Electric blower and electric vacuum cleaner equipped with same

Abstract

To provide an electric air blower that is compact and lightweight, has high efficiency in a wide air volume range, and in which cooling efficiency of a motor is high.SOLUTION: In an electric air blower, a first flow passage passes through an air blower part, and a second flow passage passes through a motor part. The motor part comprises a motor housing holding a stator core, in which an upstream side radial opening and a downstream side radial opening are opened in a side surface. The air blower part comprises a fan casing, an upstream side housing surrounding an upstream side outer periphery of the motor part, and a downstream side housing surrounding a downstream side outer periphery of the motor part. The first flow passage passes through between an inner wall and an outer wall of the upstream side housing, and between an inner wall and an outer wall of the downstream side housing. The second flow passage passes through the downstream side radial opening, the inside of the motor part, the upstream side radial opening, between the motor housing and the inner wall and the upstream side housing, and between the motor housing and the inner wall of the downstream side housing. An annular diffuser opposed to the downstream side radial opening is provided on the downstream side of the downstream side housing.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

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

[0002] As an example of an electric blower (blower device) built into an electric vacuum cleaner, Patent Document 1 describes a blower device comprising: "an impeller 10 that rotates around a central axis C that extends vertically; a motor 20 that is positioned below the impeller and has a stator 24 to rotate the impeller; a motor housing 21 that houses the stator; and a fan casing 2 that houses the impeller and the motor housing and defines a first flow path 5 in the gap between the motor housing and the fan casing; the upper part of the fan casing covers the top of the impeller and has an air intake 3 that opens in the vertical direction; the lower part of the fan casing has an exhaust port 4 that communicates with the air intake via the first flow path; the motor housing has an inlet 21a that penetrates radially below the upper surface of the stator fixed to the inner surface of the motor housing and communicates with the first flow path; and the motor housing has a second flow path 6 that extends upward from the inlet and communicates with the space above the stator." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-105269 Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that the operating air volume of electric vacuum cleaners varies greatly depending on operating conditions such as filter clogging due to dust, the material of the floor being cleaned, etc. Therefore, electric blowers for electric vacuum cleaners are required to have strong suction power over a wide range of air volumes.

[0005] In addition, to improve the ease of use of electric vacuum cleaners, there is a demand for smaller and lighter electric blowers. However, this reduces the heat dissipation area of ​​the electric blower and increases the heat density inside the electric blower, making it necessary to improve the cooling performance of the motor and bearings.

[0006] In particular, battery-powered vacuum cleaners (secondary batteries), such as cordless stick vacuum cleaners and autonomous vacuum cleaners (robot vacuum cleaners), have low power consumption and a small maximum airflow rate due to the battery capacity. This poses a problem: when the filter becomes clogged, the dust-transporting capacity decreases, and the suction power of the vacuum cleaner decreases. Furthermore, battery-powered vacuum cleaners are required to be small and lightweight, and the electric blowers installed in them are required to have strong suction power over a wide range of airflow rates while also being compact.

[0007] Here, if a diffuser vane (referred to as "stationary vane 40" in Patent Document 1) is used, excellent pressure recovery can be achieved at the design point airflow rate. However, if the airflow rate drops below the design point airflow rate due to factors such as filter clogging, the diffuser performance will decrease due to a mismatch between the inlet angle of the diffuser vane and the inlet angle of the air flow into the diffuser, which may result in a decrease in the suction power of the vacuum cleaner.

[0008] Furthermore, in the blower device of Patent Document 1, as shown in FIG. 4 and the like in the document, a portion of the airflow S flowing through the outer first flow path 5 flows into the inner second flow path 6 via the inlet 21a provided in the peripheral wall of the motor housing 21, cools the upper bearing 26, and then cools the lower bearing 26. The airflow is then exhausted to the outside of the blower device 1 from the outlet (outlet 29a) of the second flow path 6 without merging with the first flow path 5. In this way, when the second flow path 6 branching from the first flow path 5 is configured not to merge with the first flow path 5, the pressure loss (resistance) occurs when a portion of the airflow S flowing through the first flow path 5 branches into the second flow path 6, and the airflow volume downstream of the inlet 21a (branching point) in the first flow path 5 is reduced compared to the airflow volume upstream of the inlet 21a (branching point).

[0009] In addition, the second flow path 6 in Patent Document 1 is small in size, so the flow path area is small, and furthermore, since the air flows while bending inside the motor 20, there is a concern that the pressure loss in the flow path is large, the amount of cooling air is reduced, the temperature inside the motor 20 is high, and motor efficiency is reduced.

