US20190017514A1

US20190017514A1 - Impeller, air-sending apparatus, and cleaning machine

Info

Publication number: US20190017514A1
Application number: US16/024,936
Authority: US
Inventors: Akikazu FUJIWARA; Ryosuke HAYAMITSU
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2017-07-14
Filing date: 2018-07-02
Publication date: 2019-01-17
Also published as: JP2019019744A; CN109253110A

Abstract

An impeller includes a main plate spreading radially with respect to the center axis, a plurality of blades provided on an upper surface of the main plate and arranged side by side in a circumferential direction, a shroud connected to tops of the plurality of blades and having an intake port that is an opening extending upward, and a mount portion provided on the upper surface of the main plate and positioned on an inner side with respect to a radially outer end of the main plate. The mount portion has a plurality of recesses each being depressed downward from an upper surface of the mount portion and extending in a direction away from the center axis.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2017-138108 filed on Jul. 14, 2017. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to an impeller, an air-sending apparatus, and a cleaning machine.

2. Description of the Related Art

An impeller included in an electric air-sending apparatus is known. The impeller included in the electric air-sending apparatus is fastened to a motor shaft with a nut. The impeller includes a front shroud, a rear shroud, and a plurality of blades.
The front shroud has an umbrella-like shape and is provided on the air-inlet side. The rear shroud is a flat plate and is provided across an air-passage space in the impeller from the front shroud. The plurality of blades are held between the front shroud and the rear shroud. Air flows from a central part of the front shroud into the impeller. The air thus flowed into the impeller is deflected by 90° and is ejected toward the radially outer side of the impeller.
The known impeller has a problem in that turbulence may occur near the radially inner ends of the blades. Consequently, the air-sending efficiency of the impeller may be reduced.

SUMMARY OF THE INVENTION

An impeller according to an exemplary embodiment of the present disclosure rotates on a center axis extending in a vertical direction. The impeller includes a main plate spreading radially with respect to the center axis, a plurality of blades provided on an upper surface of the main plate and arranged side by side in a circumferential direction, a shroud connected to tops of the plurality of blades and having an intake port that is an opening extending upward, and a mount portion provided on the upper surface of the main plate and positioned on an inner side with respect to a radially outer end of the main plate. The mount portion has a plurality of recesses each being depressed downward from an upper surface of the mount portion and extending in a direction away from the center axis.
The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall perspective view of an exemplary cleaning machine according to an embodiment of the present disclosure.

FIG. 2 is an overall perspective view of an air-sending apparatus included in the cleaning machine according to the embodiment of the present disclosure.

FIG. 3 is a vertical sectional view of the air-sending apparatus according to the embodiment of the present disclosure.

FIG. 4 is a vertical sectional view of an impeller included in the air-sending apparatus according to the embodiment of the present disclosure.

FIG. 5 is a top view of the impeller according to the embodiment of the present disclosure.

FIG. 6 is an enlarged top view of a part of the impeller according to the embodiment of the present disclosure.

FIG. 7 is a top view of the impeller according to the embodiment of the present disclosure, with a shroud thereof removed.

FIG. 8 is a vertical sectional perspective view of the impeller according to the embodiment of the present disclosure.

FIG. 9 is a perspective view of a washer included in the impeller according to the embodiment of the present disclosure.

FIG. 10 is a top view of an impeller according to a first modification of the embodiment of the present disclosure, with a shroud thereof removed.

FIG. 11 is a top view of a washer included in an impeller according to a second modification of the embodiment of the present disclosure.

FIG. 12 is a vertical sectional view of a part of the washer included in the impeller according to the second modification of the embodiment of the present disclosure.

FIG. 13 is a vertical sectional view of a washer include in an impeller according to a third modification of the embodiment of the present disclosure.

