Electric blower and vacuum cleaner equipped with it

Abstract

To provide a small, lightweight electric blower that is highly efficient and also has high motor cooling efficiency, and an electric vacuum cleaner equipped with it. [Solution] The electric blower 200 has a first flow path F1 passing through the impeller 1 and a second flow path F2 passing through the motor section 202. The motor section 202 has a rotating shaft, a stator core 24, and motor housings 6 and 7 having an upstream radial opening 6a and a downstream radial opening 7a on their sides. The blower section has an impeller 1, a fan casing, and an upstream housing 4. The first flow path F1 passes between the inner and outer walls of the impeller 1 and the upstream housing 4. The second flow path F2 passes through an axial opening 7b, a downstream radial opening 7a, the inside of the motor section 202, the upstream radial opening 6a, between the motor housing 7 and the inner wall of the upstream housing, and between the motor housing 7 and the inner wall 5a of the downstream housing. The second diffuser blade 9 has a cylindrical shroud and a hub 5a, and protrudes downstream from the hub 5a towards the shroud.

Description

Technical Field

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

Background Art

[0002] As an example of an electric blower (blowing device) incorporated in a vacuum cleaner, Patent Document 1 describes "an impeller (10) that rotates around a central axis C extending vertically, a motor (20) that is disposed below the impeller (10) and has a stator 24 to rotate the impeller (10), a motor housing (21) that houses the stator (24), and a fan casing (2) that houses the impeller (10) and the motor housing (21) and forms a first flow path 5 in a gap with the motor housing (21). The upper part of the fan casing (2) covers above the impeller (10) and has an air inlet (3) that opens vertically. An exhaust port (4) that communicates with the air inlet via the first flow path (5) is provided at the lower part of the fan casing (2). In the motor housing (21), 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). The motor housing (21) has a second flow path (6) that extends upward from the inlet (21a) and communicates with a space above the stator (24)".

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] It is known that the operating airflow of a vacuum cleaner varies greatly depending on operating conditions such as filter clogging due to dust and the material of the floor being cleaned. Therefore, there is a need for electric blowers for vacuum cleaners that have a wide airflow range and strong suction power. Furthermore, due to the need for user-friendliness in vacuum cleaners, there is a demand for smaller and lighter electric blowers. Consequently, the heat dissipation area of ​​the electric blower decreases, and the internal heat density increases. Therefore, improvements in the cooling performance of the motor (20) and bearings (26) are necessary.

[0005] In particular, battery-powered vacuum cleaners, such as cordless stick vacuums and autonomous vacuum cleaners (robot vacuums), have low power consumption and low maximum airflow due to the battery capacity. As a result, when the filter becomes clogged, the dust collection capacity decreases, and the vacuum cleaner's suction power decreases. Furthermore, battery-powered vacuum cleaners are required to be small and lightweight, and the electric blowers installed in them must be compact while also having strong suction power over a wide airflow range.

[0006] Here, by using diffuser blades (referred to as "stator blades (40)" in Patent Document 1), excellent pressure recovery can be achieved at the design point airflow. However, if the airflow decreases below the design point airflow due to factors such as filter clogging, the diffuser performance may deteriorate due to a mismatch between the inlet angle of the diffuser blades and the angle at which the airflow enters the diffuser, potentially reducing the suction power of the vacuum cleaner.

[0007] Furthermore, in the blower described in Patent Document 1, as shown in Attached Figure 4, a portion of the airflow (S) flowing through the outer first flow path (5) flows into the inner second flow path (6) through an inlet (21a) provided on the peripheral wall of the motor housing (21), cools the upper bearing 26, and then cools the lower bearing (26), and flows out of the outlet (outlet (2)) of the second flow path (6) without merging with the first flow path (5). The exhaust from 9a) is directed to the outside of the blower (1).

[0008] Thus, in the configuration where the second channel (6) branching off from the first channel (5) does not merge with the first channel (5), the pressure loss (resistance) when a portion of the airflow (S) flowing through the first channel (5) branches off into the second channel (6) resulted in a decrease in the airflow downstream of the inlet (21a) (branching point) in the first channel (5) compared to the airflow upstream of the inlet (21a) (branching point).

[0009] In addition, the second flow path (6) in Patent Document 1 is small in size, resulting in a small flow path area. Furthermore, because it flows while bending inside the motor (20), there is a concern that the pressure loss in the flow path will be large, the cooling airflow will decrease, the temperature inside the motor (20) will rise, and the motor efficiency will decrease.

[0010] This invention was conceived in view of the above circumstances, and aims to provide a small, lightweight electric blower that is highly efficient and also has high motor cooling efficiency, and an electric vacuum cleaner equipped with the same. [Means for solving the problem]

[0011] To solve the aforementioned problems, the blower of the present invention comprises a rotor that rotates around a central axis extending vertically, a stator radially opposite to the rotor, an impeller fixed to the rotor, and a diffuser positioned below the impeller to rectify the airflow generated by the impeller. The diffuser comprises an inner cylinder, an outer cylinder positioned radially apart from the inner cylinder, and a plurality of stationary vanes positioned circumferentially apart in the gap between the inner and outer cylinders. The inner cylinder has a connecting portion that connects the inner and outer portions radially. In a cross-sectional shape obtained by cutting the connecting portion through a cross-section including the central axis, the upper edge of the connecting portion extends downward as it becomes perpendicular to the central axis or radially outward, and the lower edge of the connecting portion extends downward as it becomes perpendicular to the central axis or radially outward. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a small, lightweight electric blower that is highly efficient and also has high motor cooling efficiency, and an electric vacuum cleaner equipped with the same.

