CN102654140B - Electric air blower and electric dust collector provided with the same - Google Patents

Abstract

The invention provides an electric air blower and an electric dust collector provided with the same. The invention aims at providing an electric air blower and an electric dust collector provided with the same advantageous in that, even under the condition that an electromotor is provided at the downstream of the electric air blower, and the air stream of the air blower is used for cooling the electromotor, high efficiency is provided. The electric air blower is characterized in that, the thickness of each diffusion blade (301) disposed on a diffuser (300) is made in a way that, the inner periphery of each diffusion blade (301) to the outer periphery is from thickening to thinning, making the position (313) of the largest blade thickness be in an adjacent joint with the outlet throat portion (303) of an overlapping portion (304).

Description

Electric blower and electric vacuum cleaner equipped with the same

technical field

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

Background technique

As an electric blower used in an existing electric vacuum cleaner, for example, as shown in Patent Document 1, the electric blower has an electric motor; a centrifugal impeller coaxial with the rotating shaft of the electric motor; between the electric motor and the centrifugal impeller, the centrifugal impeller There are diffuser blades on one side, and a diffuser with return flow drainage blades on the opposite side of the centrifugal impeller; a fan casing with a centrifugal impeller and a diffuser inside; The space between the flow passages of the diffuser blade, and the partition plate separating the diffuser vane side from the return flow guide vane side is formed with a flow channel that becomes a recess, and the recess is cut inward from the outer peripheral end of the diffuser blade along the surface of the outer peripheral side of the diffuser blade. , whose termination coincides with the peripheral end of the adjacent diffuser vane.

In addition, the structure of the conventional diffuser is shown, for example in the following non-patent document 1. The content described in the conventional diffuser shows a diffuser with thick blades, and the overlapping length L of the blades is four times the inlet width (width seen in the air flow plane) a (in this case, the approximate area ratio b/a=1.6 (b is the outlet width of the overlapping outlet of the blades), expansion angle=8.5°).

prior art literature

Patent Document 1: Japanese Patent No. 3758050 (Japanese Patent Application Laid-Open No. 9-119396),

Non-Patent Document 1: Turbo fluid machine and diffuser published by Nikkan Kogyo Shimbun (Published on September 30, Showa 58).

Conventional diffusers are thick-blade diffusers, and if attention is paid to the shape, the maximum thickness of the blades is formed on the outer diameter side of the overlapping portion (range of L). Such a thick vane diffuser can increase the amount of static pressure recovery inside the diffuser when there is an ideal flow path downstream of the diffuser (eg, a vaneless diffuser and a volute housing). However, in the electric blower which is the object of the present invention, the motor is provided downstream of the diffuser, and an air flow is supplied for cooling the motor. Therefore, there is a curved flow path formed by the fan casing, diffuser blades and partitions. In such an electric blower, if the thick blade diffuser described in Non-Patent Document 1 is used, since the maximum thickness of the blade is located on the outer diameter side of the overlapping portion, the area of the curved portion cannot be ensured. The amount, due to the increase in the loss of the bending part, may reduce the performance of the electric blower.

In addition, in Non-Patent Document 1, the blade overlap length L of each blade of the thick-blade diffuser is four times the inlet width (width seen in the air flow plane) a. On the other hand, in the diffuser of the electric blower, the speed of the airflow flowing into the diffuser in the circumferential direction is the dominant airflow, and since the airflow angle is often less than 10°, in order not to cause separation of the airflow at the overlapping part of the diffuser, it is necessary to Make L/a larger than 4.

Contents of the invention

Therefore, it is an object of the present invention to provide an electric blower with high efficiency and an electric vacuum cleaner equipped with the electric blower even when there is a motor downstream of the blower and the air flow of the blower is used for cooling the motor.

The electric blower of the present invention is used to guide the fluid discharged from the impeller that sucks the fluid to the annular diffuser provided on the outer periphery of the impeller, and then deflect the fluid by using the fan case covering the outer periphery of the diffuser to divert the fluid to the The return guide formed on the surface opposite to the surface on which the diffuser is formed guides all or part of the fluid to the motor that rotates the impeller. Each diffuser vane has a cross-section in the direction of the rotation axis of each diffuser vane in a shape that first expands and then narrows from the inner edge toward the outer edge of each diffuser vane.

