US20200284267A1

US20200284267A1 - Sirocco fan, blowing device, and air conditioner

Info

Publication number: US20200284267A1
Application number: US16/648,940
Authority: US
Inventors: Masaki Kawamura
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2017-09-25
Filing date: 2018-01-11
Publication date: 2020-09-10
Also published as: CN111094757A; JPWO2019058573A1; WO2019058573A1

Abstract

A boss of an impeller and a rotation shaft are fastened together without partially notching or removing a blade of the impeller. A sirocco fan includes an impeller including a boss formed to protrude outward from and end face sucking air when the impeller rotates. The boss is provided with a screw hole opening, on a side face of a protruding portion of the boss, for fastening the rotation shaft with a screw.

Description

TECHNICAL FIELD

The present invention relates to a sirocco fan and an air conditioner including the sirocco fan as a blowing device.

TECHNICAL FIELD

A conventional indoor unit for an air conditioner includes inside: an air blower; and a heat exchanger surrounding an upper portion and a front portion of the air blower, as disclosed, for example, in Patent Document 1. In such an indoor unit, the air blower rotates to suck air from an inlet in an upper portion of the indoor unit. The sucked air passes through the heat exchanger, and then blows out from an outlet in a front-lower portion of the indoor unit.
An air conditioner recently developed is capable of purifying air in addition to conditioning air. For example, a high efficiency particulate air filter (HEPA filter) has a large air-flow resistance. Hence, the use of the HEPA filter for air purification inevitably reduces a volume of air blowing from the outlet. When the HEPA filter is used for air purification, it is necessary to secure a sufficient volume of the air (a sufficient volume of the air to be sucked).
A typical air conditioner includes a cross-flow fan as a blowing device. In order to obtain a sufficient volume of air, use of a sirocco fan is preferable. As illustrated in FIG. 8, for example, multiple sirocco fans 113 (two in FIG. 8) each including two impellers 113 a and 113 b are connected in series to be used as a blowing device.
To rotate the sirocco fan 113, the two impellers 113 a and 113 b need to be mounted on a rotation shaft 132 which transmits rotational force of a not-shown motor. In mounting the rotation shaft 132, for example, the rotation shaft 132 is passed through a boss 131 formed inside the impeller 113 a, and is fastened with a screw inserted into a screw hole 131 a opened on the boss 131.

CITATION LIST

Patent Literature

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2005-147508 (published on Jun. 9, 2005).

SUMMARY OF INVENTION

Technical Problem

As illustrated in FIG. 8, for example, the conventional sirocco fan has the boss 131 formed inside the impeller 113. Hence, the screw hole 131 a for fastening the rotation shaft 132 is also formed inside the boss 131. Hence, when the screw is inserted in the screw hole 131 a on the boss 131, a notch 113 a has to be provided to a portion of a blade of the impeller 113 a. Alternatively, the blade of the impeller 113 a has to be partially removed for the screw to pass through the removed portion. Accordingly, when the blade of the impeller 113 a is partially notched or removed, the impeller 113 a fails to obtain a sufficient volume of air.
An aspect of the present invention intends to provide a sirocco fan in which a boss of an impeller and a rotation shaft can be fastened together without partially notching or removing a blade of the impeller.

Solution to Problem

In order to solve the above problem, a sirocco fan according to an aspect of the present invention includes: an impeller including a boss for securing a rotation shaft transmitting rotational force of a motor, the impeller being configured to rotate to suck air from a direction in parallel with the rotation shaft, and to eject the air from a rotation face of the impeller, wherein the boss is formed to protrude outward from an end face of the impeller sucking the air, and is provided with a screw hole opening, on a side face of a protruding portion of the boss, for fastening the rotation shaft with a screw.

Advantageous Effects of Invention

An aspect of the present invention makes it possible to fasten a boss of an impeller and a rotation shaft together without partially notching or removing a blade of the impeller.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an appearance of an indoor unit for an air conditioner according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the indoor unit illustrated in FIG. 1.

