CN112814944A - Air supply device and dust collector - Google Patents

Abstract

The invention provides an air supply device and a dust collector. The casing has a spiral flow path at least a part of which is disposed between an inner surface of the casing and a radial direction of the impeller and connected to the exhaust portion. The housing has a tongue portion disposed at a start end portion of the flow path. The axial length of the flow path increases at a first average increase rate from a position at which the center angle is a first angle to a position at which the center angle is a second angle, and at a second average increase rate from the position at which the center angle is a third angle, in the direction in which the gas flow flows, with a line connecting the tongue portion and the center axis as a starting point. The first average rate of increase is greater than the second average rate of increase.

Description

Air supply device and dust collector

Technical Field

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

Background

A conventional centrifugal blower includes a casing having an air inlet, a fan rotatably housed in the casing, and a drive source for rotating the fan. In this centrifugal blower, a part of the discharge passage is provided radially inward of the outer peripheral end of the fan, and the discharge passage is formed such that the volume of the first passage portion on the air intake side is reduced with respect to the volume of the second passage portion on the opposite side of the air intake with respect to the reference, with respect to one end portion in the axial direction of the fan on the opposite side of the air intake as the reference (see japanese patent application laid-open No. 2016-17510).

Documents of the prior art

Patent document 1: japanese patent laid-open publication No. 2016-17510

However, in the centrifugal blower described above, it is difficult to reduce the axial size, and if the centrifugal blower is reduced in axial size, the blowing efficiency may be reduced.

Disclosure of Invention

The invention aims to provide a small air supply device with high air supply efficiency.

An exemplary air blower of the present invention includes an impeller rotatable around a central axis extending in a vertical direction, a motor disposed below an axial direction of the impeller and rotating the impeller, and a casing housing the impeller, the casing including an air intake portion disposed above the impeller in the axial direction, an air discharge portion disposed radially outward of the impeller, and a spiral flow path at least a part of which is disposed between an inner surface of the casing and a radial direction of the impeller and connected to the air discharge portion, the casing including a tongue portion disposed at a leading end portion of the flow path, a length of the flow path in the axial direction increasing at a first average increase rate from a position where a central angle is a first angle to a position where a second angle larger than the first angle is a first average increase rate toward a direction in which an air flow flows from a line connecting the tongue portion and the central axis, and a length of the flow path increasing at a second average increase rate from the position where the second angle is a third angle larger than the second angle Additionally, the first average rate of increase is greater than the second average rate of increase.

The effects of the present invention are as follows.

According to the exemplary air blowing device of the present invention, miniaturization can be achieved and high air blowing efficiency can be achieved.

Drawings

Fig. 1 is a perspective view of a self-propelled cleaner according to the present embodiment.

Fig. 2 is a perspective view of the air blowing device.

Fig. 3 is a longitudinal sectional view of an imaginary plane III-III of the air blowing device shown in fig. 2.

Fig. 4 is a plan view of the air blower shown in fig. 2 with a cover member removed.

Fig. 5 is a sectional view in the imaginary plane V-V in fig. 4.

Fig. 6 is a diagram showing the result of the first simulation.

Fig. 7 is a graph showing the result of the second simulation.

Fig. 8 is an enlarged view showing another example of the method of determining the starting point.

In the figure: 10-motor, 11-shaft, 20-impeller, 21-base plate, 22-rotor blade, 23-shroud, 30-housing, 31-base member, 32-shroud member, 33-flat plate portion, 34-motor holding portion, 35-side wall portion, 36-suction portion, 37-discharge portion, 38-flow path, 100-self-propelled cleaner, 102-cabinet, 103-suction port, 104-discharge port, 105-air flow path, 106-driving wheel, 107-driven wheel, 111-fixed member, 210-upper surface, 211-impeller hub, 212-collar portion, 231-suction port, 331-collar portion, 332-flat plate through hole, 361-tapered bottom, 362-inflow pipe portion, 380-start end portion, 381-flow path upper surface, 382-flow path bottom surface, 383-exhaust flow path, 384-tongue portion, a-blower, Av 1-first average increase rate, Av 2-second average increase rate, Cx-center shaft, F-floor surface, l1-first elevation difference, L2-second elevation difference, L3-third elevation difference, P1-first position, P2-second position, P3-third position, PS-origin, Rs 1-first ratio, Rs 2-second ratio, θ 1-first angle, θ 2-second angle, θ 3-third angle.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification, in the air blowing device a, a direction parallel to the central axis Cx of the air blowing device a is referred to as an "axial direction", a direction orthogonal to the central axis Cx of the air blowing device a is referred to as a "radial direction", and a direction along an arc centered on the central axis Cx of the air blowing device a is referred to as a "circumferential direction", respectively.