Brief Description of the Drawings

[0013] [Figure 1A] External view of the electric blower according to the embodiment. [Figure 1B] Longitudinal sectional view of the electric blower according to the embodiment. [Figure 2A] Perspective view of the impeller. [Figure 2B] Longitudinal sectional view of the impeller. [Figure 3A] View in the direction of arrow I of FIG. 1A, which is a plan view of the upstream housing seen from the upstream side. Plan view of the upstream housing of an embodiment. [Figure 3B] Longitudinal sectional view of the upstream housing. [Figure 3C] External view including a partial cross-section of the upstream housing seen from the outer periphery. [Figure 4A] View in the direction of arrow I of FIG. 1A, which is a plan view of the downstream housing seen from the upstream side. [Figure 4B] Longitudinal sectional view of the downstream housing. [Figure 4C] Perspective view including a partial cross-section of the downstream housing seen from the outer peripheral side. [Figure 5A] Side external view of the motor part. [Figure 5B] Longitudinal sectional view of the motor part. [Figure 6] Longitudinal sectional view of the electric blower of an example of the first flow path and the second flow path. [Figure 7A] Longitudinal sectional view of the electric blower of an example of the first flow path and the second flow path of Modification 1. [Figure 7B] Longitudinal sectional view of the electric blower of an example of the first flow path and the second flow path of Modification 2. [Figure 8A] Perspective view including a partial cross-section of the second diffuser covered by the downstream housing. [Figure 8B] View in the direction of arrow II including a partial cross-section of FIG. 8A. [Figure 9] Graph comparing the electric blower efficiencies with a vertical duct (horizontal line hatch) and an inclined duct (diagonal line hatch). [Figure 10]Temperature rise test results for the upstream bearing, coil, and stator core on the impeller side, under three conditions: without duct, with vertical duct, and with inclined duct. [Figure 11] A perspective view of an electric vacuum cleaner 100 according to an embodiment of the present invention. [Figure 12] A longitudinal cross-sectional view of the vacuum cleaner 100 according to the embodiment. [Modes for carrying out the invention]

[0014] Hereinafter, an embodiment of the electric blower and vacuum cleaner equipped therewith of the present invention will be described in detail with reference to the drawings. <Outline configuration of the 100-type vacuum cleaner>

[0015] Figure 11 shows a perspective view of a vacuum cleaner 100 according to an embodiment of the present invention. Figure 12 shows a longitudinal cross-sectional view of the vacuum cleaner 100 according to the embodiment. The vacuum cleaner 100 in this embodiment is a rechargeable cordless stick vacuum cleaner. The vacuum cleaner 100 is used by attaching the vacuum cleaner body 110 to the holder 120. The electric vacuum cleaner 100 is charged by being placed on the charging base 130. Although Embodiment 1 illustrates a rechargeable cordless stick vacuum cleaner, the electric blower 200 of the present invention may also be incorporated into a non-rechargeable stick vacuum cleaner equipped with a power cord.

[0016] The vacuum cleaner unit 110 can be used as a handheld vacuum cleaner on its own. The vacuum cleaner body 110 has a main body grip section 111 at the top for the user to hold, and a suction opening 112 (see Figure 12) at the bottom for sucking up dust and dirt during cleaning.

[0017] The main body grip portion 111 shown in Figure 11 is provided with a main body switch portion 111a for turning the electric blower 200 on and off when using it as a handheld vacuum cleaner. The vacuum cleaner body 110 shown in Figure 12 contains an electric blower 200, a drive circuit 114, a battery unit 115, and a dust collection chamber 113. The electric blower 200 generates the suction airflow necessary for dust collection. The drive circuit 114 controls the operation of the electric blower 200. The battery unit 115 supplies power to the drive circuit 114. Dust is collected in the dust collection chamber 113.

[0018] The holding unit 120 is a unit to which the vacuum cleaner body 110 can be attached and detached. The holding unit 120 has a grip portion 121 on its upper part for the user to grasp. The grip portion 121 of the holding unit 120 is provided with a switch portion 121a for turning the electric blower 200 on and off when used as a stick vacuum cleaner. The lower part of the holding section 120 is equipped with a suction port 122 for sucking up dust during cleaning, and a connecting section 122a that connects the suction port 122 to the air intake opening 112. Although this embodiment describes a configuration in which a connecting part 122a is provided between the vacuum cleaner body and the suction nozzle 122, the connecting part may be long, and the connecting part may be a hose or tube that can be attached to and detached from the suction nozzle and the body.

[0019] <Electric blower 200> Next, we will explain the electric blower 200. Figure 1A shows an external view of the electric blower 200 according to the embodiment.

[0020] Figure 1B shows a longitudinal cross-sectional view of the electric blower 200 according to the embodiment. The electric blower 200 consists of a blower and a motor that rotate the impeller 1 to generate airflow. Therefore, the upstream and downstream sides of the airflow are defined. Furthermore, focusing on the installation position of the rotating shaft 2, we define the axial direction and the radial direction.