FIG. 14 is a vertical sectional view of an impeller according to a fourth modification of the embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present disclosure will now be described in detail with reference to the drawings. Herein, a direction in which a center axis of an impeller extends is simply referred to as “the axial direction,” a direction spreading from and being orthogonal to the center axis of the impeller is simply referred to as “the radial direction,” and a direction in which an arc centered on the center axis of the impeller extends is simply referred to as “the circumferential direction.” A center axis of an air-sending apparatus coincides with the center axis of the impeller. Herein, as a matter of convenience in description, the axial direction is regarded as the vertical direction, and shapes and relative positions of relevant elements will be described on the basis of a definition that the vertical direction in FIGS. 3 and 4 corresponds to the vertical direction of the impeller and the air-sending apparatus. “The upper side” of the impeller and the air-sending apparatus corresponds to “the intake side,” and “the lower side” of the impeller and the air-sending apparatus corresponds to “the exhaust side.” The above definition of the vertical direction does not limit the orientations and the relative positions of the impeller and the air-sending apparatus at the time of use.
Herein, shapes and relative positions of elements included in a cleaning machine will be described on the basis of a definition that a side of the cleaning machine nearer to the floor surface corresponds to “the lower side,” and a side of the cleaning machine farther from the floor surface corresponds to “the upper side.” The definition of the sides do not limit the orientation and the relative position of the cleaning machine at the time of use. The relative positions of relevant elements may also be described by using the terms “the upstream side” and “the downstream side” in the direction in which air flows from the intake side toward the exhaust side at the activation of the air-sending apparatus. The terms “parallel” and “perpendicular” used herein do not necessarily mean exactly parallel and exactly perpendicular but imply substantially parallel and substantially perpendicular, respectively.
FIG. 1 is an overall perspective view of an exemplary cleaning machine 100 according to an embodiment of the present disclosure. The cleaning machine 100 is a so-called stick-type electric cleaning machine and includes a casing 102 having an intake part 103 and an exhaust part 104 that are openings provided in the lower surface and in the upper surface thereof, respectively. The casing 102 is provided with a power cord (not illustrated) drawn from one surface thereof. The power cord is connected to a power socket (not illustrated) provided on a wall of a room and thus supplies power to the cleaning machine 100. The cleaning machine 100 may alternatively be a so-called robot-type, canister-type, or handy-type electric cleaning machine.
The casing 102 has thereinside with an air passage (not illustrated) that connects the intake part 103 and the exhaust part 104 to each other. The air passage is provided thereinside with a dust-collecting portion (not illustrated), a filter (not illustrated), and an air-sending apparatus 1 in that order from the upstream side toward the downstream side in the direction of airflow. Dust such as dirt particles contained in the air flowing through the air passage is collected by the filter and is stored in the dust-collecting portion, which has a container-like shape. Thus, the cleaning machine 100 can clean a floor surface F. The dust-collecting portion and the filter are detachably attached to the casing 102.
The casing 102 is provided in an upper part thereof with a grip portion 105 and an operation portion 106. The user can hold the grip portion 105 and thus move the cleaning machine 100. The operation portion 106 includes a plurality of buttons 106 a. The user operates the buttons 106 a to make instructions and settings for the operation of the cleaning machine 100. For example, with the operation of a relevant one of the buttons 106 a, an instruction for the activation of the air-sending apparatus 1, the stopping of the air-sending apparatus 1, a change in the rotation speed of the air-sending apparatus 1, or the like can be made.
The intake part 103 receives the downstream end of a suction pipe 107 (the upper end of the suction pipe 107 in FIG. 1) connected thereto. The suction pipe 107 extends substantially linearly. The upstream end of the suction pipe 107 (the lower end of the suction pipe 107 in FIG. 1) is provided with a suction nozzle 110 detachably attached thereto.
FIG. 2 is an overall perspective view of the air-sending apparatus 1 included in the cleaning machine 100 according to the embodiment of the present disclosure. FIG. 3 is a vertical sectional view of the air-sending apparatus 1 according to the embodiment of the present disclosure. Roughly speaking, the air-sending apparatus 1 includes a fan casing 2, an impeller 3, a motor 4, and a substrate 5. When the impeller 3 is driven to rotate by the motor 4, air is taken into the fan casing 2 from the upper side (the upper side in FIG. 3) of the air-sending apparatus 1 and is exhausted from the lower end of the fan casing 2 toward the lower side (the lower side in FIG. 3). Seen from the upper side in the axial direction, the impeller 3 rotates counterclockwise.
The fan casing 2 is a cylinder whose section taken in the radial direction has a substantially circular shape. The fan casing 2 houses the impeller 3 and the motor 4. The fan casing 2 includes an upper case 21 and a lower case 22.
The upper case 21 has a substantially circular cylindrical shape with the lower side thereof being open. The upper case 21 covers the impeller 3. The lower case 22 has a substantially circular cylindrical shape with the upper side and the lower side thereof being open. The lower case 22 covers the motor 4. The lower end of the upper case 21 and the upper end of the lower case 22 are connected to each other, whereby the internal spaces of the two become continuous with each other. The upper case 21 and the lower case 22 may be provided separately from each other as described above or integrally with each other.
