Electric blower and vacuum cleaner equipped with same

Abstract

To provide an electric blower which is compact and lightweight, and has a wide air capacity range and high efficiency, and to provide a vacuum cleaner which has a wide air capacity range and is improved in suction force.SOLUTION: An electric blower comprises: an electric motor comprising a rotor and a stator; a rotary shaft provided for the rotor; rotor blades 1 fixed to the rotary shaft; a centrifugal type diffuser which has a plurality of centrifugal type diffuser blades 23 formed radially on outer peripheral sides of the rotor blades; and a fan casing 3 which covers an impeller, and further comprises an axial flow type diffuser which has axial flow type diffuser blades 12 forming a blade height radially downstream from the centrifugal type diffuser blades.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A conventional blower is disclosed in WO2016 / 194697 (Patent Document 1).

[0003] Patent Document 1 describes the following: "A blower comprising: a motor having a shaft arranged along a central axis extending vertically; an impeller connected to the shaft and rotating integrally with the shaft; an impeller housing arranged above or radially outward of the impeller; a motor housing arranged radially outward of the motor; a flow path member arranged radially outward from the motor housing with a gap therebetween; and a plurality of stator vanes arranged circumferentially in the gap between the motor housing and the flow path member, wherein at least one of the stator vanes has a first stator vane portion formed on one side of the motor housing or the flow path member, and a second stator vane portion formed on the other side of the motor housing or the flow path member, and the first stator vane portion and the second stator vane portion are connected radially or axially." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2016 / 194697 issue Summary of the Invention [Problem to be solved by the invention]

[0005] Since the operating air volume of a vacuum cleaner varies greatly depending on the operating conditions, such as the clogged filter and the material of the floor being cleaned, an electric blower with strong suction power over a wide range of air volumes is required. The air flowing in from the suction port of the electric blower is pressurized and accelerated by the impeller, and is decelerated by the diffuser blades, so that the kinetic energy of the air flowing in to the diffuser is converted into pressure energy and the static pressure increases.

[0006] The vaned diffuser can perform excellent pressure recovery at the design airflow, but at non-design airflow, the diffuser performance is reduced due to the mismatch between the diffuser vane inlet angle and the airflow inlet angle to the diffuser. Therefore, the suction power of the vacuum cleaner is high at the design airflow, but there is a risk that it will decrease at non-design airflow.

[0007] In vacuum cleaners that are powered by batteries (secondary batteries), such as cordless stick-type or autonomous vacuum cleaners, the power consumption of the electric blower is low, and the maximum air volume is also small. This causes an issue that the dirt-transporting capacity decreases when the filter becomes clogged, and the suction power of the vacuum cleaner decreases. Furthermore, cordless stick-type or battery-powered (secondary battery) vacuum cleaners are required to be small and lightweight, and the electric blower installed in the vacuum cleaner is required to have strong suction power over a wide range of air volumes, while also being compact.

[0008] Patent Document 1 states, "Related to a blower device and a vacuum cleaner." Patent Document 1 shows multiple stator vanes arranged in an exhaust flow path, and states, "The stator vanes have a lower stator vane and an upper stator vane, and the lower stator vane 67a extends in the axial direction (Z-axis direction)."

[0009] In the blower of Patent Document 1, a curved passage that redirects the radial wind speed to the axial direction is formed downstream of the impeller, and a stator vane extending in the axial direction is present downstream of the curved passage. When the technology of Patent Document 1 is applied to an electric blower mounted on a vacuum cleaner, which is required to be compact, there is a concern that the wind speed at the curved part is fast, increasing the pressure loss at the curved part and degrading performance. In order to reduce the pressure loss at the curved part, it is considered effective to increase the radial distance between the impeller (hereinafter, impeller) and the curved part, but this increases the outer diameter of the blower, and there is a risk that the product will become large.

[0010] The object of the present invention is to solve the above-mentioned problems by providing a small, lightweight electric blower that is highly efficient over a wide range of air volumes, and to provide a small vacuum cleaner with improved suction power over a wide range of air volumes. [Means for solving the problem]

[0011] In order to solve the above problems and to achieve the above objects, for example, the configurations described in the claims are adopted.

[0012] The present invention includes many means for solving the above problems, and one example thereof is a fan assembly including an electric motor having a rotor and a stator, a rotating shaft provided on the rotor, an impeller fixed to the rotating shaft, a fan casing that covers the impeller, and a partition plate that is disposed on the outer periphery of the impeller and is formed from a hub surface of the partition plate toward the fan casing and is integral with the partition plate. shape a centrifugal type diffuser vane arranged on the outer circumferential side of the centrifugal type diffuser vane; and a rear stage centrifugal type diffuser vane arranged on the outer circumferential side of the centrifugal type diffuser vane. shapeand an axial-flow type diffuser vane having a blade height in a radial direction from a hub surface of the partition plate, the axial-flow type diffuser vane being disposed downstream of the rear-stage centrifugal-type diffuser vane and radially overlapping with the rear-stage centrifugal-type diffuser vane as viewed in the axial direction, the rear-stage centrifugal-type diffuser vane being separate from the centrifugal-type diffuser vane and molded integrally with the inner surface of the fan casing, and the radial position of the leading edge being positioned further outward than the outer circumferential end of the partition plate. Effect of the Invention

[0013] According to the present invention, it is possible to realize a small-sized and lightweight electric blower that is highly efficient over a wide range of air volumes, and also a small-sized vacuum cleaner that has improved suction power over a wide range of air volumes.