[0021] As shown in Figures 11 and 12, an electric blower 200 is installed inside the vacuum cleaner 100 with its intake port 200a (Figure 1A) facing downwards and its exhaust port 200b facing upwards, so that dust can be sucked up from the suction port 122 at the bottom of the vacuum cleaner 100 to the dust collection chamber 113 at the top. The outer periphery of the electric blower 200 is covered by an outer shell that integrates the fan casing 3, the upstream housing 4, and the downstream housing 5.

[0022] The fan casing 3 is a cover that surrounds the outer circumference of the impeller 1 and functions as a shroud plate for 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 opening on the upstream side of the airflow from the impeller 1.

[0023] As shown in Figure 1B, the electric blower 200 draws in air from the upper intake port 200a and expels air from the lower exhaust port 200b by the rotation of the impeller 1 (arrow F1 in Figure 1B).

[0024] Inside the electric blower 200, a rotating shaft 2 is rotatably positioned. An impeller 1, which rotates integrally with the rotating shaft 2, is fixed to the upper end of the rotating shaft 2. In Figure 1B, the impeller 1 is fixed with a nut n1 screwed onto the upper end of the rotating shaft 2. Alternatively, the impeller 1 may be fixed by press-fitting it onto the tip of the rotating shaft 2. The electric blower 200 mainly consists of a blower section 201 and a motor section 202.

[0025] The blower unit 201 shown in Figure 1B includes an impeller 1, a rotating shaft 2, a first diffuser blade 8, and a second diffuser blade 9. The impeller 1 is fixed to the rotating shaft 2 and driven by a motor unit 202. The motor unit 202 is covered by the upstream motor housing 6 and the downstream motor housing 7. When the impeller 1 rotates, a first airflow is generated inside the electric blower 200, flowing through the first flow path F1 within the blower unit 201 from the intake port 200a towards the exhaust port 200b, as shown by the solid arrow F1 on the left side of Figure 1B.

[0026] The first airflow, which passes through the second diffuser blade 9 and flows through the first channel F1, has a high wind speed and a decrease in static pressure, resulting in the generation of a low-pressure section T at the outlet of the second diffuser blade 9 (shown in Figure 6). The low-pressure section T forms second channels F2a and F2b through which the second airflow, which circulates from downstream to upstream within the motor section 202, flows. The electric blower 200 can sufficiently cool the inside of the motor section 202 while maintaining the suction power of the vacuum cleaner 100 over a wide airflow range by circulating a first airflow through the first flow path F1 and a second airflow through the second flow paths F2a and F2b. The structure of the electric blower 200 will be described below, divided into the blower section 201 and the motor section 202.

[0027] <Blower section 201> The blower unit 201 shown in Figure 1B generates an airflow that allows the vacuum cleaner 100 to suck up dust. It is a unit for that purpose. The blower unit 201 has the following components arranged in order from the upstream side of the first flow path F1 through which the first airflow flows: the impeller 1, the first diffuser blade 8, and the second diffuser blade 9. The first and second diffuser blades 8 and 9 reduce the wind speed of the airflow downstream of the impeller 1, controlling the wind speed, flow direction, and static pressure.

[0028] In other words, 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 wing 8 is located on the inner circumference of the upstream housing 4. The second diffuser wing 9 is located on the inner circumference of the downstream housing 5.

[0029] <Impeller 1 and fan casing 3> Figure 2A shows a perspective view of impeller 1. Figure 2B shows a longitudinal cross-sectional view of impeller 1. Impeller 1 is an open-type diagonal flow impeller without a shroud plate. Impeller 1 is integrally molded from engineering plastic or thermoplastic resin. The impeller 1 has a hub 11, multiple blades 12, and a boss 13 for inserting the rotating shaft 2. The impeller 1 may be a diagonal flow impeller with a shroud plate, or it may be a centrifugal impeller or an axial flow impeller.

[0030] The outermost diameter 11a of the hub of impeller 1 shown in Figure 1B is located between the shroud diameter 5g and the hub diameter 5f of the second stage diffuser (9). In other words, the length 11a of the diameter of the hub 11 of the impeller 1 in the radial direction, as shown in Figure 1B, is shorter than the length 5g of the inner diameter of the shroud of the second diffuser 9D (inner diameter of the shroud), and longer than the length 5f of the diameter of the hub of the first diffuser (hub diameter). That is, the relationship 5f < 11a < 5g holds.

[0031] The length 11a of the hub diameter of impeller 1 is longer than the length 5f of the hub diameter of the first diffuser 8D, thereby enabling higher power input. Furthermore, the length 11a of the hub diameter of impeller 1 is shorter than the shroud diameter (length of the inner diameter of the shroud) 5g of the second diffuser 9D, thereby achieving both efficient cooling of the motor section 202 and promoting the venturi cooling described later. The second airflow flowing through the second flow path F2 (F2a, F2b) is directed to follow the flow along the inner diameter of the diffuser hub 5a and the outer diameter of the motor casing (downstream motor housing 7), thereby enabling miniaturization of the electric blower 200 and the motor section 202. It achieves both cooling and high efficiency.