In the present specification, the shape and positional relationship of the respective portions will be described with the axial direction as the vertical direction and the suction portion 36 side of the cover member 32 of the housing 30 as the upper side in the blower a. The vertical direction is simply a name used for explanation, and does not limit the positional relationship and direction in the use state of the air blowing device a. "upstream" and "downstream" respectively indicate upstream and downstream in the flow direction of the air generated in the flow path 38 when the impeller 20 is rotated. In the air blower a of the present specification, the air flow flows in the flow path 38 in a counterclockwise direction in a plan view.

In the blower a, the impeller 20 rotates in the circumferential direction about the central axis Cx. In the present specification, in the rotation direction of the impeller 20, the front side of the rotation is referred to as "front side in the rotation direction", and the front side of the rotation is referred to as "rear side in the rotation direction". In other words, with a certain point on the impeller 20 as a reference, the side that reaches after a predetermined time has elapsed from that point is taken as the front side in the rotation direction, and the side that has passed through is taken as the rear side in the rotation direction.

In the present specification, the shape and positional relationship of the respective parts will be described with reference to the direction toward the floor surface F (surface to be cleaned) in fig. 1 as "lower" and the direction away from the floor surface F as "upper" in the self-propelled cleaner 100. These directions are names used for the sake of explanation, and do not limit the positional relationship and the directions of the self-propelled cleaner 100 in the use state. "upstream" and "downstream" respectively indicate upstream and downstream in the flow direction of the air sucked through the air inlet 103 when the blower a is driven.

< 1. integral Structure of self-propelled cleaner 100

The self-propelled cleaner 100 according to the exemplary embodiment of the present invention will be described. Fig. 1 is a perspective view of a self-propelled cleaner according to the present embodiment. The self-propelled cleaner 100 is a so-called robot-type electric cleaner. The self-propelled cleaner 100 has a housing 102 with a suction port 103 opened at the bottom and an exhaust port 104 opened at the side.

An air passage 105 connecting the intake port 103 and the exhaust port 104 is formed in the casing 102. A dust collecting unit (not shown), a filter (not shown), and an air blower a are disposed in the air passage 105 in this order from the upstream side to the downstream side. The dust such as dust contained in the air flowing through the air passage is cut by the filter and collected in the dust collecting part formed in a container shape. The dust collecting unit and the filter are configured to be detachable from the housing 102.

The lower part of the cabinet 102 has a pair of drive wheels 106 and 1 driven wheel 107. The pair of driving wheels 106 are rotated by a driving unit, not shown, having a motor or the like. Thereby, the self-propelled cleaner 100 travels on the floor surface F. The self-propelled cleaner 100 can change the traveling direction by controlling the driven wheels 107, or can change the traveling direction by adjusting the rotation speed and rotation direction of the driving wheels 106.

As described above, the self-propelled cleaner 100 includes the blower a. This makes it possible to realize a self-propelled cleaner 100 having a blower device a with high blowing efficiency. The vacuum cleaner provided with the blower device a is a self-propelled vacuum cleaner 100, but the present invention is not limited thereto, and may be a so-called canister type or portable type electric vacuum cleaner.

< 2. integral Structure of air supply device

Fig. 2 is a perspective view of the blower a. Fig. 3 is a longitudinal sectional view of an imaginary plane III-III of the air blowing device a shown in fig. 2. As shown in fig. 2 and 3, the blower a includes a motor 10, an impeller 20, and a casing 30.

< 3. electric machine 10 >

As shown in fig. 3, the motor 10 is disposed within a housing 30. The motor 10 is disposed axially below the impeller 20 and rotates the impeller 20. The motor 10 includes a shaft 11, a rotor not shown, and a stator not shown. The motor 10 may be an inner rotor type motor in which a rotor is disposed radially inside a stator, or an outer rotor type motor in which a rotor is disposed radially outside a stator.

The rotor includes a magnet, not shown, fixed to the shaft 11. The stator is radially opposed to the rotor. The stator has a coil, not shown. When a current is supplied to the coil, the coil is excited to generate an attractive force and a repulsive force with the coil. The shaft 11 rotates around the central axis Cx when the rotor rotates by the attractive force and the repulsive force.

< 4. Structure of impeller 20

Next, the impeller 20 will be described with reference to the drawings. As shown in fig. 2 and 3, the impeller 20 is disposed inside the casing 30. That is, the casing 30 houses the impeller 20. The impeller 2 includes a base plate 21, a plurality of rotor blades 22, and a shroud 23. The impeller 20 is formed of an engineering plastic. Also, the impeller 20 may be formed of metal such as aluminum alloy.

< 4.1 substrate 21 >

The substrate 21 is disk-shaped. The base plate 21 has an impeller hub 211 at the center in the radial direction. The upper end of the shaft 11 penetrates the impeller hub 211. A fixing member 111 is attached to the upper end of the shaft 11, and the shaft 11 and the base plate 21 are fixed. That is, the impeller 20 is fixed to the shaft 11. The impeller 20 rotates together with the rotation of the shaft 11 about the central axis Cx. That is, the impeller 20 is rotatable around the central axis Cx extending upward and downward.

