JP7399682B2 - Electric blower and vacuum cleaner equipped with it - Google Patents

Description

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

Conventionally, the following Patent Document 1 has been disclosed as an electric blower.
Patent Document 1 describes, as shown in the attached FIGS. 1 to 4, "an impeller (10) that rotates around a central axis (C) extending vertically, and a stator (10) disposed below the impeller (10). 24) to rotate the impeller (10), a motor housing (21) that houses the stator (24), and a motor housing that houses the impeller (10) and the motor housing (21). (21) and a fan casing (2) that constitutes a first flow path (5), the upper part of the fan casing (2) covers the upper part of the impeller (10), and the intake air that opens in the vertical direction An exhaust port (104) is provided at the lower part of the fan casing (2) and communicates with the intake port (103) through 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 of the motor housing (21). (21) is a blower device (1) having a second flow path (6) extending upward from the inlet (21a) and communicating with the space above the stator (24).'' .

JP 2018-105269 (Figures 1 to 4, paragraphs 0012 to 0037, etc.)

Incidentally, 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. For this reason, vacuum cleaners are required to be electric blowers with strong suction power over a wide air volume range. In addition, electric blowers are required to be smaller and lighter in terms of ease of use of vacuum cleaners. As a result, the heat dissipation area is reduced, the heat generation density inside the electric blower is increased, and there is a need to improve the cooling performance of the electric motor and bearings.

In addition, although a diffuser with wings can perform excellent pressure recovery at the design point air volume, at non-design point air volume, the diffuser performance deteriorates due to the mismatch between the inlet angle of the diffuser blade and the inflow angle of the air flow into the diffuser. descend. Therefore, although the suction force of the vacuum cleaner is high at the design point air volume, there is a fear that it may decrease at non-design point air volume.

Cordless stick type or autonomous type vacuum cleaners that are powered by batteries (secondary batteries) consume less power and have a smaller maximum airflow due to the battery capacity. 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, vacuum cleaners powered by batteries (secondary batteries), such as cordless stick or self-driving types, are required to be small and lightweight, and electric blowers installed in vacuum cleaners have suction power over a wide range of air volume. It is required to be both strong and compact.

As mentioned above, Patent Document 1 discloses that ``a fan casing (2) that configures a first flow path (5) in a gap between an impeller (10) and a motor housing (21) that houses a motor (20). The upper part of the fan casing (2) covers the upper part of the impeller (10) and has an intake port (103) that opens in the vertical direction, and the lower part of the fan casing (2) has a first flow path (5). The motor housing (21) is provided with an exhaust port (104) that communicates with the intake port (103) through the motor housing (21). An inlet (21a) is provided which penetrates in the direction and communicates with the first flow path (5), and the motor housing (21) extends upward from the inlet (21a) to form a space above the stator (24). It has a second flow path (6) that is in communication with the second flow path (6).'' That is, in Patent Document 1, the flow in the first flow path (5) flows into the second flow path (6), and flows near the bearing (26) of the fan-side ball bearing located above the stator (24). Thereafter, the bearing (26) of the sliding bearing on the side opposite to the fan is cooled, and the air is exhausted to the outside of the electric motor (motor 20).

In the blower (1) of Patent Document 1, the air volume of the first flow path (5) passes through the inflow port (21a) that penetrates in the radial direction and communicates with the first flow path (5), and the air volume flows through the second flow path (6). ), the air volume in the first flow path (5) downstream of the inlet (21a) communicating with the inlet (21a) decreases compared to the air volume upstream of the inlet (21a) due to pressure loss (resistance) in the flow path. .

Note that a diffuser with wings can perform excellent pressure recovery at the design point air volume, but if the air volume falls below the design point air volume, the diffuser Performance may decrease and the suction power of the vacuum cleaner may decrease. The second flow path (6), which extends upward from the inlet (21a) of the second flow path (6) and communicates with the space above the stator (24), has a small flow path area. Furthermore, since the flow curves inside the electric motor (20), the pressure loss in the flow path is large, the cooling air volume decreases, the temperature inside the electric motor (motor 20) increases, and there is a concern that the motor efficiency will decrease. .

The present invention was devised to solve the above-mentioned problems in view of the above-mentioned circumstances, and aims to provide a compact and lightweight electric blower that is highly efficient in a wide air volume range, and a vacuum cleaner equipped with the same.

In order to solve the above problems, the electric blower of the present invention includes a front-stage axial flow diffuser and a rear-stage axial flow diffuser each having blades in the circumferential direction downstream of the impeller in the axial direction, and a radial direction of the axial flow diffuser. a stator and a rotor located inside and arranged to overlap with the axial diffuser in the axial direction; a first flow path passing through a suction port provided in an impeller and a flow path of the axial flow diffuser; an end bracket that holds a bearing on the side opposite to the impeller and is provided with an opening; a second flow path in which at least a portion of the flow path extends from the opening in contact with the outer peripheral surface of the stator in the axial direction; The first flow path and the second flow path are connected, and are formed from near the impeller side end of the outer peripheral surface of the stator to the outlet of the front-stage axial flow diffuser , and are connected to the second flow path. a connecting portion of an annular flow path formed to be inclined toward the blade , the stator having an axial dimension longer than a radial dimension, and the second flow path having a longer axial dimension than the connecting portion; It is located far from the impeller, and the opening area of the opening is larger than the flow passage cross-sectional area of the connection part, and the wind flowing from the connection part through the second flow passage can cause the rear stage to The axial flow diffuser is characterized in that it is configured to suppress separation of air flow from the blades of the axial flow diffuser .