[0014] Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0015] [Figure 1(a)] FIG. 1 is an external view of an electric blower according to a first embodiment of the present invention. [Figure 1(b)] FIG. [Diagram 2] FIG. 1(a) is a perspective view of an impeller in a first embodiment of the present invention, and FIG. [Diagram 3] FIG. 1(b) is a cross-sectional view taken along line AA of the electric blower in FIG. 1(a), showing a blower section in the first embodiment of the invention. [Figure 4] FIG. 2 is a diagram showing a diffuser portion of a blower according to the first embodiment of the invention. [Diagram 5] FIG. 2 is a diagram showing a fan casing of a blower according to the first embodiment of the invention. [Figure 6] FIG. 11 is a diagram comparing the fan efficiency (fluid analysis results) between a fan according to an embodiment of the present invention and a fan having only an axial-flow type diffuser blade. [Figure 7]FIG. 6 is a diagram showing a diffuser portion of a blower according to a second embodiment of the invention. [Figure 8] 1 is a perspective view of an electric vacuum cleaner to which an electric blower according to an embodiment of the present invention is applied. [Figure 9] 9 is a cross-sectional view of the vacuum cleaner body in the electric vacuum cleaner of FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. EXAMPLES

[0017] An electric vacuum cleaner 300 according to an embodiment of the present invention will be described with reference to Fig. 8 and Fig. 9. Fig. 8 shows a perspective view of an electric vacuum cleaner to which the electric blower of this embodiment is applied. As shown in Fig. 8, reference numeral 100 denotes a vacuum cleaner body that houses a dust collecting chamber 101 for collecting dust and an electric blower 200 (Fig. 1) for generating a suction airflow required for dust collection, 102 denotes a holding part for mounting the vacuum cleaner body 100, 103 denotes a grip part provided at one end of the holding part 102, and 104 denotes a switch part provided at the grip part for turning on and off the electric blower 200. A suction body 105 is attached to the other end of the holding part 102, and the vacuum cleaner body 100 and the suction body 105 are connected by a connection part 106. Reference numeral 107 denotes a charging stand for charging a battery unit 108.

[0018] In the above configuration, when switch portion 104 of grip portion 103 is operated, electric blower 200 housed in vacuum cleaner body 100 operates to generate a suction airflow. Dust is then sucked in through suction port body 105 and collected in dust collection chamber 101 of vacuum cleaner body 100 through connection portion 106.

[0019] Next, the vacuum cleaner body 100 will be described using the cross-sectional view of the vacuum cleaner body 100 shown in Fig. 9, which is a schematic diagram of the vacuum cleaner body 100. Inside the vacuum cleaner body 100, an electric blower 200 that generates suction force, a battery unit 108 that drives the electric blower 200, a drive circuit 109, and a dust collection chamber 101 are arranged.

[0020] The vacuum cleaner body 100 can be removed from the holding part 102 and used as a handheld vacuum cleaner, and is provided with a body grip part 110 and a suction port opening 111. Reference numeral 112 (FIG. 8) denotes a body switch part that turns the electric blower 200 on and off when used as a handheld vacuum cleaner. The body switch 112 can be operated even when the vacuum cleaner body 100 is attached to the holding part 102. Although FIGS. 8 and 9 show a cordless vacuum cleaner in which the suction port opening 111 and the connection part 106 are removable, a vacuum cleaner with a power cord and no batteries may also be used.

[0021] Next, an electric blower 200 will be described with reference to the external view of the electric blower shown in FIG. 1(a) and the vertical cross-sectional view of the electric blower shown in FIG. 1(b). The electric blower 200 is roughly divided into a blower section 201 and an electric motor section 202. The blower section 201 is composed of an impeller 1, which is a rotor, and a partition plate 2, which forms the hub surface of the first row of centrifugal diffuser vanes present on the outer periphery of the impeller, arranged on the electric motor section 202 side, which is the back surface of the impeller 1, and a resin fan casing 3, which covers the impeller, on which two rows of centrifugal diffuser vanes 23 and 24 are arranged in the radial direction on the outer periphery of the impeller 1. The partition plate 2 is formed with a curved flow path 25 that redirects the radial flow to the axial direction between the inner surface of the fan casing 3 and the outer periphery end 2a of the partition plate 2. An air suction port 4 is provided on the upper surface of the fan casing 3. The impeller 1 is made of thermoplastic resin and is directly connected to a rotating shaft 5. Here, in this embodiment, the impeller 1 which is a rotor is press-fitted and fixed to the rotary shaft 5, but it is also possible to provide a screw at the end of the rotary shaft 5 and fix the impeller 1 using a fixing nut.