< 4.2 moving blade 21 >

The plurality of rotor blades 22 are arranged in a circumferential direction on the upper surface 210 of the base plate 21. In the present embodiment, the plurality of rotor blades 22 are arranged on the upper surface 210 at equal intervals in the circumferential direction with the center axis Cx as the center. The plurality of rotor blades 22 are formed as the same member as the base plate 21. The moving blade 22 is a member different from the base plate 21, and may be fixed by a fixing method such as adhesion, press-fitting, or welding. The method of fixing the base plate 21 and the rotor blade 22 is not limited to this. A fixing method capable of firmly fixing the base plate 21 and the rotor blade 22 can be widely adopted.

< 4.3 pipe sleeve 23 >

The shroud 23 contacts the upper end of each of the plurality of rotor blades 22 in the axial direction. The shroud 23 extends axially upward as it goes toward the center. As shown in fig. 3, the shroud 23 has a curved shape in which the angle of inclination with respect to the central axis Cx becomes gradually smaller toward the central axis. The sleeve 23 is annular when viewed axially. That is, the sleeve 23 has a suction hole 231 penetrating in the axial direction at the center in the radial direction.

The shroud 23 is formed as the same member as the base plate 21 and the plurality of rotor blades 22. However, the shroud 23 may be manufactured separately from the base plate 21 and the plurality of rotor blades, and may be fixed to the upper ends of the plurality of rotor blades 22 in the axial direction. Examples of the method of fixing the shroud 23 to the rotor blade 22 include, but are not limited to, bonding and welding. A fixing method capable of firmly fixing the shroud 23 and the rotor blade 22 can be widely adopted.

Since the impeller 20 rotates about the center axis Cx, the rotor blades 22 rotate about the center axis Cx to generate an air flow. At this time, the airflow is sucked from the suction hole 231. Then, the gas is accelerated and pressurized in the rotor blade 22, and then is discharged radially outward from between the base plate 21 and the shroud 23 on the outer edge in the radial direction. The impeller 20 of the air blower a of the present embodiment rotates counterclockwise as viewed from the axial direction in the axial direction. However, the present invention is not limited to this, and an impeller that rotates clockwise when viewed axially from the axial direction may be used in some cases as in the case of the configuration of the casing 30.

< 5. outer shell 30 >

As shown in fig. 2 and 3, the housing 30 includes a base member 31 and a cover member 32. A cover member 32 is attached to the housing 30 axially above the base member 31. The impeller 20 is disposed between the base member 31 and the cover member 32 in a state where the cover member 32 is attached to the base member 31 in the axial direction upward. The casing 30 has an air intake part 36 and an air discharge part 37. More specifically, the housing 30 includes a flat plate portion 33, a motor holding portion 34, a side wall portion 35, an air intake portion 36, and an air discharge portion 37. Further, a flow path 38 is formed inside the casing 30.

< 5.1 Flat plate part 33 >

The flat plate portion 33 is a circular plate shape perpendicular to the central axis Cx. The flat plate portion 33 is formed on the base member 31. The base plate 21 of the impeller 20 is arranged above the flat plate portion 33 in the axial direction with a gap therebetween in the axial direction. The upper surface of the flat plate portion 33 has a recessed ring portion 331 recessed in the axial direction and continuous in the circumferential direction. The recessed ring portion 331 is formed in an annular shape when viewed in the axial direction.

An annular convex ring portion 212 is provided on the lower surface of the base plate 21 of the impeller 20, and is partially fitted into the concave ring portion 331. A curved gap is formed between the flat plate portion 33 and the base plate 21 by a part of the convex ring portion 212 being fitted into the concave ring portion 331. Since the gap between the convex ring portion 212 and the concave ring portion 331 is narrow, the airflow generated by the rotation of the impeller 20 is less likely to flow into the gap between the base plate 21 and the flat plate portion 33 of the impeller 20. This enables impeller 20 to stably rotate, and the air flow can be effectively utilized. The flat plate portion 33 has a flat plate through hole 332 penetrating in the axial direction at the radial center.

< 5.2 Motor holding part 34 >

The motor holding portion 34 is formed at a lower portion in the axial direction of the flat plate portion 33. The motor protector 34 is formed on the base member 31. The motor holding portion 34 is cylindrical, and fixes the motor 10 on the inner surface in the radial direction. The motor 10 may be fixed by press fitting, or by a fixing method such as screwing, bonding, or welding. When the motor 10 is attached to the motor holding portion 34, the shaft 11 of the motor 10 penetrates the flat plate through hole 332. The impeller 20 is fixed to a portion projecting upward in the axial direction from the flat plate through hole 332 of the shaft 11.

< 5.3 side wall part 35 >

The side wall portion 35 is disposed radially outward of the radially outer end of the flat plate portion 33. The side wall 35 is disposed to surround the flat plate portion 33 at a radially outer portion than the flat plate portion 33.