[0032] As shown in Figure 2B, a metal sleeve 14 is integrally molded on the back side of the hub 11, coaxially with the boss 13 of the impeller 1. By using the sleeve 14, variations in the fitting gap between the impeller 1 and the rotating shaft 2, which are likely to occur if the sleeve is not used, can be reduced, thereby reducing the imbalance of the impeller 1. As a result, vibration and noise during rotational drive of the impeller 1 can be reduced. Furthermore, if sleeve 14 is not used, there is a high possibility of variations in the fitting gap between impeller 1 and rotating shaft 2, and an imbalance in impeller 1. Furthermore, a recess 14a is provided on the downstream side of the sleeve 14. Furthermore, 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 the molding of the impeller 1 and alleviates strain. It also reduces residual stress during the molding of the impeller 1 and improves fatigue strength. The cross-sectional shape of the recess 11b1 may be an arc or ellipse that does not cause stress concentration, and may be uniform in the circumferential direction with respect to the axis of rotation, or may be a discontinuous configuration in the circumferential direction.

[0033] The fan casing 3 will now be described. A portion of the outer wall of the fan casing protrudes toward the side connecting to the upstream housing 4, and a notch is formed extending from the side connecting to the upstream housing 4 toward the impeller side, forming an L-shaped notch 3a that extends in the circumferential direction of the fan casing 3. The notch 3a is formed in three locations in the circumferential direction of the outer wall. The fan casing 3 is rotated in the axial direction and assembled to the upstream housing 4, and then fixed in place by adhesive.

[0034] <Upstream Housing 4 and First Diffuser Wing 8> Figure 3A shows a view of the upstream housing 4 from the upstream side, as seen from the upstream side, as indicated by the arrow in direction I in Figure 1A.

[0035] Figure 3B shows a longitudinal section of the upstream housing 4. Figure 3C shows an external view of the upstream housing 4, including a partial cross-section as seen from the outer periphery. Note that in Figure 3C, the shape of the first diffuser wing 8 (particularly the positions of the leading edge 8a and trailing edge 8b) is shown by partially omitting the shroud of the upstream housing 4. The upstream housing 4 and the first diffuser wing 8 will be described. The upstream housing 4 and the first diffuser blade 8 are integrally molded from engineering plastic or thermoplastic resin.

[0036] Between the inner wall 4a (hub) and outer wall 4b (shroud) of the upstream housing 4, multiple first diffuser blades 8, which are integrally molded with them, are arranged at equal intervals in the circumferential direction (see Figure 3A).

[0037] As shown in Figure 3C, the length (chord length) of the first diffuser blade 8 from the leading edge 8a to the trailing edge 8b 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 side is faster than on the inner side. By making the outer side of the first diffuser blade 8 longer than the inner side, losses are suppressed, and the area in which dynamic pressure is converted to static pressure is enlarged, thereby improving the efficiency of the blower. Note that here, a configuration with 15 first diffuser blades 8 is shown as an example, but the number of first diffuser blades 8 can be changed according to the specifications of the electric blower 200.

[0038] As shown in Figures 3A and 3C, protrusions 4c are provided at equal intervals on three locations around the outer perimeter of the outer wall 4b of the upstream housing 4. The claw portion 5c of the downstream housing 5, shown in Figure 4B, is fitted onto the projection 4c, thereby aligning and integrating the upstream housing 4 and the downstream housing 5 (see Figure 1B).

[0039] As shown in Figures 3A and 3B, fastening portions 4d are provided at two locations on the upper surface of the upstream housing 4. The motor portion 202 shown in Figure 1B can be fastened to the fastening portions 4d while being centered. The shroud 4e of the first diffuser is inclined radially inward toward the axial downstream direction. It has an inclined portion 4e1. The outer wall 4b of the first diffuser wing 8 forms a flow path with approximately the same radius.

[0040] The inclined portion 4e1 of the shroud 4e gently redirects the flow from the outlet of the impeller 1 radially inward, aligning the flow with the inner diameter of the diffuser hub 5a and the outer diameter of the motor casing (downstream motor housing 7). This achieves both miniaturization of the electric blower 200 and improved cooling and efficiency of the motor section 202.

[0041] <Downstream Housing 5 and Second Diffuser Wing 9> Figure 4A shows a plan view of the downstream housing 5 (see Figure 1A) as seen from the upstream side, as seen from the direction of arrow I in Figure 1A.

[0042] Figure 4B shows a longitudinal cross-sectional view of the downstream housing 5 (see Figure 1A). Figure 4C shows a perspective view of the downstream housing 5 (see Figure 1A), including a partial cross-section as seen from the outer periphery. In Figure 4C, the shape of the second diffuser wing 9 (particularly the positions of the leading edge 9a and trailing edge 9b) is shown by partially omitting the outer wall 5B (shroud) of the downstream housing 5.

[0043] The downstream housing 5 and the second diffuser blade 9 shown in Figures 4A to 4C will be explained below. The downstream housing 5 and the second diffuser blade 9 are integrally molded from engineering plastic or thermoplastic resin. Between the inner wall (diffuser hub 5a) (hub) and the outer wall 5b (shroud) of the downstream housing 5, multiple integrally molded second diffuser wings 9 are arranged at equal intervals in the circumferential direction (see Figure 4C).

[0044] Although the example shows a configuration with 15 second diffuser blades 9, this is because the second diffuser blades 9 are positioned downstream of each first diffuser blade 8, and the number of first diffuser blades 8 and second diffuser blades 9 must be the same. However, the number of second diffuser blades may differ from the number of first diffuser blades.