[0022] The electric motor section 202 is composed of a rotor core 7 fixed to a rotating shaft 5 housed in a motor housing 9, and a stator core 8 on its outer periphery. A winding is wound around the stator core 8, and the stator core 8 is electrically connected to a drive circuit 109 provided in the electric blower 200.

[0023] The rotor core 7 is made of a rare earth bonded magnet. The rare earth bonded magnet is made by mixing a rare earth magnetic powder with an organic binder. For example, a samarium iron nitrogen magnet or a neodymium magnet can be used as the rare earth bonded magnet. The rotor core 7 is integrally formed with or fixed to the rotating shaft 5.

[0024] In this embodiment, a permanent magnet is used for the rotor core 7, but the present invention is not limited to this and a reluctance motor, which is a type of commutatorless motor, may also be used.

[0025] A bearing 10 is provided between the impeller 1 and the rotor core 7, and a bearing 11 is provided on the opposite side of the rotor core 7 in the direction of the rotation axis to rotatably support the rotating shaft 5. The motor housing 9 is made of metal, and is fastened to a bearing housing 34 that supports the bearing 11.

[0026] A screw hole 15 extending in the direction of the rotation shaft is formed at the end of the metal motor housing 9. A fixing screw 16 can be screwed into the screw hole 15, and the partition plate 2 is fixed to the metal motor housing 9 by screwing the fixing screw 16 into the screw hole 15.

[0027] The minimum area of ​​the circular flow passage formed between the inner surface 3a of the fan casing 3 and the outer peripheral end 2a of the partition plate 2 is set to be larger than the outlet area of ​​the impeller 1. This prevents the wind speed and pressure loss in the circular flow passage from increasing.

[0028] A plurality of centrifugal diffuser vanes 23 closest to the rotor are arranged on the partition plate 2 in the circumferential direction centered on the rotation axis 5. A plurality of rear-stage centrifugal diffuser vanes 24 are arranged on the outer periphery of the centrifugal diffuser vanes 23 in the circumferential direction centered on the rotation axis 5. The radial position of the leading edge 24a of the second row centrifugal diffuser vane 24 is larger than the outer periphery end (outer periphery end 2a of the partition plate 2) of the hub surface of the centrifugal diffuser vane 23 closest to the rotor, and the centrifugal diffuser vane 24 protrudes from the outer periphery end 2a of the partition plate 2 into the curved flow passage 25. A plurality of axial-flow diffuser vanes 12 located downstream of the centrifugal diffuser vanes 24 are arranged on the partition plate 2 centered on the rotation axis.

[0029] Further, an annular ring 6 is provided on a shroud (the radially outer end of the blade) of the axial flow type diffuser blade 12, and the fan casing 3 is fixed to the ring 6.

[0030] In addition, anti-vibration rubber 19 is installed at the installation area of ​​the fan casing 3 and the vacuum cleaner body to suppress vibration of the electric blower and prevent air leakage between the installation area of ​​the fan casing 3 and the main body, thereby achieving low noise and high efficiency. The electric blower is fixed to the vacuum cleaner body by a support part 14 extending axially from the partition plate 2.

[0031] The centrifugal diffuser vane 23 of the partition plate 2 has a blade inlet angle that is approximately equal to the flow discharged from the impeller 1 at the design point, and the centrifugal diffuser vane 23 reduces the rotational velocity component of the flow, thereby enhancing the diffuser effect and improving the blower efficiency. In addition, the centrifugal diffuser vane 24 installed on the outer periphery of the centrifugal diffuser vane 23 further reduces the rotational velocity component of the flow discharged from the centrifugal diffuser vane 23 and can redirect the flow in the axial direction, thereby suppressing the pressure loss occurring in the curved flow path. Furthermore, the axial flow type diffuser vane 12 efficiently reduces the rotational velocity component present in the axial flow discharged from the centrifugal diffuser vane 24 by its blade shape, thereby enabling further improvement of the blower efficiency. In addition, since the flow is fast on the fan casing side (3a side) of the centrifugal diffuser vane 24 of the shroud of the axial flow type diffuser vane 12, the chord length (leading edge 12a and trailing edge 12b) may be shortened, and the chord length on the hub side (2a side) where the flow is slower is lengthened to gently redirect the flow, thereby efficiently reducing the rotational direction velocity component.

[0032] Next, the air flow in the electric blower 200 will be described. When the electric motor unit 202 is driven to rotate the impeller 1, which is a rotor, air flows in from the air inlet 4 of the fan casing 3 and into the impeller 1. The air that flows in is pressurized and accelerated in the impeller 1, and flows out from the outer periphery of the impeller 1. When the air flow that flows out from the impeller 1 passes through the centrifugal diffuser vanes 23 and 24, the air flows along the vanes, and the rotational velocity component of the flow is reduced. Furthermore, the air that passes through the centrifugal diffuser vanes 24 is turned in the axial direction, passes through the curved flow passage 25 formed by the inner surface of the fan casing 3 and the outer periphery end 2a of the partition plate 2, flows into the axial diffuser vane 12, and flows along the vanes, further reducing the rotational velocity component of the flow, and is exhausted.