< 5.4 air intake part 36 and exhaust part 37 >

The air intake portion 36 is provided at an axial upper end of the housing 30. The air intake portion 36 is formed in the cover member 32 and penetrates in the axial direction. The center of the air intake portion 36 coincides with the central axis Cx. That is, the air intake portion 36 is formed axially above the impeller 20. The suction unit 36 has a tapered bottom 361 and an inflow pipe portion 362. The tapered bottom 361 is a curved surface facing radially inward and downward. The tapered bottom 361 has a diameter that smoothly decreases from the top to the bottom. The inflow pipe portion 362 is annular and extends along the central axis Cx, and is connected to an inner end portion of the tapered bottom 361. This allows the air flow to be smoothly sucked from the air suction unit 36 during operation of the impeller 20. Accordingly, the blowing efficiency of the blower A can be improved.

The exhaust portion 37 is formed in the housing 30. The exhaust portion 37 is an opening disposed radially outward of the impeller 20. That is, the exhaust portion 37 is formed radially outward of the impeller 20. The air sucked from the air suction unit 36 passes through the flow path 38 and is discharged to the outside from the air discharge unit 37.

< 5.5 flow path 38 >

Next, the shape of the flow path 38 will be described in detail with reference to the drawings. Fig. 4 is a plan view of the air blower a shown in fig. 2 with the cover member 32 removed. Fig. 5 is a sectional view in the imaginary plane V-V in fig. 4. Fig. 5 is a plan view showing a cross-sectional view of the virtual plane V-V.

As shown in fig. 4, a part of the flow path 38 is formed between the radially outer edge of the impeller 20 and the radially inner surface of the side wall portion 35. The air sucked from the air suction unit 36 by the rotation of the impeller 20 is accelerated and pressurized by the impeller 20, flows through the flow path 38, and is discharged to the outside from the exhaust unit 37. That is, the flow path 38 is a conduit for communicating the intake section 36 and the exhaust section 37. In fig. 4 and 5, the direction Ar of the airflow in the flow path 38 is indicated by an arrow line.

The impeller 20 rotates counterclockwise when viewed axially from the axial direction. The airflow generated by the rotation of the impeller 20 has an axial velocity component, a radially outward velocity component, and a counterclockwise velocity component when viewed axially from the axial direction.

The flow path 38 is radially open to the impeller 20 over the entire circumference in the circumferential direction. Therefore, when the impeller 20 rotates, the airflow generated around the entire radial outer edge of the impeller 20 flows into the flow path 38. The incoming airflow flows along the flow path 38 in the counterclockwise direction as viewed from the axial direction in the axial direction. That is, the counterclockwise direction when viewed axially from the axial direction in the flow path 38 is the direction Ar in which the air flows.

The flow path upper surface 382, which is the upper surface of the flow path 38 in the axial direction, is a curved surface that is curved downward radially outward with respect to a surface perpendicular to the central axis Cx. That is, the flow path upper surface 382 includes a plane whose axial position is constant from the most upstream to the most downstream of the flow path 38. That is, at least a part of the upper surface 382 of the flow path 38 is orthogonal to the central axis Cx. In the blower a, the air blown out from the impeller 20 has a velocity component directed axially downward. Thus, the airflow mainly flows along the flow path bottom surface 381. Therefore, even if the upper surface 382 is formed by a surface orthogonal to the central axis Cx, the influence on the efficiency of the air blower a is small. Further, by forming at least a part of the upper surface 382 of the flow path 38 as a surface perpendicular to the central axis Cx, the structure of the cover portion 32 of the housing 30 is simplified.

At least a part of the flow path bottom surface 381 which is the lower surface in the axial direction of the flow path 38 is inclined in the axial downward direction as it goes downstream in the airflow direction Ar. That is, the bottom surface 381 of the flow path 38 faces the exhaust portion 37 and is axially downward. The flow path upper surface 382 is smoothly continuous with the radially inner surface of the side wall portion 35. The flow path bottom surface 381 is also smoothly continuous with the radially inner surface of the side wall portion 35, similarly to the flow path upper surface 382. With such a configuration, the air flow is less likely to be disturbed at the boundary between the passage upper surface 382 and the radially inner surface of the side wall portion 35 and at the boundary between the passage bottom surface 381 and the radially inner surface of the side wall portion 35. Thereby, the airflow can be efficiently made to flow.

In the casing 30, the flow path 38 has an exhaust flow path 383 reaching the exhaust portion 37 at the most downstream portion in the flow direction Ar of the gas flow. The exhaust flow path 383 extends in a tangential direction of the casing 30. The most upstream portion in the flow direction Ar of the airflow in the flow path 38 communicates with the intermediate portion of the exhaust flow path 383. The most upstream portion in the flow direction Ar of the gas flow in the flow path 38 is defined as the start end portion 380 of the flow path 38. The flow path 38 has a shape that increases in volume counterclockwise as viewed from the axial direction in the axial direction, i.e., a so-called spiral shape. That is, the flow path 38 is formed into a spiral shape at least a part of which is disposed between the inner surface of the casing 30 and the radial direction of the impeller 20 and connected to the exhaust portion 37.