FIG. 3 (a) is a schematic side view of the indoor unit, illustrating conditions of an open-close lid and an air guiding plate when the air conditioner of the embodiment is OFF. FIG. 3 (b) is a schematic side view of the indoor unit, illustrating conditions of the open-close lid and the air guiding plate when the air conditioner is in an air-conditioning mode and set cooling. FIG. 3 (c) is a schematic side view of the indoor unit, illustrating conditions of the open-close lid and the air guiding plate when the air conditioner is in an air purification mode and set cooling.

FIG. 4 is a perspective view schematically illustrating a configuration of a blowing device according to this embodiment.

FIG. 5 is a view illustrating how to connect together a sirocco fan and motor included in the blowing device illustrated in FIG. 4.

FIG. 6 is a schematic view illustrating a configuration of a blowing device according to a second embodiment of the present invention.

FIG. 7 is a schematic view illustrating a configuration of a blowing device according to a third embodiment of the present invention.

FIG. 8 is a schematic view illustrating a configuration of a conventional sirocco fan.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Described below are embodiments of the present invention, with reference to the drawings. FIG. 1 is a perspective view illustrating an appearance of an indoor unit 1 for an air conditioner according to this embodiment. FIG. 2 is a vertical cross-sectional view of the indoor unit 1 for the air conditioner illustrated in FIG. 1.
(Outline of Indoor Unit 1)
As illustrated in FIG. 1, the indoor unit 1 of the air conditioner includes an air guiding plate 3 in front of an indoor-unit body 2. As illustrated in FIG. 2, the indoor-unit body 2 includes: a first inlet 11 in an upper portion thereof; a second inlet 12 in a lower portion thereof; an air-blowing fan 13 and a heat exchanger 14 therein; and an outlet 17 in a front portion thereof. The air-blowing fan 13 and the heat exchanger 14 constitute a blowing device.
Moreover, the indoor unit 1 includes: a first filter 15 inside (below) the first inlet 11; and a second filter 16 inside (above) the second inlet 12. For example, the first filter 15 is functionally equivalent to a prefilter, and lower in performance and smaller in air-flow resistance than the second filter 16. For example, the second filter 16 is an HEPA filter, and higher in performance and greater in air-flow resistance than the first filter 15.
In the indoor unit 1, the air sucked from the first inlet 11 passes through the first filter 15, the air-blowing fan 13, and the heat exchanger 14, and blows out from the outlet 17. Furthermore, the air sucked from the second inlet 12 passes through the second filter 16, the air-blowing fan 13, and the heat exchanger 14, and blows out from the outlet 17.
The first inlet 11 is provided with an open-close lid 18 opening and closing the first inlet 11. FIG. 3 (a) is a schematic side view of the indoor unit 1, illustrating conditions of the open-close lid 18 and the air guiding plate 3 when the air conditioner is OFF. FIG. 3 (b) is a schematic side view of the indoor unit 1, illustrating conditions of the open-close lid 18 and the air guiding plate 3 when the air conditioner is in an air-conditioning mode and set cooling. FIG. 3 (c) is a schematic side view of the indoor unit, illustrating conditions of the open-close lid 18 and the air guiding plate 3 when the air conditioner is in an air purification mode and set cooling.
As illustrated in FIG. 3 (a), the open-close lid 18 is closed when the air conditioner is OFF. Moreover, as illustrated in FIG. 3 (b), the open-close lid 18 is open when the air conditioner operates, prioritizing air conditioning over air purification (in the air-conditioning mode). Furthermore, as illustrated in FIG. 3 (c), the open-close lid 18 is closed when the air conditioner operates, prioritizing air purification over air conditioning (in the air purification mode).
The air-blowing fan is a sirocco fan, and serves as a blowing device of the indoor unit 1 for the air conditioner. The blowing device will be described later in detail.
The heat exchanger 14 includes two heat exchangers vertically connected together with the connection of the two heat exchangers protruding forward (in a dogleg shape), and provided in front of the air-blowing fan 13 (closer to the front of the indoor unit 1 than the air-blowing fan 13 is).
(Structure of Blowing Device)
