JP2025034604A - Electric blower and vacuum cleaner equipped with same - Google Patents

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

The present invention relates to an electric blower and a vacuum cleaner equipped with the same.

In cordless stick vacuum cleaners and self-propelled electric 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 the miniaturization of electric vacuum cleaners, there is also a demand for miniaturization of electric blowers. In order to miniaturize electric blowers, 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 rotation speed of approximately 50,000 revolutions per minute or more. Examples of such electric blowers include those disclosed in Patent Document 1 and Patent Document 2.

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 enclosed in a bearing cover, and the bearing cover is molded integrally 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 rear surface of the diffuser vanes. A heat sink is provided on the outer periphery of the bearing cover, and a reference surface on the side of the bearing cover where no heat sink is provided is provided. The reference surface serves as the reference surface when the bearing cover and resin housing are insert molded together, and as the reference when cutting the inner diameter to fix the outer ring of the bearing."

Patent Document 2 also 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. The inner wall of the impeller-side housing has 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."

JP 2016-138510 A JP 2022-81860 A

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 intake port 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 roughly 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 the return guide. The airflow that passes through the return guide blade flows into the inside of the housing from an opening in the housing, cools the cooling fins of the bearing cover, cools the bearings via the bearing cover, and cools the rotor core, stator core, and conductors before being discharged to the outside. It is also shown that some of the airflow that passes through the return guide vanes is discharged to the outside through the housing's exhaust port without flowing through the cooling fins.

However, in the conventional technology described in Patent Document 1, the air discharged from the diffuser vanes hits the inner surface of the fan casing, is redirected axially in a roughly triangular flow path, and is further redirected into a radially inward flow by the return guide vanes. In Patent Document 1, the bearings can be cooled by directing the discharge flow (cooling air) from the blower against 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 is a risk that the bearings and the stator core and conductors inside the motor cannot be sufficiently cooled.

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 from the motor housing is located at approximately the center of the stator core, and assembled by bonding or press fitting. In addition, openings are provided in the motor housing 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 and 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.

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, rises. The temperature of the motor housing rises 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 pressing. 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 impeller side motor housing tends to become hotter than the anti-impeller side motor housing.

In addition, because the opening in the impeller-side motor housing is located on the side away from the impeller than the bearing, the cooling air does not reach the impeller-side bearing and is discharged from the opening in the motor housing, meaning that the impeller-side bearing cannot be sufficiently cooled.

Furthermore, the motor housing that holds the bearings is attached to both sides of the stator core by bonding or press-fitting, so the distance between the bearings is long and the fitting of the stator core and motor housing reduces the precision of concentricity, and the shaft is installed at an angle, which can cause vibration and noise.

Furthermore, when the temperature of the stator core and windings rises, 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 stretch in the axial direction. This causes the outer ring of the bearing fixed to the motor housing to stretch in the axial direction, which can cause vibrations and noise.

The object of the present invention is to solve the above-mentioned problems and to provide an electric blower with improved cooling performance for the bearings and motor, and an electric vacuum cleaner equipped with the same.

To solve the above problem, the present invention comprises 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 enclosing the bearing, the stator core comprises a yoke and a plurality of teeth extending inward from the yoke and around which the windings are wound, the outer periphery of the bearing cover comprises cooling fins extending along the axial direction, and the cooling fins are arranged between adjacent teeth.

The present invention provides an electric blower with improved cooling performance for the bearings and motor, and an electric vacuum cleaner equipped with the same.

Issues, configurations, and advantages other than those described above will become clear from the description of the embodiments below.

