first flow passage 31 and the second flow passage 32 at the lower end 3c of the inner wall 3a of the housing 3 on the opposite side to the impeller, a flow is generated in the second flow passage 32 by the Venturi effect due to the main flow of the second axial diffuser vane 30, and cooling air is taken into the electric motor from the axial direction of the electric motor unit 202. This improves the cooling performance of the electric motor unit 202 and increases the efficiency of the electric blower 200 in a wide operating range.

[0055] Next, the air flow within electric blower 200 will be described. When electric motor unit 202 shown in Fig. 3B is driven to rotate impeller 1, air flows in from suction port 6 of fan casing 4 and into impeller 1. In the case of a mixed-flow impeller, the air that flows in is pressurized within impeller 1, while imparting a radial component to the flow sucked in from the direction of rotating shaft 5, generating a flow inclined from the direction of rotating shaft 5. Thus, at impeller outlet 1a, the air becomes a flow having a rotational component and a directional component of rotating shaft 5, and flows out of impeller 1.

[0056] When the airflow discharged from the impeller 1 passes through the first axial diffuser vane 29 and the second axial diffuser vane 30, the airflow flows along the first axial diffuser vane 29 and the second axial diffuser vane 30, and the rotational velocity component of the airflow is reduced. In addition, the lower end 3c of the inner wall of the anti-impeller housing 3 is located upstream of the trailing edge 30b of the second axial diffuser vane 30 (the trailing edge 30b of the second axial diffuser vane 30 protrudes from the inner wall of the second axial diffuser vane 30), so that the flow path expands radially inward in the rear half of the second axial diffuser vane 30. This generates a radially inward flow in the rear half of the second axial diffuser vane 30, and the flow path expands in the direction where there is no inner wall 3a, and is exhausted. This radially inward flow promotes the flow into the electric motor section 202. It should be noted that the first flow passage 31 is a flow passage from the suction port 6 of the fan casing 4 to the exhaust section 7 of the housing 3 on the side opposite to the impeller, as indicated by a solid arrow α1 in FIG. 3B.

[0057] The second flow passage 32 draws air into the electric motor section 202 from the gaps between the windings 23 wound around the teeth 19 of the stator core 17 due to the Venturi effect, as the outlet wind speed of the second axial diffuser vane 30 is high, thereby cooling the stator core 17 and the windings 23. The air passing between the windings 23 flows toward the impeller 1 side, hits the cooling fins 14 of the bearing cover 9 directly, and cools the bearing 8 via the bearing cover 9. The air that has cooled the cooling fins 14 flows toward the inner wall 2a of the impeller-side housing 2, passes through the gap between the inner wall 3a of the anti-impeller-side housing 3 and the stator 25 toward the axial downstream (the outlet of the second axial diffuser vane 30), joins with the air in the first flow passage 31, and is exhausted from the electric blower 200 through the exhaust port 7. The air flows around the outer periphery of the stator 25, thereby cooling the stator 25.

[0058] The first flow passage 31 and the second flow passage 32 join near the second axial diffuser vane 30, making it possible to efficiently utilize the Venturi effect and cool the inside of the motor. That is, the cooling air for the motor is drawn in from the motor section 202 side by the Venturi effect, so that the blower efficiency can be increased and the stator core 17, the windings 23, and the bearings 8 can be efficiently cooled.

[0059] Next, the configuration of blower section 201 of this embodiment will be described with reference to FIGS. 4A to 6B.

[0060] First, the impeller 1 of a rotor according to an embodiment of the present invention will be described with reference to Figures 4A and 4B. The impeller 1 is configured to have a hub plate 33 and a plurality of blades 34. The hub plate 33 and the blades 34 are integrally molded from engineering plastic or thermoplastic resin.

[0061] A recess 35 is formed on the back side of the hub plate 33, and the balance of the impeller 1 can be corrected by cutting the inner diameter side of the hub plate 33 on the impeller outlet 1a side of the recess 35. This reduces the amount of imbalance of the impeller 1, and reduces vibration and noise. In addition, a metal sleeve 1b is provided as an integrally molded product on the back side of the hub plate 33. By using the sleeve 1b, it is possible to reduce the variation in the fit gap between the rotating shaft 5 and the impeller 1 that occurs without the sleeve, and the amount of imbalance of the impeller 1 can be reduced, thereby reducing vibration and noise. Furthermore, the end of the sleeve 1b of the impeller 1 abuts against the inner ring of the bearing 8, thereby determining the position of the impeller 1, and the heat generated by the bearing 8 is transferred to the sleeve 1b, thereby promoting the cooling performance of the bearing 8 by the rotation of the sleeve 1b.