FIG. 4 is a perspective view schematically illustrating a blowing device according to this embodiment.
The illustration (a) in FIG. 5 shows a side view of the blowing device. The illustration (b) shows a side cross-sectional view of the blowing device in the illustration (a). Note that, for the sake of the description, FIG. 5 exemplifies a case where the air-blowing fan 13 is placed to one side of a driving motor (a motor) 33.
As illustrated in FIG. 4, the blowing device according to this embodiment includes: a cabinet 30; two air-blowing fans 13; and a driving motor 33. The air-blowing fans 13 and the driving motor 33 are longitudinally arranged inside the cabinet 30. The driving motor 33 is placed between the two air-blowing fans 13, and transmits rotational force to the both air-blowing fans 13. That is, the driving motor 33 here is a dual-shaft motor having rotation shafts 32 longitudinally aligned.
Each of the rotation shafts 32 for transmitting the rotational force from the driving motor 33 is inserted in a boss 31 for one of the air-blowing fans 13. The rotation shaft 32 is then screwed and fastened. Across the driving motor 33 from the air-blowing fan 13, the rotation shaft 32 is supported by a bearing 34, and inserted in the boss 31 for the air-blowing fan 13. The rotation shaft 32 is then screwed and fastened.
The air-blowing fan 13 shown in the illustration (b) of FIG. 5 is a sirocco fan including two impellers 13 a connected together through their respective disc faces 13 b. That is, in the air-blowing fan 13, each of the impellers 13 a rotates in a predetermined direction to suck air from an end face 13 c, of the impeller 13 a, in parallel with the rotation shaft 32, and ejects the air from a rotation face 13 d of the impeller 13 a.
The boss 31 of the impeller 13 a is a hollow tube made of aluminum. The boss 31 is formed to penetrate the disc face 13 b of the impeller 13 a, and partially protrudes out of the end face 13 c across from the disc face 13 b. That is, the boss 31 is formed to protrude outward from the end face 13 c (the end face across from the disc face 13 b) sucking the air when the impeller 13 a rotates. The boss 31 is provided with a screw hole 31 a opening, on a side face of a portion of the boss 31 partially protruding from the impeller 13 a, for fastening the rotation shaft 32 with a screw. The rotation shaft 32 is made of stainless, and transmits driving force of the driving motor 33.
Hence, the screw hole 31 a is open on the side face of the boss 31 protruding from the impeller 13 a. Such a feature eliminates the need of a conventional notch to be provided to the impeller 13 a for tightening a screw, facilitating the tightening with a screwdriver.
As to the position of each screw hole 31 a, as shown in the illustration (b) in FIG. 5, the screw holes 31 a are open, on their respective bosses 31 for the horizontally arranged impellers 13 a, to face completely opposite from each other (i.e., one of the screw holes 31 a faces up and the other screw hole 31 faces down); that is, the screw holes 31 a shift 180° from each other in a rotation direction of the rotation shaft 32. Such a feature makes it possible to attain a weight-distribution balance when a screw is tightened in the screw hole 31, contributing to stable rotation of the air-blowing fan 13.
Note that the screw holes 31 a may be open on different positions of the bosses 31 of the two impellers 13 a. The screw holes 31 a do not have to shift 180° from each other in the rotation direction of the rotation shaft 32.
In other words, preferably, the two impellers 13 a may be connected through the disc faces 13 b across from the end faces 13 c sucking air, and the screw hole 31 a opening on the boss 31 of one of the two impellers 13 a and the screw hole 31 a opening on the boss 31 of another one of the two impellers 13 a may be provided not in a single plane.
Moreover, when the air-blowing fan 13 includes multiple air-blowing fans 13, the screw holes 31 opening on the bosses 31 of the impellers 13 a may sequentially shift 90° from each other in the rotation direction of the rotation shaft 32.
Furthermore, the screw hole 31 a may be open on the side face of the boss 31 protruding completely outward from the end face 13 c sucking the air when the impeller 13 a rotates. Alternatively, the screw hole 31 a may be open on a side face of the boss 31 slightly inward in relation to the end face 13 c. At least, the screw hole 31 a may be positioned to allow for an easy access of a screwdriver when the screw is tightened in the screw hole 31 a.