In addition, the shell 30 has a tongue 384 at the start end 380. That is, the housing 30 has a tongue 384 disposed at the start end 380 of the flow path 38. The tongue 384 projects radially inward from the side wall 35 and upstream in the air flow direction Ar at the start end 380 of the flow path 38. The tongue 384 suppresses the reverse flow of the gas flow flowing from the impeller 20 into the flow path 38 around the start end 380 of the flow path 38. That is, by having the tongue 384, the gas flow from the impeller 20 is guided in the direction Ar in which the gas flow flows in the flow path 38. This reduces the flow of air flowing into the exhaust passage 383 from the portion communicating with the exhaust passage 383 on the start end 380 side of the passage 38, and can suppress the disturbance of the flow of air discharged from the exhaust part 37.

As shown in fig. 5, the axial length of the flow path 38 increases downstream in the flow direction Ar of the gas flow. The axial length is the axial length of the flow path upper surface 382 and the flow path bottom surface 381. In the present embodiment, the axial length of the surface orthogonal to the central axis Cx in the flow path 382 and the flow path bottom surface 381 is defined. When both the flow path upper surface and the flow path bottom surface are complex curved surfaces, the axial length may be set to a length at which the axial length between the flow path upper surface and the flow path bottom surface is maximized. In the blower a of the present embodiment, since the position in the axial direction of at least a part of the flow path upper surface 382 is constant, the length in the axial direction substantially changes in accordance with the change in the flow path bottom surface 381.

Also, the axial length increases at an average rate of increase that varies from location to location. The average increase rate is a value obtained by dividing the circumferential length of the flow path along the region by the axial length of the flow path 38 in a certain region. That is, the mean increase rate is larger and the axial length is more drastically changed, similarly to the slope in the case of the linear change.

The shape of the flow path 38 will be described below. As shown in fig. 4, in the flow path 38, a line connecting the central axis Cx and the tip end portion of the tongue 384 is set as a starting point PS. The flow path 38 extends from the starting point PS in the flow direction Ar of the gas flow, i.e., counterclockwise when viewed axially from the axial direction, along the outer edge in the radial direction of the impeller 20. In the flow path 38 viewed axially from the axial direction, a position where the center angle θ is shifted from the starting point PS by the first angle θ 1 in the direction Ar in which the airflow flows is defined as a first position P1. Similarly, a position deviated from the starting point PS by a second angle θ 2 larger than the first angle θ 1 is defined as a second position P2. Then, a position deviated from the starting point PS by the third angle θ 3 is defined as a third position P3.

As shown in fig. 5, the axial length of the flow path 38 is constant in the portion from the start point PS to the position P1 at the first angle θ 1. That is, the flow path bottom surface 381 is formed as a plane orthogonal to the central axis Cx from the starting point PS to the first position P1.

The start end 380 side of the flow path 38 is connected to the middle portion of the exhaust flow path 383. By providing the tongue 384 on the flow path 38 and making the axial length constant from the starting point PS to the first position P1, the pressure between the view point of the flow path 38 and the first position P1 is maintained higher than the pressure of the exhaust flow path 383. This can suppress the backflow from the exhaust passage 383 to the start end portion 380 side, and can improve the air blowing efficiency of the air blower a. Further, compared to the case where the axial length is longer from the starting point PS to the first position P, the separation of the airflow at the bottom surface of the flow path is suppressed by suppressing the decrease in pressure. The air blowing efficiency of the air blowing device a can be improved by these measures.

Also, the axial length increases at a first average rate of increase Av1 from the first position P1 to the second position P2 of the flow path 38. Further, in the flow passage 38 shown in fig. 5, the axial length linearly increases from the first position P1 to the second position P2, but the present invention is not limited thereto. The rate of increase may vary locally. That is, the axial length of the flow passage 38 increases at the first average increase rate Av1 from the first position P1 where the center angle θ is the first angle θ 1 to the position P2 where the center angle θ 2 is greater than the first angle θ 1 in the direction Ar in which the airflow flows, with the line connecting the tongue 384 and the center axis Cx as the starting point PS.

The difference between the axial length of the exhaust portion 37 and the axial length of the first position P1 is defined as a first height difference L1. In addition, the difference between the axial length in the first position P1 and the axial length in the second position P2 is taken as a second level difference L2. At this time, the first ratio Rs1, which is the ratio of the first level difference L1 to the second level difference L2, is represented by the following formula (1).

Rs1＝L2/L1···(1)

Further, from the second position P2 to the third position P3 of the flow passage 38, the axial length increases at a second average increase rate Av 2. The first average rate of increase Av1 is greater than the second average rate of increase Av 2. Further, in the flow passage 38 shown in fig. 5, the axial length linearly increases from the second position P2 to the third position P3, but the present invention is not limited thereto. The rate of increase may vary locally. That is, the axial length of the flow passage 38 increases from the position P2 at the second angle θ 2 to the position P3 at the third angle θ 3 larger than the second angle θ 2 at the second average increase rate Av 2. The first average rate of increase Av1 is greater than the second average rate of increase Av 2.