According to the present invention, it is possible to provide an electric blower that is highly efficient, small and lightweight in a wide air volume range, and a vacuum cleaner equipped with the electric blower.

1 is an external view of an electric blower according to a first embodiment of the present invention. FIG. 1B is a vertical cross-sectional view of the electric blower shown in FIG. 1A. FIG. 2 is a perspective view of the impeller of the first embodiment. FIG. 2B is a cross-sectional view of the impeller shown in FIG. 2A. FIG. 3 is a perspective view of an axial diffuser blade on the impeller side, viewed from the shroud side. A perspective view of the rear-stage axial flow type diffuser blade viewed from the shroud side. FIG. 3 is a perspective view of the blower section viewed from the shroud side. The figure which shows the comparison of the blower efficiency of the electric blower of 1st Embodiment, and the blower which had the structure where the flow flows into the inside of an electric motor at the diffuser exit similarly to the prior art. FIG. 7 is a vertical cross-sectional view of an electric blower according to a second embodiment of the present invention. 1 is a perspective view of a vacuum cleaner to which an electric blower according to a first embodiment of the present invention is applied. FIG. 9 is a sectional view taken in the I direction of the vacuum cleaner body shown in FIG. 8;

Embodiments of the present invention will be described in detail below with reference to the drawings as appropriate.
<<First embodiment>>
FIG. 8 is a perspective view of a vacuum cleaner 300 to which the electric blower 200 according to the first embodiment of the present invention is applied.
FIG. 9 is a cross-sectional view of the vacuum cleaner main body 100 in the vacuum cleaner 300 of the first embodiment taken in the I direction.
A vacuum cleaner 300 according to a first embodiment of the present invention will be described.

<Configuration of vacuum cleaner 300>
The vacuum cleaner 300 includes a vacuum cleaner main body 100, a holding section 102 to which the vacuum cleaner main body 100 is attached, a grip section 103 that is held by a user, and a suction body 105 that sucks dust.
The battery unit 108 (see FIG. 9) that is the drive source of the vacuum cleaner 300 is charged using the charging stand 107 (see FIG. 8). The battery unit 108 is housed in the vacuum cleaner main body 100.

The vacuum cleaner body 100 houses a dust collection chamber 101 that collects dust and an electric blower 200 (see FIG. 9) that generates a suction airflow necessary for collecting dust.
A grip portion 103 is provided at one end of the holding portion 102 . The grip section 103 is provided with a switch section 104 (see FIG. 8) that turns on/off the electric blower 200.
A mouthpiece 105 is attached to the other end of the holding part 102. The suction body 105 and the cleaner main body 100 that generates the suction airflow are connected through a connecting portion 106.

When using the vacuum cleaner 300, the user turns on the switch section 104 of the grip section 103. Then, the electric blower 200 housed in the vacuum cleaner main body 100 starts operating, and a suction airflow is generated in the suction body 105. Dust on the floor surface Y (see FIG. 8) is sucked in from the suction body 105 by the suction airflow. The sucked dust passes through the connection part 106 and is collected in the dust collection chamber 101 of the cleaner body 100.

<Vacuum cleaner body 100>
Next, the vacuum cleaner main body 100 will be explained.
As shown in FIG. 9, an electric blower 200, a battery unit 108, a driving circuit 109, and a dust collection chamber 101 are arranged inside the vacuum cleaner main body 100.
Battery unit 108 drives electric blower 200 . The electric blower 200 generates suction force at the mouthpiece 105 .
The vacuum cleaner main body 100 includes a main body grip part 110 and a suction opening 111.
The user can grip the main body grip part 110, remove the vacuum cleaner main body 100 from the holding part 102, and use it as a handy vacuum cleaner.

The main body switch section 112 shown in FIG. 8 is a switch that turns on/off the electric blower 200 when the vacuum cleaner main body 100 is used as a handy vacuum cleaner. The main body switch 112 can be turned on/off in place of the switch part 104 even when the vacuum cleaner main body 100 is attached to the holding part 102.
Note that the vacuum cleaner 300 shown in FIGS. 8 and 9 is a cordless vacuum cleaner in which the suction opening 111 (see FIG. 9) and the connection part 106 are removable; however, the vacuum cleaner 300 shown in FIGS. You can also use a vacuum cleaner.

<Electric blower 200>
FIG. 1A is an external view of an electric blower 200 according to a first embodiment of the present invention, and FIG. 1B is a longitudinal cross-sectional view of the electric blower 200 shown in FIG. 1A. Note that FIG. 1B shows a case where an annular anti-vibration rubber 19 is applied to the electric blower 200.
Next, electric blower 200 will be explained. Note that in FIG. 1B, a typical air flow is shown only on the left side of FIG. B1 by a solid line arrow α1 and a dotted line arrow α2.