[0045] As shown in Figure 4B, the trailing edge 9b of the second diffuser wing 9 extends axially downstream, and the wing height from the outer wall 5b of the shroud decreases radially outward. The trailing edge 9b is not monotonically varied, but can be composed of curves, multiple curves, or multiple lines, and its shape is arbitrary.

[0046] The axial length L1 on the shroud side of the second diffuser wing 9, as shown in Figure 4B, is set to be approximately twice or more the length L2 of the inner wall (diffuser hub 5a). Because the second diffuser blade 9 has a different length from the radially outer blade, the pressure increases radially outward, promoting the flow toward the inner wall (diffuser hub 5a) (hub) in the downstream housing 5, thereby promoting the cooling of the motor section 202 (see Figure 1B).

[0047] As shown in Figure 4C, the protruding surface 9c of the second diffuser blade 9 on the forward side in the rotational direction of the impeller 1 is substantially flat, and the plate thickness decreases towards the trailing edge 9b. By making the plate thickness t (see Figure 4C) of the second diffuser blade 9 thinner towards the trailing edge 9b, the volume of the first flow path F1 is increased, promoting flow deceleration and improving the efficiency of the electric blower. Furthermore, by reducing the plate thickness t of the second diffuser wing 9 (see Figure 4C), shrinkage of the resin during molding is suppressed.

[0048] As shown in Figures 4A to 4C, three claw portions 5c are provided at equal intervals on the outer circumference of the upper end of the downstream housing 5. A fitting portion 5d is provided in the area excluding the claw portion 5c on the outer circumference of the upper end as shown in Figures 4B and 4C. By pressing the lower end of the upstream housing 4 against the fitting portion 5d of the downstream housing 5 and fitting the three claw portions 5c (see Figures 4B and 4C) into the three protrusions 4c (see Figure 3A), the upstream housing 4 and the downstream housing 5 can be integrated while being centered (see Figure 1B). Furthermore, the fan casing 3 and the upstream housing 4, and the upstream housing 4 and the downstream housing 5 are fixed by adhesive, which suppresses the increase in noise due to rattling caused by minute gaps.

[0049] Furthermore, as shown in Figures 4B and 4C, a ring-shaped diffuser 5e without a second diffuser wing 9 is provided on the downstream side of the downstream housing 5. In the electric blower 200 shown in Figure 1B, the inner wall 4a of the upstream housing 4 (see Figure 3A) and the inner wall (diffuser hub 5a) of the downstream housing 5 (see Figures 4A and 4B), and the outer wall 4b of the upstream housing 4 (see Figures 3A and 3B) and the outer wall 5b of the downstream housing 5 (see Figures 4A and 4B) are all integrated while their radial positions are approximately aligned.

[0050] This smooths the inner surfaces of each channel formed in the upstream housing 4 and the downstream housing 5, thereby reducing losses in each channel. Furthermore, in the electric blower 200, the circumferential positions of the trailing edge 8b of the first diffuser blade 8 shown in Figure 3C and the leading edge 9a of the second diffuser blade 9 shown in Figure 4C are aligned so that the pair of first diffuser blades 8 and second diffuser blades 9 function as a single diffuser blade, and the curved surfaces of the first diffuser blade 8 and the second diffuser blade 9 are smoothly continuous.

[0051] <Motor section 202> Figure 5A shows a side view of the motor unit 202. Figure 5B shows a longitudinal cross-sectional view of the motor unit 202. Next, we will explain the motor unit 202. The motor unit 202 is a unit for rotating the impeller 1 of the blower unit 201 (see Figure 1B) within a range of, for example, 50,000 to 200,000 rpm.

[0052] The motor unit 202 shown in Figure 5B consists of 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. Each part will be described in turn below.

[0053] <Housing of motor unit 202> As shown in Figure 5A, the motor unit 202 has an upstream motor housing 6 and a downstream motor housing 7 as housings for holding the stator core 24, etc. (see Figure 5B).

[0054] The motor unit 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 Figure 1B with screws or the like. The upstream motor housing 6 shown in Figure 5A is a metal enclosure (made of aluminum alloy, steel, etc.) that covers the upstream side of the motor unit 202. The upstream motor housing 6 has a plurality (for example, 6) radial openings 6a on its side.

[0055] As shown in Figure 5B, the center of the upper surface of the upstream motor housing 6 protrudes upward, and an upstream bearing 21 is provided inside it, which rotatably supports the upstream side of the rotating shaft 2. Furthermore, the upstream bearing 21 is positioned axially by the upstream spacer 21a located below the upstream bearing 21. The upstream motor housing 6 may also be provided with an axial opening, in which case cooling air can flow to the bearing 21 for cooling.

[0056] The downstream motor housing 7 shown in Figure 5A is a metal enclosure (made of aluminum alloy, steel, etc.) that covers the downstream side of the motor unit 202. The downstream motor housing 7 has multiple (for example, six) radial openings 7a on its side and multiple axial openings 7b on its bottom surface (see Figure 5B). The center of the lower surface of the downstream motor housing 7 protrudes downward, and a downstream bearing 22 is provided inside it to rotatably support the downstream side of the rotating shaft 2. The downstream bearing 22 is positioned axially by a downstream spacer 22a located above it.

