JP2024014328A - Electric blower and vacuum cleaner equipped with it - Google Patents

Abstract

To provide a compact and lightweight electric air blower having high efficiency and having high motor cooling efficiency, and a vacuum cleaner comprising the same.SOLUTION: An electric air blower 200 comprises a first flow passage F1 passing through an impeller 1, and a second flow passage F2 passing through the inside of a motor part 202. The motor part 202 comprises a rotating shaft, a stator core 24, and motor housings 6 and 7 comprising an upstream side radial opening 6a and a downstream side radial opening 7a in side surfaces. An air blower part comprises the impeller 1, a fan casing, and an upstream side housing 4. The first flow passage F1 passes through the impeller 1 and between inner and outer walls of the upstream side housing 4. The second flow passage F2 passes through an axial opening 7b, the downstream side radial opening 7a, the inside of the motor part 202, the upstream side radial opening 6a, between the motor housing 7 and the inner wall of the upstream side housing, and between the motor housing 7 and an inner wall 5a of a downstream side housing. A second diffuser blade 9 comprises a shroud on a circular pipe, and a hub 5a, and protrudes on the downstream side toward the side of the shroud from the hub 5a.SELECTED DRAWING: Figure 6

Description

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

As an example of an electric blower (air blower) built into a vacuum cleaner, Patent Document 1 describes ``an impeller (10) that rotates around a central axis C that extends vertically, and a stator 24 disposed below the impeller (10). A motor housing (21) housing the impeller (10) and the motor housing (21), a motor housing (21) housing the stator (24), and a motor housing (21) housing the impeller (10) and the motor housing (21). ), the upper part of the fan casing (2) covers the upper part of the impeller (10), and an intake port (3) that opens in the vertical direction. The lower part of the fan casing (2) is provided with an exhaust port (4) that communicates with the intake port via the first flow path (5), and the motor housing (21) is provided with an exhaust port (4) that communicates with the intake port via the first flow path (5). An inlet (21a) that penetrates in the radial direction and communicates with the first flow path (5) is provided below the upper surface of the stator (24) fixed to the inner surface, and the motor housing (21) is connected to the inlet (21a). 21a) and has a second flow path (6) that extends upward from the stator (24) and communicates with the space above the stator (24).

Japanese Patent Application Publication No. 2018-105269

It is known that the operating air volume of a vacuum cleaner varies greatly depending on operating conditions such as clogging of the filter due to dust and the material of the floor to be cleaned. Therefore, as an electric blower for a vacuum cleaner, there is a demand for an electric blower that has strong suction power over a wide range of air volume.
Furthermore, in order to improve the usability of vacuum cleaners, electric blowers used in vacuum cleaners are required to be smaller and lighter. Accordingly, the heat radiation area of the electric blower decreases, and the internal heat generation density increases. Therefore, it is necessary to improve the cooling performance of the motor (20) and bearings (26).

In particular, vacuum cleaners that are powered by batteries (secondary batteries), such as cordless stick vacuum cleaners and autonomous vacuum cleaners (robot vacuum cleaners), consume less power than electric blowers due to battery capacity, and have a lower maximum air volume. small. Therefore, there is a problem that when the filter becomes clogged, the dirt conveying ability is reduced and the suction power of the vacuum cleaner is reduced. Furthermore, battery-powered vacuum cleaners are required to be small and lightweight, and electric blowers mounted on vacuum cleaners are required to have both strong suction power over a wide air volume range and small size.

Here, if a diffuser blade ("stationary blade (40)" in Patent Document 1) is used, excellent pressure recovery can be performed at the design point air volume. However, if the air volume decreases from the design point air volume due to filter clogging, etc., the diffuser performance will decrease due to the mismatch between the inlet angle of the diffuser blade and the inflow angle of the air flow into the diffuser, and the suction force of the vacuum cleaner will decrease. may decrease.

In addition, in the blower device of Patent Document 1, as shown in the attached FIG. It flows into the inner second flow path (6) through the inlet (21a), cools the upper bearing 26, further cools the lower bearing (26), and flows into the first flow path (5). The air is exhausted to the outside of the blower device (1) from the outlet (outlet (2) 9a) of the second flow path (6) without merging with the air blower (1).

In this way, when adopting a configuration in which the second flow path (6) branched from the first flow path (5) does not merge with the first flow path (5), the air flow (S) flowing through the first flow path (5) is ) Due to the pressure loss (resistance) when a part of the flow branches into the second flow path (6), the air volume in the first flow path (5) is lower than that on the upstream side of the inlet (21a) (branch point). The air volume on the downstream side of the inlet (21a) (branch point) was decreasing.

In addition, the second flow path (6) of Patent Document 1 is small, so the flow path area is small, and furthermore, since the flow curves inside the motor (20), the pressure loss in the flow path is large, and the cooling air volume is small. There is a concern that the temperature inside the motor (20) will decrease, and the temperature inside the motor (20) will increase, resulting in a decrease in motor efficiency.

The present invention was devised in view of the above-mentioned circumstances, and aims to provide a small and lightweight electric blower with high efficiency and high motor cooling efficiency, and a vacuum cleaner equipped with the same.

In order to solve the above problems, an electric blower of the present invention includes a blower section and a motor section, a first flow path passing through an impeller inside the blower section, and a second flow path passing inside the motor section. The motor section includes a rotating shaft, a bearing that rotatably supports the rotating shaft, a rotor core fixed to the rotating shaft, a stator core disposed around the outer periphery of the rotor core, and holding the stator core. and a motor housing having an upstream radial opening and a downstream radial opening on the side surface, and the blower section includes an impeller fixed to the rotating shaft and an outer periphery of the impeller. It has a fan casing that covers and an upstream housing that surrounds the upstream outer periphery of the motor section, the first flow path passing between the impeller and an inner wall and an outer wall of the upstream housing, and the second flow path , the axial opening, the downstream radial opening, the opening of the downstream housing, the inside of the motor section, the upstream radial opening, between the motor housing and the inner wall of the upstream housing, and the motor The second diffuser blade of the downstream housing passes between the housing and the inner wall of the downstream housing, and the second diffuser blade of the downstream housing includes a shroud on a circular tube located on the outer periphery of the second diffuser blade, and a shroud of the second diffuser blade. The second diffuser blade has a hub on the inner diameter side, and the second diffuser blade gradually protrudes downstream from the hub toward the shroud.