The electric blower 200 is attached to the vacuum cleaner 300 shown in FIGS. 8 and 9 with the impeller 1 facing the suction body 105 at the bottom.
As shown in FIG. 1B, the electric blower 200 includes an electric motor section 202 inside a blower section 201 in the radial direction.
The blower section 201 includes, from the upstream side of the suction airflow, an impeller 1 that is a rotary blade, an impeller-side axial-flow type diffuser blade 23, a rear-stage axial-flow type diffuser blade 24, and a bladeless diffuser 25. An exhaust port 16 is provided downstream of the bladeless diffuser 25.

The axial diffuser blade 23 on the impeller 1 side (closer to the impeller 1) is located between the inner wall 2a and outer wall 2b of the motor housing 2 on the impeller 1 side in the radial direction of the impeller 1. .
The rear-stage axial flow type diffuser blade 24 arranged on the side opposite to the impeller 1 (the side far from the impeller 1) is connected to the inner wall 9a and the outer wall of the motor housing 9 on the side opposite to the impeller 1 in the radial direction of the impeller 1. It is located between 9b and 9b.

The bladeless diffuser 25 is formed from an inner wall 9a and an outer wall 9b.
The electric motor section 202 is covered with an inner wall 2a of the motor housing 2 and an inner wall 9a of the motor housing 9.
An opening 15 and a second flow path 14 for cooling are configured inside the electric motor section 202 .

The opening 15 is provided in the end bracket 13. The end bracket 13 holds the bearing 11 on the side opposite to the impeller 1 in the axial direction of the motor section 202 .
At least a portion of the second flow path 14 passes through the outer periphery of the stator core 8 and the opening 15 .
A first flow path 17 is provided on the side of the electric blower 200, passing through the impeller 1, the impeller-side axial flow type diffuser blade 23, the rear stage axial flow type diffuser blade 24, and the bladeless diffuser 25. . The first flow path 17 is a flow path through which the airflow due to the suction force at the mouthpiece body 105 flows.

The electric blower 200 has a connecting portion 28 that connects the first flow path 17 and the second flow path 14 to communicate with each other. That is, the second flow path 14 and the first flow path 17 are connected at the connection portion 28 between the impeller side axial flow type diffuser blade 23 and the rear stage axial flow type diffuser blade 24. By forming the connection part 28, cooling air is generated from the opening 15 of the end bracket 13 by the venturi effect (details will be described later), and the axial flow type diffuser blade 23 on the impeller side and the rear stage axial flow type diffuser blade 24 are generated. , and increase the wind speed at the vaneless diffuser 25. Thereby, it is possible to improve the cooling performance of the electric motor unit 202 and increase the efficiency of the electric blower 200 over a wide operating range.

The second flow path 14 is located on the side opposite to the impeller 1 in the axial direction with respect to the connecting portion 28 .
Further, the opening area of the opening portion 15 is configured to be larger than the flow path cross-sectional area of the connecting portion 28 . This promotes the Vencheri effect at the connection portion 28 and allows the motor section 202 to be further cooled by the air flowing from the second flow path 14 to the connection portion 28.
Here, the cross-sectional area of the flow path of the connecting portion 28 is the cross-sectional area that is the minimum area in the cross section perpendicular to the flow path, and if there is a fillet or R shape in the cross section, the fillet or R shape is ignored. It may be calculated.

Note that a part of the winding comes out from the opening 15 and is electrically connected to the driving circuit 109 (see FIG. 9). Here, in the case of a configuration in which the winding passes through the opening 15, the area when the winding is removed may be equal to or larger than the cross-sectional area of the flow path of the connecting portion 28. Further, the opening 15 may have a square hole, a round hole, or a hole of another shape.

The impeller 1 shown in FIG. 1B is made of thermoplastic resin. The impeller 1 is fixed by a fixing nut 18 screwed into a female screw threaded at the end of the rotating shaft 5. In the first embodiment, the impeller 1, which is a rotary blade, is provided with a female thread at the end of the rotary shaft 5, and is fixed using a fixing nut, but it may also be fixed by press-fitting. . Further, although the impeller 1 shown in FIG. 1B is a mixed flow type impeller, it may be a centrifugal type or an axial type impeller.
The electric motor section 202 is provided with a rotor core 7 and a stator core 8 disposed on the outer periphery of the rotor core 7.

The rotor core 7 is fixed to a rotating shaft 5 housed within a motor housing 9.
A winding is wound around the outer periphery of the stator core 8. The winding is electrically connected to a drive circuit 109 (see FIG. 9) included in the electric blower 200.

The rotor core 7 includes a rare earth bonded magnet. Rare earth bonded magnets are made by mixing rare earth magnetic powder and an organic binder. As the rare earth bonded magnet, for example, a samarium iron nitrogen magnet, a neodymium magnet, or the like can be used. The rotor core 7 is integrally molded with the rotating shaft 5 or is fixed thereto. Note that the operating rotational speed of the electric blower 200 is 50,000 to 200,000 cycles/min.

Note that in this embodiment, a permanent magnet is used for the rotor core 7, but the present invention is not limited to this, and a reluctance motor, which is a type of commutatorless motor, or the like may be used.
A bearing 10 is provided between the impeller 1 and the rotor core 7. A bearing 11 is provided on the opposite side of the rotor core 7 in the direction of the rotating shaft 5 of the bearing 10 . The rotating shaft 5 is rotatably supported by a bearing 10 on one side of the rotating shaft 5 and a bearing 11 on the other side.