[0010] The present invention is devised to solve the above-mentioned problems, and aims to provide an electric blower that is small and lightweight, yet has high blower efficiency over a wide range of air volume and high motor cooling efficiency, and an electric vacuum cleaner equipped with the same. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides an electric blower in which a first flow path flows inside a blower section and a second flow path flows inside a motor section, wherein the motor section includes a rotating shaft, a bearing for rotatably supporting the rotating shaft, a rotor core fixed to the rotating shaft, a stator core disposed so as to surround the outer periphery of the rotor core, and a motor housing for holding the stator core and having an upstream radial opening and a downstream radial opening on a side surface thereof, and the blower section includes an impeller fixed to a tip of the rotating shaft, a fan casing for covering the outer periphery of the impeller, and a second flow path for passing through the upstream side of the motor section. the first flow path runs between the inner and outer walls of the upstream housing and between the inner and outer walls of the downstream housing; the second flow path runs through the downstream radial opening, the interior of the motor section, the upstream radial opening, between the motor housing and the inner wall of the upstream housing, and between the motor housing and the inner wall of the downstream housing; and a circular diffuser is provided on the downstream side of the downstream housing, facing the downstream radial opening. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an electric blower that is small and lightweight, yet has high blower efficiency over a wide range of air volume and high motor cooling efficiency, and an electric vacuum cleaner equipped with the same. [Brief explanation of the drawings]

[0013] [Figure 1A] 1 is an external view of an electric blower according to an embodiment of the present invention; [Figure 1B] 1 is a longitudinal sectional view of an electric blower according to an embodiment of the present invention; [Figure 2A] FIG. 2 is a perspective view of an impeller according to an embodiment. [Figure 2B] FIG. 2 is a longitudinal cross-sectional view of an impeller according to an embodiment. [Figure 3A] FIG. 2 is a plan view of an upstream housing according to an embodiment. [Figure 3B] FIG. 2 is a longitudinal cross-sectional view of an upstream housing according to an embodiment. [Figure 3C] FIG. 2 is a partial cross-sectional view of an example upstream housing. [Figure 4A] FIG. 2 is a plan view of an embodiment of a downstream housing. [Figure 4B] FIG. 2 is a longitudinal cross-sectional view of a downstream housing according to an embodiment. [Figure 4C] FIG. 2 is a partial cross-sectional perspective view of an embodiment of a downstream housing. [Figure 5A] FIG. 2 is an external view of a motor unit according to an embodiment. [Figure 5B] FIG. 2 is a longitudinal cross-sectional view of a motor unit according to an embodiment. [Figure 6A] FIG. 4 is a longitudinal cross-sectional view showing an example of the structure of a second flow path. [Figure 6B] FIG. 4 is a longitudinal cross-sectional view showing an example of the structure of a second flow path. [Figure 6C] FIG. 4 is a longitudinal cross-sectional view showing an example of the structure of a second flow path. [Figure 6D] FIG. 4 is a longitudinal cross-sectional view showing an example of the structure of a second flow path. [Figure 7] FIG. 1 is a perspective view of an electric vacuum cleaner according to an embodiment. [Figure 8] FIG. 1 is a vertical cross-sectional view of an electric vacuum cleaner according to an embodiment. [Figure 9] 10 is a graph comparing the fan efficiency of the electric fan of the example and the comparative example. [Figure 10] 6 is a graph comparing temperature rises of an electric blower according to an embodiment and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric blower according to the present invention and an electric vacuum cleaner equipped with the same will be described in detail below with reference to the drawings.

[0015] <General configuration of the vacuum cleaner 100> First, an electric vacuum cleaner 100 according to one embodiment of the present invention will be described with reference to Figures 7 and 8. Figure 7 is a perspective view of the electric vacuum cleaner 100, and Figure 8 is a vertical cross-sectional view of the electric vacuum cleaner 100. The electric vacuum cleaner 100 shown in the figure is a rechargeable cordless stick vacuum cleaner in which the vacuum cleaner main body 110 is attached to a holder 120, and can be charged while placed on a charging stand 130. Note that although a rechargeable cordless stick vacuum cleaner is shown here as an example, the electric blower 200 of the present invention may also be built into a non-rechargeable stick vacuum cleaner that is equipped with a power cord.

[0016] The vacuum cleaner body 110 is a unit that can be used alone as a handheld vacuum cleaner, and has a body grip part 111 at the top that the user holds when using it as a handheld vacuum cleaner, and an intake opening 112 at the bottom that sucks in dust when using it as a handheld vacuum cleaner. The inside of the vacuum cleaner body 110 is provided with a dust collection chamber 113 for collecting dust, an electric blower 200 for generating the suction airflow required for dust collection, a drive circuit 114 for driving the electric blower 200, and a battery unit 115 for supplying power to the drive circuit 114.