According to the present invention, it is possible to provide a small and lightweight electric blower with high efficiency and high motor cooling efficiency, and a vacuum cleaner equipped with the same.

An external view of an electric blower according to an embodiment. FIG. 1 is a vertical cross-sectional view of an electric blower according to an embodiment. A perspective view of an impeller. A vertical cross-sectional view of an impeller. FIG. 1A is a plan view of the upstream housing viewed from the upstream side; FIG. FIG. 2 is a plan view of an upstream housing according to an embodiment. A vertical cross-sectional view of the upstream housing. An external view including a partial cross section of the upstream housing viewed from the outer periphery. FIG. 1A is a plan view of the downstream housing viewed from the upstream side, taken in the direction of arrow I in FIG. 1A. FIG. 3 is a vertical cross-sectional view of the downstream housing. FIG. 3 is a perspective view including a partial cross section of the downstream housing viewed from the outer circumferential side. FIG. 3 is a side external view of the motor section. FIG. 3 is a vertical cross-sectional view of the motor section. FIG. 2 is a vertical cross-sectional view of an electric blower showing an example of a first flow path and a second flow path. FIG. 7 is a longitudinal cross-sectional view of an electric blower showing an example of a first flow path and a second flow path of Modification 1. FIG. 7 is a longitudinal cross-sectional view of an electric blower showing an example of a first flow path and a second flow path of Modification 2. FIG. 3 is a perspective view, partially in section, of a second diffuser covered by a downstream housing. II direction arrow view including a partial cross section of FIG. 8A. A graph comparing the efficiency of electric blowers with vertical ducts (horizontal hatches) and slanted ducts (diagonal hatches). Temperature rise test results for the upstream bearing, coil, and stator core on the impeller side without a duct, with a vertical duct, and with an inclined duct. FIG. 1 is a perspective view of a vacuum cleaner 100 according to an embodiment of the present invention. FIG. 1 is a vertical cross-sectional view of a vacuum cleaner 100 according to an embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric blower and a vacuum cleaner equipped with the electric blower of the present invention will be described in detail below with reference to the drawings.
<Schematic configuration of vacuum cleaner 100>

FIG. 11 shows a perspective view of a vacuum cleaner 100 according to an embodiment of the present invention.
FIG. 12 shows a vertical cross-sectional view of the vacuum cleaner 100 of the embodiment.
The vacuum cleaner 100 of the embodiment is a rechargeable cordless stick vacuum cleaner. The vacuum cleaner 100 is used by attaching the vacuum cleaner main body 110 to the holding part 120.
The vacuum cleaner 100 is placed on the charging stand 130 and charged. Although the first embodiment exemplifies a rechargeable cordless stick vacuum cleaner, the electric blower 200 of the present invention may be built into a non-rechargeable stick vacuum cleaner equipped with a power cord.

The vacuum cleaner main body 110 can be used alone as a handy vacuum cleaner.
The vacuum cleaner main body 110 includes a main body grip portion 111 held by a user at the top, and a suction opening 112 (see FIG. 12) at the bottom for sucking dust during cleaning.

The main body grip part 111 shown in FIG. 11 is provided with a main body switch part 111a for turning on/off the drive of the electric blower 200 when used as a handy cleaner.
The interior of the vacuum cleaner main body 110 shown in FIG. 12 includes an electric blower 200, a drive circuit 114, a battery unit 115, and a dust collection chamber 113.
Electric blower 200 generates suction airflow necessary for dust collection. The drive circuit 114 drives and controls the electric blower 200. Battery unit 115 supplies power to drive circuit 114 . Dust is collected in the dust collection chamber 113.

The holding part 120 is a unit to which the cleaner main body 110 can be attached and detached. The holding part 120 includes a grip part 121 on the upper part that is held by the user. The grip portion 121 of the holding portion 120 is provided with a switch portion 121a for turning on/off the drive of the electric blower 200 when used as a stick vacuum cleaner.
The lower part of the holding part 120 is provided with a suction body 122 that sucks dust during cleaning, and a connection part 122a that connects the suction body 122 and the intake opening 112.
Although a configuration in which the connecting portion 122a is provided between the vacuum cleaner main body and the suction body 122 in this embodiment is described, the connecting portion may be long, and the connecting portion may be connected to the suction body and the main body with a removable hose. Or a pipe.

<Electric blower 200>
Next, electric blower 200 will be explained.
FIG. 1A shows an external view of an electric blower 200 according to an embodiment.

FIG. 1B shows a longitudinal cross-sectional view of the electric blower 200 of the embodiment.
The electric blower 200 includes a blower and a motor that rotate the impeller 1 to generate airflow. Therefore, the upstream side and downstream side of the air flow will be defined.
Further, focusing on the installation position of the rotating shaft 2, the axial direction and the radial direction will be defined.

As shown in FIGS. 11 and 12, the air inlet 200a (FIG. 1A) of the electric blower 200 is moved downward so that dust can be sucked up from the suction body 122 at the bottom of the vacuum cleaner 100 to the dust collection chamber 113 above. The electric blower 200 is installed inside with the exhaust port 200b facing upward.
The outer periphery of the electric blower 200 is covered with an outer shell that integrates the fan casing 3, the upstream housing 4, and the downstream housing 5.