The difference between the axial length of the exhaust portion 37 and the axial length of the first position P1 is defined as a first height difference L1. In addition, the difference between the axial length in the first position P1 and the axial length in the third position P3 is taken as a third level difference L3. At this time, the second ratio Rs2, which is the ratio of the first level difference L1 to the third level difference L3, is represented by the following formula (2).

Rs2＝L3/L1···(2)

The axial length of the flow path 38 of the blower a of the present embodiment increases from the first position P1 to the second position P2 at the first average increase rate Av 1. In addition, the second average rate of increase Av2 increases from the second position P2 to the third position P3. And the first average increase rate Av1 > the second average increase rate Av 2.

Since the blower a is a centrifugal fan, the airflow flows radially outward over the entire circumferential direction of the impeller 20. The airflow from the impeller 20 flows through the flow path 38 in the entire circumferential direction. That is, at some point in the flow path 38, the airflow flowing in from upstream of the flow path 38 is mixed with the airflow flowing in from the impeller 20. That is, in the flow path 38, the flow rate of the downstream air flow is larger than that of the upstream air flow. Since the volume of the flow path 38 increases as it goes downstream, even if the flow rate of the airflow increases due to the airflow directly flowing from the impeller 20, the turbulence of the airflow in the flow path 38 can be suppressed. Therefore, the air flow can be stabilized, and the efficiency of the air supply device can be improved.

As described in more detail below. The axial length of the flow path 38 sharply increases from the first position P1 to the second position P2. That is, the pressure is sharply reduced between the first position P1 and the second position P2. Thereby, the airflow compressed in a depressurized manner in the region from the starting point PS to the first position P1 easily flows toward the second position P2 side. The airflow generated by the rotation of the impeller 20 can be made to flow in a constant direction in the flow path 38 at all times.

Further, the pressure of the airflow from the second position P2 to the third position P3 is kept substantially constant by setting the axial length to the second average increase rate Av2 smaller than the first average increase rate Av1 between the second position P2 and the third position P3. This can keep the pressure of the air flow discharged from the discharge portion 37 at a constant pressure or higher, and can improve the air blowing efficiency of the air blower a.

Further, the axial length increases at a third average increase rate Av3 from the third position P3 of the flow path 38 to the exhaust section 37. The third average rate of increase Av3 is less than the second average rate of increase Av 2. Further, in the flow path 38 shown in fig. 5, the axial length linearly increases from the third position P3 to the exhaust portion 37, but the present invention is not limited to this. The rate of increase may vary locally. That is, as the exhaust section 37 moves from the position P3 at the third angle θ 3, the axial length of the flow path increases at the third average increase rate Av 3. The third average rate of increase Av3 is less than the second average rate of increase Av 2.

Compared with the case where the third average increase rate Av3 is larger than the second average increase rate Av2, peeling of the airflow in the flow path bottom surface 381 can be suppressed. Therefore, the air blowing efficiency of the air blowing device a can be further improved. Further, the pressure can be kept constant or higher by decreasing the flow rate increase rate to be smaller than that on the upstream side and by decreasing the flow path expansion rate. In this respect, the efficiency of the air blowing device a can be improved.

Next, description will be made regarding the first angle θ 1 that determines the first position P1, the second angle θ 2 that determines the second position P2, and the third angle θ 3 that determines the third position P3. As described above, the range from the starting point PS to the first position P1 is a region having a constant axial length in order to ensure a pressure for suppressing the backflow from the exhaust passage 383 to the starting end of the passage 38.

The start end side of the flow path 38 is connected to the middle portion of the exhaust flow path 383. By providing the tongue 384 in the flow passage 38 and making the axial length constant from the starting point PS to the first position P1, the pressure from the starting point PS to the first position P1 of the flow passage 38 is maintained higher than the pressure of the exhaust flow passage 383. This suppresses the backflow from the exhaust passage 383 to the start end portion 380 side, and improves the air blowing efficiency of the air blower a. Further, since the reduction in pressure can be suppressed as compared with the case where the axial length is increased from the starting point PS to the first position P1, separation of the airflow at the bottom surface of the flow path can be suppressed. In this respect, the air blowing efficiency of the air blowing device a can be improved.

If the distance from the starting point PS to the first position P1 is short, the gas flow flows from the upstream to the downstream of the flow path 38, and therefore it is difficult to obtain a sufficient pressure. Conversely, if the length is too long, the pressure of the airflow around the starting point PS becomes too high, and an excessive airflow tends to flow into the exhaust passage 383 from the starting end portion 380 side. Therefore, the distance from the starting point PS to the first position P1 is preferably not too long, but not too short. Therefore, in the flow path 38 of the air blower a, the first angle θ 1, which is the center angle θ from the starting point PS to the first position P1, is 45 ° or more and 65 ° or less. That is, the first angle θ 1 is 45 ° or more and 65 ° or less. This improves the air blowing efficiency of the air blower a.