[0017] On the other hand, the holding part 120 is a unit to which the vacuum cleaner body 110 can be attached and detached, and has at its upper part a grip part 121 that the user holds when using it as a stick vacuum cleaner, and at its lower part a suction body 122 that sucks up dust when using it as a stick vacuum cleaner, and a connection part 122a that connects the suction body 122 to the intake opening 112.

[0018] In addition, the main body grip portion 111 of the vacuum cleaner main body 110 is provided with a main body switch portion 111a for turning on / off the operation of the electric blower 200 when used as a handheld vacuum cleaner, and the grip portion 121 of the holding portion 120 is provided with a switch portion 121a for turning on / off the operation of the electric blower 200 when used as a stick vacuum cleaner.

[0019] <Electric blower 200> Next, electric blower 200 of this embodiment will be described in detail using Figures 1A to 6, 9 and 10. Electric blower 200 of this embodiment mainly includes impeller 1, rotating shaft 2, fan casing 3, upstream housing 4, downstream housing 5, upstream motor housing 6, downstream motor housing 7, upstream diffuser blades 8, downstream diffuser blades 9, etc., which together form blower section 201 and motor section 202.

[0020] FIG. 1A is an external view of electric blower 200, and FIG. 1B is a longitudinal cross-sectional view of electric blower 200. Electric blower 200 of this embodiment is a blower that draws in air through upper air intake port 200a and expels air through lower air exhaust port 200b when impeller 1 rotates, and therefore defines the upstream and downstream sides as shown. Focusing on the installation direction of rotating shaft 2, axial and radial directions are also defined as shown. Note that electric blower 200 is installed inside electric vacuum cleaner 100 with air intake port 200a facing downward and exhaust port 200b facing upward so that dust can be sucked up from suction body 122 at the bottom of electric vacuum cleaner 100 to dust collection chamber 113 above (see FIG. 8).

[0021] 1A, the outer periphery of electric blower 200 is covered by an outer shell that integrates fan casing 3, upstream housing 4, and downstream housing 5. A specific method for integrating these will be described later.

[0022] 1B, a rotating shaft 2 is rotatably disposed inside electric blower 200, and an impeller 1 is fixed to the upper end of the rotating shaft 2, rotating integrally with the rotating shaft 2. In FIG. 1B, impeller 1 is fixed by a nut threaded onto the upper end of rotating shaft 2, but impeller 1 may also be fixed by press-fitting it onto the tip of rotating shaft 2.

[0023] 1B , an air flow path (hereinafter referred to as "first flow path F1") indicated by solid arrows that flows through blower section 201 from air inlet 200a toward air outlet 200b, and an air flow path (hereinafter referred to as "second flow path F2") indicated by dotted arrows that branches off downstream from first flow path F1 and flows from downstream to upstream within motor section 202, are formed inside electric blower 200. The structure of electric blower 200 of this embodiment, which allows desired airflows to flow through first flow path F1 and second flow path F2 and can sufficiently cool the inside of motor section 202 while maintaining suction force over a wide range of airflow volumes, will be described below, separated into blower section 201 and motor section 202.

[0024] <Blower section 201> 1B , from upstream to downstream, there are arranged an impeller 1, which is a rotary blade, an upstream diffuser vane 8 provided on the inner periphery of an upstream housing 4, a downstream diffuser vane 9 provided on the inner periphery of a downstream housing 5, and the like. In this embodiment, upper and lower diffuser vanes are provided to control the flow velocity of the airflow downstream of the impeller 1 and to control the static pressure, but some or all of the diffuser vanes may be omitted as long as the Venturi effect, which will be described later, is sufficiently maintained. Each part will be described below in order.

[0025] <Impeller 1 and fan casing 3> First, the impeller 1 will be described using Figures 2A and 2B. Figure 2A is a perspective view of the impeller 1, and Figure 2B is a longitudinal cross-sectional view of the impeller 1. The impeller 1 in both figures is an open-type mixed-flow impeller without a shroud plate, and has a hub 11, a plurality of blades 12, and a boss 13 for inserting the rotating shaft 2, which are integrally molded from engineering plastic or thermoplastic resin. Note that the impeller 1 of this embodiment may be a mixed-flow impeller with a shroud plate, or may be a centrifugal impeller or an axial-flow impeller.