[0033] Next, the blower section 201 of this embodiment will be described with reference to Figures 2 and 3. Figure 2(a) is a perspective view of an impeller according to one embodiment of the present invention, (b) is a cross-sectional view of the impeller, and Figure 3 is a blower section according to one embodiment of the present invention, which is a cross-sectional view of the electric blower of Figure 1(a) taken along line AA.

[0034] First, an impeller 1, which is a rotor in one embodiment of the present invention, will be described with reference to Figure 2. The impeller 1 in one embodiment of the present invention is composed of a shroud plate 33, a hub plate 26, and a plurality of blades 27. The hub plate 26 and the blades 27 are integrally molded from a thermoplastic resin. The shroud plate 33, which is made of a thermoplastic resin, has a circular suction opening 28 formed in the center for drawing in air.

[0035] A concave groove 29 is formed in the flow passage surface of the shroud plate 33 at a position corresponding to the blade 27, and extends to the outer diameter side. A through hole 30 is provided in the concave groove 29. A convex boss 31 into which the rotating shaft 5 is inserted and fixed is formed in the center of the hub plate 26. The blades 27 integrally molded with the hub plate 26 are installed at equal intervals in the circumferential direction, and have a blade shape that retreats in the rotation direction as it moves from the inner diameter side to the radially outer side. The boss 31 is formed with a boss curved surface 31a that extends from the axial direction to the radial direction. A protruding claw 32 and a rib for welding are formed on the upper surface of the blade 27. The protruding claw 32 of the blade 27 is engaged with the through hole 30 of the shroud plate 33, and the concave groove 29 of the shroud plate 33 is engaged with the blade 27, and the claw 32 and the welding rib are joined by welding to form the impeller 1.

[0036] Since the welding rib melts in the concave groove 29, the volume of the welding rib is made smaller than the volume of the gap when the blade 27 is inserted into the concave groove 29. In other words, it is possible to suppress the molten resin material from overflowing into the flow path of the impeller 1. In addition, since the welding rib of the blade 27 melts and is welded to the shroud plate 33, it is possible to prevent leakage flow between the blades 27. In this embodiment, the shroud plate 33 is provided with a through hole 30 to determine the position of the shroud plate 33 and the blade 27, but without being limited to this, a recess shape that does not penetrate may be used, and any shape may be used as long as the claw 32 of the blade 27 is engaged to position the shroud plate 33 and the blade 27. In addition, a convex portion 26a is provided on the outer periphery of the back side of the blade 27 of the hub plate 26, and the balance can be corrected by rotating the impeller 1 and cutting the convex portion 26a. This makes it possible to reduce the amount of imbalance of the impeller 1, thereby reducing vibration and noise. Although FIG. 2 shows a closed type centrifugal impeller provided with a shroud plate 33, it may be an open type centrifugal impeller that does not have a shroud plate 33, or a mixed flow impeller in which the boss curved surface 31a is inclined in the axial direction toward the outer periphery of the impeller, regardless of whether or not it has a shroud plate.

[0037] Next, a blower 201 according to an embodiment of the present invention will be described with reference to Fig. 1 and Figs. 3 to 5. The blower 201 according to the embodiment of the present invention has 15 centrifugal diffuser vanes 23 arranged at equal intervals in the circumferential direction on the outer periphery of the impeller 1, which is a rotor. The blade shape of the centrifugal diffuser vanes 23 is formed from the partition plate 2 toward the fan casing, and is formed integrally with the partition plate 2. shape (FIG. 4) The axial-flow diffuser vane 12 extending from the partition plate 2 in a substantially radial direction is integrally formed with a ring 6. shape For the purpose of explanation, Fig. 4 shows the shape of the axial-flow type diffuser vane 12 with a part of the ring 6 removed. The same number of centrifugal type diffuser vanes 24 as the centrifugal type diffuser vane 23 are installed on the outer periphery of the centrifugal type diffuser vane 23. Fig. 5 is a perspective view of the fan casing 3 as seen from the electric motor side.

[0038] The height direction of the centrifugal diffuser vane 24 is formed from the suction opening 28 side of the fan casing 3 toward the partition plate 2, and is resin molded integrally with the fan casing 3. The radial position of the leading edge 24a of the centrifugal diffuser vane 24 is located on the outer periphery of the outer periphery end 2a of the partition plate 2. In other words, the centrifugal diffuser vane 24 is located radially outward from the outer periphery end 2a of the partition plate 2.