FIG. 2 is a perspective view of the appearance of an electric vacuum cleaner 400 equipped with an electric blower 200 when used as a stick type vacuum cleaner. FIG. 4 is a side view of the vacuum cleaner 400 when used as a handheld type. 4 is a vertical cross-sectional view of a vacuum cleaner body 410 of the electric vacuum cleaner 400. FIG. 1 is an external view of an electric blower 200 according to an embodiment of the present invention. 1 is a vertical cross-sectional view of an electric blower 200 according to an embodiment of the present invention. FIG. 1 is a cross-sectional view of an impeller 1 cut along an axial direction. 1 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. 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. FIG. 1 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. FIG. 1 is a perspective view of a housing 3 on an opposite side to the impeller 1, the housing 3 having a second axial flow diffuser vane 30. FIG. 4 is a cross-sectional view of the anti-impeller housing 3 having a second axial flow diffuser vane 30. FIG. 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. 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. 8 is a cross-sectional view of the electric blower 200 of FIG. 3A taken along line VIIIA-VIIIA. FIG. 8B is a partially enlarged view of the dotted line VIIIB in FIG. 8A.

Below, an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail with reference to the drawings. Note that each figure merely shows a schematic view to the extent that the present invention can be fully understood. Therefore, the present invention is not limited to the illustrated examples. In addition, in each figure, common or similar components are given the same reference numerals, and duplicate explanations thereof will be omitted.

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

In this embodiment, the electric blower 200 is assumed to be mounted on a rechargeable vacuum cleaner 400 that can be switched between stick and handheld types as appropriate. The electric blower 200 can be mounted on various types of vacuum cleaners 400, including not only stick and handheld types, but also canister and self-propelled types.

As shown in FIG. 1A, the electric vacuum cleaner 400 includes a vacuum cleaner body 410 forming an outer shell, an expandable pipe 402 that is extendable relative to the vacuum cleaner body 410, a grip portion 403 provided at one end of the expandable pipe 402, and a switch portion 404 provided on the grip portion 403. The vacuum cleaner body 410 houses an electric blower 200 (see FIG. 2) that generates the suction airflow required for dust collection, and a dust collection chamber 401 that collects dust sucked in by the suction airflow generated by the electric blower 200. The switch portion 404 turns the electric blower 200 (see FIG. 2) on and off.

In the example shown in FIG. 1A, the vacuum cleaner 400 is in a stick state, with the telescopic pipe 402 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.

On the other hand, in the example shown in FIG. 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 in close proximity to the telescopic pipe 402. In the handy state, the handy grip part 407, which serves as a handle, is provided on the top side of the vacuum cleaner body 410, between the adjacent grip part 403 and the dust collection chamber 401. In addition, 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.

In the above configuration, when the switch 404 of the grip 403 of the electric vacuum cleaner 400 is operated, the electric blower 200 (see FIG. 2) housed in the vacuum cleaner body 410 is activated to generate a suction airflow. The electric vacuum cleaner 400 then sucks in dust from the suction body 405 (see FIG. 1A) or the suction body 408 (see FIG. 1B) and collects the dust in the dust collection chamber 401 of the vacuum cleaner body 410 through the connection 406.

As shown in FIG. 2, the vacuum cleaner body 410 includes an electric blower 200 that generates suction power, a battery unit 420 that supplies power to the electric blower 200, and a drive circuit 430. In the example shown in FIG. 2, the electric vacuum cleaner 400 is in a handheld state, and the suction body 408 is detached from the vacuum cleaner body 410.

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

Next, the configuration of the electric blower 200 will be described with reference to Figures 3 to 8. Figure 3A is an external view of the electric blower 200 according to an embodiment of the present invention. Figure 3B is a vertical cross-sectional view of the electric blower 200 according to an embodiment of the present invention. Figure 4A is a perspective view of the impeller 1. Figure 4B is a cross-sectional view of the impeller 1 cut along the axial direction. Figure 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. Figure 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. Figure 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. Figure 6A is a perspective view of the anti-impeller-side housing 3 having the second axial diffuser vane 30 as seen from the impeller 1 side. Figure 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 the stator 25 in which the winding frame 24 is fitted to the stator core 17 of the electric motor section 202 and the windings 23 are wound around it. FIG. 7B is a cross-sectional view of the stator 25 in which the winding frame 24 is fitted to the stator core 17 of the electric motor section 202 and the windings 23 are wound around it. FIG. 8A is a cross-sectional view of the electric blower 200 in FIG. 3A taken along line VIIIA-VIIIA. FIG. 8B is an enlarged view of the portion indicated by the dotted line VIIIB in FIG. 8A. Note that in FIG. 3B, a typical air flow is shown by the solid arrow α1 and the dotted arrow α2 only on the left side of FIG. 3B.