[0057] As shown in Figure 5A, the upstream radial opening 6a and the downstream radial opening 7a are axial ( It is positioned so as not to overlap (in the vertical direction of the paper) as shown in Figure 5A. The radial openings (6a, 7a) of each motor housing (6, 7) are positioned to overlap in the axial direction with the axial end of the 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 such that the greatest common divisor of the number of radial openings (6a, 7a) and the number of diffuser blades (8, 9) is 3.

[0058] As a result, the same flow field is formed at three locations in the circumferential direction inside the motor section 202, thereby reducing the temperature distribution in the circumferential direction. Alternatively, 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 this embodiment, the following configuration is used to improve the cooling performance of the motor unit 202.

[0059] Firstly, each motor housing (6, 7) is made of a metal with high thermal conductivity to improve heat dissipation performance. Secondly, an exposed portion 24a (see Figure 5A) is provided between the upper and lower motor housings (6, 7) where the stator core 24 is exposed, allowing the stator core 24 to be cooled from the outside. Furthermore, if the amount of heat generated by the motor section 202 is relatively small, each motor housing (6, 7) could be made of a heat-resistant resin that has a lower thermal conductivity, or the upper and lower motor housings (6, 7) could be connected. Alternatively, the upstream motor housing may be made longer in the axial direction, and the downstream motor housing may be made shorter, resulting in a structure where the stator core 24 is not exposed and heat dissipation is reduced.

[0060] The radial opening 7a and axial opening 7b of the downstream motor housing 7 shown in Figure 5B are radially Motor cooling is possible with opening 7a alone. However, the presence of the axial opening 7b reduces pressure loss when taking in the motor cooling airflow (airflow in the second flow path F2). This increases the cooling airflow to the motor section 202, enabling effective cooling.

[0061] <Rotor of motor unit 202> As shown in Figure 5B, the rotor core 23 is fixed to the rotating shaft 2 in the region sandwiched between the upper and lower spacers (21a, 22a). The rotor core 23 forms the rotor of the motor unit 202, and incorporates rare-earth bonded magnets such as samarium iron nitrogen magnets and neodymium magnets.

[0062] As shown in Figure 5A, a collar 25 is fixed to the rotating shaft 2 that protrudes from the top of the upstream motor housing 6. A protrusion 25a (see Figure 5A) is provided on the top of the collar 25. The protrusion 25a is fitted into a recess 14a (see Figure 2B) of the sleeve 14 of the impeller 1. The fitting of the protrusion 25a and the recess 14a (see Figure 2B) ensures that the torque of the rotating shaft 2 is reliably transmitted to the impeller 1, preventing the impeller 1 from spinning freely.

[0063] <Stator of motor unit 202> As shown in Figure 5B, the stator core 24 of the motor unit 202 is arranged around the outer circumference of the motor unit 202, surrounding the rotor core 23, which is the rotor of the motor unit 202. A coil 24b (see Figure 5B), made of aluminum wire or copper wire covered with a coating material, is wound around the stator core 24. By supplying the desired AC power to the coil 24b from the drive circuit 114 shown in Figure 12, the stator core 24 is turned into an electromagnet. This allows the rotor core 23, the rotating shaft 2, and the impeller 1 fixed to the rotating shaft 2 to rotate together at high speed.

[0064] As shown in Figure 5B, the upstream motor housing 6 is pressed into the upstream side of the stator core 24. The stator core 24 is pressed into place and secured with adhesive. The downstream motor housing 7 is also pressed into place on the downstream side of the stator core 24 and secured with adhesive. This allows the stator core 24, the upstream motor housing 6, and the downstream motor housing 7 to be integrated into a single unit. Furthermore, a radial opening 6a of the upstream motor housing 6 is provided at the height of the upstream end of the coil 24b. Also, a radial opening 7a of the downstream motor housing 7 is provided at the height of the downstream end of the coil 24b.

[0065] <First channel F1 and second channel F2> Figure 6 shows a longitudinal cross-sectional view of an electric blower 200, which is an example of a first flow path F1 and a second flow path F2. Next, using Figures 1B and 6A, we will describe in detail the first flow path F1 through which the airflow from the impeller 1 of the embodiment flows, and the second flow path F2 (F2a, F2b) through which the cooling airflow from the motor unit 202 flows. 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. Also, the furthest downstream point 9d of the trailing edge 9b of the second diffuser blade 9 is located downstream of the front end 7c. The configuration in which the trailing edge 9b of the second diffuser blade 9 straddles the front end 7c creates a pressure difference that redirects the outlet flow of the second diffuser 9D towards the motor section 202 (radially inward, downward in the plane of the paper in Figure 6), thereby improving cooling performance and increasing efficiency (by increasing the length of the shroud blade).

[0066] Specifically, the airflow generated by the impeller 1 flows through the first channel F1, passing through the first diffuser 8D which has the first diffuser blade 8, and the second diffuser 9D which has the second diffuser blade 9, and then flows downstream. The airflow through the first channel F1, which has passed through the second diffuser 9D, has a high wind speed, and a low-pressure area T is generated at the outlet of the second diffuser blade 9. Then, the airflow through the second channel F2 flows towards the motor side (Coanda effect).