Alternatively, the present invention is characterized in that the blade thickness of each diffuser blade increases from the inner edge toward the outer edge of each diffuser blade and then becomes thinner, and the position of the maximum blade thickness of each diffuser blade is the same as that of the adjacent diffuser blades in the circumferential direction. The exit portion of the overlapping portion is adjacent. Preferably, the position of the maximum blade thickness of each of the diffuser blades is located on the inner diameter side of the outlet portion of the overlapping portion.

Alternatively, the present invention is characterized in that the blade thickness of each diffuser blade increases from the inner edge toward the outer edge of each diffuser blade and then becomes thinner, and the position of the maximum blade thickness of the diffuser blade is located at the position formed by the fan housing and the concave portion. The position corresponding to the position of the minimum diameter of the circle centered on the center point of the rotation axis of the above-mentioned impeller in the curved flow path of the above-mentioned impeller.

Alternatively, the present invention is characterized in that the vane angle distribution of the pressure surface of the diffuser vane increases from the inlet diameter of the diffuser vane toward a central radius, decreases the vane angle after the central radius, and then increases again to the outlet diameter.

Alternatively, the present invention is characterized in that the flow path angle at the middle point of the throat width of the overlapping portion of the adjacent diffuser blades in the circumferential direction is made substantially constant from the inlet side of the overlapping portion to a position of dimensionless overlapping length 0.2. , increasing from the position of the dimensionless overlap length of 0.2 to the position of the dimensionless overlap length of 0.7, taking the maximum value of the flow channel angle at the position of the dimensionless overlap length of 0.7, and then decreasing until the position of the dimensionless overlap length of 0.9 A small runner angle, thereafter decreases the variation of the inclination of the runner angle towards the overlap outlet.

Alternatively, the present invention is characterized in that the ratio of the maximum blade thickness of the diffuser blade to the blade thickness at the leading edge portion of the diffuser blade is about 4.

The effects of the present invention are as follows.

According to the present invention, by suppressing the detachment of the airflow generated by the overlapping portion of the diffuser, since the outlet velocity of the diffuser can be reduced and the static pressure recovery amount of the diffuser can be increased, performance can be improved, and the airflow supplied to the motor can be sufficiently Ensuring the area of the curved flow path composed of the fan case, diffuser blades, and partitions enables high efficiency of the blower due to the reduction of the diffuser outlet velocity and securing the area of the curved flow path is associated with a low loss rate at the bend.

In addition, according to the present invention, by suppressing the detachment of the airflow generated by the overlapped part of the diffuser, since the outlet velocity of the diffuser can be reduced and the static pressure recovery amount of the diffuser can be increased, performance can be improved. Sufficiently ensure the area of the curved flow path formed by the fan casing, diffuser blades, and partitions, and reduce the outlet velocity of the diffuser and ensure the area of the curved flow path is associated with a low loss rate of the curved portion, thus providing a low energy loss. A high-efficiency electric blower and an electric vacuum cleaner equipped with the electric blower.

Description of drawings

Fig. 1 is a schematic cross-sectional view of a vacuum cleaner main body.

Fig. 2 is a sectional view of an electric blower for a vacuum cleaner.

Fig. 3 is a shape diagram of the diffuser of the first embodiment.

Fig. 4 is a diagram showing the positional relationship between the maximum thickness of the diffuser vane and the minimum diameter of the separator.

FIG. 5 is a diagram showing definitions of blade thicknesses and blade angles on the blade surface for each radius of the diffuser blade.

FIG. 6 is a diagram showing blade thickness distributions of diffuser blades at respective radii.

Fig. 7 is a diagram showing the angular distribution of the blade pressure surface and the negative pressure surface at each radius of the diffuser blade.

8 is a diagram showing the definition of the flow path angle formed by the center point of the throat width of the flow path in the overlapping portion of the diffuser vanes.