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

As shown in FIG. 3B, the electric blower 200 has an electric motor section 202 arranged radially inward of the blower section 201. The blower section 201 is provided with an impeller 1, which is a rotor, a first axial diffuser vane 29 on the impeller 1 side, and a second axial diffuser vane 30, arranged from the upstream of the suction air flow. A fan casing 4 is arranged to cover the impeller 1, and the fan casing 4 is provided with an intake port 6. An exhaust port 7 is arranged downstream of the second axial diffuser vane 30 to exhaust the air sucked in from the intake port 6.

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.

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

The bearing cover 9 has a support part 10 of a generally cylindrical shape that is molded as one piece, and the bearing cover 9 is integrated with the impeller-side housing 2 via the support part 10 and fixed to the impeller-side housing 2.

The support part 10, which is substantially cylindrical, protrudes toward the impeller 1 from 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 arranged so as to overlap with the impeller 1 in the radial direction perpendicular to the axial direction. The support part 10 has a support 11 on the side opposite the impeller for fixing the stator 25 with a fixing screw 15, and has a screw hole 11a.

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

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

The bearing cover 9 is formed in a cylindrical shape. A number of cooling fins 14 are provided on the outer periphery of the bearing cover 9, protruding toward the outer periphery and extending along the axial direction. The cooling fins 14 are arranged on the outer periphery of the bearing 8 and function as a heat sink to cool the bearing 8.

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 on the impeller 1 side (see Figs. 8A and 8B). In other words, the cooling fins 14 are disposed between adjacent teeth 19, in slots 20, which will be described later.

The cooling fins 14 are also arranged so as to overlap the bearings 8 located above the rotating shaft 5 in the radial direction perpendicular to the axial direction (see FIG. 3B). The bearings 8 located above the rotating shaft 5 tend to be hotter than the bearings 8 located below the rotating shaft 5. Therefore, in this embodiment, the cooling fins 14 and the bearings 8 located above the rotating shaft 5 are arranged so as to overlap in the radial direction perpendicular to the axial direction, thereby improving the cooling performance of the bearings 8 located above the rotating shaft 5.

As shown in FIG. 3B, the bearing cover 9 contains the bearings 8 and springs 13. The springs 13 are arranged in a compressed state and abut against the outer rings of the bearings 8 to apply preload.

In the impeller 1 shown in Figures 3B, 4A, and 4B, the metal sleeve 1b is covered with a hub plate 33 made of thermoplastic resin. The impeller 1 is fixed by screwing a fixing nut 26 onto a female thread that is threaded into 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 is fixed using the fixing nut 26, but it may also be fixed to the rotating shaft 5 by press fitting.

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 with a gap on its outer periphery. 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.

As shown in Figures 7A and 7B, multiple teeth 19 and slots 20 are arranged at equal intervals around the entire circumference of the stator core 17 on the inner diameter side of the stator core 17. The slots 20 are formed between adjacent teeth 19. The outer periphery of the yoke 18 of the stator core 17 has a recess 21 recessed toward the radial inner diameter side, and a protrusion 22 protruding toward the radial outer diameter side.

The space surrounded by the yoke 18 and the teeth 19 forms a slot 20 into which the winding 23 is inserted, and the winding 23 is wound around the teeth 19 via a winding frame 24.

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

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 an approximately annular shape without the recessed portion 21.

The stator core 17 is made by laminating multiple electromagnetic steel sheets that have been pressed using a die, but by making the yoke 18 approximately annular in shape, the die structure of the stator core 17 can be simplified.