[0026] A metal sleeve 14 is integrally molded on the back side of the hub 11 and is coaxial with the boss 13 of the impeller 1. By using this sleeve 14, it is possible to reduce variations in the fit gap between the impeller 1 and the rotating shaft 2, which is likely to occur when no sleeve is used, and to reduce imbalance in the impeller 1, thereby reducing vibration and noise when the impeller 1 is driven to rotate. In addition, a protrusion 14a is provided on the downstream side of the sleeve 14. The function of this protrusion 14a will be described later.

[0027] The fan casing 3 is a cover that covers the outer periphery of the impeller 1 and is integrally molded from engineering plastic or thermoplastic resin. As shown in FIG. 1B, the fan casing 3 has an air intake port 200a opening on the upstream side and also functions as a shroud plate for the impeller 1.

[0028] <Upstream housing 4 and upstream diffuser vane 8> Next, the upstream housing 4 and the upstream diffuser vanes 8 will be described with reference to Figures 3A to 3C. Figure 3A is a plan view of the upstream housing 4 as seen from the upstream side, Figure 3B is a vertical cross-sectional view of the upstream housing 4, and Figure 3C is a partial cross-sectional view of the upstream housing 4 as seen from the outer periphery. In FIG. 3C, the shroud of the upstream housing 4 is partially omitted to show the shape of the upstream diffuser vane 8 (particularly the positions of the leading edge 8a and the trailing edge 8b).

[0029] The upstream housing 4 and the upstream diffuser vanes 8 are integrally molded from engineering plastic or thermoplastic resin, and as shown in Figures 3A to 3C, a plurality of upstream diffuser vanes 8 integrally molded with the inner wall 4a (hub) and outer wall 4b (shroud) of the upstream housing 4 are arranged at equal intervals in the circumferential direction between them.

[0030] The length (blade chord length) from the leading edge 8a to the trailing edge 8b of the upstream diffuser vanes 8 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 is faster on the outer peripheral side than on the inner peripheral side, so by making the outer side of the upstream diffuser vanes 8 longer than the inner side, loss can be suppressed and the efficiency of the blower can be improved. Note that, although a configuration with 15 upstream diffuser vanes 8 is shown here as an example, the number of upstream diffuser vanes 8 can be changed depending on the specifications of the electric blower 200.

[0031] As shown in Figures 3A and 3C, protrusions 4c are provided at three equally spaced locations on the outer periphery of the outer wall 4b of the upstream housing 4, and by fitting the claw portions 5c of the downstream housing 5 (described later) into these protrusions 4c, the upstream housing 4 and the downstream housing 5 can be integrated while being centered (see Figure 1B).

[0032] As shown in FIGS. 3A and 3B, fastening portions 4d are provided at two locations on the upper surface of the upstream housing 4, and the motor portion 202 can be fastened to these fastening portions while being centered (see FIG. 1B).

[0033] Furthermore, as shown in Figures 3A to 3C, a fitting portion 4e is provided on the outer wall 4b of the upstream housing 4 in the area other than the outer periphery of the protrusion 4c, and by fitting the lower end of the fan casing 3 into this and adhesively fixing it, the fan casing 3 and the upstream housing 4 can be integrated while being centered (see Figure 1B).

[0034] <Downstream housing 5 and downstream diffuser vane 9> Next, the downstream housing 5 and the downstream diffuser vanes 9 will be described with reference to Figures 4A to 4C. Figure 4A is a plan view of the downstream housing 5 as seen from the upstream side, Figure 4B is a longitudinal cross-sectional view of the downstream housing 5, and Figure 4C is a partially cross-sectional perspective view of the downstream housing 5 as seen from the outer periphery. Note that in Figure 4C, the shroud of the downstream housing 5 is partially omitted to show the shape of the downstream diffuser vanes 9 (particularly the positions of the leading edge 9a and the trailing edge 9b).

[0035] The downstream housing 5 and the downstream diffuser vanes 9 are integrally molded from engineering plastic or thermoplastic resin, and as shown in Figures 4A to 4C, a plurality of downstream diffuser vanes 9 integrally molded with the inner wall 5a (hub) and outer wall 5b (shroud) of the downstream housing 5 are arranged at equal intervals in the circumferential direction. Note that, although a configuration with 15 downstream diffuser vanes 9 is shown here as an example, this is because the number of upstream diffuser vanes 8 and downstream diffuser vanes 9 is made to match, as each downstream diffuser vane 9 is arranged downstream of each upstream diffuser vane 8.

[0036] 4A to 4C, claws 5c are provided at three equally spaced locations on the outer periphery of the upper end of the downstream housing 5, and fitting portions 5d are provided on the outer periphery of the upper end excluding the claws 5c. By pressing the lower end of the upstream housing 4 against the fitting portions 5d of the downstream housing 5 and fitting the three claws 5c into the three protrusions 4c, the upstream housing 4 and the downstream housing 5 can be integrated while being centered (see FIG. 1B).