The motor housing 2 on the side closer to the impeller 1 is fastened to an end bracket 12 that supports a bearing 10. The motor housing 9 on the side far from the impeller 1 supports a bearing 11 via an end bracket 13. The motor housing 9 is fastened to an end bracket 13 having an opening 15. The end bracket 13 is made of metal. The end bracket 13 is press-fitted into the motor housing 9 or integrally molded with the motor housing 9 by insert molding.

A balance ring 6 is installed at the end of the rotor core 7 to correct eccentricity of the rotating body (impeller 1, rotor core, rotating shaft 5, etc.).
By cutting the unbalanced side of the rotating body in the balance ring 6, the amount of unbalance of the rotating body is minimized. Thereby, the noise and vibration of the electric blower 200 are reduced.

On the outer periphery of the motor housing 2 on the impeller 1 side (closer to the impeller 1), claw-like protrusions 20 are provided at three locations in the circumferential direction. The protrusion 22 provided on the outer periphery of the motor housing 9 on the side opposite to the impeller 1 (the side far from the impeller 1) and the mounting hole 21 of the motor housing 2 on the side of the impeller 1 are fitted and connected. Ru. Also, the number of blades of the axial diffuser blade 23 on the side of the impeller 1, the number of protrusions 22 on the end of the motor housing 9 on the side opposite to the impeller 1, and the number of mounting holes 21 of the motor housing 2 on the side of the impeller 1. is composed of the greatest common divisor of the number of blades and the mounting hole 21. In this way, the circumferential positions of the axial flow type diffuser blade 23 on the side of the impeller 1 and the subsequent stage axial flow diffuser blade 24 are set at predetermined circumferential positions, thereby improving mass productivity.

The fan casing 3 that covers the impeller 1 shown in FIG. 1B is adhesively fixed to the motor housing 2 with the outer circumference of the motor housing 2 on the side of the impeller 1 and the inner surface 3a of the fan casing coming into contact. Furthermore, a vibration isolating rubber 19 shown in FIG. 1B is installed at the installation part of the cleaner body 100 of the fan casing 3. By providing the anti-vibration rubber 19, vibration of the electric blower 200 is suppressed and air leakage between the fan casing 3 and the installation part of the cleaner body 100 is prevented, thereby reducing noise and increasing efficiency. I'm trying.

At the design point, the axial flow type diffuser blade 23 on the side of the impeller 1 makes the flow flowing out from the impeller 1 and the blade inlet angle approximately coincide with each other, thereby reducing pressure loss. As a result, the axial diffuser blades 23 reduce the rotational velocity component of the flow, thereby increasing the diffuser effect and improving the blower efficiency. Further, the downstream axial-flow diffuser blade 24 installed axially downstream of the axial-flow diffuser blade 23 further reduces the rotational velocity component of the flow flowing out from the axial-flow diffuser blade 23. Further, the bladeless axial flow diffuser 25 downstream of the rear stage axial flow type diffuser blade 24 has a flow passage cross-sectional area expanding toward the radially inward side toward the opening 16 at the axial end. This increases the deceleration of the air flow in the direction of the rotating shaft 5 and further improves the efficiency of the blower.

<Air flow within electric blower 200>
Next, the flow of air within the electric blower 200 will be explained.
When the electric motor section 202 shown in FIG. 1B is driven to rotate the impeller 1, air flows in from the air suction port 4 of the fan casing 3 and into the impeller 1. In the case of a diagonal flow type impeller, the incoming air is pressurized within the impeller 1 and gives a radial component 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. . In this way, at the impeller outlet 1a, the flow becomes a flow having a rotation direction component and a direction component of the rotation axis 5, and flows out from the impeller 1.

The airflow flowing out from the impeller 1 flows along the blades (23, 24) when passing through the impeller-side axial-flow type diffuser blade 23 and the rear-stage axial-flow type diffuser blade 24, causing rotation of the flow. The directional velocity component is reduced. Furthermore, as the flow passing through the bladeless diffuser 25 moves toward the opening 16 of the motor housing 9 on the side opposite to the impeller 1, the flow passage cross-sectional area increases, so that the directional speed of the rotating shaft 5 is reduced, and the pressure After being recovered, the air is evacuated through the opening 16. Note that the first flow path 17 is a flow path from the air suction port 4 of the fan casing 3 to the opening 16 of the motor housing 9, as shown by the solid arrow α1 in FIG. 1B.

The exit wind speed of the axial-flow type diffuser blade 23 on the side of the impeller 1 is higher than the wind speed of the opening 16 of the motor housing 9 on the side opposite to the impeller 1. has a lower static pressure than the opening 16.
As shown by the broken line arrow α2 in FIG. 1B, the second flow path 14 is connected to an opening 15 provided in the end bracket 13 on the side opposite to the impeller 1 that holds the bearing 11 of the electric motor, and at least part of the flow path. portion passes around the outer periphery of stator core 8.

The second flow path 14 and the first flow path 17 shown in FIG. 1B are connected at a connecting portion 28 between the outlet of the impeller side axial flow type diffuser blade 23 and the rear stage axial flow type diffuser blade 24. There is. Further, the second flow path 14 is located downstream of the connection portion 28 in the axial direction, and the opening area of the opening portion 15 is larger than the flow path cross-sectional area of the connection portion 28 .
The connecting portion 28 is formed by the motor housing 2 on the side of the impeller 1 and the motor housing 9 on the side opposite to the impeller 1. It is inclined in the axial direction on the axial flow type diffuser blade 24 side. Thereby, the air flow flowing through the connecting portion 28 can smoothly merge with the air flow flowing through the first flow path 17, and the air volume can be increased.