Fig. 9 is a diagram showing flow path angle distribution of overlapping portions of diffuser blades

In the picture:

100-Electric vacuum cleaner main body, 101-Hose connector, 102-Dust collection chamber, 103-Paper bag, 104-Filter part, 105-Motor room, 106-Electric blower, 107-Anti-vibration rubber, 108-Blower inlet, 109 -Blower outlet, 110-cord reel, 111-wheel, 201-blower, 202-electric motor, 203-housing, 204-end frame, 205-rotary shaft, 206-rotor, 207-stator, 208-brush, 209-commutator, 210-impeller, 211, 300, 400, 500, 800-diffuser, 212, 408-baffle, 213-reflux guide, 214, 406-fan casing, 215-bearing part, 216-seal Parts, 217-electric blower inlet, 301, 401, 501, 801-diffusion blade, 302-inlet throat, 303-exit throat, 304-overlapping part, 305, 511, 803-negative pressure surface, 306, 510, 802-pressure surface, 307-overlap length, 308, 403-curved flow channel, 309-diffuser inlet diameter, 310-diffuser outlet diameter, 311-flow from the impeller, 312-curved flow channel airflow, 313, 405, 601-maximum blade thickness position, 402-minimum diameter position of curved flow channel, 404-minimum diameter of curved flow channel, 407, 507, 808-rotation axis center point, 502-blade thickness, 503-blade surface Point, 504-(connecting the center point of the rotation axis and the point on the blade surface) straight line, 505, 807-orthogonal line, 506-blade surface, 508-tangent line, 509-blade angle, 600-blade thickness distribution, 602-minimum Blade thickness, 700-blade angle distribution, 701-inflection point of blade angle distribution on the pressure surface, 805-flow path angle, 806-(connecting the center point of the rotating shaft and the center point of the throat) straight line, 809-the total length of the overlapping part , 900-runner angle distribution, 901-maximum angle.

Detailed ways

Hereinafter, one embodiment of the present invention will be described using the drawings.

First, the overall structure of the electric vacuum cleaner will be described using FIG. 1 . The configuration of the vacuum cleaner main body 100 will be described in a cross-sectional view viewed from above the vacuum cleaner main body 100 schematically shown in FIG. 1 . If the side of the vacuum cleaner body 100 on which the hose connector 101 is mounted is defined as the front side of the vacuum cleaner body 100 , the front end of the vacuum cleaner body 100 has a detachable hose connector 101 .

On the front side of the electric vacuum cleaner main body 100, there is a dust collection chamber 102 for holding the paper bag 103; There is a filter part 104 for suppressing the dust in the dust collecting chamber 102 from flowing into the motor chamber 105 between them. The dust collection chamber 102 communicates with the motor chamber 105 via the filter unit 104 . A detachable paper bag 103 is provided on the dust collecting chamber 102 . The opening of the paper bag 103 communicates with the hose connector 101 . When dust accumulates in the paper bag 103 , the paper bag 103 expands so that the bottom of the paper bag 103 abuts against the filter unit 104 on the side opposite to the opening of the paper bag 103 . An electric blower 106 that generates suction is provided in the motor room 105 . Anti-vibration rubber 107 (vibration-proof member) for preventing the vibration of the electric blower 106 from being transmitted to the vacuum cleaner body 100 is provided between the front ends of the electric blower 106 and the front inner wall of the motor chamber 105 . The anti-vibration member may be a spring instead of rubber. The electric blower 106 has a blower inlet 108 for sucking in air at the front end and a blower outlet 109 for discharging air on the rear side. Furthermore, the blower inlet 108 is open to the filter unit 104 . A cord reel 110 for winding and accommodating a power supply cord is provided on a side surface of the motor chamber 105 . Wheels are provided on both rear sides of the electric blower 106 . In addition, although not shown, a hose is connected to the hose joint 101, an operation pipe is connected to the hose, an extension pipe is connected to the operation pipe, and a suction tool is connected to the extension pipe. The side (upstream side) where the hose joint 101 exists is the front side of the vacuum cleaner main body 100 , and the opposite side is the rear side of the vacuum cleaner main body 100 . When the vacuum cleaner main body 100 is viewed from above, the direction perpendicular to the front-back direction of the vacuum cleaner main body 100 is the left-right direction of the vacuum cleaner main body 100 . A side surface means a left side or a right side with respect to the center of the vacuum cleaner main body 100 in the left-right direction.