The fan casing 3 is a cover that covers the outer periphery of the impeller 1 and functions as a shroud plate of the impeller 1.
The fan casing 3 is integrally molded from engineering plastic or thermoplastic resin. The fan casing 3 has an air intake port 200a opened on the upstream side of the airflow caused by the impeller 1.

As shown in FIG. 1B, the electric blower 200 sucks in air from an upper intake port 200a and discharges air from a lower exhaust port 200b by rotating the impeller 1 (arrow F1 in FIG. 1B).

Inside the electric blower 200, a rotary shaft 2 is rotatably arranged. An impeller 1 that rotates integrally with the rotating shaft 2 is fixed to the upper end of the rotating shaft 2. In addition, in FIG. 1B, the impeller 1 is fixed with a nut n1 screwed onto the upper end of the rotating shaft 2. Note that the impeller 1 may be fixed by press-fitting the impeller 1 to the tip of the rotating shaft 2.
The electric blower 200 mainly includes a blower section 201 and a motor section 202.

The blower section 201 shown in FIG. 1B has an impeller 1, a rotating shaft 2, a first diffuser blade 8, and a second diffuser blade 9. The impeller 1 is fixed to a rotating shaft 2 and driven by a motor section 202.
The motor section 202 is covered with an upstream motor housing 6 and a downstream motor housing 7.
When the impeller 1 rotates, inside the electric blower 200, as shown by the solid arrow F1 on the left side of FIG. A first airflow of airflow is generated.

The first air flow flowing through the first flow path F1 that has passed through the second diffuser 9 has a high wind speed and a low static pressure, so a low pressure part T is generated at the outlet of the second diffuser blade 9 (Fig. 6 ). The low pressure portion T forms second flow paths F2a and F2b through which the second airflow flows from the downstream side to the upstream side within the motor portion 202.
The electric blower 200 maintains the suction power of the vacuum cleaner 100 over a wide air volume range by circulating the first air flow through the first flow path F1 and the second air flow through the second flow paths F2a and F2b. At the same time, the inside of the motor section 202 can be sufficiently cooled.
Hereinafter, the structure of the electric blower 200 will be explained in order by dividing it into a blower section 201 and a motor section 202.

<Blower section 201>
The blower section 201 shown in FIG. 1B is a unit for the vacuum cleaner 100 to generate an air flow that sucks dust.
In the blower section 201, an impeller 1, which is a rotary blade, a first diffuser blade 8, and a second diffuser blade 9 are arranged in order from the upstream side of the first flow path F1 through which the first airflow flows.
The first and second diffuser blades 8 and 9 reduce the wind speed of the air flow on the downstream side of the impeller 1, and control the wind speed and flow direction, and control the static pressure.

That is, the first diffuser blade 8 and the second diffuser blade 9 convert the dynamic pressure of the airflow generated by the impeller 1 into static pressure.
The first diffuser blade 8 is provided on the inner periphery of the upstream housing 4 .
The second diffuser blade 9 is provided on the inner periphery of the downstream housing 5.

<Impeller 1 and fan casing 3>
FIG. 2A shows a perspective view of the impeller 1.
FIG. 2B shows a longitudinal cross-sectional view of the impeller 1.
The impeller 1 is an open type mixed flow impeller without a shroud plate. The impeller 1 is integrally molded from engineering plastic or thermoplastic resin.
The impeller 1 has a hub 11, a plurality of blades 12, and a boss 13 into which the rotating shaft 2 is inserted. Note that the impeller 1 may be a mixed-flow impeller with a shroud plate, a centrifugal impeller, or an axial-flow impeller.

The outermost diameter 11a of the hub of the impeller 1 shown in FIG. 1B is located between the shroud diameter 5g and the hub diameter 5f of the second stage diffuser (9).
That is, the length 11a of the diameter of the hub 11 of the impeller 1 in the radial direction shown in FIG. 1B is shorter than the length 5g of the inner diameter of the shroud of the second diffuser 9D, and the length of the diameter of the hub of the first diffuser It is longer than 5f. That is, there is a relationship of 5f<11a<5g.

Since the diameter length 11a of the hub of the impeller 1 is longer than the diameter length 5f of the hub 5 of the first diffuser, a high input can be achieved. Moreover, since the length 11a of the hub diameter of the impeller 1 is shorter than the length 5g of the inner diameter of the shroud of the second diffuser, cooling of the motor section 202 can be achieved at the same time. Further, venturi cooling, which will be described later, can be promoted.
The second air flow flowing through the second flow path F2 (F2a, F2b) is made to flow along the inner diameter of the diffuser hub 5a and the outer diameter of the motor casing 7, thereby reducing the size of the electric blower 200, cooling the motor section 202, and increasing efficiency. It is compatible with both

A metal sleeve 14 is integrally molded on the back side of the hub 11 shown in FIG. 2B, coaxially with the boss 13 of the impeller 1. By using the sleeve 14, it is possible to reduce variations in the fitting clearance between the impeller 1 and the rotary shaft 2, which are likely to occur when the sleeve is not used, and to reduce unbalance of the impeller 1. Therefore, vibration and noise when the impeller 1 is driven to rotate can be reduced.
Note that if the sleeve 14 is not used, there is a high possibility that variations in the fitting clearance between the impeller 1 and the rotating shaft 2 and imbalance of the impeller 1 will occur.
Furthermore, a recess 14a is provided on the downstream side of the sleeve 14.
Further, the end portion 11b of the hub 11 of the impeller 1 is provided with a recess (notch) 11b1 in the circumferential direction. This reduces thermal stress during molding of the impeller 1 and relieves strain. Further, residual stress during molding of the impeller 1 is reduced, and fatigue strength is improved. Note that the cross-sectional shape of the recessed portion 11b1 may be an arc or an ellipse that does not cause stress concentration, may be uniform in the circumferential direction with respect to the rotation axis, or may be configured to be discontinuous in the circumferential direction.