[0067] Furthermore, because the shroud side of the second diffuser wing 9 is longer in the axial direction, the outer wall 5 (shroud By creating a pressure difference in the airflow from (D) to the motor section 202, the airflow is directed inward. An airflow can be directed towards the motor section 202. From the radial opening 7a and axial opening 7b of the downstream motor housing 7, the Venturi effect As a result, a flow is generated toward the low-pressure section T, and the cooling airflow from the second flow path F2 (F2a, F2b) is drawn into the motor, cooling the stator core 24, coil 24b, downstream bearing 22, and upstream bearing 21 of the stator.

[0068] The airflow through the second channel F2 after cooling passes through the radial opening 6a of the upstream motor housing 6 and mixes with the main flow (the airflow of the first airflow F1 that has passed through the impeller 1) in the low-pressure section T. At this time, the temperature decreases and is then discharged downstream of the electric blower 200 from the exhaust port 200b (see Figure 1B) along with the airflow through the first channel F1.

[0069] Figure 7A shows a longitudinal cross-sectional view of an electric blower 200A, which is an example of the first flow path F1 and second flow path F2 of Modification 1. In Modification 1, in order to increase the cooling airflow for the motor section 202, a duct 20 is provided between the first diffuser blade 8 of the first stage and the second diffuser blade 9 of the second stage, in the shape of the diffuser hub 5a which serves as an air passage. The rest of the configuration is the same as that shown in Figure 6 of the embodiment.

[0070] The downstream starting point (20a) of the duct 20 is located downstream of the opening end 6b of the radial opening 6a of the upstream motor housing 6. The duct 20 is located downstream from the coaxial position of the radial opening 6a of the upstream motor housing 6. It is positioned to the side. This ensures that the direction of the airflow in the second channel F2, which flows from the radial opening 6a to the duct 20, aligns with the direction of the airflow in the first channel F1, thereby reducing losses when mixing with the diffuser channel.

[0071] Figure 7B shows a longitudinal cross-sectional view of an electric blower 200B, an example of the first flow path F1 and second flow path F2 of Modified Example 2. In Modification 1, the duct 20 is a vertical duct, but in Modification 2, in order to reduce losses when the airflow flowing through the first channel F1 and the airflow flowing through the second channel F are mixed, the duct 20A is made inclined with an inclined surface 20a. The other configurations are the same as in Modification 1.

[0072] Experiments have confirmed that Modification 2 reduces the loss due to the incline compared to Modification 1, and it is possible to increase the efficiency of the electric blower. In the configurations shown in Figures 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. However, even if the upstream motor housing 6 is positioned to cover the stator, the effect can be obtained as long as the radial openings (radial openings 6a, 7a) and axial opening (7b) of the motor casing, and the configuration of the diffuser blades (8, 9) and ducts 20, 20A are the same.

[0073] Also, as shown in Figure 5A, a part of the stator core 24 of the stator is the motor casing ( When exposed from the upstream motor housing 6 and the downstream motor housing 7, The cooling air from the second channel F2 flows over the surface of the stator core 24 of the engine, thereby increasing the cooling effect.

[0074] Figure 8A shows a perspective view including a partial cross-section of the second diffuser 9D, which is covered by the downstream housing 5. Figure 8B shows a view in direction II, including a partial cross-section of Figure 8A. Conventionally, the airflow from the diffuser hub 5a to the first flow path F1 tended to separate easily. Therefore, as a method to promote inward flow at the outlet of the second diffuser 9D, a notch (recess) 5h is provided in the diffuser hub 5a of the second stage diffuser 9D.

[0075] By providing a notch (recess) 5h in the diffuser hub 5a, the airflow in the first channel F1 becomes less likely to separate, and the airflow in the first channel F1 flows inward from the notch (recess) 5h (Figure 8A). Arrow α11). In other words, the airflow in the first channel F1 of the outlet flow of the second diffuser 9D is A radially inward flow towards the motor section 202 can be formed. Therefore, the cooling effect of the motor section 202 can be enhanced.

[0076] In Figure 8B, when viewing the rotation axis C of the impeller 1 in the vertical direction, if the depth of the notch (recess) 5h is Lc, the width dimension of the notch (recess) 5h is Wc, and the dimension of the diffuser hub 5a between the second diffuser blades 9 is W, then the following relationship (1) holds. Lc≧0.6×L2 Wc≧0.5W (1) The inclination angle θ of the inclined surface 5h1 of the notch (recess) 5h of the impeller 1 with respect to the rotation axis C is set to approximately 30 degrees.

[0077] For the cooling effect of the notch (recess) 5h, the width dimension Wc and depth Lc of the notch (recess) 5h are highly sensitive. The circumferential position of the notch 5h shown in Figure 8B coincides with the forward side 9c of the rotation direction of the impeller 1 of the second diffuser blade 9. This allows the flow on the side of the diffuser hub 5a, which is prone to separation, and the forward side 9c (negative pressure surface) of the second diffuser blade 9 to be drawn towards the motor unit 202. As a result, the efficiency reduction of the electric blower 200 is suppressed, and cooling performance can be improved.

[0078] <Effects of presence or absence of duct 20, vertical duct 20, and inclined duct 20A> Figure 9 shows a graph comparing the efficiency of electric blowers with a vertical duct 20 (horizontal hatching) and an inclined duct 20A (diagonal hatching). One division on the vertical axis represents a 2% efficiency of the electric blower. It was confirmed that the efficiency of the electric blower was slightly higher when an inclined duct 20A was installed compared to when a vertical duct 20 was installed.