[0062] As shown in Fig. 3B, a substantially cylindrical support part 10 of the bearing cover 9 is disposed in the recess 35 of the impeller 1. Rotation of the impeller 1 generates a swirling flow in the recess 35, so the support part 10 acts as a heat sink. Heat generated in the bearing 8 is transferred by thermal conduction through the bearing cover 9 made of a non-magnetic metal material, and is dissipated by the support part 10 of the bearing cover 9, thereby effectively cooling the bearing 8. The support part 10 is substantially cylindrical, and by providing irregularities or ribs on the surface facing the impeller 1, the surface area is increased, further improving the cooling performance of the bearing 8.

[0063] The impeller 1 and the fan casing 4 are made of resin, each made of a resin material with different sliding properties. By running the impeller 1 and the fan casing 4 in contact with each other, the material of either the impeller 1 or the fan casing 4 is worn away, making it possible to minimize the gap between the impeller 1 and the fan casing 4.

[0064] If the deformation of the blades due to centrifugal stress during operation of the impeller 1 is large, by using a material with a small Young's modulus for the fan casing 4 so that the resin of the fan casing 4 is scraped away, the gap between the impeller 1 and the fan casing 4 during operation can be minimized, resulting in a highly efficient electric blower.

[0065] Next, the stationary diffuser vanes (first axial diffuser vane 29, second axial diffuser vane 30) in the embodiment according to the present invention will be described with reference to FIG. 3B to FIG. 5A to FIG. 6B. As shown in FIG. 3B to FIG. 5 and FIG. 6, the blower 201 of the present embodiment is provided with 15 first axial diffuser vanes 29 on the impeller 1 side, which are arranged at equal intervals in the circumferential direction on the axial downstream side of the impeller 1. The first axial diffuser vanes 29 are provided between the inner wall 2a and the outer wall 2b of the impeller-side housing 2, and are molded integrally with the impeller-side housing 2. The second axial diffuser vane 30 is provided between the inner wall 3a and the outer wall 3b of the anti-impeller-side housing 3, and is molded integrally with the anti-impeller-side housing 3. The second axial diffuser vane 30 has the same number of vanes as the first axial diffuser vane 29 on the impeller 1 side, 15.

[0066] The circumferential positions of the trailing edge 29b of the first axial diffuser vane 29 of the impeller-side housing 2 and the leading edge 30a of the second axial diffuser vane 30 of the anti-impeller-side housing 3 are approximately aligned. Also, the inner wall 2a of the impeller-side housing 2 and the inner wall 3a of the anti-impeller-side housing 3 are approximately aligned. It is desirable that the flow passage surfaces formed by the inner wall 2a of the impeller-side housing 2 and the first axial diffuser vane 29, and the inner wall 3a of the anti-impeller-side housing 3 and the second axial diffuser vane 30 are flush. This is because if there is a step on the flow passage surface, loss at the first axial diffuser vane 29 and the second axial diffuser vane 30 increases.

[0067] By fitting the protrusion 36 provided on the outer wall 2b of the impeller side housing 2 into the claw portion 37 provided on the outer wall 3b of the anti-impeller side housing 3, the impeller side housing 2 and the anti-impeller side housing 3 can be circumferentially positioned and fixed, resulting in an easy-to-assemble structure and improved mass productivity.

[0068] The air flowing out from the impeller 1 is a flow having a rotational component and an axial component. As the air flows along the first axial diffuser vane 29 and the second axial diffuser vane 30, the rotational speed component of the flow is decelerated between the vanes and the kinetic energy of the air flow is converted into pressure energy, increasing the pressure, thereby improving the efficiency of the blower.

[0069] As shown in Figs. 5A to 5C, the impeller-side housing 2 is made of synthetic resin and has a support portion 10 that fixes a bearing cover 9 that contains a bearing 8 to the impeller-side housing 2. The outer periphery of the bearing cover 9 is cylindrical, and a plurality of cooling fins 14 that are long in the direction of the rotation axis are provided on the outer periphery. The cooling fins 14 are rectangular plate-shaped and are arranged at axial positions on the impeller 1 side at approximately the centers of the slots 20 between the teeth 19 of the stator core 17 (see Figs. 8A and 8B). In this embodiment, there are six slots 20 and the cooling fins 14 are also six, but this is not restrictive and the number of cooling fins 14 may be reduced if the temperature of the bearing 8 is lower than the allowable temperature of the bearing. This allows the weight of the electric blower 200 to be reduced.