The upper case 21 has an intake port 211 at the upper end thereof. The intake port 211 is an opening extending in the vertical direction. The intake port 211 is positioned on the upper side with respect to the upper end of the impeller 3. The inside diameter of the intake port 211 is smaller than the inside diameter of the upper case 21. The lower case 22 has an exhaust port 221 at the lower end thereof. The exhaust port 221 is an opening extending in the vertical direction. The exhaust port 221 is defined between the inner surface of the lower case 22 and a motor housing 41 to be described below. In the cleaning machine 100, the air-sending apparatus 1 is oriented such that the intake port 211 thereof faces downward.
The impeller 3 is positioned inside the upper case 21 of the fan casing 2. The impeller 3 is fixed to a shaft 431, to be described below, of the motor 4. The impeller 3 rotates on a center axis C extending in the vertical direction.
When the impeller 3 is driven to rotate by the motor 4, air is taken from the intake port 211 of the upper case 21 into the impeller 3. The air thus taken into the impeller 3 is guided toward the radially outer side by the impeller 3 and is further blown toward the radially outer side of the impeller 3. Details of the impeller 3 will be described separately below.
The motor 4 is positioned inside the lower case 22 of the fan casing 2. Roughly speaking, the motor 4 includes the motor housing 41, a stator 42, and a rotor 43.
The motor housing 41 includes an upper housing 411 and a lower housing 412. The upper housing 411 has a substantially circular cylindrical shape with the lower side thereof being open. The lower housing 412 has a substantially circular cylindrical shape with the upper side thereof being open. The lower end of the upper housing 411 and the upper end of the lower housing 412 are connected to each other, whereby the internal spaces of the two become continuous with each other. The upper housing 411 and the lower housing 412 are fixed to each other with screws 41A provided at predetermined intervals in the circumferential direction. The motor housing 41 houses the stator 42 and the rotor 43.
The upper housing 411 includes a bearing-holding portion 4111 in a radially central part of the upper surface thereof. The bearing-holding portion 4111 is depressed downward from the upper surface of the upper housing 411 and is a concavity having a circular shape when sectioned in the radial direction. The bearing-holding portion 4111 has a hole 4111A in the center of the inner bottom thereof. The hole 4111A extends in the vertical direction along the center axis C through the bottom of the bearing-holding portion 4111. The bearing-holding portion 4111 receives an upper bearing 44 fixedly fitted therein from the upper side. The upper bearing 44 is, for example, a ball bearing. Alternatively, the upper bearing 44 may be a sleeve bearing or the like.
The upper housing 411 is provided with a plurality of stator vanes 4112 on the outer circumferential surface thereof. The plurality of stator vanes 4112 are arranged at predetermined intervals in the circumferential direction and each extend in the vertical direction. An upper portion of each of the stator vanes 4112 is curved toward the backward side in the direction of rotation of the impeller 3 with respect to a lower portion of the stator vane 4112. The air blown from the impeller 3 that is rotating is guided between circumferentially adjacent ones of the stator vanes 4112 from the upper side toward the lower side. Thus, air currents can be rectified.
The lower housing 412 has an attaching hole 412A in a central part of the lower surface thereof. The attaching hole 412A extends in the vertical direction through the lower surface of the lower housing 412. The attaching hole 412A receives a bracket 45 fitted therein from the lower side and fixed thereto with screws (not illustrated).
The bracket 45 includes a bearing-holding portion 451 in a radially central part of the upper surface thereof. The bearing-holding portion 451 is depressed downward from the upper surface of the bracket 45 and is a concavity having a circular shape when sectioned in the radial direction. The bearing-holding portion 451 has a hole 451A in the center of the inner bottom thereof. The hole 451A extends in the vertical direction along the center axis C through the bottom of the bearing-holding portion 451. The bearing-holding portion 451 receives a lower bearing 46 fixedly fitted therein from the upper side. The lower bearing 46 is, for example, a ball bearing. Alternatively, the lower bearing 46 may be a sleeve bearing or the like.
The stator 42 is positioned on the radially inner side of the inner circumferential surface of the motor housing 41. The stator 42 includes a stator core 421, a plurality of coils 422, and an insulator 423.
The stator core 421 is obtained by stacking electromagnetic steel sheets in the vertical direction. The stator core 421 includes an annular core back 4211 and a plurality of teeth 4212. The plurality of teeth 4212 extend from the inner circumferential surface of the core back 4211 toward the radially inner side. The teeth 4212 each have a substantially T shape when seen from either side in the axial direction. The plurality of coils 422 are each formed of a conducting wire wound around a corresponding one of the teeth 4212 with the insulator 423, having an insulating characteristic, interposed therebetween. A lead wire 422A is drawn downward from each of the coils 422. The lead wire 422A is electrically connected to the substrate 5.
The inner circumferential surface and the outer circumferential surface of the core back 4211 are flat in areas near the roots of the respective teeth 4212. Thus, the collapsing of the coils 422 can be suppressed. In the other areas excluding the areas near the roots of the respective teeth 4212, the inner circumferential surface and the outer circumferential surface of the core back 4211 are curved. The curved portions of the outer circumferential surface of the core back 4211 are in contact with the inner circumferential surface of the motor housing 41.