The flow in the second flow path 14 is caused by the high wind speed at the outlet of the impeller side axial flow type diffuser blade 23, resulting in low static pressure, and due to the Venturi effect, from the opening 15 of the end bracket 13 to the impeller side shaft. A flow is generated towards the outlet connection 28 of the flow diffuser 23. The flow in the second flow path 14 sucks a low temperature flow into the electric motor 202 from the opening 15 of the end bracket 13 on the side opposite to the impeller. Thereby, the bearing 11 on the side opposite to the impeller 1 is cooled, and by flowing on the outer peripheral side of the stator core 8, it flows to the connection part 28 while cooling the stator core 8 and its windings.

The flow in the end bracket 12 on the impeller 1 side inside the electric motor section 202 includes a venturi effect generated at the outlet of the axial diffuser blade 23 on the impeller 1 side, and a swirling component flow due to the rotation of the rotor core 7. This flow cools the bearing 10 and the end bracket 12 on the impeller 1 side.
The flow that has flowed into the first flow path 17 from the connecting portion 28 joins the flow that has been pressurized by the impeller 1, flows to the downstream axial flow type diffuser blade 24, and is decelerated by passing through the bladeless diffuser portion 25. , is exhausted from the opening 16 of the motor housing 9 on the side opposite to the impeller 1. Note that the amount of air passing through the rear-stage axial-flow type diffuser blade 24 is the sum of the amount of air passing from the impeller 1 through the axial-flow type diffuser blade 23 on the impeller side, and the amount of air flowing from the second flow path 14 through the connecting portion 28. , the maximum air volume is achieved inside the electric blower 200.

In the rear-stage axial-flow type diffuser blade 24, trailing vortices are likely to occur at the trailing edge of the axial-flow type diffuser blade 23 on the side of the impeller 1 at non-design points where the air volume is small. The inlet flow tends to be complicated. However, in the rear-stage axial-flow type diffuser blade 24 of this configuration, the air volume from the connection part 28 merges with the axial-flow type diffuser blade 23 on the impeller side and flows to the latter-stage axial-flow type diffuser 24.

As a result, the air volume inside the rear stage axial flow type diffuser 24 increases even at the non-design point. Therefore, separation inside the rear-stage axial flow type diffuser 24 is suppressed, and the blower efficiency is improved. Note that the amount of air flowing from the opening 15 of the end bracket 13 on the side opposite to the impeller 1 to the connecting portion 28 flows more on the large air amount side where the air amount at the outlet of the axial diffuser 23 on the side of the impeller 1 increases. Therefore, with this configuration, the efficiency of the blower on the large air volume side can be improved, and high efficiency can be achieved over a wide range of operation.

<Blower section 201>
Next, the configuration of the blower section 201 of the first embodiment will be explained.
FIG. 2A is a perspective view of the impeller 1 of the first embodiment, and FIG. 2B is a sectional view of the impeller 1.
FIG. 3 is a perspective view of the axial diffuser blade 23 on the impeller 1 side, viewed from the shroud side.
FIG. 4 is a perspective view of the rear stage axial flow type diffuser blade 24 viewed from the shroud side.
FIG. 5 is a perspective view of the blower section 201 viewed from the shroud side.
Note that in FIGS. 3 to 5, the outer wall of the motor housing that constitutes the shroud of the diffuser blades (23, 24) is omitted for the sake of explanation.

<Impeller 1>
First, an impeller 1 of a rotary blade according to an embodiment of the present invention will be described using FIGS. 2A and 2B.
The impeller 1 includes a hub plate 26 and a plurality of blades 27. The hub plate 26 and the blades 27 are integrally molded from thermoplastic resin.

A convex portion 26a (see FIG. 2B) is provided on the back side of the hub plate 26. By rotating the impeller 1 and scraping the convex portion 26a, the balance of the impeller 1 can be corrected. Thereby, the amount of unbalance of the impeller 1 can be reduced, and vibration and noise can be reduced.

The impeller 1 is a mixed flow impeller in which the boss curved surface 29a extends around the outer circumferential portion of the impeller and is inclined in the direction of the rotating shaft 5 (downward in FIG. 2B). Although FIGS. 2A and 2B show the impeller 1 as an open mixed flow impeller without a shroud plate, a centrifugal impeller may be used with or without a shroud plate.

Next, the blower 201 of the first embodiment will be explained.
As shown in FIG. 1B, an exemplary blower 201 includes 15 impeller-side axial flow type diffuser blades 23 arranged on the downstream side of the impeller 1 in the axial direction at equal intervals in the circumferential direction. The blades of the axial diffuser blades 23 on the side of the impeller 1 are provided between the inner wall 2a and the outer wall 2b of the motor housing 2 on the side of the impeller 1, and are integrally molded with the motor housing 2. The rear stage axial flow type diffuser blade 24 is installed between the inner wall 9a and the outer wall 9b of the anti-impeller motor housing 9, and is integrally molded with the motor housing 9. Further, the number of blades of the rear stage axial flow type diffuser 24 is the same as that of the axial flow type diffuser blades 23 on the impeller 1 side.