In addition, the average rate of increase in the axial length is large from the first position P1 to the second position P2. Thus, the pressure of the gas flow decreases sharply. Therefore, if the length from the first position P1 to the second position P2 is too long, the pressure of the airflow is too low. Further, if the length from the first position P1 to the second position P2 is short and the pressure change is small, it is difficult to stabilize the direction Ar in which the gas flows. Therefore, the distance from the first position P1 to the second position P2 is also desirably not too long or too short. Therefore, in the flow path 38 of the blower a, the distance from the first position P1 to the second position P2 is set to be the same length as the distance from the starting point PS to the first position P1. In the flow path 38 of the air blower a, a second angle θ 2, which is a center angle θ from the starting point PS to the second position P2, is 90 ° or more and 110 ° or less. That is, the second angle θ 2 is 90 ° or more and 110 ° or less. This improves the air blowing efficiency of the air blower a.

Further, the average rate of increase in the axial length is small from the second position P2 to the third position P3. Therefore, the distance from the second position P2 to the third position P3 is a length equal to or longer than the distance from the start point PS to the second position P2. In the flow path 38 of the air blower a, a third angle θ 3, which is a center angle θ from the starting point PS to the third position P3, is 220 ° or more and 250 ° or less. That is, the third angle θ 3 is 220 ° or more and 250 ° or less. This improves the air blowing efficiency of the air blower a.

< 6. numerical simulation >

Next, the first ratio Rs1 and the second ratio Rs2 of the air blowing device a of the present embodiment are obtained as appropriate values based on simulations. Here, the simulation will be explained.

< 6.1 first simulation

The simulated model makes the first angle θ 1 45 °, the second angle θ 2 100 °, and the third angle θ 3 235 °. The blade efficiency η (%) when the first ratio Rs1 of the second position P2 was changed with the second ratio Rs2 of the third position P3 fixed at 0.89 was compared. The blade efficiency η (%) is a ratio of the operation output from the impeller 20 with respect to the input energy for rotating the impeller 20. In other words, the power lost by the circuit, the motor, and the like, and the ratio of the operation output from the impeller 20 are removed from the electric power input for the rotation of the impeller 20. Fig. 6 is a diagram showing the result of the first simulation. Fig. 6 is a graph in which the vertical axis represents the vane efficiency η and the horizontal axis represents the first ratio Rs 1.

As shown in fig. 6, the vane efficiency η is maximum when the first ratio Rs1 is about 0.2. In the section where the first ratio Rs1 is 0.15 or more and 0.3 or less, the vane efficiency η is high. Therefore, in the blower a of the present embodiment, the appropriate first ratio Rs1 is set to 0.15 or more and 0.3 or less.

That is, the ratio Rs1 of the difference L2 between the axial length of the flow path 38 in the position P1 at the first angle θ 1 and the axial length of the flow path 38 in the position P2 at the second angle θ 2 with respect to the difference L1 between the axial length of the flow path 38 in the position P1 at the first angle θ 1 and the axial length of the flow path 38 in the exhaust portion 37 is 0.15 or more and 0.3 or less. With such a configuration, the air blowing efficiency can be improved.

< 6.2 second simulation

The simulated model makes the first angle θ 1 45 °, the second angle θ 2 100 °, and the third angle θ 3 235 °. The vane efficiency η (%) when the second ratio Rs2 of the third position P3 was changed with the first ratio Rs1 of the second position P2 fixed at 0.2 was compared. Fig. 7 is a graph showing the result of the second simulation. Fig. 7 is a graph in which the vertical axis represents the vane efficiency η and the horizontal axis represents the second ratio Rs 2.

As shown in fig. 7, the vane efficiency η is maximum when the second ratio Rs2 is about 0.89. In addition, the vane efficiency η is large in the section where the first ratio Rs1 is 0.86 or more and 0.97 or less. Therefore, in the blower a of the present embodiment, the second ratio Rs2 is set to be preferably 0.86 or more and 0.97 or less.

That is, the ratio Rs2 of the difference L3 between the axial length of the flow path 38 in the position P1 at the first angle θ 1 and the axial length of the flow path 38 in the position P3 at the third angle θ 3 with respect to the difference L1 between the axial length of the flow path 38 in the position P1 at the first angle θ 1 and the axial length of the flow path in the exhaust portion 37 is greater than 0.86 and less than 0.97. By doing so, the air blowing efficiency can be improved.

The air blowing efficiency can be improved by the air blowing device a having the above configuration.

< 7. variants, etc. >

Modifications and the like of the present embodiment will be described. In the present embodiment, as the starting point PS for specifying the first position P1, the second position P2, and the third position P3 in the flow passage 38, a line connecting the tip of the tongue 384 and the central axis Cx is used as viewed in the axial direction. However, the present invention is not limited thereto.