The rotor 43 is positioned on the radially inner side of the stator 42. The rotor 43 is rotatable on the center axis C relative to the stator 42. The rotor 43 includes the shaft 431 and a magnet 432.
The shaft 431 extends along the center axis C. The shaft 431 is supported by the upper bearing 44 and the lower bearing 46 in such a manner as to be rotatable relative to the motor housing 41. The magnet 432 has a cylindrical shape and is fixed to the shaft 431 extending therethrough. The outer circumferential surface of the magnet 432 is covered with a rotor cover (not illustrated). The magnet 432 and the rotor cover are positioned on the radially inner side of the teeth 4212 and face the teeth 4212 in the radial direction.
The substrate 5 has a disc-like shape spreading radially with respect to the center axis C. The substrate 5 is positioned on the lower side with respect to the lower housing 412 and the bracket 45. The substrate 5 is fixed to the lower housing 412 with screws 52 with a plurality of spacers 51 interposed therebetween. The spacers 51 are positioned on the lower side of the lower housing 412 and are arranged side by side in the circumferential direction.
The substrate 5 is a rigid substrate or a flexible substrate. The lead wires 422A drawn from the respective coils 422 of the motor 4 are electrically connected to a driving circuit (not illustrated) mounted on the substrate 5. Thus, power can be supplied to the coils 422.
FIG. 4 is a vertical sectional view of the impeller 3 included in the air-sending apparatus 1 according to the embodiment of the present disclosure. FIG. 5 is a top view of the impeller 3 according to the embodiment of the present disclosure. FIG. 6 is an enlarged top view of a part of the impeller 3 according to the embodiment of the present disclosure. FIG. 7 is a top view of the impeller 3 according to the embodiment of the present disclosure, with a shroud 33 thereof removed. FIG. 8 is a vertical sectional perspective view of the impeller 3 according to the embodiment of the present disclosure. FIG. 9 is a perspective view of a washer 34 included in the impeller 3 according to the embodiment of the present disclosure. In FIGS. 5 to 11, the direction of rotation of the impeller 3 is represented by an arrow R.
The impeller 3 is a metal member, for example, and has a circular shape when seen in the axial direction. The impeller 3 includes a main plate 31, a plurality of blades 32, the shroud 33, and a mount portion. In the present embodiment, the mount portion corresponds to the washer 34.
The main plate 31 is positioned at the bottom of the impeller 3. The main plate 31 spreads radially with respect to the center axis C. The main plate 31 is a disc-like member. The main plate 31 has a hole 31A extending in the vertical direction along the center axis C through the center thereof. The main plate 31 supports the bottoms of the blades 32.
The plurality (for example, fourteen) of blades 32 are positioned on the upper surface of the main plate 31 and are arranged thereon side by side in the circumferential direction. The bottoms of the respective blades 32 are connected to the main plate 31. The tops of the respective blades 32 are connected to the shroud 33.
The blades 32 are each a plate-like member standing in the vertical direction and extending from the radially inner side toward the radially outer side. Seen in the axial direction, the blades 32 are each curved in such a manner as to be convex toward the forward side in the direction of rotation R, with the radially inner end thereof being positioned on the forward side in the direction of rotation R with respect to the radially outer end thereof.
The plurality of blades 32 are of two kinds: first blades 32A and second blades 32B that are provided in the same number (seven each, for example). Herein, the first blades 32A and the second blades 32B may also be generally denoted as “the blades 32” unless they need to be distinguished from each other.
The length of the first blades 32A in the radial direction is greater than the length of the second blades 32B in the radial direction. The radially outer ends of the first blades 32A and the radially outer ends of the second blades 32B substantially coincide with the radially outer end (the outer circumferential edge) of the main plate 31. The radially inner ends of the first blades 32A are positioned near the radially outer end of the washer 34 to be described below. The radially inner ends of the second blades 32B are positioned near the midpoint between the center axis C and the radially outer end of the main plate 31. Therefore, the air passage between circumferentially adjacent ones of the first blades 32A is divided near the midpoint in the direction of airflow (the radial direction) by a corresponding one of the second blades 32B into a passage on the forward side in the direction of rotation R and a passage on the backward side in the direction of rotation R.
In an upstream portion of the impeller 3 in the direction of airflow, air passes through a gap between the radially inner ends of circumferentially adjacent ones of the first blades 32A and flows toward the radially outer side of the main plate 31. The air that has passed through the gap between the radially inner ends of the circumferentially adjacent ones of the first blades 32A is divided by the corresponding second blade 32B, before reaching the radially outer end of the main plate 31, into an airflow on the forward side in the direction of rotation R and an airflow on the backward side in the direction of rotation R.