Next, the air flow in the vacuum cleaner main body 100 will be described. The air flowing in from the hose joint 101 enters the dust collecting chamber 102 . Although the paper bag 103 is shown as a dust collector in FIG. 1, the material of a bag is not mentioned. In addition, in the case of the cyclone method, a cyclone chamber (cyclone dust collecting box) is used instead of the paper bag 103 for collection. The air from which most of the dust is removed by the paper bag 103 passes through the filter unit 104 to remove fine dust. Thereafter, the air flow flows into the motor chamber 105 . The electric blower 106 is suspended in the motor chamber 105 via anti-vibration rubber 107, and the air flowing in from the blower inlet 108 is discharged from the blower outlet 109 after the pressure rises.

Next, electric blower 106 will be described using FIG. 2 . The electric blower 106 is composed of a blower 201 for sucking air and a motor 202 for driving the blower 201 .

The rotating shaft 205 of the electric motor 202 is supported by the motor case which consists of the housing|casing 203 and the end frame 204, and the rotor 206 is attached to the rotating shaft 205. A stator 207 of a fixed portion is disposed on the outer periphery of the rotor 206 . The electric power supplied to the rotor 206 of the rotating part is transmitted through a brush 208 and a commutator 209 in contact therewith.

The blower 201 has a structure in which the following components are accommodated in the fan casing 214, and these components include: a centrifugal impeller 210 directly connected to the rotating shaft 205; an annular diffuser 211 arranged on the outer peripheral side of the impeller 210; The separator 212 is disposed on the return flow guide 213 opposite to the diffuser 211 . The impeller 210 is substantially in contact with the seal 216 provided on the fan casing 214 side at the bearing portion 215 , and has a leak-proof structure. The rotation shaft 205 is rotated by the drive of the motor 202, and the impeller 210 is rotated. The diffuser 211 is preferably a diffuser made of resin. The diffuser 211 can be made integral with the partition 212 by injection molding. The impeller 210 has a substantially disk-shaped hub, an annular shroud, and a plurality of blades arranged in the circumferential direction formed between the hub and the shroud.

The air that has passed through the electric blower inlet 217 corresponding to the blower inlet 108 in FIG. 1 passes through the vicinity of the bearing portion 215 once, and then is pressurized and accelerated by the impeller 210 . Then, the airflow passing through the diffuser 211 hits the inner surface of the fan casing 214 and turns roughly 180° to flow into the return flow guide 213 . However, the airflow decelerates during this process and the pressure rises accordingly. All or part of the airflow passing through the return flow guide 213 flows into the housing 203 of the motor, and is discharged after cooling the rotor 206, the stator 207, the brushes 208, the commutator 209, and the like. The axial direction of the rotating shaft 205 is substantially coincident with the front-back direction of the electric vacuum cleaner main body 100 . With the rotating shaft 205 as a reference, the direction perpendicular to the axial direction is the radial direction. The side where the blower 201 exists is the front side of the electric blower 106 , and the side where the motor 202 exists is the rear side of the electric blower 106 .

As the object of the present invention, the impeller outer diameter of the electric blower for vacuum cleaner is approximately in the range of ф60mm～ф120mm, the height of the blade outlet is approximately in the range of 6～12mm, and the thickness of the blade is approximately in the range of 0.5～1.5mm. The number of pieces is about 6-9 pieces, the input power is about 500W-1500W, and the maximum number of revolutions is about 35000-50000 revolutions per minute.