[0039] The trailing edge 24b of the centrifugal diffuser vane 24 is integrated with the inner surface 3a of the fan casing 3, and a fillet (corner R) is provided on the retreating side 24c in the rotational direction of the corner where the trailing edge 24b of the centrifugal diffuser vane 24 and the inner surface 3a of the fan casing come into contact. By providing the fillet on the retreating side 24c, the rotational velocity component of the flow on the trailing edge side of the centrifugal diffuser vane 24 is reduced, the draft angle during molding of the fillet is utilized to promote the axial flow, and the pressure loss of the flow occurring in the curved flow passage 25 is suppressed. In addition, by making the fillet on the retreating side 24c larger, it is possible to prevent sink marks during molding.

[0040] Here, the axial positional relationship of the centrifugal diffuser vanes will be described. The ratio b3 / b2 of the inlet height b3 of the centrifugal diffuser (the axial dimension of the hub plate at the leading edge of the centrifugal diffuser blade and the fan casing 3b on the fan casing side of the partition plate 2) to the flow passage height (outlet height b2) at the outermost diameter of the rotor is set to be approximately 1.0 to 1.2, and the axial position of the hub surface of the centrifugal diffuser and the rotor hub plate are approximately aligned. This reduces the flow at the inlet of the centrifugal diffuser, achieving high efficiency, and reducing the performance variation due to the axial position of the rotor blade, which is likely to occur during mass production. In addition, the ratio D3 / D2 of the centrifugal diffuser inlet diameter D3 to the outermost diameter D2 of the rotor blade is set to approximately 1.1, achieving both high efficiency and low noise. An axial end 24d of the leading edge of the centrifugal diffuser vane 24 is located closer to the suction side than the outer circumferential end 2b constituting the hub surface of the partition plate 2 or at substantially the same axial position, and an axial end 24e of the trailing edge of the centrifugal diffuser vane 24 is located closer to the electric motor than the outer circumferential end 2b constituting the hub surface of the partition plate 2. With this configuration, the flow colliding with the fan casing is guided and efficiently redirected in the axial direction, suppressing pressure loss of the flow occurring at the curved portion of the curved flow passage 25.

[0041] Here, the shape of the centrifugal diffuser vane will be explained. The chord length of the centrifugal diffuser vane 23 (the length from the leading edge 23a to the trailing edge 23b of the diffuser vane 23) is longer than the chord length of the centrifugal diffuser vane 24 (the length from the leading edge 24a to the trailing edge 24b of the centrifugal diffuser vane 24), and the flow turning is large at the diffuser vane 23 close to the impeller. The circumferential positions of the centrifugal diffuser vane 23 and the rear-stage centrifugal diffuser vane 24 are set so that the angle θ between the line connecting the trailing edge 23b of the centrifugal diffuser vane 23 and the center 5a of the rotation shaft and the line connecting the leading edge 24a of the centrifugal diffuser vane 24 and the center 5a of the rotation shaft is about 9% of the circumferential mounting interval of the centrifugal diffuser vanes (the value obtained by dividing 360° by the number of vanes), and the leading edge 24a of the rear-stage centrifugal diffuser vane 24 is positioned in the counter-rotational direction compared to the trailing edge 23b of the centrifugal diffuser vane 23. The chord of the centrifugal diffuser vane 24 is approximately parallel to the chord of the centrifugal diffuser vane 23.

[0042] Moreover, the centrifugal diffuser vane 23 has a vane shape in which the solidity, calculated by dividing the blade chord length C (the length connecting the leading edge 23a to the trailing edge 23b of the centrifugal diffuser vane 23) by the distance along the circumferential direction of the blade attachment interval, is approximately 1. Note that the solidity may be approximately 1 to 1.3, and if the solidity is 1 or more, the throat portion 13 is formed by the adjacent vane, and the throat portion 13 is characterized by being formed on the trailing edge 23b side from the center of the blade chord length of the adjacent vane, enabling high efficiency.

[0043] Also, the maximum thickness ratio obtained by dividing the maximum thickness t of the centrifugal diffuser vane by the diffuser chord length C is between 8 and 25%, and is the same value for the centrifugal diffuser vane 23 and the diffuser vane 24 (excluding the plate thickness of the corner R formed by the diffuser vane trailing edge 24b and the fan casing inner surface 3a). In other words, the maximum blade thickness of the centrifugal diffuser vane 23 close to the impeller is made thicker than that of the centrifugal diffuser vane 24 at the rear stage. This makes it possible to prevent damage to the vane due to repeated stress even when operating under unstable phenomena such as rotating stall that is likely to occur under operating conditions with a lower air volume compared to the design point air volume.

[0044] In addition, the maximum blade thickness is secured to 0.7 mm or more to prevent sink marks during molding and reduce performance variations during mass production. The minimum thickness of the centrifugal type diffuser vane 23 and the centrifugal type diffuser vane 24 is set to 4% or more of the blade chord length to prevent chipping of the resin during molding.