[0079] Figure 10 shows the temperature rise test results for the upstream bearing 21, coil 24b, and stator core 24 on the impeller 1 side with duct 20 absent (black), vertical duct 20 (horizontal hatch), and inclined duct 20A (diagonal hatch). Each division on the vertical axis represents 10K (Kelvin). The temperature reduction of the upstream bearing 21 and coil 24b was significant when the duct 20 was present, confirming high cooling performance. The temperature reduction of the upstream bearing 21 and coil 24b was achieved by adding a duct 20 between the first diffuser 8D of the first stage and the second diffuser 9D of the second stage, compared to the case without the duct 20 (Figure Compared to (see 6), the amount of cooling air entering from opening 7b (see Figure 5B) and flowing inside the motor section 202 is This is because the cooling performance has improved due to increased capacity.

[0080] Furthermore, according to fluid analysis results, the increase in cooling airflow due to the addition of duct 20 is approximately 1.3 times compared to the case without duct 20. The temperature reduction effect of the inclined duct 20A is achieved when the airflow flowing through the second channel F2 mixes with the airflow flowing through the main first channel F1 (flow from impeller 1). By setting the inclination angle to 45 degrees as shown in Figure 7B, the airflow flowing through the main first channel F1 mixes with the airflow flowing through the diffuser hub 5. The flow becomes easier to achieve on side a (flowing along the hub end 5i), and the flow from the outlet of the second diffuser 9D of the second stage toward the inclined duct 20A collides with the stator core 24, thereby promoting the cooling of the stator's stator core 24.

[0081] According to the embodiment, a vacuum cleaner 100 equipped with the electric blower 200 having the above-described configuration can be obtained that provides the above-described effects of the electric blower 200. Based on the above, we can provide a small, lightweight electric blower 200 with high efficiency and high motor cooling efficiency, and an electric vacuum cleaner 100 equipped with it.

[0082] <<Other Embodiments>> 1. The present invention is not limited to the embodiments and modified configurations described above, and various modified and specific forms are possible within the scope of the appended claims. [Explanation of Symbols]

[0083] 1. Impeller 2. Axis of rotation (central axis) 3. Fan casing 3a Notch in the fan casing 4 Upstream Housing 4a Inner wall (upstream housing, inner cylinder section, first inner cylinder section) 4b Exterior wall (upstream housing, outer cylinder section) 5 Downstream Housing 5a Diffuser hub (downstream housing, hub, inner cylinder section, second inner cylinder section) 5b Exterior wall (downstream housing, shroud, outer cylinder section) 5i Downstream end of the second diffuser 5f First diffuser hub diameter 5g 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) 8. First diffuser wing (stator wing, first stator wing section) 8D First diffuser (first diffuser section) 9. Second diffuser wing (stator wing, second stator wing section) 9D Second diffuser (second diffuser section) 11a Length of the impeller hub diameter, outermost diameter of the hub 11b1 Notch (recess) 20 Duct (connecting section) 20A Inclined duct (connecting section) 23 Rotor core (rotor) 24 Stator core (stator) 100 Electric Vacuum Cleaners 200 Electric blower (blower device) 201 Blower section 202 Motor section F1 First channel F2 Second flow path

Claims

1. A rotor that rotates around a central axis that extends vertically, A stator facing the rotor in the radial direction, An impeller fixed to the rotor, It includes a diffuser positioned below the impeller to straighten the airflow generated by the impeller, The aforementioned diffuser is Inner cylinder part, The inner cylinder portion and the outer cylinder portion are arranged with a gap in the radial direction between them, It has a plurality of stationary vanes arranged at circumferential intervals in the gap between the inner cylinder portion and the outer cylinder portion, The inner cylinder portion has a communication portion that connects the inside and outside in the radial direction, A blower in which, in a cross-sectional shape obtained by cutting the communication portion in a cross-section including the central axis, the upper side of the communication portion extends downward as it becomes perpendicular to the central axis or radially outward, and the lower side of the communication portion extends downward as it becomes perpendicular to the central axis or radially outward.

2. The blower according to claim 1, wherein the upper and lower edges extend downward as they move radially outward.

3. The diffuser is divisible into a first diffuser section and a second diffuser section located below the first diffuser section in a direction along the central axis. The blower according to claim 1, wherein the communication portion is the gap between the first inner cylinder portion of the first diffuser portion and the second inner cylinder portion of the second diffuser portion.

4. The aforementioned stationary vane is Multiple first stationary vanes are arranged in the first diffuser section, It has a plurality of second stationary vanes arranged in the second diffuser section, The blower according to claim 1, wherein at least a portion of the communication portion is disposed between the first stator vane and the second stator vane.

5. The blower according to claim 1, wherein the communication portion is a through hole that penetrates the inner cylinder portion in the radial direction.

6. The blower according to claim 1, characterized in that it has a motor housing that holds the stator and has a downstream radial opening.

7. The blower according to claim 1, characterized in that the stator has a downstream radial opening on the axial downstream side that allows air to flow from the radially outside to the inside.

8. A vacuum cleaner having a blower according to any one of claims 1 to 7.

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