The windings 23 are electrically connected to a drive circuit 430 (see FIG. 2) provided in the electric blower 200. Note that although copper wire is used for the windings 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. Note that although the windings 23 shown in FIGS. 7A and 7B are wire material, they are shown as an integrated unit.

As shown in FIG. 3B, an end bracket 27 for mounting a circuit (not shown) is attached to the stator 25 on the side opposite the impeller with a fixing screw 15. The end bracket 27 has a screw hole 27a for fixing the circuit, and the circuit (not shown) is fixed to the end bracket 27.

A winding frame 24 is arranged around the stator core 17. The winding frame 24 is made of insulating synthetic resin material, and is fitted to prevent the windings 23 from coming into direct contact with the stator core 17. The stator core 17 shown in Figures 7A and 7B is shown as an integrated laminate of electromagnetic steel sheets. The winding frame 24 may be made of any material that is easy to mold and has electrical insulation properties, 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.

The rotor 16 of the motor section 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 rare earth magnetic powder with an organic binder. Examples of rare earth bonded magnets that can be used include samarium iron nitrogen magnets and neodymium magnets. The rotor 16 is molded integrally with the rotating shaft 5. Note that in this embodiment, a permanent magnet is used for the rotor 16, but without being limited to this, a reluctance motor, which is a type of commutatorless motor that allows high-speed rotation of about 50,000 to 200,000 revolutions per minute, may also be used.

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 manufactured, for example, from a sintered product such as copper or by machining.

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

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

The first flow passage 31 and the second flow passage 32 join at the lower end 3c (axial end) of the inner wall 3a of the anti-impeller housing 3. The lower end 3c of the inner wall 3a of the anti-impeller housing 3 is located at 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 anti-impeller housing 3, a flow is generated in the second flow passage 32 by the Venturi effect caused by 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 section 202. This improves the cooling performance of the electric motor section 202 and increases the efficiency of the electric blower 200 over a wide operating range.

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

When the airflow discharged from the impeller 1 passes through the first axial diffuser vane 29 and the second axial diffuser vane 30, it flows along the first axial diffuser vane 29 and the second axial diffuser vane 30, and the rotational velocity component of the flow is reduced. In addition, the lower end 3c of the inner wall of the anti-impeller side 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. The first flow path 31 is a flow path from the intake port 6 of the fan casing 4 to the exhaust section 7 of the housing 3 on the opposite side to the impeller, as shown by the solid arrow α1 in FIG. 3B.

The second flow passage 32 cools the stator core 17 and the windings 23 by drawing 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, due to the high wind speed at the outlet of the second axial diffuser vane 30. The air passing between the windings 23 flows to the impeller 1 side and hits the cooling fins 14 of the bearing cover 9 directly, cooling the bearings 8 through the bearing cover 9. The air that has cooled the cooling fins 14 flows to the inner wall 2a side 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), merges with the air in the first flow passage 31, and is exhausted from the electric blower 200 through the exhaust port 7. The stator 25 is cooled by the air flowing around the outer periphery of the stator 25.

The first flow passage 31 and the second flow passage 32 join near the second axial diffuser vane 30, making it possible to efficiently use the Venturi effect and cool the inside of the motor. In other words, the cooling air for the motor is sucked in from the motor section 202 side by the Venturi effect, which increases the blower efficiency and allows the stator core 17, windings 23, and bearings 8 to be cooled efficiently.

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

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

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 by reducing the amount of imbalance of the impeller 1, it is possible to reduce vibration and noise. Furthermore, the end of the sleeve 1b of the impeller 1 abuts against the inner ring of the bearing 8, so that the position of the impeller 1 can be determined, and by transferring heat from the bearing 8 to the sleeve 1b, the cooling performance of the bearing 8 due to the rotation of the sleeve 1b can be promoted.

As shown in FIG. 3B, the roughly cylindrical support part 10 of the bearing cover 9 is disposed within the recess 35 of the impeller 1. Rotation of the impeller 1 creates a swirling flow within 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, which is made of a non-magnetic metal material, and is dissipated by the support part 10 of the bearing cover 9, effectively cooling the bearing 8. The support part 10 is roughly 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.