The fan casing 3 will be explained. A part of the outer wall of the fan casing protrudes toward the side connecting with the upstream housing 4, is cut out from the side connecting with the upstream housing 4 toward the impeller, and extends in the circumferential direction of the fan casing 3. An L-shaped notch 3a is formed in the. The cutout portions 3a are formed at three locations in the circumferential direction of the outer wall portion. Note that the fan casing 3 is rotated in the axial direction, assembled to the upstream housing 4, and then fixed with adhesive.

<Upstream housing 4 and first diffuser blade 8>
FIG. 3A shows a plan view of the upstream housing 4 seen from the upstream side, which is a view taken in the direction of arrow I in FIG. 1A.

FIG. 3B shows a longitudinal cross-sectional view of the upstream housing 4.
FIG. 3C shows an external view including a partial cross section of the upstream housing 4 viewed from the outer periphery. In addition, in FIG. 3C, the shape of the first diffuser blade 8 (particularly the positions of the leading edge 8a and the trailing edge 8b) is shown by partially omitting the shroud of the upstream housing 4.
The upstream housing 4 and the first diffuser blade 8 will be explained.
The upstream housing 4 and the first diffuser blade 8 are integrally molded from engineering plastic or thermoplastic resin.

Between the inner wall 4a (hub) and outer wall 4b (shroud) of the upstream housing 4, a plurality of first diffuser blades 8 integrally molded therewith are arranged at equal intervals in the circumferential direction (see FIG. 3A). ing.

The length (chord length) from the leading edge 8a to the trailing edge 8b of the first diffuser blade 8 shown in FIG. 3C is longer on the outer wall 4b side than on the inner wall 4a side. This is because downstream of the impeller 1, the wind speed on the outer circumferential side is faster than on the inner circumferential side, so by making the outer side of the first diffuser blade 8 longer than the inner side, loss can be suppressed and the dynamic pressure can be kept quiet. This is to increase the efficiency of the blower by increasing the area that is converted into pressure. Although a configuration in which 15 first diffuser blades 8 are provided is illustrated here, the number of first diffuser blades 8 can be changed according to the specifications of the electric blower 200.

As shown in FIGS. 3A and 3C, protrusions 4c are provided at three locations on the outer periphery of the outer wall 4b of the upstream housing 4 at equal intervals.
By fitting the claw portion 5c of the downstream housing 5 shown in FIG. 4B into the protrusion 4c, the upstream housing 4 and the downstream housing 5 can be integrated while being centered (see FIG. 1B).

As shown in FIGS. 3A and 3B, fastening portions 4d are provided at two locations on the upper surface of the upstream housing 4. As shown in FIGS. The motor part 202 shown in FIG. 1B can be fastened to the fastening part 4d while being centered.
The shroud 4e of the first diffuser has an inclined portion 4e1 that slopes radially inward toward the axially downstream side.
The outer wall 4b of the first diffuser blade 8 forms a flow path having approximately the same radius.

By gently turning the flow at the outlet of the impeller 1 radially inward at the inclined portion 4e1 of the shroud 4e, the flow is aligned with the inner diameter of the diffuser hub 5a and the outer diameter of the motor casing 7, and the electric blower 200 This achieves both miniaturization of the motor unit 202, cooling of the motor unit 202, and high efficiency.

<Downstream housing 5 and second diffuser blade 9>
FIG. 4A shows a plan view of the downstream housing 5 (see FIG. 1A) viewed from the upstream side in the I direction of FIG. 1A.

FIG. 4B shows a longitudinal cross-sectional view of the downstream housing 5 (see FIG. 1A).
FIG. 4C shows a perspective view including a partial cross section of the downstream housing 5 (see FIG. 1A) viewed from the outer peripheral side. In FIG. 4C, the shape of the second diffuser blade 9 (particularly the positions of the leading edge 9a and the trailing edge 9b) is shown by partially omitting the outer wall 5B (shroud) of the downstream housing 5.

The downstream housing 5 and second diffuser blade 9 shown in FIGS. 4A to 4C will be explained.
The downstream housing 5 and the second diffuser blade 9 are integrally molded from engineering plastic or thermoplastic resin.
Between the inner wall 5a (hub) and outer wall 5b (shroud) of the downstream housing 5, a plurality of integrally molded second diffuser blades 9 are arranged at equal intervals in the circumferential direction (see FIG. 4C). ).

Although a configuration in which 15 second diffuser blades 9 are provided is illustrated, this is because the second diffuser blades 9 are arranged downstream of each first diffuser blade 8. This is to match the number of blades 8 and the number of second diffuser blades 9. Note that the number of second diffuser blades may be different from the number of first diffuser blades.

As shown in FIG. 4B, the trailing edge 9b of the second diffuser blade 9 extends downstream in the axial direction, and the height of the blade from the outer wall 5b of the shroud decreases toward the outside in the radial direction.
The trailing edge 9b does not have a monotonous change, but can be curved, have a plurality of curves, or have a plurality of lines, and can have any shape.

The axial length L1 on the shroud side of the second diffuser blade 9 shown in FIG. 4B is approximately twice or more the length L2 of the inner wall 5a.
Since the length of the second diffuser blade 9 is different from the radially outer blade, the pressure applied to the radially outer side is increased, which promotes the flow toward the inner inner wall 5a (hub) of the downstream housing 5. Cooling of the motor section 202 (see FIG. 1B) is promoted.

A surface 9c of the protrusion of the second diffuser blade 9 on the forward side in the rotational direction of the impeller 1 shown in FIG. 4C is substantially flat, and the plate thickness decreases toward the trailing edge 9b. As a result, by reducing the plate thickness t (see FIG. 4C) of the second diffuser blade 9 toward the trailing edge 9b, the volume of the first flow path F1 is expanded, and the deceleration of the flow is promoted to improve the efficiency of the electric blower. is improving.
Further, by reducing the plate thickness t (see FIG. 4C) of the second diffuser blade 9, shrinkage of the resin during molding is suppressed.