Next, the shape of the diffuser 300 will be described using FIG. 3 . FIG. 3 is a front view of the diffuser 300 viewed from the axial front side. In the diffuser 300 of FIG. 3 , a plurality of diffuser blades 301 having different blade thicknesses from the diffuser inlet diameter 309 to the diffuser outlet diameter 310 are arranged at equal intervals in the circumferential direction. That is to say, when viewed from the axial direction, the diffuser blade 301 has a blade thickness gradually increasing and then gradually decreasing from the leading edge on the inner peripheral side to the trailing edge on the outer peripheral side (thickening first and then thinning). )shape. The dimensions of the diffuser 300 shown here are as an example: the diameter of the diffuser inlet 309 is about 91 mm, the diameter of the diffuser outlet 310 is about 125 mm, and the number of blades is about 13. The arrangement interval of the diffuser blades 301 is approximately 360°/13=27.7°. The diffuser 300 is formed by a pressure surface 306 on the convex side of the diffuser vane 301 and a negative pressure surface 305 on the concave side of the adjacent diffuser vane 301, and has an inlet throat 302 defined by the front edge of the diffuser vane 301 and The overlapping portion 304 surrounded by the outlet throat 303 is defined by the trailing edge portions of adjacent diffuser blades 301 . In the overlapping portion 304 , part of the pressure surface 306 of the diffuser blade 301 (except the rear edge) is substantially opposed to a part of the negative pressure surface 305 of the adjacent diffuser 301 (except the front edge). In addition, the airflow inside the diffuser is such that the airflow 311 flowing out from the impeller passes through the half-opened part and the overlapping part 304 of the inlet throat 302 to decelerate the airflow, and passes through the gap formed by the fan case 214 and the partition plate 212 at the diffuser outlet. The curved flow path 308 bends the airflow 312 toward the curved flow path in the depth direction of the paper of FIG. In addition, the height of the diffuser vanes 301 may be substantially uniform from the leading edge to the trailing edge, or may increase from the leading edge to the trailing edge.

In this diffuser 300 , the maximum blade thickness position 313 of the diffuser blade 301 is adjacent to the outlet throat portion 303 of the overlapping portion 304 . That is, in order to secure the area of the curved flow path 308 at the diffuser outlet, the maximum blade thickness position 313 of the diffuser vane 301 is not located on the radially outer side of the outlet of the overlapping portion 304 of the diffuser 300 , but adjacent to it. In addition, the total area of the diffuser 300 viewed from the axial direction is about 2000 mm ² , and the ratio of the throat outlet area formed by the width b and the outlet height h of the outlet throat 303 of the diffuser 300 is about three times, Reduced loss in the curved flow path 308 is achieved. In addition, the maximum blade thickness position 313 of the diffuser blade 301 may be on the inner diameter side of the outlet throat 303 . In addition, the ratio (L/a) of the overlapping length 307L of the width a of the inlet throat 302 to the width b of the outlet throat 303 to the width a of the inlet throat 302 (L/a) is about 12, and the width a of the inlet throat 302 is equal to the width a of the outlet throat 303. The ratio b/a of the width b of the throat 303 is about 2.1. As shown in FIG. 3 , the negative pressure surface 305 of the diffuser blade 301 is gently curved from the leading edge to the trailing edge regardless of the maximum blade thickness position 313 , while the pressure surface 306 is curved from the leading edge to the maximum blade thickness position 313 at a ratio The surface 305 is gently curved with a larger curvature, with a small curvature at the maximum blade thickness position 313 , and gently curved with a larger curvature than the negative pressure surface 305 from the maximum blade thickness position 313 to the trailing edge. That is, the pressure face 306 turns sharply at the maximum blade thickness location 313 .

In addition, for the purpose of reducing blade passing frequency noise, square holes connecting adjacent blades may be provided so as to approximately coincide with the maximum blade thickness position 313 . As a result, improved performance and reduced blade pass frequency noise can be achieved. That is to say, a square hole penetrating from the negative pressure surface 305 to the pressure surface 306 of the diffuser blade 301 may be provided near the maximum blade thickness position 313 of the diffuser blade 301 . Round holes can also be used instead of square holes, but the square or round holes are not necessary.

Compared with the conventional diffuser 300 , in this embodiment, the maximum blade thickness position 313 of the diffuser blade 301 is made adjacent to the outlet throat portion 303 of the overlapping portion 304 . Thus, by suppressing the separation of the airflow generated by the overlapping portion 304, the outlet velocity of the diffuser can be reduced, the static pressure recovery amount of the diffuser 300 can be increased, and the airflow provided by the fan case 214 can be sufficiently ensured for supplying the airflow to the motor 202. 1. The area of the curved flow path 308 formed by the diffuser blades 301 and the partition plate 212, because reducing the outlet velocity of the diffuser and ensuring the area of the curved flow path 308 is related to the low loss of the curved portion, so the performance of the overlapping portion 304 can be improved at the same time It is possible to increase the efficiency of the blower 201 both by reducing the loss of the bent portion.