The shroud 33 is positioned over the plurality of blades 32. Seen in the axial direction, the shroud 33 is an annular plate member with the radially inner end and the radially outer end thereof being circular. A portion of the shroud 33 that is on the radially outer side with respect to the substantial midpoint of the shroud 33 between the radially inner end and the radially outer end extends parallel to the main plate 31 with a gap therebetween in the axial direction. A portion of the shroud 33 that is on the radially inner side is curved upward. The shroud 33 has an intake port 331 that is an opening extending upward (in a radially central part thereof). A portion of the shroud 33 around the intake port 331 has a cylindrical shape. The shroud 33 supports the tops of the respective blades 32. That is, the shroud 33 is connected to the tops of the plurality of blades 32 and has the intake port 331 as an opening extending upward.
In the impeller 3, the upper end of each of the first blades 32A extends from the radially outer end to the radially inner end of the shroud 33 along the lower surface of the shroud 33. The upper end of each of the first blades 32A has a highest part 32Aa immediately below the radially outer end of the intake port 331, i.e., immediately below the inner end of the shroud 33. The upper end of each of the first blades 32A smoothly descends from the highest part 32Aa toward the radially inner side and eventually reaches the upper surface of the main plate 31 at the radially inner end.
The washer 34 is provided on the upper surface of the main plate 31 and is positioned on the inner side with respect to the radially outer end of the main plate 31. The washer 34 is a disc-like member having a predetermined height from the upper surface of the main plate 31 and spreading radially with respect to the center axis C. The washer 34 has a boss 34A projecting upward at the center thereof. The boss 34A has a hole 34B in the center thereof. The hole 34B extends in the vertical direction along the center axis C through the boss 34A.
The impeller 3 is fixed to the shaft 431 at the main plate 31 and the washer 34 thereof.
As illustrated in FIG. 3, a spacer 471 is provided above the upper bearing 44 and below the main plate 31. The spacer 471 is fixed to the shaft 431. The shaft 431 is made to pass through the hole 31A of the main plate 31, whereby the impeller 3 is positioned on the upper surface of the spacer 471. Subsequently, the shaft 431 is made to pass through the hole 34B of the washer 34, whereby the washer 34 is positioned on the upper surface of the main plate 31. Then, a fixing member, such as a nut 472, is screwed onto the upper end of the shaft 431 with the main plate 31 and the washer 34 being held between the spacer 471 and the nut 472. Thus, the impeller 3 is fixed to the shaft 431 with the nut 472.
Referring now to FIG. 9, the washer 34 includes an outer circumferential portion 34C on the radially outer side with respect to the boss 34A. The upper surface of the outer circumferential portion 34C is parallel to the upper surface of the main plate 31. The outer circumferential portion 34C has a plurality of recesses 34D.
The recesses 34D are each depressed downward from the upper surface of the outer circumferential portion 34C. The recesses 34D each extend in a direction away from the center axis C. Specifically, the recesses 34D are each a groove having a rectangular shape when sectioned in the axial direction. The recesses 34D each have a side surface 34Da on the forward side in the direction of rotation R, and a side surface 34Db on the backward side in the direction of rotation R. The side surfaces 34Da and 34Db each extend in the vertical direction parallel to the center axis C. The plurality (for example, seven) of recesses 34D provided in the upper surface of the outer circumferential portion 34C are arranged side by side in the circumferential direction. That is, the washer 34 has the recesses 34D each being depressed downward from the upper surface thereof and extending in the direction away from the center axis C.
Since the washer 34 has the recesses 34D as described above, the occurrence of turbulence near the radially inner ends of the blades 32 can be suppressed. If the washer 34 has no recesses 34D, some of the air taken from the intake port 331 may flow toward the radially inner side when flowing near the radially outer side of hills 34E to be described below. Consequently, turbulence may occur near the radially outer side of the hills 34E. In contrast, since the washer 34 according to the present embodiment has the recesses 34D, when the impeller 3 is rotated, the recesses 34D generate air currents flowing toward the radially outer side. Therefore, the occurrence of radially inward flow of the air near the radially outer side of the hills 34E can be suppressed. Hence, the impeller 3 configured as above can exhibit improved air-sending efficiency.
As illustrated in FIG. 9, seen in the axial direction, the recesses 34D are each curved in such a manner as to be convex toward the forward side in the direction of rotation R, with the radially inner end thereof being positioned on the forward side in the direction of rotation R with respect to the radially outer end thereof. That is, the radially inner end of each recess 34D is positioned on the forward side in the direction of rotation R of the impeller 3 with respect to the radially outer end of the recess 34D. Hence, when the impeller 3 is rotated, the recesses 34D can more easily generate the air currents flowing toward the radially outer side. Therefore, the occurrence of turbulence near the radially inner ends of the blades 32 can be suppressed effectively.
The recesses 34D are each concave by a predetermined depth from the upper surface of the outer circumferential portion 34C. That is, the bottom surface of each recess 34D at the radially outer end of the recess 34D is positioned above the upper surface of the main plate 31. In such a relationship, if the height in the recess 34D, i.e., the depth of the recess 34D, is adjusted, the effect of suppressing the occurrence of turbulence can be increased.