As shown in FIGS. 4A to 4C, claw portions 5c are provided at three locations on the outer periphery of the upper end of the downstream housing 5 at equal intervals.
A fitting portion 5d is provided on the outer periphery of the upper end except for the claw portion 5c shown in FIGS. 4B and 4C. While pressing the lower end of the upstream housing 4 against the fitting portion 5d of the downstream housing 5, fit the three claw portions 5c (see FIGS. 4B and 4C) into the three protrusions 4c (see FIG. 3A). Thus, the upstream housing 4 and the downstream housing 5 can be integrated while being centered (see FIG. 1B). Note that the fan casing 3 and the upstream housing 4, and the upstream housing 4 and the downstream housing 5 are fixed by adhesive to suppress an increase in noise due to rattling when a minute gap is generated.

Furthermore, as shown in FIGS. 4B and 4C, on the downstream side of the downstream housing 5, an annular diffuser 5e without the second diffuser blade 9 is provided.
In the electric blower 200 shown in FIG. 1B, the inner wall 4a of the upstream housing 4 (see FIG. 3A), the inner wall 5a of the downstream housing 5 (see FIGS. 4A and 4B), and the outer wall 4b of the upstream housing 4 (see FIG. 3A) , FIG. 3B) and the outer wall 5b of the downstream housing 5 (see FIGS. 4A and 4B) are integrated with their radial positions substantially aligned.

This makes the inner surface of each flow path formed by the upstream housing 4 and the downstream housing 5 smooth, thereby reducing loss in each flow path.
In the electric blower 200, the trailing edge 8b of the first diffuser blade 8 shown in FIG. 3C and the rear edge 8b of the first diffuser blade 8 shown in FIG. The leading edge 9a of the second diffuser blade 9 shown in FIG. 4C is aligned in the circumferential direction, and the curved surfaces of the first diffuser blade 8 and the second diffuser blade 9 are smoothly continuous.

<Motor section 202>
FIG. 5A shows a side external view of the motor section 202.
FIG. 5B shows a longitudinal cross-sectional view of the motor section 202.
Next, the motor section 202 will be explained.
The motor section 202 is a unit for rotating the impeller 1 of the blower section 201 (see FIG. 1B) within a range of, for example, 50,000 to 200,000 rpm.

The motor section 202 shown in FIG. 5B includes a rotating shaft 2, an upstream bearing 21, a downstream bearing 22, a rotor core 23, a stator core 24, a collar 25, an upstream motor housing 6, and a downstream motor housing 7. ing. Each part will be explained below.

<Housing of motor unit 202>
As shown in FIG. 5A, the motor section 202 includes an upstream motor housing 6 and a downstream motor housing 7 as a housing that holds the stator core 24 and the like (see FIG. 5B).

The motor section 202 is built into the electric blower 200 by fixing the upper surface of the upstream motor housing 6 to the lower surface of the upstream housing 4 shown in FIG. 1B with screws or the like.
The upstream motor housing 6 shown in FIG. 5A is a metal (aluminum alloy, steel, etc.) housing that covers the upstream side of the motor section 202.
The upstream motor housing 6 has a plurality of (for example, six) radial openings 6a on the side surface.

As shown in FIG. 5B, the center of the upper surface of the upstream motor housing 6 protrudes upward, and an upstream bearing 21 that rotatably supports the upstream side of the rotating shaft 2 is provided therein.
The upstream bearing 21 is positioned in the axial direction by the upstream spacer 21a below the upstream bearing 21. Note that the upstream motor housing 6 may be provided with an axial opening, and if provided, cooling air can flow to the bearing 21 to perform cooling.

The downstream motor housing 7 shown in FIG. 5A is a metal (aluminum alloy, steel, etc.) housing that covers the downstream side of the motor section 202.
The downstream motor housing 7 has a plurality of (for example, six) radial openings 7a on the side surface and a plurality of axial openings 7b (see FIG. 5B) on the lower surface.
The center of the lower surface of the downstream motor housing 7 protrudes downward, and a downstream bearing 22 that rotatably supports the downstream side of the rotating shaft 2 is provided therein. The downstream spacer 22a above the downstream bearing 22 positions the downstream bearing 22 in the axial direction.

As shown in FIG. 5A, the radial opening 6a on the upstream side and the radial opening 7a on the downstream side are installed so as not to overlap in the axial direction (vertical direction in FIG. 5A).
The radial openings (6a, 7a) of each motor housing (6, 7) are arranged so as to overlap in the axial direction an axial end of a coil 24b, which will be described later. The radial openings (6a, 7a) of each motor housing (6, 7) are uniformly arranged in the circumferential direction.
The number of radial openings (6a, 7a) and the number of diffuser blades (8, 9) are set so that the greatest common divisor of the number of radial openings (6a, 7a) and the number of diffuser blades (8, 9) is 3. It is set.

Thereby, the same flow field is formed at three locations in the circumferential direction inside the motor section 202, so that the temperature distribution in the circumferential direction can be reduced. Note that the number of radial openings (6a, 7a) and the number of diffuser blades (8, 9) may be set using a predetermined value other than 3 as the greatest common divisor.
In addition, in this embodiment, in order to improve the cooling performance of the motor part 202, the following structure is adopted.

First, each motor housing (6, 7) is made of metal with high thermal conductivity to improve heat dissipation performance.
Second, by providing an exposed portion 24a (see FIG. 5A) in which the stator core 24 is exposed between the upper and lower motor housings (6, 7), the stator core 24 can be cooled from the outside.
In addition, in cases where the amount of heat generated by the motor section 202 is relatively small, each motor housing (6, 7) may be made of heat-resistant resin that has low thermal conductivity, or the upper and lower motor housings (6, 7) may be connected. Alternatively, the motor housing on the upstream side may be made longer in the axial direction, and the motor housing on the downstream side may be made shorter, thereby creating a structure in which the stator core 24 is not exposed and heat dissipation is reduced.