[0037] 4B and 4C, an annular diffuser 5e without downstream diffuser vanes 9 is provided downstream of the downstream housing 5. Details of this annular diffuser 5e will be described later.

[0038] 1B , in this embodiment, the inner wall 4a of the upstream housing 4 and the inner wall 5a of the downstream housing 5, and the outer wall 4b of the upstream housing 4 and the outer wall 5b of the downstream housing 5, are integrated with their radial positions substantially aligned. This smooths the inner surface of each flow passage, reducing loss in each passage. Furthermore, in this embodiment, the circumferential positions of the trailing edge 8b of the upstream diffuser vane 8 and the leading edge 9a of the downstream diffuser vane 9 are aligned, and the curved surfaces of the upstream diffuser vane 8 and the downstream diffuser vane 9 are smoothly continuous, so that a pair of upstream and downstream diffuser vanes 8 and 9 function as a single diffuser vane. Furthermore, in this embodiment, the thickness of each diffuser vane increases from the upstream side to the downstream side, thereby increasing static pressure and achieving high efficiency of the blower section 201.

[0039] <Motor section 202> Next, motor section 202 will be described with reference to Figures 5A and 5B. Figure 5A is a side external view of motor section 202, and Figure 5B is a longitudinal cross-sectional view of motor section 202. Motor section 202 shown in the figure is a unit for rotating impeller 1 of blower section 201 within a range of, for example, 50,000 to 200,000 rpm, and is composed of rotating shaft 2, upstream bearing 21, downstream bearing 22, rotor core 23, stator core 24, collar 25, upstream motor housing 6, downstream motor housing 7, etc. Each section will be described in order below.

[0040] <Housing of motor unit 202> As shown in both figures, motor section 202 has an upstream motor housing 6 and a downstream motor housing 7 as housings for holding stator core 24 and the like, and by fixing the upper surface of upstream motor housing 6 to the lower surface of upstream housing 4 with screws or the like, motor section 202 can be built into electric blower 200 (see Figure 1B).

[0041] The upstream motor housing 6 is a metal (aluminum alloy, steel, etc.) housing that covers the upstream side of the motor section 202, and as shown in FIG. 5A, has multiple (e.g., six) radial openings 6a on its side. As shown in FIG. 5B, the center of the top surface of the upstream motor housing 6 protrudes upward, and an upstream bearing 21 that rotatably supports the upstream side of the rotating shaft 2 is provided inside this protrusion. The upstream bearing 21 is positioned in the axial direction by an upstream spacer 21a below the upstream bearing 21. The upstream motor housing 6 may be provided with an axial opening, in which case cooling air can flow to the bearing 21 for cooling.

[0042] On the other hand, downstream motor housing 7 is a metal (aluminum alloy, steel, etc.) casing that covers the downstream side of motor section 202, and as shown in Fig. 5A, has multiple (e.g., six) radial openings 7a on its side and multiple axial openings 7b on its bottom surface. Also, as shown in Fig. 5B, the center of the bottom surface of downstream motor housing 7 protrudes downward, and a downstream bearing 22 that rotatably supports the downstream side of rotating shaft 2 is provided inside this protrusion. A downstream spacer 22a above downstream bearing 22 determines the axial position of downstream bearing 22.

[0043] As shown in FIG. 5A, in this embodiment, the upstream radial opening 6a and the downstream radial opening 7a are arranged so as not to overlap in the axial direction. The radial openings 6a and 7a of each motor housing are arranged so as to overlap in the axial direction with the axial end of a coil 24b (described later). The radial openings of each motor housing are uniformly arranged in the circumferential direction, and the number of openings and the number of diffuser vanes are set so that the greatest common divisor between the number of radial openings and the number of diffuser vanes is 3. This creates an identical flow field at three circumferential locations inside the motor section 202, thereby reducing the circumferential temperature distribution. The number of radial openings and the number of diffuser vanes may be set using a predetermined value other than 3 as the greatest common divisor.

[0044] In this embodiment, in order to improve the cooling performance of the motor section 202, each motor housing is made of metal to improve heat dissipation performance, and an area where the stator core 24 is exposed (exposed section 24a) is provided between the upper and lower motor housings so that the stator core 24 can be cooled from the outside. However, in cases where the amount of heat generated by the motor section 202 is relatively small, each motor housing may be made of heat-resistant resin, or the upper and lower motor housings may be connected to form a structure in which the stator core 24 is not exposed.