As illustrated in FIG. 9, the washer 34 includes the plurality of hills 34E provided in correspondence with the plurality of recesses 34D arranged side by side in the circumferential direction. The plurality of hills 34E are each positioned between circumferentially adjacent ones of the plurality of recesses 34D. The hills 34E project upward with respect to the recesses 34D. That is, the washer 34 has the plurality of recesses 34D arranged side by side in the circumferential direction, and the plurality of hills 34E each provided between circumferentially adjacent ones of the recesses 34D and projecting upward with respect to the recesses 34D. A circumferential length L1 of each recess 34D at the radially outer end is smaller than a circumferential length L2 of each hill 34E at the radially outer end. Since the circumferential length L1 of the recess 34D at the radially outer end, i.e., the width of the recess 34D in the form of a groove, is set smaller than the circumferential length L2 of the hill 34E as described above, the occurrence of backward flow of the air toward the radially inner side can be suppressed more than in a case where the recess 34D has a greater width.
Referring now to FIG. 6, the washer 34 is positioned on the radially inner side with respect to the radially inner ends of the first blades 32A. There is a predetermined distance between the radially outer end of the washer 34 and the radially inner end of each of the first blades 32A. Specifically, a distance D1 from the center axis C to the radially outer end of the washer 34 is smaller than a distance D2 from the center axis C to the radially inner end of each of the first blades 32A. In such a relationship, the radially inner ends of the first blades 32A are not positioned on the radially inner side with respect to the radially outer end of the washer 34. Thus, the narrowing of air passages near the radially inner ends of the blades 32 can be suppressed, and the occurrence of turbulence can be suppressed.
As illustrated in FIG. 6, a circumferential opening angle G1 of each of the recesses 34D at the radially outer end with respect to the center axis C is smaller than a circumferential angle G2 formed between the radially inner ends of circumferentially adjacent ones of the first blades 32A with respect to the center axis C. Since the circumferential opening angle G1 of each recess 34D at the radially outer end, that is, the width of the recess 34D in the form of a groove, is set smaller than the interval between adjacent ones of the blades 32 as described above, the occurrence of backward flow of the air toward the radially inner side can be suppressed.
As illustrated in FIG. 6, seen in the axial direction, the washer 34 is positioned on the radially inner side with respect to the radially outer end of the intake port 331. Specifically, the distance D1 from the center axis C to the radially outer end of the washer 34 is smaller than a distance D3 from the center axis C to the radially outer end of the intake port 331. In such a relationship, the outside diameter of the washer 34 is reduced. Therefore, the weight of the impeller 3 can be reduced. Moreover, the occurrence of turbulence near the radially inner ends of the blades 32 can be suppressed. That is, the narrowing of a passage of the air taken from the intake port 331 into the impeller 3 can be suppressed more than in a case where the radially outer end of the washer 34 is positioned on the outer side with respect to the radially outer end of the intake port 331. Therefore, the occurrence of turbulence can be suppressed.
Referring now to FIG. 4, a height H1 of the washer 34 at the radially outer end thereof is smaller than a height H2 of each first blade 32A on the radially inner side thereof. In the present embodiment, the height H2 refers to the height of the first blade 32A at the highest part 32Aa defined in a portion of the first blade 32A that is on the radially inner side thereof. In such a relationship, the narrowing of the air passage on the radially inner side of each of the blades 32 can be suppressed more than in a case where the height H1 of the washer 34 at the radially outer end thereof is greater than the height H2 of the first blade 32A on the radially inner side thereof. Furthermore, the occurrence of turbulence can be suppressed.
The washer 34 is a member provided separately from the main plate 31. The lower surface of the washer 34 is in contact with the upper surface of the main plate 31. The upper surface of the washer 34 is in contact with the lower surface of the fixing member. The fixing member corresponds to the nut 472, for example. The impeller 3 is configured such that the main plate 31 is fixed to the shaft 431, which is rotatable on the center axis C, with the fixing member. In such a configuration, since the member having the recesses 34D is the washer 34, not only the occurrence of turbulence can be suppressed, but also the strength of fixing the impeller 3 to the shaft 431 can be increased.
The air-sending apparatus 1 includes the impeller 3. In the above configuration according to the present embodiment, the occurrence of turbulence in the impeller 3 included in the air-sending apparatus 1 can be suppressed. Accordingly, the air-sending apparatus 1 can exhibit improved air-sending efficiency. The cleaning machine 100 includes the air-sending apparatus 1. Therefore, the occurrence of turbulence in the air-sending apparatus 1 included in the cleaning machine 100 can be suppressed. Accordingly, the cleaning machine 100 can exhibit improved performance in suction.
FIG. 10 is a top view of an impeller 3 according to a first modification of the embodiment of the present disclosure, with a shroud 33 thereof removed.
As illustrated in FIG. 10, the impeller 3 includes a plurality (for example, seven) of blades 32. The radially outer ends of the blades 32 substantially coincide with the radially outer end (the outer circumferential edge) of the main plate 31. The radially inner ends of the blades 32 are positioned near the radially outer end of the washer 34. The impeller 3 according to the first modification illustrated in FIG. 10 includes no second blades 32B, unlike the impeller 3 described above with reference to FIGS. 4 to 9.
Letting the number of recesses 34D be N1 and the number of blades 32 be N2, a value expressed by N1/N2 preferably falls within a range from 0.5 to 1.2. More preferably, (N1/N2) is about 1.0.