Next, the shape of the diffuser blade 401 will be described using FIG. 4 . Fig. 4 is an enlarged view of the diffuser 400, which is a front view viewed from the axial front side. FIG. 4 shows that the blade thickness of the diffuser blade 401 is centered on the maximum blade thickness position 405 . The maximum blade thickness position 405 in Fig. 4 is in the shape of the curved flow passage 403 (the oblique line part in Fig. 4 ) constituted by the fan casing 406 and the partition plate 408, and the center point 407 of the rotating shaft of the rotating shaft 205 is a circle (Dotted line in FIG. 4 ) The minimum diameter position 402 of the curved channel in the center is consistent. In addition, reference numeral 404 denotes the minimum diameter of the curved flow path. The partition plate 408 has a concave portion cut into the inner peripheral side of the partition plate 408 from the rear edge of the diffuser blade 401 along the convex surface of the rear edge portion of the diffuser blade 401 . The concave portion is an opening provided at the outer peripheral end portion of the partition plate 408 . The shape of the recess is approximately triangular. Such recesses are formed between adjacent diffuser blades 401 at the outer peripheral end of the annular partition 408 , and as a result, the outer periphery of the annular partition 408 is formed in a concave-convex shape. The curved flow channel 403 is formed between the concave portion of the partition plate 408 and the inner peripheral surface of the fan housing 406 , and the cross section of the curved flow channel 403 is roughly rhombus or triangle.

Next, the blade thickness 502 of the diffuser blade 501 and the blade angle 509 on the blade surface will be described using an example using FIGS. 5 to 7 . FIG. 5 is a diagram illustrating the definition of the blade thickness 502 of the diffuser blade 501 and the blade angle 509 on the blade surface of the diffuser blade. As far as the blade angle 509 is concerned, draw a straight line 504 connecting a point 503 on the blade face (in the figure, the pressure face 510) and the center point 507 of the axis of rotation, and draw an orthogonal line 505 relative to the straight line 504, which will be determined by The blade angle 509 formed by the orthogonal line 505 and the tangent 508 of the blade surface 506 on the outside is taken as blade angle "β". In addition, the definition of the vane angle of the negative pressure surface 511 is also the same.

FIG. 6 is a graph showing the blade thickness distribution using the blade thickness 502 defined in FIG. 5 and the radius connecting the center point of the circle defining the blade thickness 502 and the rotation axis center point 507 . The blade thickness profile of the present diffuser blade 501 has a minimum blade thickness 602 at the inlet diameter and increases toward the outlet diameter, and has a maximum blade thickness 601 near the approximate center and decreases blade thickness toward the diffuser outlet diameter. Here, the leading edge blade thickness as blade thickness 502 at the inlet diameter is 0.6 mm, the ratio to the maximum blade thickness being about 4.

7 shows the blade angle distribution of the diffuser blade 501 using the blade angle 509 of the pressure surface 510 and the negative pressure surface 511 defined in FIG. The vane angle on the negative pressure surface 511 monotonously increases from the inlet diameter toward the outlet diameter, is constant at the inner diameter side of the outlet diameter, and then the vane angle 509 decreases sharply toward the outlet diameter. The angle until the outlet diameter decreases sharply makes the main airflow of the diffuser 500 deflect to the side of the negative pressure surface 511 of the blade. In order to reduce the collision angle between the airflow and the fan casing at the outlet of the diffuser, the airflow is turned sharply. In addition, the point where the vane angle 509 changes sharply on the negative pressure surface 511 is about 97% of the outlet diameter. On the other hand, although the vane angle distribution of the pressure surface 510 increases and decreases from the angle of the inlet diameter, they all increase toward the center of the inlet diameter and the outlet diameter. Then, the vane angle 509 is sharply decreased after the central radius, and then increased again until the exit diameter. In addition, the radius of the inflection point 701 where the vane angle 509 of the pressure surface is sharply reduced and then increased again is about 1.2 times the diffuser inlet radius.