The radial opening 7a and the axial opening 7b of the downstream motor housing 7 shown in FIG. 5B can cool the motor with just the radial opening 7a. However, the presence of the axial opening 7b can reduce the pressure loss when taking in the motor cooling air flow (the air flow in the second flow path F2). This increases the amount of cooling air for the motor section 202, making cooling possible.

<Rotor of motor section 202>
A rotor core 23 is fixed to the rotating shaft 2 shown in FIG. 5B in a region sandwiched between upper and lower spacers (21a, 22a). The rotor core 23 forms a rotor of the motor section 202, which includes a rare earth bonded magnet such as a samarium iron nitrogen magnet or a neodymium magnet.

As shown in FIG. 5A, a collar 25 is fixed to the rotating shaft 2 protruding from the upper part of the upstream motor housing 6. As shown in FIG. A convex portion 25a (see FIG. 5A) is provided at the top of the collar 25. The convex portion 25a is fitted into the concave portion 14a (see FIG. 2B) of the sleeve 14 of the impeller 1. By fitting the convex portion 25a and the concave portion 14a (see FIG. 2B), the torque of the rotating shaft 2 can be reliably transmitted to the impeller 1, and idling of the impeller 1 can be prevented.

<Stator of motor section 202>
On the outer periphery of the motor section 202 shown in FIG. 5B, a stator core 24 of the stator of the motor section 202 is arranged surrounding a rotor core 23 that is a rotor of the motor section 202.
A coil 24b (see FIG. 5B) made of aluminum wire or copper wire covered with a covering material is wound around the winding frame portion of the stator core 24. By supplying desired AC power to the coil 24b from the drive circuit 114 shown in FIG. 12, the stator core 24 is made into an electromagnet. Thereby, the rotor core 23, the rotating shaft 2, and the impeller 1 fixed to the rotating shaft 2 can be rotated together at high speed.

As shown in FIG. 5B, the upstream motor housing 6 is driven (press-fitted) onto the upstream side of the stator core 24 and fixed with an adhesive. Further, the downstream motor housing 7 is driven (press-fitted) onto the downstream side of the stator core 24 and fixed with an adhesive. Thereby, the stator core 24, the upstream motor housing 6, and the downstream motor housing 7 can be integrated.
A radial opening 6a of the upstream motor housing 6 is provided at the height of the upstream end of the coil 24b. Furthermore, a radial opening 7a of the downstream motor housing 7 is provided at the height of the downstream end of the coil 24b.

<First flow path F1 and second flow path F2>
FIG. 6 shows a longitudinal cross-sectional view of the electric blower 200 as an example of the first flow path F1 and the second flow path F2.
Next, using FIG. 1B and FIG. 6A, the first flow path F1 through which the air flow by the impeller 1 of the embodiment flows and the second flow path F2 (F2a, F2b) through which the air flow of the cooling air of the motor section 202 flows. I will explain in detail.
The hub end 5i of the second diffuser blade 9 is located upstream of the front end 7c of the radial opening 7a of the downstream motor housing 7 on the downstream side. Further, the most downstream point 9d of the trailing edge 9b of the second diffuser blade 9 is located downstream of the front end 7c. With the configuration in which the trailing edge 9b of the second diffuser blade 9 straddles the front end 7c, the outlet flow of the second diffuser 9D is diverted toward the motor section 202 side (inward in the radial direction, downward in the plane of the paper in FIG. 6). By creating a pressure difference, it is possible to improve cooling performance and increase efficiency (by increasing the length of the shroud blades).

Specifically, the airflow generated by the impeller 1 and flowing through the first flow path F1 flows through a first diffuser 8D having a first diffuser blade 8 and a second diffuser 9D having a second diffuser blade 9. flows downstream through the
The airflow flowing through the first flow path F1 that has passed through the second diffuser 9D has a high wind speed, and a low pressure portion T is generated at the outlet of the second diffuser blade 9. Then, the airflow flowing through the second flow path F2 flows toward the motor side (Coanda effect).

In addition, since the shroud side of the second diffuser blade 9 is long in the axial direction, a pressure difference is created in the airflow from the outer wall 5 (shroud) to the motor section 202, thereby directing the airflow inward toward the motor section 202. Allows airflow.
From the radial opening 7a and axial opening 7b of the downstream motor housing 7, a flow toward the low pressure section T is generated due to the Venturi effect, and an airflow of cooling air flows through the second flow path F2 (F2a, F2b) inside the motor. is taken in, and the stator core 24, coil 24b, downstream bearing 22, and upstream bearing 21 of the stator are cooled.

The airflow flowing through the second flow path F2 after cooling passes through the radial opening 6a of the upstream motor housing 6, and forms a main stream (airflow of the first airflow F1 that has passed through the impeller 1) at the low pressure section T. Mix. At this time, the temperature decreases, and the air is then discharged from the exhaust port 200b (see FIG. 1B) together with the airflow flowing through the first flow path F1 downstream of the electric blower 200.

FIG. 7A shows a longitudinal cross-sectional view of an electric blower 200A of an example of the first flow path F1 and the second flow path F2 of Modification 1.
In the first modification, in order to increase the cooling air of the motor section 202, a diffuser hub 5a serving as an air path is provided between the first diffuser blade 8 of the first stage and the second diffuser blade 9 of the second stage. A duct 20 is provided depending on the shape. The configuration other than this is the same as the configuration of the embodiment shown in FIG. 6.

The downstream starting point 20a of the duct 20 is located downstream of the open end 6b of the radial opening 6a of the upstream motor housing 6.
The duct 20 is located downstream of the same axial position of the radial opening 6a of the upstream motor housing 6. Thereby, the direction of the air flow in the second flow path F2 flowing from the radial opening 6a to the duct 20 is along the direction of the air flow in the first flow path F1, and the loss when mixing with the diffuser flow path can be reduced.