[0070] As shown in Fig. 8B, the thickness t1 (see Fig. 5C) of the cooling fin 14 when viewed from the axial direction is smaller than the gap t2 (see Fig. 7B) formed between the windings 23 wound around adjacent teeth 19. The cooling air from the motor section 202 flows through the gap t2 between the windings 23 toward the impeller 1. Because the thickness t1 of the cooling fin 14 is smaller than the gap t2, the cooling air can flow up to the vicinity of the support part 10 of the cooling fin 14, and the bearing 8 on the impeller 1 side can also be cooled via the bearing cover 9.

[0071] Since the bearing cover 9 has a complex shape with cooling fins 14, support 10, heat sink 12, etc., it is possible to reduce production costs and obtain high dimensional accuracy by manufacturing it by die casting. The material used for the bearing cover 9 is preferably a non-magnetic metal, an aluminum alloy, which has high thermal conductivity.

[0072] Here, the rotating shaft 5 is assembled into the bearing cover 9 with the rotor 16 magnetized. However, since the bearing cover 9 is made of a non-magnetic metal, it is not affected by the attractive force of the magnet, and is therefore easy to assemble.

[0073] The support part 10 of the bearing cover 9 has a substantially cylindrical shape and protrudes toward the impeller 1 side beyond the end 2c of the impeller-side housing 2 on the impeller 1 side, and the support part 10 is disposed in the recess 35 of the impeller 1. When the impeller 1 rotates, a swirling flow is generated in the recess 35 of the impeller 1. Since the support part 10 is disposed in the recess 10, the support part 10 acts as a heat sink, and the heat generated in the bearing 8 is dissipated by the support part 10, and the bearing 8 is effectively cooled. The cooling fins 14 and the support part 10 act as a heat sink, so that the heat generated in the bearing 8 can be effectively removed. Furthermore, the cooling effect of the bearing 8 can be improved by providing irregularities or ribs on the end face of the support part 10 on the impeller 1 side.

[0074] By disposing the support portion 10 of the bearing cover 9 in the recess 35 of the impeller 1, the axial length of the electric blower 200 can be shortened, and the electric blower 200 can be made smaller and lighter. Furthermore, since two bearings 8 are disposed in the bearing cover 9 and rotatably support the rotating shaft 5, the distance between the bearings 8 can be shortened. This reduces the amount of elongation of the bearing cover 9 due to thermal expansion of the bearing cover 9, and the change in the amount of preload applied to the bearings 8 by the springs 13 is small, allowing the electric blower 200 to operate stably. Furthermore, since the two bearings 8 are held in the bearing cover 9, the mounting precision of the rotating shaft 5 can be improved, and the generation of vibration and noise can be suppressed.

[0075] The support portion 10 of the bearing cover 9 is provided with a support pillar 11 for mounting the stator 25 to the impeller-side housing 2, and a heat sink 12 on both circumferential sides of the support pillar 11. The support pillar 11 is formed with a screw hole 11a for mounting the stator 25, and is fixed to the impeller-side housing 2 by a fixing screw 15. The heat sink 12 is longer in the rotation axis direction than the support pillar 11 so as to contact the recess 21 of the stator core 17 and the yoke 18, and has a tapered structure in which the distance between the heat sink plates 12 on the stator 25 side is wider than the support pillar 11 side. This serves as a guide when mounting the stator 25, facilitating the assembly of the stator 25 and improving mass productivity.

[0076] Cooling fins 14 are provided on the outer periphery of the bearing cover 9 and on the support part 10, and are molded integrally with the impeller side housing 2, thereby increasing the rigidity of the bearing cover 9 and the impeller side housing 2 and enabling high speed rotation of approximately 50,000 revolutions per minute or more.

[0077] The electric blower 200 of this embodiment described above comprises a rotor 16 provided on a rotating shaft 5, an impeller 1 fixed to the rotating shaft 5, a stator 25 arranged with a gap on the outer periphery of the rotor 16 and having a stator core 17 and windings 23, a bearing 8 supporting the rotating shaft 5, and a bearing cover 9 containing the bearing 8, the stator core 17 comprising a yoke 18 and a plurality of teeth 19 extending inward from the yoke 18 and around which the windings 23 are wound, the outer periphery of the bearing cover 9 being provided with cooling fins 14 extending along the axial direction, and the cooling fins 14 being arranged between adjacent teeth 19.