[0045] The centrifugal diffuser vane 23 explained with reference to Figs. 4-5 is formed integrally with the partition plate 2, and the centrifugal diffuser vane 24 is formed integrally with the fan casing, and the centrifugal diffuser vane 23 close to the impeller and the rear diffuser vane 24 are formed in different locations. In addition, by contacting the contact surface 3b of the fan casing 3 and the centrifugal diffuser vane 23 with a sealant or a different soft material (e.g., synthetic rubber), it is possible to suppress leakage flow between the centrifugal diffuser vanes, and high efficiency is possible. In order to suppress leakage flow between the centrifugal diffuser vanes, it is desirable to have a configuration in which the blade tip of the centrifugal diffuser vane 23 contacts or bites into the contact surface 3b of the fan casing 3.

[0046] In addition, the number of the centrifugal diffuser vanes 23 and 24, the number of the projections 20 at the end of the fan casing 3, and the number of the mounting holes 21 for fixing the fan casing 3 to the housing 6 are configured by their greatest common denominators, so that the circumferential positions of the diffuser vanes 23 and 24 are set to predetermined positions, and mass productivity is improved so that no mistake in the circumferential positions occurs during assembly. Note that, although the number of centrifugal diffuser vanes in this embodiment is 15, it may be 13 to 19. Note that, when the number of centrifugal diffuser vanes is large, the blade length and maximum thickness of the centrifugal diffuser vane 23 close to the impeller and the centrifugal diffuser vane 24 at the rear stage may be approximately the same.

[0047] Next, the configuration of the axial-type diffuser vane 12 located downstream of the centrifugal-type diffuser vane 24 will be described. The blade height of the axial-type diffuser vane 12 extends from the hub surface of the partition plate 2 in a substantially radially outward direction, and a plurality of vanes are installed around the rotation axis. The number of vanes of the axial-type diffuser vane 12 is preferably the same as that of the centrifugal-type diffuser vane 24. The axial-type diffuser vane 12 is installed so as to overlap the centrifugal-type diffuser vane 24 of the final stage in the radial direction when viewed from the suction side in the axial direction. The trailing edge of the axial-type diffuser vane 12 (the end 12b on the downstream side of the vane in the axial direction) is installed so as to intersect with the chord length of the centrifugal-type diffuser vane 24 when viewed from the axial direction. In addition, by overlapping the axial-type diffuser vane 12 and the centrifugal-type diffuser vane 24 in the radial direction, the flow passing through the radial outer side (3a side) of the centrifugal-type diffuser vane 24 of the fan casing 3 flows out along the centrifugal-type diffuser vane 24, so that the rotational velocity component on the shroud side of the axial-type diffuser vane 12 can be efficiently reduced, thereby improving efficiency and enabling miniaturization.

[0048] Here, the shape of the axial type diffuser vane 12 will be described. The chord length 12d of the hub side (blade root 2a integral with the partition plate 2) of the axial type diffuser vane 12 is longer than that of the shroud (radial outer side 12c of the vane). That is, the chord length on the hub side is made longer to make the flow turn gently. Also, the circumferential position of the hub side leading edge of the axial type diffuser vane 12 approximately coincides with the leading edge of the centrifugal type diffuser vane 24. By making the circumferential position of the hub side leading edge of the axial type diffuser vane 12 approximately coincident with the leading edge of the centrifugal type diffuser vane 24 and making the flow turn gently on the hub side, separation of the flow on the hub side is suppressed and efficiency is improved.

[0049] The shroud outlet angle βs of the axial diffuser vane 12 is set to be approximately axial, and the hub outlet angle βh is shaped to have a larger outlet angle from the axial direction than the shroud. That is, the axial diffuser vane 12 is twisted in the blade height direction, and the blade chord length is shorter from the hub side to the shroud side. By making the axial diffuser vane 12 twisted in the height direction and orienting the outlet angle on the shroud side to the axial direction, the flow can be turned significantly on the shroud side where it is easy to turn, and the turning can be suppressed on the hub side where the flow is easy to separate, making it possible to achieve high efficiency over a wide operating range. Incidentally, if the outlet angle is aligned with the axial direction, it is possible to reduce the rotational component speed.

[0050] When the turning angle of the axial flow diffuser 12 is small, even if an axial flow diffuser vane similar to the axial flow diffuser 12 is provided downstream of the axial flow diffuser vane 12 and two rows of axial flow diffuser vanes are arranged in the axial direction, the rotational velocity component can be efficiently decelerated, making it possible to achieve high efficiency within a wide operating range.

[0051] In addition, the axial-type diffuser vane 12 has a vane shape in which the solidity, calculated by dividing the chord length C (the length connecting the leading edge 12a to the trailing edge 12b of the axial-type diffuser vane 12 in the shroud) by the distance along the circumferential direction of the vane attachment interval, is approximately 1 or less for both the shroud and the hub, and the solidity of the shroud is small. If the solidity is 1 or less, the vane shape can be molded using a resin mold, and the mold configuration is easy, which reduces costs.

[0052] The maximum thickness ratio, obtained by dividing the maximum thickness t of the axial diffuser vane 12 by the diffuser blade chord length C, is set to between 8 and 25%. The maximum blade thickness is set to 0.7 mm or more to prevent sink marks during molding and reduce performance variations during mass production. The minimum thickness of the axial diffuser vane 12 is set to 4% or more of the blade chord length to prevent chipping of the resin during molding.