The circumferential positions of the shroud side (outer circumferential side) trailing edge 23d of the impeller side diffuser blade 23 and the shroud side (outer circumferential side) leading edge 24c of the rear stage axial flow type diffuser blade 24 shown in FIG. 5 are approximately the same in the circumferential direction. We are doing so.
Efficiency on the low air volume side can be improved by making the circumferential positions of the trailing edge 23d of the impeller-side diffuser blade 23 and the leading edge 24c of the rear-stage axial flow type diffuser 24 approximately coincide with each other. In order to improve the efficiency on the large air volume side, the (23, 24) pitch between the blades is preferably 15 to 50% (360/Zd).

As shown in FIG. 1B, the hub surface 30 of the impeller-side axial-flow type diffuser blade 23 and the hub surface 31 of the rear-stage axial-flow type diffuser blade 24 substantially match. Here, it is desirable that the hub surface 30 of the impeller side axial flow type diffuser blade 23 and the hub surface 31 of the rear stage axial flow type diffuser blade 24 be flush with each other. For example, if the inner wall 9a of the motor housing 9 after merging is large and the diameter of the hub surface is large and protrudes into the flow path, the loss in the axial diffuser blades 23 and 24 will increase.

Note that even if the hub surface 31 of the rear-stage axial-flow type diffuser blade 24 is radially inward from the hub surface 30 of the axial-flow type diffuser blade 23 on the side of the impeller 1, separation may occur due to the inflow of flow from the connecting portion 28. can be suppressed and high efficiency can be achieved.
Here, in the electric blower 200 having the above configuration, the blower efficiency on the large air volume side increases due to an increase in the air volume in the rear stage axial flow type diffuser blade 24 due to the Venturi effect. Furthermore, on the low air volume side, the blower efficiency increases depending on the circumferential position of the impeller 1 side and the rear stage axial flow type diffuser blade 24. This makes it possible to achieve higher efficiency over a wider operating air volume range.

As shown in FIG. 1B, the inner wall 2a of the motor housing 2 on the side of the impeller 1 and the inner wall 9a of the motor housing 9 on the opposite side of the impeller have a gap in the axial direction, and the first flow path 14 and the second flow path A connecting portion 28 that connects the flow path 17 is configured.
The connecting portion 28 is an annular flow path that extends from the inside of the electric motor 202 to the first flow path 17 and is inclined from the radial direction toward the rear diffuser blade 24 side.

The inner wall 2a of the motor housing 2 on the side of the impeller 1 and the outer wall 9a of the motor housing 9 on the opposite side of the impeller are arranged so that the center of each motor housing 2 is exposed through the fitting part 32, thereby ensuring the flow path area of the connecting part 28. , aiming to improve ease of assembly.

The shape in the height direction of the axial diffuser blade 23 on the impeller 1 side shown in FIG. 3 extends from the inner wall 2a to the outer wall 2b of the motor housing 2 on the impeller side, and ) (see FIG. 1B), and curves in the height direction from near the center in the radial direction to the outer periphery, with an inclination that returns upstream in the direction of the rotating shaft 5.

As shown in FIG. 3, the chord length L2 (the line connecting the leading edge 23c and the trailing edge 23d) on the shroud side of the axial diffuser blade 23 on the impeller 1 side is on the hub side (the side of the inner wall 2a). ) is longer than the chord length L1 of the blade. Note that since the wind speed on the shroud side at the outlet of the impeller 1 is high, the chord length L2 on the shroud side is set to a gentle shape to suppress loss and improve efficiency. In addition, by curving the axial diffuser blade 23 in the height direction, 2 Next, the flow can be suppressed. Therefore, peeling inside the diffuser (the blade surface on the inner wall 2a side of the axial diffuser blade 23 and the inner wall 2a) can be suppressed, and high efficiency can be achieved.

As shown in FIG. 4, the axial flow type diffuser blade 24 in the latter stage has a blade thickness t24 (blade thickness on the trailing edge side of the blade) that becomes thicker as it approaches the bladeless diffuser 25, and the axial flow type diffuser blade 24 on the side of the impeller 1 becomes thicker. It is thicker than the blade thickness t23 (see FIG. 3) of the blade 23.

The chord length L3 of the rear stage axial diffuser blade 24 shown in FIG. 5 is approximately the same as the chord length L2 of the shroud side of the axial diffuser blade 23 on the impeller side. By increasing the chord length L3 of the rear stage axial flow diffuser blade 24 and increasing the blade thickness t24 toward the trailing edge of the rear stage axial flow diffuser blade 24, as shown in FIG. This allows for improved static pressure recovery and higher efficiency.

As shown in FIG. 5, the axial length L5 of the bladeless diffuser flow path 25 located downstream of the rear stage axial flow diffuser blade 24 is the axial length L5 of the impeller side and the rear stage axial flow type diffuser blade. It has approximately the same length as L4.