Compared with the existing diffuser, this embodiment makes the vane angle distribution of the pressure surface into the following shape: from the inlet diameter to the central radius increases, after the central radius, the vane angle decreases sharply, and then increases again until the exit diameter. Thus, by suppressing the separation of the airflow generated by the overlapping part of the diffuser, the outlet speed of the diffuser can be reduced, and the static pressure recovery amount of the diffuser can be increased, and it is also possible to ensure sufficient air flow from the fan case, the diffuser, and the airflow supply to the motor. The area of the curved flow path constituted by the blades and partitions can improve both the performance of the overlapping portion of the diffuser and the low cost of the curved portion by reducing the outlet velocity of the diffuser and securing the area of the curved flow path and reducing the loss of the curved portion. By reducing both of these losses, it is possible to increase the efficiency of the blower.

Next, the channel angle 805 at the channel center of the overlapping portion will be described with reference to FIGS. 8 and 9 . 8 is a diagram defining the angular distribution of the flow path at the midpoint 804 of the throat width formed by the pressure surface 802 of the diffuser vane 801 and the negative pressure surface 803 of the adjacent diffuser vane 801 using the diffuser 800 . The midpoint 804 is the center of a circle inscribed on the throat formed by the pressure surface 802 of the diffuser vane 801 and the negative pressure surface 803 of the adjacent diffuser vane 801 . Regarding the flow path angle 805, draw a straight line 806 connecting the midpoint 804 of the throat width formed by the pressure surface 802 of the diffuser vane 801 and the negative pressure surface 803 of the adjacent diffuser vane 801 and the center point 808 of the rotation axis The angle formed by the orthogonal line 807 and the straight line connecting the runners is defined as the runner angle 805 . FIG. 9 shows the distribution of the dimensionless overlapping length obtained by converting the position of each overlapping portion to the total length 809 of the overlapping portion, and the flow path angle 805 formed by the center point of the throat width. In this diffuser 800, the flow path angle 805 from the inlet side of the overlapping portion to the dimensionless overlapping length 0.2 is made approximately constant, and is increased from the dimensionless overlapping length 0.2 to 0.7. Then, when the dimensionless overlap length is 0.7, it is the maximum angle 901, and then until the dimensionless overlap length is 0.9, the channel angle 805 decreases sharply, and then the inclination of the channel angle 805 decreases at the outlet of the overlapping portion.

Compared with the existing diffuser, this embodiment makes the flow path angle at the middle point of the throat width of the overlapping part roughly constant from the inlet side of the overlapping part to the dimensionless overlapping length of 0.2, so that it can be changed from dimensionless overlapping The length increases from 0.2 to 0.7, and the maximum value of the flow path angle is taken at the dimensionless overlap length of 0.7, and then the flow path angle decreases sharply until the dimensionless overlap length of 0.9, and then decreases toward the exit of the overlap portion. slope. Thus, by suppressing the separation of the airflow generated by the overlapping part of the diffuser, the outlet speed of the diffuser can be reduced, and the static pressure recovery amount of the diffuser can be increased, and it is also possible to ensure sufficient air flow from the fan case, the diffuser, and the airflow supply to the motor. The area of the curved flow path constituted by the blades and partitions can improve both the performance of the overlapping portion of the diffuser and the low cost of the curved portion by reducing the outlet velocity of the diffuser and securing the area of the curved flow path and reducing the loss of the curved portion. By reducing both of these losses, it is possible to increase the efficiency of the blower.

Claims (8)