FIG. 7B shows a longitudinal cross-sectional view of an electric blower 200B of an example of the first flow path F1 and the second flow path F2 of Modification 2.
The duct 20 of Modification 1 is a vertical duct, but in Modification 2, the duct is tilted in order to reduce loss when the air flow flowing through the first flow path F1 and the air flow flowing through the second flow path F mix. The inclined duct 20A has a sloped surface 20a. The other configurations are the same as Modification Example 1.

In Modification 2, the loss reduction effect of the slope compared to Modification 1 has been confirmed through experiments, and it is possible to improve the efficiency of the electric blower.
Note that in the configurations shown in FIGS. 5A to 7B, the upstream motor housing 6 and the downstream motor housing 7, which are the same motor casing, are configured to sandwich the stator core 24 of the stator, but the upstream motor housing 6 is the same as the stator. Even if the radial openings (radial openings 6a, 7a) and axial openings (7b) of the motor casing, the diffuser blades (8, 9), and the ducts 20, 20A have the same configuration. If so, the effect will be obtained.

Further, as shown in FIG. 5A, when a part of the stator core 24 of the stator is exposed from the motor casing (upstream motor housing 6, downstream motor housing 7), the surface of the stator core 24 of the stator is Cooling air flows through the flow path F2, increasing the cooling effect.

FIG. 8A shows a perspective view including a partial cross section of the second diffuser 9D covered by the downstream housing 5.
FIG. 8B shows a view taken in the direction II direction including a partial cross section of FIG. 8A.
Conventionally, the air flow in the first flow path F1 tends to separate from the diffuser hub 5a.
Therefore, as a method of promoting inward flow at the outlet of the second diffuser 9D, a cutout (recess) 5h is provided in the diffuser hub 5a of the second stage second diffuser 9D.

By providing the notch (recess) 5h in the diffuser hub 5a, the air flow in the first flow path F1 becomes difficult to separate, and the air flow in the first flow path F1 flows inward from the notch (recess) 5h (arrow α11 in FIG. 8A). ). That is, the air flow in the first flow path F1 of the outlet flow of the second diffuser 9D can form a radially inward flow flowing toward the motor section 202 side. Therefore, the cooling effect of the motor section 202 can be enhanced.

In FIG. 8B, when looking at the rotation axis C of the impeller 1 in the vertical direction, the depth Lc of the notch (recess) 5h, the width Wc of the notch (recess) 5h, and the diffuser hub between the second diffuser blades 9. In the case of the dimension W of 5a, the following equation (1) holds.
Lc≧0.6×L2 Wc≧0.5W (1)
The inclination angle θ of the inclined surface 5h1 of the notch (recess) 5h with respect to the rotation axis C of the impeller 1 is approximately 30 degrees.

Regarding the cooling effect of the notch (recess) 5h, the width Wc of the notch (recess) 5h and the depth Lc of the notch (recess) 5h are highly sensitive.
The circumferential position of the notch 5h shown in FIG. 8B is aligned with the forward side 9c of the second diffuser blade 9 in the rotational direction of the impeller 1, so that it is on the side of the diffuser hub 5a that is easy to peel off and the second diffuser blade 9. The flow on the forward side 9c side (negative pressure side) can be sucked out to the motor section 202 side. Therefore, a decrease in efficiency of the electric blower 200 is suppressed, and cooling performance can be improved.

<Effects of presence/absence of duct 20, vertical duct 20, and inclined duct 20A>
FIG. 9 shows a graph comparing the electric blower efficiency with the vertical duct 20 (horizontal hatched) and with the inclined duct 20A (diagonal hatched). One scale on the vertical axis indicates electric blower efficiency of 2%.
It was confirmed that when the inclined duct 20A was provided, the electric blower efficiency was slightly higher than when the vertical duct 20 was provided.

FIG. 10 shows a temperature rise test of the upstream bearing 21, coil 24b, and stator core 24 on the impeller 1 side without duct 20 (black color), with vertical duct 20 (horizontal hatch), and with inclined duct 20A (diagonal hatch). Show the results. One scale on the vertical axis is 10K (Kelvin).
It was confirmed that the amount of temperature reduction in the upstream bearing 21 and the coil 24b when the duct 20 was present was large, and that the cooling performance was high.
The temperature of the upstream bearing 21 and coil 24b can be reduced by adding a duct 20 between the first diffuser 8D of the first stage and the second diffuser 9D of the second stage, which can be achieved without the duct 20 (see Fig. 6). ) This is because the amount of cooling air that enters through the opening 7b (see FIG. 5B) and flows through the motor section 202 is increased, and the cooling performance is improved.

Note that, according to fluid analysis results, the amount of increase in cooling air volume due to the addition of the duct 20 is approximately 1.3 times that of the case without the duct 20.
The temperature reduction effect due to the slope of the sloped duct 20A is shown in FIG. 7B when the air flow flowing through the main flow path F1 (flow from the impeller 1) and the air flow flowing through the second flow path F2 mix. By setting the inclination angle to 45 degrees, the airflow flowing through the main flow first flow path F1 can easily flow through the diffuser hub 5a side (flowing along the hub end 5i), and the inclined duct can flow from the second stage second diffuser 9D outlet. The flow toward 20A collides with the stator core 24, thereby promoting cooling of the stator core 24 of the stator.

According to the embodiment, the vacuum cleaner 100 including the electric blower 200 configured as described above can provide the vacuum cleaner 100 that has the effects of the electric blower 200 described above.
From the above, it is possible to provide a small and lightweight electric blower 200 with high efficiency and high motor cooling efficiency, and a vacuum cleaner 100 equipped with the electric blower 200.

<<Other embodiments>>
1. The present invention is not limited to the configurations of the embodiments and modifications described above, and various modifications and specific forms are possible within the scope of the appended claims.