[0045] Furthermore, although the radial opening 7a and axial opening 7b of the downstream motor housing 7 can cool the motor using only the radial opening 7a, the presence of the axial opening 7b reduces pressure loss when taking in motor cooling air, increasing the amount of motor cooling air and making it possible to cool the motor.

[0046] <Rotor of the motor section 202> 5B, rotor core 23 is fixed to the rotating shaft 2 in an area sandwiched between upper and lower spacers. This rotor core 23 is the rotor of motor section 202, which incorporates a rare earth bonded magnet such as a samarium-iron-nitrogen magnet or a neodymium magnet.

[0047] As shown in FIG. 5A, a collar 25 is fixed to the rotary shaft 2 protruding from the upper part of the upstream motor housing 6, and a recess 25a is provided on the upper part of the collar 25. By fitting this recess 25a into the protrusion 14a of the sleeve 14 of the impeller 1 described above, the torque of the rotating shaft 2 can be reliably transmitted to the impeller 1, and the impeller 1 can be prevented from spinning freely.

[0048] <Stator of motor section 202> As shown in Fig. 5B, stator core 24, which is the stator of motor section 202, is arranged on the outer periphery of motor section 202 so as to surround rotor core 23, which is the rotor of motor section 202. Coil 24b, which is made of aluminum wire or copper wire covered with a coating material, is wound around the winding frame of stator core 24, and stator core 24 can be made into an electromagnet by supplying desired AC power to coil 24b from drive circuit 114 in Fig. 8, and rotor core 23, rotating shaft 2, and impeller 1 can be rotated at high speed integrally.

[0049] Furthermore, by fixing the upstream motor housing 6 to the upstream side of the stator core 24 with an adhesive and fixing the downstream motor housing 7 to the downstream side with an adhesive, the stator core 24, the upstream motor housing 6, and the downstream motor housing 7 can be integrated together, thereby providing a radial opening 6a in the upstream motor housing 6 at the height of the upstream end of the coil 24b, and a radial opening 7a in the downstream motor housing 7 at the height of the downstream end of the coil 24b.

[0050] <Structure of first flow path F1 and second flow path F2> Next, the structures of the first flow path F1 and the second flow path F2 of this embodiment will be described in detail with reference to FIGS. 1B and 6A.

[0051] 1B, assuming that the dimensions defining the shapes of first flow path F1 and second flow path F2 are the radial height H1 of downstream diffuser vane 9, the radial distance H2 between the inner surface of annular diffuser 5e and the outer surface of downstream motor housing 7, the axial length L1 of inner wall 5a, the axial length L2 of downstream diffuser vane 9, and the axial length L3 of annular diffuser 5e, in electric blower 200 of this embodiment, the dimensions are set using the following equations to achieve both improved blower efficiency of blower section 201 and improved cooling efficiency of motor section 202. The functions of these equations will be explained below using Figure 6A, which is an enlarged cross-sectional view of the right-hand flow path in Figure 1B.

[0052] H1 ≧ 0.5×H2 (Formula 1) More preferably, H1 ≧ 0.66×H2 (Equation 1′) 0.5×L2 ≦ L1 ≦ L2 (Formula 2) More preferably, L1≒0.5×L2 (Equation 2') L3 ≧ 2.5×H1 (Formula 3) More preferably, L3 ≧ 3×H1 (Equation 3′) 6A, when electric power is supplied to motor section 202 to rotate impeller 1, a first flow path F1 through blower section 201 and a second flow path F2 that mainly flows within motor section 202 are formed inside electric blower 200. Second flow path F2 branches off from first flow path F1 and is exhausted from exhaust port 200b of electric blower 200 via the following flow paths (1) to (5).

[0053] (1) First, the airflow branched from the first flow path F1 inside the annular diffuser 5e flows into the motor section 202 through the downstream radial openings 7a and the axial openings 7b. In this embodiment, the annular diffuser 5e is disposed on the outer circumferential side of the downstream radial openings 7a, which suppresses the airflow flowing out from the downstream diffuser vanes 9 from diffusing in the outer circumferential direction. This allows the airflow branched from the first flow path F1 to be efficiently guided into the motor section 202.

[0054] (2) The airflow that flows into the motor section 202 from the downstream radial opening 7a flows from downstream to upstream, efficiently cooling the downstream bearing 22, rotor core 23, stator core 24, upstream bearing 21, etc., which are in a high temperature state.

[0055] (3) The air flow that flows upstream inside the motor section 202 flows out to the outside of the motor section 202 through the upstream radial opening 6a, and then flows downstream through the gap between the inner surface of the inner wall 4a of the upstream housing 4 and the outer surface of the upstream motor housing 6, further cooling the exposed portion 24a of the stator core 24.