As shown in fig. 4, a line passing through the central axis Cx and contacting the inner surface of the housing 30 at one point when viewed in the axial direction may be used as the starting point PS. With this configuration, the efficiency of the blower a can be improved. Since the axial length of the flow passage 38 is made the shortest at the upstream end in the direction Ar in which the gas flows in the tongue 384, the gas can be smoothly guided to the downstream side in the direction Ar in which the gas flows.

Further, when viewed in the axial direction, a line connecting the point where the axial length of the flow path 38 is the smallest and the central axis Cx can be used as the starting point PS. With this configuration, the efficiency of the blower a can be improved. In particular, since the axial length can be increased from the point at which the axial length of the flow path 38 is the shortest, the gas flow can be smoothly guided to the downstream side in the gas flow direction Ar. When the axial length of the flow path 38 is the smallest in a region having a constant length in the direction Ar in which the gas flows, the end portion on the upstream side in the direction Ar in which the gas flows in this region may be the starting point PS.

As shown in fig. 8, in the portion where the distance from the central axis Cx to the inner surface of the casing 30 is shortest as viewed in the axial direction, a line connecting the central axis Cx and an intersection 386 between a tangent line 385 of the inflection point of the inner surface of the casing 30 on the start end 380 side of the flow path 38 and the flow path 383 on the exhaust portion 37 side may be used as the starting point PS. With this configuration, the efficiency of the blower a can be improved. Further, since the tongue portion does not have a shape that projects into the flow path in a long manner, turbulence around the tongue portion can be suppressed.

The embodiments of the present invention are described below, but the embodiments may be variously modified within the scope of the present invention.

Industrial applicability is as follows.

The present invention can be used for an air blowing device and a self-propelled cleaner including the air blowing device.

Claims (14)

1. An air supply device is characterized in that,

the disclosed device is provided with:

an impeller rotatable around a central axis extending in the vertical direction;

a motor disposed below the impeller and configured to rotate the impeller; and

a casing for accommodating the impeller,

the housing has:

an air suction part formed above the impeller in the axial direction; and

an exhaust part formed on the radial outer side of the impeller,

a spiral flow path at least a part of which is arranged between the inner surface of the casing and the radial direction of the impeller and connected with the exhaust part is formed,

the housing has a tongue portion disposed at a starting end portion of the flow path,

as for the length in the axial direction of the flow path,

increasing at a first average increasing rate from a position having a first central angle to a position having a second central angle larger than the first central angle in a direction in which the gas flow flows from a line connecting the tongue portion and the central axis as a starting point,

increases at a second average increase rate from the position of the second angle to a position of a third angle larger than the second angle,

the first average rate of increase is greater than the second average rate of increase.

2. The air supply arrangement according to claim 1,

when viewed in the axial direction, a line passing through the central axis and contacting the inner surface of the housing at one point is defined as the starting point.

3. The air supply arrangement according to claim 1,

a line connecting a point where the axial length of the flow path is the smallest and the central axis is defined as the starting point when viewed in the axial direction.

4. The air supply arrangement according to claim 1,

in a portion where the distance from the central axis to the housing inner surface is shortest as viewed in the axial direction, a line connecting an intersection point of a tangent line connecting an inflection point of the housing inner surface on the flow path starting end side and the flow path on the exhaust portion side and the central axis is set as the starting point.

5. The air supply apparatus according to any one of claims 1 to 4,

the axial length of the flow path is constant in a portion from the starting point to the first angle position.

6. The air supply apparatus according to any one of claims 1 to 5,

the axial length of the flow path increases at a third average rate of increase from the third angular position toward the exhaust portion,

the third average rate of increase is smaller than the second average rate of increase.

7. The air supply apparatus according to any one of claims 1 to 6,

a ratio of a difference between an axial length of the flow path at the first angle position and an axial length of the flow path at the second angle position with respect to a difference between the axial length of the flow path at the first angle position and the axial length of the flow path at the exhaust portion is 0.15 or more and 0.3 or less.

8. The air supply apparatus according to any one of claims 1 to 7,

a ratio of a difference between an axial length of the flow path at the first angle position and an axial length of the flow path at the third angle position with respect to a difference between the axial length of the flow path at the first angle position and the axial length of the flow path at the exhaust portion is 0.86 or more and 0.97 or less.

9. The air supply apparatus according to any one of claims 1 to 8,

the first angle is 45 ° or more and 65 ° or less.

10. The air supply apparatus according to any one of claims 1 to 9,

the second angle is 90 ° or more and 110 ° or less.

11. The air supply apparatus according to any one of claims 1 to 10,

the third angle is 220 ° or more and 250 ° or less.

12. The air supply apparatus according to any one of claims 1 to 11,

at least a part of the upper surface of the flow path is orthogonal to the central axis.

13. The air supply apparatus according to any one of claims 1 to 12,

the bottom surface of the flow path faces the exhaust unit and is directed axially downward.

14. A self-propelled dust collector, which is characterized in that,

an air supply device according to any one of claims 1 to 13 is provided.

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