1 Impeller 2 Rotating shaft 3 Fan casing 3a Notch of fan casing 4 Upstream housing 4a Inner wall of upstream housing (upstream housing)
4b Outer wall of upstream housing (upstream housing)
5 Downstream housing 5a Downstream housing inner wall (downstream housing, hub)
5b Downstream housing outer wall (downstream housing, shroud)
5i Downstream end of the second diffuser 5f Length of the hub diameter of the first diffuser, hub diameter 5g Length of the inner diameter of the shroud of the second diffuser, shroud diameter 6 Upstream motor housing (motor housing)
6a Radial opening (upstream radial opening)
7 Downstream motor housing (motor housing)
7a Radial opening (downstream radial opening)
7b Axial opening 8 First diffuser blade 9 Second diffuser blade 11a Length of impeller hub diameter, outermost diameter of hub 11b1 Notch (recess)
20 Duct 20A Inclined duct (duct)
21 Upstream bearing (bearing)
22 Downstream bearing (bearing)
23 Rotor core 24 Stator core 100 Vacuum cleaner 200 Electric blower 201 Blower section 202 Motor section F1 First flow path F2 Second flow path

Claims (8)

Equipped with a blower section and a motor section,
a first flow path passing through an impeller inside the blower section;
a second flow path passing through the inside of the motor section;
The motor section is
a rotating shaft and a bearing that rotatably supports the rotating shaft;
a rotor core fixed to the rotating shaft and a stator core disposed surrounding the outer periphery of the rotor core;
a motor housing that holds the stator core and has an upstream radial opening, a downstream radial opening, and an axial opening;
The blower section is
an impeller fixed to the rotating shaft; a fan casing that covers the outer periphery of the impeller; an upstream housing that surrounds the upstream outer periphery of the motor section; and a downstream housing that surrounds the downstream outer periphery of the motor section;
The first flow path passes between the impeller and the inner and outer walls of the upstream housing,
The second flow path includes the axial opening, the downstream radial opening, the inside of the motor section, the upstream radial opening, between the motor housing and the inner wall of the upstream housing, and the motor housing. and an inner wall of the downstream housing,
The second diffuser blade of the downstream housing is
The second diffuser blade has a shroud on a circular tube located on the outer periphery of the second diffuser blade, and a hub on the inner diameter side of the second diffuser blade, and the second diffuser blade gradually extends downstream from the hub to the shroud side. An electric blower characterized by protruding from the side. Equipped with a blower section and a motor section,
a first flow path passing through an impeller inside the blower section;
a second flow path passing through the inside of the motor section;
The motor section is
a rotating shaft and a bearing that rotatably supports the rotating shaft;
a rotor core fixed to the rotating shaft and a stator core disposed surrounding the outer periphery of the rotor core;
a motor housing that holds the stator core and has an upstream radial opening, a downstream radial opening, and an axial opening on the side surface;
The blower section is
an impeller fixed to the rotating shaft; a fan casing that covers the outer periphery of the impeller; an upstream housing that surrounds the upstream outer periphery of the motor section; and a downstream housing that surrounds the downstream outer periphery of the motor section;
The first flow path passes between the impeller and the inner and outer walls of the upstream housing,
The second flow path includes the axial opening, the downstream radial opening, the inside of the motor section, the upstream radial opening, between the motor housing and the inner wall of the upstream housing, and the motor housing. and an inner wall of the downstream housing,
The second diffuser blade of the downstream housing is
The second diffuser blade has a shroud on a circular tube located on the outer periphery of the second diffuser blade, and a hub on the inner diameter side of the second diffuser blade, and the second diffuser blade is connected from the hub to the center of rotation of the impeller. An electric blower characterized in that as it moves away from the outer periphery, it gradually protrudes to the downstream side of the airflow caused by the impeller. Equipped with a blower section and a motor section,
a first flow path passing through an impeller inside the blower section;
a second flow path passing through the inside of the motor section;
The motor section is
a rotating shaft and a bearing that rotatably supports the rotating shaft;
a rotor core fixed to the rotating shaft and a stator core disposed surrounding the outer periphery of the rotor core;
a motor housing that holds the stator core and has an upstream radial opening, a downstream radial opening, and an axial opening;
The blower section is
an impeller fixed to the rotating shaft; a fan casing that covers the outer periphery of the impeller; an upstream housing that surrounds the upstream outer periphery of the motor section; and a downstream housing that surrounds the downstream outer periphery of the motor section;
The first flow path passes between the impeller and the inner and outer walls of the upstream housing,
The second flow path includes the axial opening, the downstream radial opening, the inside of the motor section, the upstream radial opening, between the motor housing and the inner wall of the upstream housing, and the motor housing. and an inner wall of the downstream housing,
The length of the diameter of the hub of the impeller in the radial direction is:
shorter than the length of the inner diameter of the shroud of the second diffuser;
The electric blower is characterized in that the diameter is longer than the diameter of the hub of the first diffuser. In the electric blower according to claim 1 or claim 2,
The hub from which the second diffuser blade projects is located upstream of the downstream radial opening, and the downstream end of the second diffuser blade is downstream of the downstream radial opening. Position to,
An electric blower characterized in that an end portion of the second diffuser blade is arranged at a position facing the downstream radial opening. The electric blower according to any one of claims 1 to 3,
a first diffuser blade upstream of the second diffuser blade,
An electric blower characterized in that a duct connecting a first flow path and a second flow path is installed in a hub between the first diffuser blade and the second diffuser blade in the axial direction. The electric blower according to any one of claims 1 to 3,
The electric blower is characterized in that the hub of the second diffuser has a recess in the circumferential direction. The electric blower according to claim 5,
The electric blower is characterized in that the duct is inclined toward the downstream side of the first flow path. A vacuum cleaner comprising the electric blower according to any one of claims 1 to 3.

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