[0056] (4) The airflow that has cooled the exposed portion 24a merges with the first flow path F1 near the lower end of the inner wall 5a of the downstream housing 5. In this embodiment, as shown in (Equation 1) or (Equation 1'), the radial height H1 of the downstream diffuser vane 9 is set large, so that the downstream diffuser vane 9 can be brought closer to the downstream motor housing 7, thereby increasing the flow velocity in the outer peripheral region of the downstream motor housing 7. Furthermore, as shown in (Equation 2'), by locating the lower end of the inner wall 5a of the downstream housing 5 at a position approximately half the axial length of the downstream diffuser vane 9 (for example, L1 / L2 = 0.5 to 0.6), the second flow path F2 can be merged with the first flow path F1 in the region where the high-speed airflow through the downstream diffuser vane 9 exists. Therefore, the Venturi effect of the high-speed first flow path F1 allows efficient suction of air from the upstream radial openings 6a inside the motor section 202, and as a result, cooling air can be efficiently taken in from the downstream radial openings 7a and axial openings 7b into the negative pressure inside the motor section 202. In other words, the Venturi effect of the first flow path F1 allows improved cooling efficiency of the motor section 202 regardless of the operating range of the electric blower 200.

[0057] (5) The airflow that has merged with the first flow path F1 is exhausted from the exhaust port 200b. In this embodiment, as shown in (Equation 3) or (Equation 3'), the annular diffuser 5e is provided with an axial length L3 that corresponds to the radial height H1 of the downstream diffuser vane 9. Because the axial length L3 of the annular diffuser 5e is sufficiently longer than the radial height H1 of the downstream diffuser vane 9, a sudden expansion of the flow path downstream of the downstream diffuser vane 9 is suppressed, and as a result, the blowing efficiency of the blower section 201 is improved.

[0058] <Effects of the Annular Diffuser 5e> Next, the effects of the annular diffuser 5e of this embodiment will be described with reference to the experimental results shown in Figures 9 and 10. The comparative example shown in Figures 9 and 10 corresponds to an electric blower in which the annular diffuser 5e has been removed from electric blower 200 in Figure 6A.

[0059] In the electric blower of the comparative example, because there is no annular diffuser 5e located opposite the downstream radial opening 7a, the flow path rapidly expands downstream of the trailing edge 9b of the downstream diffuser vane 9, through which the high-speed airflow flows. In this case, as shown in the experimental results in Fig. 9, the efficiency of the electric blower is significantly reduced compared to electric blower 200 of this embodiment, which is equipped with an annular diffuser 5e. As a result, the amount of air flowing into motor section 202 is reduced in the electric blower of the comparative example, and as shown in Fig. 10, the temperatures of the bearings (upstream bearing 21, downstream bearing 22), stator core 24, coil 24b, etc. inside motor section 202 are about 25 to 40 K higher than in electric blower 200 of this embodiment.

[0060] 9 and 10, electric blower 200 of this embodiment equipped with annular diffuser 5e not only improves the air-blowing efficiency of blower section 201 but also improves the cooling efficiency of motor section 202, compared to the electric blower of the comparative example not having an annular diffuser.

[0061] <Modification> Next, a modified example of the structure of FIG. 6A will be described with reference to FIGS. 6B to 6D.

[0062] In Figure 6B, the downstream radial opening 7a is positioned further downstream than in Figure 6A. In this case, the second flow path F2 branches off from the first flow path F1 near the position where the innermost airflow in the first flow path F1, shown by the solid line, contacts the downstream motor housing 7. This increases the amount of air drawn into the motor section 202 from the downstream radial opening 7a, thereby further improving the cooling efficiency of the motor section 202 compared to Figure 6A.

[0063] In Fig. 6C, the downstream radial opening 7a is positioned further upstream than in Fig. 6A. In this case, of the airflow in the first flow path F1 indicated by the solid line, the airflow on the innermost side adheres to the outer peripheral surface of the downstream motor housing 7 further upstream, which makes it possible to suppress separation of the airflow in the region of the annular diffuser 5e where the flow path expands, and thus makes it possible to further improve the blowing efficiency of the blower section 201 compared to Fig. 6A.

[0064] In Fig. 6D, instead of the radial openings 7a and axial openings 7b, corner openings 7c are provided that combine the functions of both. In this case, the same effect as in Fig. 6B can be obtained with a simplified configuration.