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

If the deformation of the blades due to centrifugal stress during operation of the impeller 1 is large, the gap between the impeller 1 and the fan casing 4 during operation can be minimized 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 off, resulting in a highly efficient electric blower.

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, 5A, 6B, and 7. As shown in FIG. 3B, 5, and 6, the blower 201 of this embodiment has 15 first axial diffuser vanes 29 on the impeller 1 side 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 number of vanes of the second axial diffuser vane 30 is the same as that of the first axial diffuser vane 29 on the impeller 1 side, 15.

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. In addition, 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 to make the flow passage surface 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 flush. This is because if there is a step on the flow passage surface, the loss at the first axial diffuser vane 29 and the second axial diffuser vane 30 increases.

By fitting the protrusion 36 on the outer wall 2b of the impeller-side housing 2 with the claw portion 37 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 positioned and fixed in the circumferential direction, making the structure easy to assemble and improving mass productivity.

The air flowing out from the impeller 1 is a flow with rotational and axial components. As it 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 and improving the efficiency of the blower.

As shown in Figures 5A to 5C, the impeller-side housing 2 is made of synthetic resin and has a support portion 10 that fixes the bearing cover 9, which contains the bearing 8, to the impeller-side housing 2. The outer periphery of the bearing cover 9 is cylindrical, and multiple 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 in the axial direction on the impeller 1 side at approximately the center of the slots 20 between the teeth 19 of the stator core 17 (see Figures 8A and 8B). In this embodiment, there are six slots 20 and the cooling fins 14 are also six, but without being limited to this, 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.

Also, as shown in FIG. 8B, the thickness t1 of the cooling fin 14 when viewed from the axial direction (see FIG. 5C) 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 portion 10 of the cooling fin 14, and the bearing 8 on the impeller 1 side can also be cooled via the bearing cover 9.

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

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 easy to assemble.

The support part 10 of the bearing cover 9 is substantially cylindrical 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 enhanced by providing irregularities or ribs on the end surface of the support part 10 on the impeller 1 side.

By arranging 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. In addition, two bearings 8 are arranged in the bearing cover 9 and rotatably support the rotating shaft 5, so 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, because 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.

The support part 10 of the bearing cover 9 is provided with a support 11 for attaching the stator 25 to the impeller-side housing 2, and a heat sink 12 on both circumferential sides of the support 11. The support 11 is formed with a screw hole 11a for attaching 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 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 sinks 12 on the stator 25 side is wider than on the support 11 side. This acts as a guide when attaching the stator 25, facilitating assembly of the stator 25 and improving mass productivity.

Cooling fins 14 are provided on the outer periphery of the bearing cover 9 and the support part 10, and are molded integrally with the impeller-side housing 2, which increases the rigidity of the bearing cover 9 and the impeller-side housing 2 and enables high-speed rotation of more than 50,000 revolutions per minute.

The electric blower 200 of this embodiment described above comprises a rotor 16 provided on the 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 comprises 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 is provided with cooling fins 14 extending along the axial direction, and the cooling fins 14 are arranged between adjacent teeth 19.

This allows the stator core 17, windings 23, and bearings 8 of the stator 25 of the motor section 202 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 installing the electric blower 200 in the electric vacuum cleaner 400, the output of the electric vacuum cleaner can be improved. Furthermore, by improving the efficiency of the electric blower 200, the input of the electric blower 200 can be lowered to obtain the same output, and the operating time can be extended in a rechargeable vacuum cleaner that uses a battery as a power source.

The present invention is not limited to the above-described embodiments, but includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. It is also possible to replace 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. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

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 , 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 blade, 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 (11)

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. 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. 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. 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. The electric blower according to claim 4,
The electric blower is characterized in that the bearing cover is manufactured by die casting. 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. 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. 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. The electric blower according to claim 7,
The electric blower, wherein the support portion is disposed so as to overlap with the impeller in a radial direction perpendicular to an axial direction. 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. 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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