[0053] As an example, this embodiment shows a diffuser vane consisting of three rows of centrifugal and axial types, with two rows of centrifugal type diffuser vanes in the radial direction downstream of the impeller and an axial type diffuser vane downstream of them. Each diffuser vane is designed to have a solidity of 1 or less, and a diffuser vane consisting of three rows with a solidity of 1 or less is shown. The solidity may be about 1 to 1.3, and if the solidity is 1 or more, a throat portion is formed by adjacent vanes, making it possible to achieve high efficiency.

[0054] Here, the axial positional relationship of the axial flow type diffuser vanes will be described. The axial position of the leading edge 12a of the axial type diffuser vane 12 on the hub side is set to be equal to or smaller than the clearance S of the bent flow passage axially downstream (shown in Figs. 3 and 4) from the axial position of the outermost diameter 2b of the hub surface having the centrifugal type diffuser vane 23. With this configuration, after the flow is turned by the centrifugal type diffuser vane 24, it can be made to flow into the axial type diffuser vane 12 before the flow separates, and the pressure loss of the flow due to the rotational velocity component can be reduced, thereby enabling high efficiency over a wide operating range.

[0055] The shroud of the axial-flow diffuser vane 12 has an annular ring 6 installed on the trailing edge side of the shroud, with a vane tip 12e protruding from the leading edge side of the shroud. The position of the annular ring 6 on the suction side is approximately aligned with the maximum vane thickness position of the shroud. With this configuration, the inner surface 3a of the fan casing 3 and the maximum thickness position are aligned, ensuring the concentricity of the shaft and improving assembly.

[0056] In addition, the ring 6 is provided with three claw-shaped projections 22 in the circumferential direction, which are fitted and connected to mounting holes 21 in the fan casing 3. The axial-type diffuser vanes 17 present at the positions of the claw-shaped projections 22 have a smaller blade height than the other axial-type diffuser vanes 12, thereby suppressing an increase in the outer diameter of the blower due to the claw structure and achieving a compact blower.

[0057] Here, FIG. 6 shows a comparison of the fan efficiency between the fan of this embodiment equipped with the centrifugal type diffuser vane 23, the centrifugal type diffuser vane 24, and the axial type diffuser vane 12, and a fan (conventional technology) having a curved passage downstream of the impeller as in the conventional technology and having an axial type diffuser vane downstream of the curved passage. In FIG. 6, the horizontal axis shows the dimensionless air volume with the design point air volume set to 1, and the vertical axis shows the fluid analysis results of the fan efficiency. Here, the definition of the fan efficiency in FIG. 6 is the product of the suction volume flow rate and the static pressure rise at the inlet and outlet of the fan divided by the shaft power of the fan. From FIG. 6, it can be seen that the present embodiment, which is a fan equipped with the centrifugal type diffuser vane of this embodiment installed in two rows in the radial direction and the axial type diffuser vane, can improve the fan efficiency in a wide operating range compared to the conventional technology fan. That is, it is understood that high efficiency can be maintained in a wide operating range by arranging two rows of centrifugal diffuser vanes and installing the axial diffuser vane 12 at the rear stage of the centrifugal diffuser. In this embodiment, the centrifugal diffuser vane 24 and the axial diffuser vane 12 are arranged so as to overlap in the radial direction when viewed from the suction side, which also enables miniaturization.

[0058] The electric blower 200 of the present embodiment described above includes an electric motor with a rotor and a stator, a rotating shaft provided on the rotor, a rotor fixed to the rotating shaft, a centrifugal diffuser with a plurality of centrifugal diffuser vanes formed in the radial direction on the outer periphery of the rotor, and a fan casing covering the impeller. In addition, an axial diffuser vane having a blade height formed in the radial direction is provided downstream of the centrifugal diffuser vane. This configuration further reduces the rotational velocity component of the flow flowing out from the centrifugal diffuser vane 24 by the axial diffuser vane 12, suppresses the pressure loss occurring at the exhaust port 18, and contributes to improving the efficiency of the blower, thereby providing a small, lightweight electric blower that is highly efficient over a wide range of air volume. EXAMPLES

[0059] Next, a second embodiment will be described with reference to Fig. 7. Fig. 7 is a perspective view of a diffuser portion of a blower in the second embodiment of the present invention. Since the basic configuration is the same as that of the first embodiment, the same elements are designated by the same reference numerals and their description will be omitted.