In the impeller 3 described with reference to FIGS. 4 to 9, N1 as the number of recesses 34D is 7, and N2 as the number of blades 32 is 14. Accordingly, (N1/N2) is 0.5. In the impeller 3 according to the first modification illustrated in FIG. 10, N1 as the number of recesses 34D is 7, and N2 as the number of blades 32 is 7. Accordingly, (N1/N2) is 1.0.
Since the number of recesses 34D and the number of blades 32 are set on the basis of the above predetermined relationship, the occurrence of turbulence near the radially inner ends of the blades 32 can further be suppressed. In particular, since the impeller 3 according to the first modification is configured such that (N1/N2)=1.0, the occurrence of turbulence near the radially inner ends of the blades 32 can be suppressed much more effectively.
FIG. 11 is a top view of a washer 34 included in an impeller 3 according to a second modification of the embodiment of the present disclosure. FIG. 12 is a vertical sectional view of a part of the washer 34 included in the impeller 3 according to the second modification of the embodiment of the present disclosure. The section illustrated in FIG. 12 is taken along line XII-XII illustrated in FIG. 11.
As illustrated in FIGS. 11 and 12, the recesses 34D each have a rectangular shape when sectioned in the axial direction. The recesses 34D each have a side surface 34Da provided on the forward side thereof in the direction of rotation R, and a side surface 34Db provided on the backward side thereof in the direction of rotation R.
The side surface 34Da of each recess 34D that is on the forward side in the direction of rotation R includes a recess-widening part 34Dc. The recess-widening part 34Dc is provided in an upper part of the side surface 34Da. The lower end of the recess-widening part 34Dc, i.e., a connecting part between the recess-widening part 34Dc and the side surface 34Da, extends parallel to the center axis C. The recess-widening part 34Dc extends upward while inclining toward the forward side in the direction of rotation R such that the recess 34D is widened. In the present embodiment, the recess-widening part 34Dc is a curved surface. In such a shape, the occurrence of turbulence near the upper end of the side surface 34Da of the recess 34D that is on the forward side in the direction of rotation R can be suppressed. More specifically, for example, if the recesses 34D each have no recess-widening part 34Dc and if the side surface 34Da of the recess 34D that is on the forward side in the direction of rotation R extends parallel to the center axis C and is connected substantially orthogonally to a corresponding one of the hills 34E, air flowing with the rotation of the impeller 3 from the forward side in the direction of rotation R toward the side surface 34Da on the forward side in the direction of rotation R may be separated from the side surface 34Da near the upper end of the side surface 34Da, causing turbulence. In contrast, according to the present embodiment, since the recesses 34D each have the recess-widening part 34Dc, the occurrence of such turbulence can be suppressed.
The recess-widening part 34Dc is not limited to a curved surface and may be a flat surface that is inclined at a predetermined angle with respect to the center axis C.
The side surface 34Db of each recess 34D that is on the backward side in the direction of rotation R extends parallel to the center axis C. Since the side surface 34Db on the backward side in the direction of rotation R extends in the vertical direction, when the impeller 3 is rotated, air can be efficiently exhausted toward the radially outer side. That is, air near the upper end of the side surface 34Db on the backward side in the direction of rotation R can be more efficiently exhausted toward the radially outer side than in a case where an upper part of the side surface 34Db on the backward side in the direction of rotation R is curved toward the backward side in the direction of rotation R with respect to the center axis C.
FIG. 13 is a vertical sectional view of a washer 34 include in an impeller 3 according to a third modification of the embodiment of the present disclosure.
As illustrated in FIG. 13, the washer 34 includes an inclined part 34Ca whose upper surface descends toward the radially outer side. More specifically, the washer 34 includes an outer circumferential portion 34C. The outer circumferential portion 34C includes the inclined part 34Ca whose upper surface descends toward the radially outer side. The inclined part 34Ca is tapered from the side thereof nearer to the center axis C. In such a shape, a reduction in the distance between the upper surface of the washer 34 and the lower surface of the shroud 33 in a direction from the center axis C toward the radially outer side can be suppressed. That is, the narrowing of the air passage can be suppressed.
FIG. 14 is a vertical sectional view of an impeller 3 according to a fourth modification of the embodiment of the present disclosure.
As illustrated in FIG. 14, the main plate 31 includes a mount portion 31B. The mount portion 31B is a part of the main plate 31. Except that the mount portion 31B is a part of the main plate 31, the mount portion 31B has the same configuration as the washer 34 described above. Specifically, the mount portion 31B includes a boss 31Ba, an outer circumferential part 31Bc, recesses 31Bd, and hills 31Be. In such a configuration, the number of components included in the impeller 3 can be reduced, and the efficiency in the work of assembling the impeller 3 can be improved.
The air-sending apparatus 1 may be included not only in a cleaning machine but also in any of various office automation apparatuses, medical apparatuses, and transport apparatuses, or any of home electric apparatuses other than the cleaning machine.
The present disclosure is applicable to, for example, an air-sending apparatus intended for a cleaning machine.
Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.
While preferred embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.