[0078] This allows stator core 17 and windings 23 of stator 25 of motor section 202, and bearings 8 to be sufficiently cooled, providing an electric blower that is small, lightweight, yet highly reliable and highly efficient over a wide range of air volumes. By mounting electric blower 200 on electric vacuum cleaner 400, the output of the electric vacuum cleaner can be improved. Furthermore, by improving the efficiency of electric blower 200, the input of electric blower 200 can be lowered to obtain the same output, and the operating time can be extended in a rechargeable vacuum cleaner driven by a battery.

[0079] The present invention is not limited to the above-described embodiment, but includes various modified examples. For example, the above-described embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to those including all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0080] 1... impeller, 1a... impeller outlet, 1b... sleeve, 2... impeller side housing, 2a... inner wall of impeller side housing, 2b... outer wall of impeller side housing, 3... anti-impeller side housing, 3a... inner wall of anti-impeller side housing, 3b... outer wall of anti-impeller side housing, 3c... lower end of inner wall of anti-impeller side housing, 4... fan casing, 5... rotating shaft, 6... suction port, 7... exhaust Ventilation port, 8...bearing, 9...bearing cover, 10...support, 11...pillar, 11a...screw hole, 12...heat sink, 13...spring, 14...cooling fin, 15...fixing screw, 16...rotor, 17...stator core, 18...yoke, 19...teeth, 20...slot, 21...recess, 22...projection, 22a...through hole, 23...winding, 24...winding frame, 25...stator, 26...fixing nut, 27...end bracket t, 28... ring, 29... first axial diffuser vane (axial diffuser vane on the impeller side), 29a... leading edge, 29b... trailing edge, 30... second axial diffuser vane (axial diffuser vane on the anti-impeller side), 30a... leading edge, 30b... trailing edge, 31... first flow passage, 32... second flow passage, 33... hub plate, 34... impeller vane, 35... recess (back side of impeller), 36... protrusion, 37... claw portion, t1 ...Cooling fin plate thickness, t2...gap on inner diameter side of teeth, 200...electric blower, 201...blower section, 202...motor section, 400...vacuum cleaner, 401...dust collection chamber, 402...telescopic pipe, 403...grip section, 404...switch section, 405...suction body, 406...connection section, 407...handy grip section, 408...suction body, 410...vacuum cleaner body, 420...battery unit, 440...flow path

Claims

1. The rotor is provided on a rotating shaft, an impeller is fixed to the rotating shaft, a stator is disposed on the outer periphery of the rotor with a gap therebetween and has a stator core and a winding, a bearing supports the rotating shaft, and a bearing cover contains the bearing, the stator core includes a yoke and a plurality of teeth extending inwardly from the yoke and around which the winding is wound; The bearing cover is provided with cooling fins extending along the axial direction on its outer periphery, An electric blower, wherein the cooling fins are disposed between adjacent ones of the teeth.

2. The electric blower according to claim 1, a cylindrical housing having a diffuser vane for decelerating and increasing the pressure of the airflow discharged from the impeller; An electric blower, wherein the bearing cover is enclosed within the housing.

3. The electric blower according to claim 2, The electric blower is characterized in that the housing and the bearing cover are integrated by insert molding.

4. The electric blower according to claim 3, 13. An electric blower, comprising: said housing made of synthetic resin; and said bearing cover made of a non-magnetic metallic material.

5. The electric blower according to claim 4, The electric blower is characterized in that the bearing cover is manufactured by die casting.

6. The electric blower according to claim 5, The bearing cover is provided with a support portion integrally molded therewith, The electric blower, wherein the bearing cover is integrated with the housing via the support portion.

7. The electric blower according to claim 6, The electric blower, wherein the support portion is provided so as to protrude toward the impeller side beyond an end position of the housing on the impeller side.

8. The electric blower according to claim 7, The electric blower, wherein the cooling fins are arranged so as to overlap with the bearings in a radial direction perpendicular to an axial direction.

9. The electric blower according to claim 7, The electric blower, wherein the support portion is disposed so as to overlap the impeller in a radial direction perpendicular to an axial direction.

10. The electric blower according to claim 1, An electric blower, characterized in that a plate thickness of the cooling fin when viewed in the axial direction is smaller than a gap formed between the windings wound around adjacent teeth.

11. An electric vacuum cleaner comprising: an electric blower that generates a suction airflow; a dust collection chamber that collects dust sucked by the suction airflow generated by the electric blower; and a vacuum cleaner body that houses the electric blower and the dust collection chamber, 11. A vacuum cleaner, wherein the electric blower is as defined in claim 1.

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