[0060] In this embodiment, the centrifugal diffuser vane 23, the axial diffuser vane 12, and the axial diffuser vane 35 located downstream thereof are configured on the partition plate 2. The blade height of the axial diffuser vane 12 extends from the hub surface of the partition plate 2 in a substantially radially outward direction, and a plurality of axial diffuser vanes 12 are installed around the rotation axis. The axial diffuser vane 35 extends in a radially outward direction from a hub 36 having the same flow passage diameter as the hub surface 2a of the axial diffuser vane 12. The hub 36 is fixed to the partition plate 2 by adhesion, welding, or a fitting structure such as the claw-shaped protrusions 22. The number of vanes of the axial diffuser vane 12 and the axial diffuser 35 is preferably the same as that of the centrifugal diffuser vane 23. Although this embodiment has been described using the centrifugal diffuser vane 23 integrated with the partition plate 2, a configuration of the centrifugal diffuser vane 24 integrated with the fan casing 3 shown in FIG. 5 may also be used.

[0061] The flow coming out of the axial flow diffuser 12 can efficiently decelerate the rotational velocity component by the axial flow diffuser vanes 35, suppressing the pressure loss occurring at the exhaust port 18 and enabling high efficiency within a wide operating range.

[0062] The electric blower 200 of the present embodiment described above includes an electric motor having a rotor and a stator, a rotating shaft provided on the rotor, rotors fixed to the rotating shaft, a centrifugal diffuser having centrifugal diffuser vanes on the outer periphery of the rotors, and a fan casing covering the impeller. In addition, downstream of the centrifugal diffuser vanes, multiple rows of axial diffuser vanes having a blade height in the radial direction are provided in the axial direction. This further reduces the rotational velocity component of the flow discharged from the centrifugal diffuser vane 23 or the centrifugal diffuser vane 24 by the axial diffuser vane 12 and the axial diffuser vane 35 downstream of it, thereby suppressing the pressure loss generated at the exhaust port 18 and contributing to improving the efficiency of the blower, thereby providing a small, lightweight electric blower that is highly efficient over a wide range of air volume.

[0063] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to easily explain the present invention, and the present invention is not necessarily limited to those including all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0064] 1 Impeller 2 Partition 2a Outer edge of partition plate 2b Outer edge of the hub surface of the partition plate 3 Fan casing 3a Inner surface of fan casing 3b The surface of the fan casing that the diffuser blades contact 4 Air Inlet 5 Rotation Axis 5a Center of rotation axis 6. Ring 7 Rotor core 8 Stator core 9 Motor housing 10. Bearings 11 Bearings 12 Axial flow type diffuser vane 13 Throat 14 Support part 15 Screw holes 16 Screws 17 Protruding axial diffuser vanes 18 Exhaust port 19 Anti-vibration rubber 20 protrusions 21 Mounting holes 22 Nail process 23 Impeller side diffuser vane 23a Leading edge of diffuser blade on impeller side 23b Trailing edge of diffuser blade on impeller side 23c The surface where the diffuser blade on the impeller side comes into contact with the partition plate 24 Rear diffuser blade 24a Leading edge of rear diffuser vane 24b Trailing edge of rear diffuser vane 24c Fillet at the corner where the rear diffuser blade and the fan casing meet (return side of rotation direction) 24d Axial end of leading edge of rear diffuser vane 24e Axial end of trailing edge of rear stage diffuser vane 25 Bent Channel 26 Hub plate 26a Convex 27 Feather 28 Suction opening 29 Concave groove 30 through holes 31 Boss 31a Boss surface 32 Nails 33 Shroud 34 Bearing housing 35 Axial flow diffuser 36 Hub of axial flow diffuser 100 Vacuum cleaner body 200 electric blower 201 Blower section 202 Electric motor section

Claims

1. the fan casing covers the impeller; centrifugal diffuser vanes arranged on the outer periphery of the impeller, formed from a hub surface of a partition plate toward the fan casing and molded integrally with the partition plate; rear-stage centrifugal diffuser vanes arranged on the outer periphery of the centrifugal diffuser vanes; and axial diffuser vanes molded integrally with the partition plate and forming a blade height in a radial direction from the hub surface of the partition plate, the axial flow type diffuser vane is disposed downstream of the rear stage centrifugal type diffuser vane so as to radially overlap with the rear stage centrifugal type diffuser vane as viewed in the axial direction, the rear-stage centrifugal type diffuser vane is separate from the centrifugal type diffuser vane, is molded integrally with the inner surface of the fan casing, and has a leading edge positioned radially outwardly of the outer circumferential end of the partition plate.

2. 2. The electric blower according to claim 1, further comprising a bent portion between the rear stage centrifugal diffuser vane and the axial flow diffuser vane for redirecting a flow from a radial direction to an axial direction.

3. 3. The electric blower according to claim 1, wherein a chord length of the axial flow type diffuser vanes on a hub side is longer than a chord length of the shroud.

4. 4. The electric blower according to claim 1, wherein a blade tip portion of the axial flow type diffuser blade on a leading edge side of the shroud contacts an inner surface of the fan casing.

5. An electric vacuum cleaner comprising: a vacuum cleaner body that houses an electric blower; and a dust collection chamber that is provided in the vacuum cleaner body and that collects dust sucked in by a suction airflow generated by the electric blower, 5. An electric vacuum cleaner, wherein the electric blower is the electric blower according to claim 1.

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