1. An electric blower for guiding fluid discharged from an impeller sucking in fluid to an annular diffuser provided on the outer periphery of the impeller, and then diverting the fluid with a fan casing covering the outer periphery of the diffuser so that Guide the fluid to a return guide formed on the surface opposite to the surface on which the diffuser is formed, thereby guiding all or part of the fluid to a motor that rotates the impeller, characterized in that, The diffuser has a plurality of diffuser blades arranged in the circumferential direction, The negative pressure surface of each of the diffusion blades is gently curved from the inner edge to the outer edge of each diffusion blade; The curvature of the larger surface is gently curved, and at the position of the maximum blade thickness, it is curved with a curvature smaller than the curvature of the negative pressure surface, and from the position of the maximum blade thickness to the outer edge is less than the negative pressure. The greater the curvature of the surface, the more gently curved it is. 2. An electric blower installed in an electric vacuum cleaner, characterized in that, It includes: an electric motor, an impeller connected to the electric motor, a diffuser disposed on the outer periphery of the impeller, a return flow guide formed on the surface opposite to the diffuser, and the impeller, the diffuser, and the return flow guide inside. guide for the fan housing, The diffuser has a plurality of diffuser blades arranged in the circumferential direction, The negative pressure surface of each of the diffusion blades is gently curved from the inner edge to the outer edge of each diffusion blade; The curvature of the larger surface is gently curved, and at the position of the maximum blade thickness, it is curved with a curvature smaller than the curvature of the negative pressure surface, and from the position of the maximum blade thickness to the outer edge is less than the negative pressure. The greater curvature of the surface curves gently, The maximum blade thickness position of each of the diffuser blades is adjacent to the exit portion of the overlapping portion of the diffuser blades adjacent in the circumferential direction. 3. The electric blower according to claim 2, characterized in that, The maximum blade thickness position of the diffuser blade is located on the inner diameter side of the outlet portion of the overlapping portion. 4. An electric blower installed in an electric vacuum cleaner, characterized in that, It includes: a motor, an impeller connected to the motor, a diffuser disposed on the outer periphery of the impeller, a return guide formed on a surface opposite to the diffuser, and a partition separating the diffuser and the return guide. , and a fan housing with the above-mentioned impeller, the above-mentioned diffuser and the above-mentioned return guide inside, The diffuser has a plurality of curved diffuser blades arranged in the circumferential direction, The partition plate has a concave portion cut into the inner peripheral side of the partition plate from the outer edge of the diffuser blade along the convex surface of the diffuser blade, The negative pressure surface of each of the diffusion blades is gently curved from the inner edge to the outer edge of each diffusion blade; The curvature of the larger surface is gently curved, and at the position of the maximum blade thickness, it is curved with a curvature smaller than the curvature of the negative pressure surface, and from the position of the maximum blade thickness to the outer edge is less than the negative pressure. The greater curvature of the surface curves gently, The position of the maximum blade thickness of the diffuser blade is located in the curved flow path formed by the fan casing and the concave portion, and is made to coincide with the minimum diameter of the curved flow path centered on the center point of the rotation axis of the impeller. 5. An electric blower installed in an electric vacuum cleaner, characterized in that, It comprises: an electric motor, an impeller connected to the electric motor, a diffuser disposed on the outer periphery of the impeller, a return flow guide formed on the surface opposite to the diffuser, and the impeller, the diffuser, and the return flow guide inside. guide for the fan housing, The diffuser has a plurality of diffuser blades arranged in the circumferential direction, The vane angle distribution of the pressure surface of the diffuser vane increases from the inlet diameter of the diffuser vane toward the central radius, the vane angle decreases after the central radius, and then increases again up to the outlet diameter. 6. An electric blower installed in an electric vacuum cleaner, characterized in that, It comprises: an electric motor, an impeller connected to the electric motor, a diffuser disposed on the outer periphery of the impeller, a return flow guide formed on the surface opposite to the diffuser, and the impeller, the diffuser, and the return flow guide inside. guide for the fan housing, The diffuser has a plurality of diffuser blades arranged in the circumferential direction, The flow path angle at the midpoint of the throat width of the overlapping portion of the adjacent diffuser blades in the circumferential direction is made approximately constant from the inlet side of the overlapping portion to a position of 0.2 of the dimensionless overlapping length. Increase from the position of 0.2 to the position of the dimensionless overlap length of 0.7, take the maximum value of the flow channel angle at the position of the above-mentioned dimensionless overlap length of 0.7, and then reduce the flow channel angle until the position of the dimensionless overlap length of 0.9, and then The change in inclination of the flow path angle decreases toward the overlapping portion outlet. 7. The electric blower according to any one of claims 1 to 6, characterized in that: The ratio of the maximum blade thickness of the diffuser blade to the blade thickness at the leading edge portion of the diffuser blade is about 4. 8. An electric vacuum cleaner, characterized in that, Equipped with the electric blower described in any one of claims 1-7.