As shown in FIG. 1B, the bladeless diffuser flow path 25 has a flow path cross-sectional area that increases toward the opening 16 of the motor housing 9 on the side opposite to the impeller 1. Therefore, the flow in the bladeless diffuser channel 25 (solid line arrow α1 in FIG. 1B, broken line arrow α2 in FIG. 1B) is exhausted from the opening 16 after its axial speed is reduced and the pressure is restored. The bladeless diffuser flow path 25 widens radially inward (towards the rotating shaft 5 in FIG. 1B) toward the opening 16 of the motor housing 9 on the side opposite to the impeller 1. The cross-sectional area of the bladeless diffuser flow path 25 increases as it advances in the axial direction, so that pressure is recovered within the bladeless diffuser flow path 25 and high blower efficiency can be achieved.

Here, the shapes of the axial diffuser blades 23 and 24 will be explained.
The axial type diffuser blade 23 on the side of the impeller 1 and the axial type diffuser blade 24 on the side opposite to the impeller 1 have a chord length shown in FIG. The blade shape has a solidity divided by the connecting length L1) and the distance along the circumferential direction of the blade attachment interval, which is less than 1. Note that if the solidity is smaller than 1, it can be manufactured with a mold configuration that molds in the direction of the rotating shaft 5, and high efficiency and productivity can be achieved.

FIG. 6 shows a comparison of the blower efficiency between the electric blower 200 of the first embodiment and a blower having a configuration in which a flow flows into the electric motor at the diffuser outlet, similar to the conventional technology. In addition, in FIG. 6, the horizontal axis shows the dimensionless air volume with the design point air volume as 1, and the vertical axis shows the fluid analysis results of the blower efficiency. The definition of blower efficiency in FIG. 6 is the product of the suction volumetric flow rate and the rise in static pressure at the blower inlet and outlet divided by the shaft power of the blower.

From FIG. 6, it can be seen that the electric blower 200 (white squares in FIG. 6) equipped with the first embodiment can improve blower efficiency over a wide operating range compared to the conventional blower (black circles in FIG. 6). It is also seen that efficiency can be improved, especially toward the larger air volume side than the design point.
That is, the electric blower 200 of the first embodiment can maintain high efficiency over a wide operating range. Therefore, it is possible to provide a vacuum cleaner 300 (see FIG. 8) that has high suction power over a wide range.

In the first embodiment, as an example, the connection portion 28 shown in FIG. However, the connecting portion 28 may be formed in either of the motor housings 2, 9 by a plurality of holes inclined either in the radial direction or in the direction of the rotation axis 5 as shown in FIG. 1B. In addition, as shown in FIG. 1B, the connecting portion 28 extends from the stator core 8 to the first flow path 17 and is formed into an annular flow path that is inclined toward the rear diffuser blade 24, thereby preventing separation of the rear diffuser blade 24. We have obtained a configuration that efficiently suppresses this. Note that even if the connecting portion 28 is configured as a connecting portion that is inclined in the radial direction or toward the impeller 1 side, motor cooling and high efficiency can be achieved.

According to the electric blower 200 of the first embodiment described above, the axial diffusers 23 and 24 have blades in the circumferential direction downstream of the rotation axis 5 of the impeller 1, and the axial diffusers 23 and 24 are provided inside the axial diffusers 23 and 24 in the radial direction. The stator (8) to the rotor (7) are located at a position that overlaps the axial diffusers 23 and 24 in the axial direction, and the first air flow is provided in the impeller 1 and passes through the air suction port 4 and the axial diffuser flow path. an end bracket 13 that holds the bearing 11 on the side opposite to the impeller 1 and is provided with an opening 15; It includes a passage 14 and a connecting portion 28 that connects the first passage 17 and the second passage 14.
The second flow path 14 is located closer to the impeller 1 than the connection portion 28 , and the opening area of the opening 15 is larger than the flow path cross-sectional area of the connection portion 28 . .

Thereby, it is possible to provide the electric blower 200 that is highly efficient in a wide air volume range, and is small and lightweight. Therefore, it is possible to cool the stator (8) and bearings 11 and 10 of the electric motor 202, and to obtain a vacuum cleaner 300 that is small in size and has improved suction power in a wide air volume range.

<<Second embodiment>>
Next, a second embodiment will be described using FIG. 7.
FIG. 7 is a longitudinal cross-sectional view of an electric blower 200A according to a second embodiment of the present invention.
The electric blower 200A of the second embodiment differs from the electric blower 200 of the first embodiment in that a connecting portion 28A is installed at the inlet of the axial diffuser blade 23 on the impeller 1 side.
The electric blower 200A has the same basic configuration as the first embodiment, so the same elements are denoted by the same reference numerals and the explanation thereof will be omitted.

The flow in the second flow path 14 is caused by the high wind speed at the inlet of the impeller-side axial-flow type diffuser blade 23, which lowers the static pressure. A flow toward the connection portion 28A at the inlet of the impeller-side axial flow diffuser 23 is generated.
The flow in the second flow path 14 is achieved by sucking a low-temperature flow into the motor section 202 from the opening 15 of the end bracket 13 on the side opposite to the impeller 1, thereby causing the bearing 11 on the side opposite to the impeller 1 to flow. By cooling and flowing around the outer circumferential side of the stator core 8, it flows to the connection portion 28A while cooling the stator core 8 and the windings.

Note that the connecting portion 28 shown in the first embodiment and the connecting portion 28A shown in the second embodiment may be used together. In that case, by making the second flow path 14 into a flow path divided in the circumferential direction, the flow from the axial diffuser blades 23 and 24 on the side of the impeller 1 can flow to the flow path inside the electric motor 202. By preventing this, it is possible to suppress separation of each diffuser blade 23, 24.