[0065] 6A to 6D, the annular diffuser 5e is provided downstream of the downstream housing 5, but the annular diffuser 5e may be omitted. In that case, in order to prevent the flow path of the first flow path F1 from suddenly expanding near the downstream radial openings 7a, the downstream diffuser vanes 9 should be extended at least to the axial position facing the downstream radial openings 7a.

[0066] The cooling by the Venturi effect of this configuration makes it possible to cool the motor even without the diffuser vanes on the upstream and downstream housings.

[0067] <Effects of this Example> According to the present embodiment described above, it is possible to provide an electric blower that is small and lightweight, yet has high blower efficiency over a wide range of air volume and high motor cooling efficiency, and an electric vacuum cleaner equipped with the same.

[0068] The present invention is not limited to the above-described embodiment, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0069] 100 vacuum cleaners 110 Vacuum cleaner body 111 Main body grip 111a Main unit switch 112 Intake opening 113 Dust Collection Chamber 114 Drive circuit 115 Battery Unit 120 Holding part 121 Grip 121a Switch section 122 Mouthpiece 122a Connection 130 Charging stand 200 electric blower 200a intake 200b exhaust port 201 Blower section 202 Motor section 1 impeller 11. Hub 11a Hub protrusion 12 Feathers 13. Boss 13a Boss surface 14 sleeve 14a Convex part 2 rotation axes 21 Upstream bearing 21a Upstream spacer 22 Downstream bearing 22a Downstream spacer 23 rotor core 24 stator core 24a Exposed part 24b coil 25 colors 25a Recess 3 Fan casing 4 Upstream housing 4a inner wall 4b Exterior wall 4c protrusion 4d fastening part 4e Mating part 5 Downstream housing 5a Inner wall 5b Exterior wall 5c Claw part 5d Mating part 5e Annular Diffuser 6 Upstream motor housing 6a radial opening 7 Downstream motor housing 7a radial opening 7b Axial opening 7c Corner opening 8 Upstream diffuser vane 8a leading edge 8b Trailing edge 9 Downstream diffuser vane 9a leading edge 9b Trailing edge F1 First flow path F2 Second flow path

Claims

1. An electric blower in which a first flow path flows inside a blower unit and a second flow path flows inside a motor unit, The motor unit includes a rotating shaft, a bearing that rotatably supports the rotating shaft, a rotor core fixed to the rotating shaft, a stator core that is disposed so as to surround the outer periphery of the rotor core, and a bearing that holds the stator core. a motor housing having an upstream radial opening and a downstream radial opening on a side surface, the blower unit including an impeller fixed to the tip of the rotary shaft, a fan casing covering the outer periphery of the impeller, an upstream housing surrounding an outer periphery of the motor unit on the upstream side; and a downstream housing surrounding an outer periphery of the motor unit on the downstream side; the first flow path extends between an inner wall and an outer wall of the upstream housing and between an inner wall and an outer wall of the downstream housing; the second flow path passes through the downstream radial opening, the interior of the motor section, the upstream radial opening, a space between the motor housing and an inner wall of the upstream housing, and a space between the motor housing and an inner wall of the downstream housing; an annular diffuser provided downstream of the downstream housing and facing the downstream radial opening;

2. The electric blower according to claim 1, an upstream diffuser vane is provided between an inner wall and an outer wall of the upstream housing; a downstream diffuser blade provided between the inner wall and the outer wall of the downstream housing;

3. The electric blower according to claim 2, an electric blower, wherein one of the following formulas is satisfied, where H1 is a radial height of the downstream diffuser vanes and H2 is a radial distance between the inner surface of the annular diffuser and the outer surface of the motor housing: H1 ≧ 0.5×H2, H1 ≧ 0.66×H2

4. The electric blower according to claim 2, 1. An electric blower, wherein when the axial length of the inner wall of the downstream housing is L1 and the axial length of the downstream diffuser vanes is L2, any one of the following formulas is satisfied: 0.5×L2 ≦ L1 ≦ L2, L1 ≒ 0.5 × L2

5. The electric blower according to claim 2, 1. An electric blower, wherein when a radial height of the downstream diffuser vanes is H1 and an axial length of the annular diffuser is L3, any one of the following formulas is satisfied: L3 ≧ 2.5×H1, L3 ≧ 3 × H1

6. The electric blower according to claim 1, The motor housing is an electric blower characterized in that an upstream motor housing covering the upstream side of the stator core and a downstream motor housing covering the downstream side of the stator core are connected together so that the stator core is not exposed.

7. The electric blower according to any one of claims 1 to 6, An electric blower having an axial opening in either an upstream motor housing, a downstream motor housing, or both.

8. An electric vacuum cleaner comprising the electric blower according to any one of claims 1 to 7.

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