Claims

What is claimed is:

1. An impeller that rotates on a center axis extending in a vertical direction, the impeller comprising:

a main plate spreading radially with respect to the center axis;

a plurality of blades provided on an upper surface of the main plate and arranged side by side in a circumferential direction;

a shroud connected to tops of the plurality of blades and having an intake port that is an opening extending upward; and

a mount portion provided on the upper surface of the main plate and positioned on an inner side with respect to a radially outer end of the main plate,

wherein the mount portion has a plurality of recesses each being depressed downward from an upper surface of the mount portion and extending in a direction away from the center axis.

2. The impeller according to claim 1,

wherein a radially inner end of each of the recesses is positioned on a forward side in a direction of rotation of the impeller with respect to a radially outer end of the recess.

3. The impeller according to claim 1,

wherein a side surface of each of the recesses that is on the forward side in the direction of rotation includes a recess-widening part extending upward while inclining toward the forward side in the direction of rotation such that the recess is widened.

4. The impeller according to claim 1,

wherein a side surface of each of the recesses that is on a backward side in the direction of rotation extends parallel to the center axis.

5. The impeller according to claim 1,

wherein a distance from the center axis to a radially outer end of the mount portion is smaller than a distance from the center axis to a radially inner end of each of the blades.

6. The impeller according to claim 1,

wherein the distance from the center axis to the radially outer end of the mount portion is smaller than a distance from the center axis to a radially outer end of the intake port.

7. The impeller according to claim 1,

wherein a height of the mount portion at the radially outer end of the mount portion is smaller than a height of each of the blades on a radially inner side of the blade.

8. The impeller according to claim 1,

wherein the mount portion includes

the plurality of recesses arranged side by side in the circumferential direction; and

hills each provided between circumferentially adjacent ones of the recesses and projecting upward with respect to the recesses, and

wherein a circumferential length of each of the recesses at the radially outer end of the recess is smaller than a circumferential length of each of the hills at a radially outer end of the hill.

9. The impeller according to claim 1,

wherein a circumferential opening angle of each of the recesses at the radially outer end of the recess with respect to the center axis is smaller than a circumferential angle formed between the radially inner ends of circumferentially adjacent ones of the blades with respect to the center axis.

10. The impeller according to claim 1,

wherein a bottom surface of each of the recesses at the radially outer end of the recess is positioned above the upper surface of the main plate.

11. The impeller according to claim 1,

wherein the mount portion includes an inclined part whose upper surface descends toward the radially outer side of the mount portion.

12. The impeller according to claim 1,

wherein, letting a number of recesses be N1 and a number of blades be N2, a value expressed by N1/N2 falls within a range from 0.5 to 1.2.

13. The impeller according to claim 1,

wherein the main plate is fixed to a shaft with a fixing member, the shaft being rotatable on the center axis,

wherein the mount portion is provided separately from the main plate,

wherein a lower surface of the mount portion is in contact with the upper surface of the main plate, and

wherein the upper surface of the mount portion is in contact with a lower surface of the fixing member.

14. The impeller according to claim 1,

wherein the mount portion is a part of the main plate.

15. An air-sending apparatus comprising:

the impeller according to claim 1.

16. A cleaning machine comprising:

the air-sending apparatus according to claim 15.