According to the electric blower 200A of the second embodiment described above, the axial diffusers 23 and 24 have blades in the circumferential direction downstream of the rotating shaft 5 of the impeller 1, and the radially inner side of the axial diffusers 23 and 24. The stator (8) to the rotor (7) of the electric motor section 202, which are located at a position axially overlapping with the axial flow diffusers 23 and 24, and the axial flow diffuser from the air suction port 4 provided in the impeller 1 A first flow path 17 passing through the flow path, an end bracket 13 that holds the bearing 11 on the side opposite to the impeller 1 and is provided with an opening 15, and at least a part of the flow path is connected to the outer periphery of the stator core 8 and the opening. 15, and a connecting portion 28A that connects the first flow path 17 and the second flow path 14.
The connecting portion 28A is located between the impeller 1 and the inlet of the axial diffuser 23 in the direction of the rotating shaft 5, and the second flow path 14 is located lower in the direction of the rotating shaft 5 than the connecting portion 28A. The opening area of the opening part 15 is larger than the flow path cross-sectional area of the connecting part 28A.

Thereby, it is possible to provide the electric blower 200A which is highly efficient in a wide air volume range, and which is small and lightweight. Therefore, the stator (8) and bearing 11 of the electric motor unit 202 are cooled, and the vacuum cleaner 300 is small and has improved suction power in a wide air volume range.

Note that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the embodiments described above are described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace some of the configurations of each embodiment with other configurations.

1 Impeller 2 Impeller side motor housing (motor housing)
2a Inner wall of the motor housing on the impeller side (inner wall of the motor housing, hub surface upstream of the axial diffuser)
4 Air intake port (suction port)
5 Rotating axis (axis)
7 Rotor core (rotor)
8 Stator core (stator)
9 Motor housing on the opposite side of the impeller (motor housing)
9a Inner wall of the motor housing on the side opposite to the impeller (inner wall of the motor housing axial flow, hub surface downstream of the axial flow diffuser)
11 Bearing (bearing on the anti-impeller side)
13 End bracket on the anti-impeller side (end bracket)
14 Second flow path 15 Opening 17 First flow path 23 Impeller side diffuser blade (axial flow diffuser)
24 Later stage diffuser blade (axial flow diffuser)
25 Bladeless diffuser 28 Connection part 200 Electric blower 300 Vacuum cleaner

Claims (6)

A front-stage axial flow diffuser and a rear-stage axial flow diffuser each having blades in the circumferential direction downstream of the impeller in the axial direction;
a stator and a rotor that are located inside the axial diffuser in the radial direction and overlap the axial diffuser in the axial direction;
a first flow path passing through a suction port provided in an impeller and a flow path of the axial diffuser;
an end bracket that holds the bearing on the opposite side of the impeller and is provided with an opening;
a second flow path in which at least a portion of the flow path extends from the opening in contact with the outer circumferential surface of the stator in the axial direction;
The first flow path and the second flow path are connected, and are formed from near the impeller side end of the outer peripheral surface of the stator to the outlet of the front-stage axial flow diffuser , and are connected to the second flow path. a connecting portion of an annular flow path formed to be inclined toward the blade ;
The stator has an axial dimension longer than a radial dimension;
The second flow path is located further from the impeller than the connection part,
The opening area of the opening is larger than the cross-sectional area of the flow path of the connecting portion, and the air flowing from the connecting portion through the second flow path causes the blades of the downstream axial diffuser to Designed to suppress separation of air flow
An electric blower characterized by: A front-stage axial flow diffuser and a rear-stage axial flow diffuser each having blades in the circumferential direction downstream of the impeller in the axial direction;
a stator and a rotor that are located inside the axial diffuser in the radial direction and overlap the axial diffuser in the axial direction;
a first flow path passing through a suction port provided in the impeller and a flow path of the axial diffuser;
an end bracket that holds the bearing on the opposite side of the impeller and is provided with an opening;
a second flow path in which at least a portion of the flow path extends from the opening in contact with the outer circumferential surface of the stator in the axial direction;
The first flow path and the second flow path are connected, and are formed from near the impeller side end of the outer circumferential surface of the stator to the outlet of the front-stage axial flow diffuser, and and a connection part of an annular flow path formed to be inclined toward the wing ,
The stator has an axial dimension longer than a radial dimension;
The second flow path is located further from the impeller than the connection portion, and the flow path of the connection portion extends axially from the outer periphery of the stator to the first flow path toward the side opposite to the impeller. The blade is slanted and configured to suppress separation of the air flow of the blade of the rear stage axial flow diffuser by the wind flowing from the connection part through the second flow path.
An electric blower characterized by: Claim 1 or Claim 2, wherein the flow path of the connection portion is radial from the outer periphery of the stator to the first flow path or is inclined toward the impeller. Electric blower as described. Hub surfaces upstream and downstream of the connecting portion of the axial diffuser, to which the flow path of the connecting portion and the first flow path are connected, have the same radius or a radius of the hub surface on the downstream side is smaller. The electric blower according to claim 1 or claim 2. The electric blower according to claim 1 or 2, wherein the flow path of the connecting portion is formed in an inner wall of a motor housing that covers an electric motor portion. A vacuum cleaner comprising the electric blower according to claim 1 or 2.

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