Advantageous Effects

In the above blowing device, a blade of the impeller 13 a does not have to be partially notched or removed in order to pass a screw through the screw hole 31 a, opening on the boss 31, when the boss 31 is fastened to the rotation shaft 32, unlike the case illustrated in FIG. 8 of the conventional art when the boss 31 is formed inward in relation to the air-sucking end face 13 c of the impeller 13 a.
Such features make it possible to reduce a decrease in a volume of the air when a blade of the impeller 13 a is partially notched or removed.
In addition, a mold for forming the impeller does not have to be shaped into a complex shape, unlike the case where a blade of the impeller is to be partially notched or removed. Such a mold contributes to reduction in manufacturing costs.
Moreover, as shown in the illustration (b) of FIG. 5, the boss 31 is formed to protrude from the impeller 13 a, and the protruding portion has the screw hole 31 a. Hence, the rotation shaft 32 does not have to pass through the boss 31. Such a feature makes it possible to make the weight of the blowing device lighter, compared with a conventional case where the rotation shaft passes through the boss.

Second Embodiment

Described below is still another embodiment of the present invention, with reference to the drawings. Note that, for the sake of explanation, identical reference signs are used to denote components with identical functions between the preceding embodiment and this embodiment. Such components will not be elaborated upon here.
Exemplified in the first embodiment is a blowing device including a dual-shaft motor serving as the driving motor 33. Alternatively, exemplified in this embodiment is a blowing device including a single-shaft motor serving as the driving motor 33. The single-shaft motor is provided with the rotation shaft 32 on one side alone.
FIG. 6 is a perspective view schematically illustrating the blowing device according to this embodiment.
As illustrated in FIG. 6, the blowing device according to this embodiment is similar in including the two air-blowing fans 13 and the one driving motor 33 to the blowing device (in FIG. 4) according to the first embodiment. The blowing device according to this embodiment is different in placement of the driving motor 33 from the blowing device according to the first embodiment. The two air-blowing fans 13 are connected together in series with a joint 35 connecting the bosses 31 facing each other. The rotation shaft 32 of the driving motor 33 is connected to the boss 31, of one of the air-blowing fans 13 (the air-blowing fan 13 on the observer's right in FIG. 6), across from the joint 35. Thus, the rotational force of the driving motor 33 is transmitted to the boss 31 connected to the rotation shaft 32 of the driving motor 33, and to the other boss 31 of the air-blowing fan 13 on the left connected through the joint 35 to the air-blowing fan 13 on the right provided with the boss 31. Hence, the two air-blowing fans 13 are rotated by the driving motor 33.
Note that, in FIG. 6, the rotation shaft 32 secured to the left boss 31 of the air-blowing fan 13 on the left is supported by a not-shown bearing.
In the above blowing device, the air-blowing fans 13 are connected together by the joint 35. By simply changing the length of the joint 35, the longitudinal length of the blowing device can be easily adjusted.
Moreover, when the joint 35 is made of stainless instead of steel, the blowing device can be made lighter.

Third Embodiment

Described below is still another embodiment of the present invention, with reference to the drawings. Note that, for the sake of explanation, identical reference signs are used to denote components with identical functions between the preceding embodiments and this embodiment. Such components will not be elaborated upon here.
FIG. 7 is a perspective view schematically illustrating the air-blowing fan 13 of a blowing device according to this embodiment.
In the air-blowing fan 13 as illustrated in FIG. 7, the disc face 13 b is inscribed with a marking 41 to distinguish between the left and the right of the disc face 13 b. An example in FIG. 7 shows that the sign “
” is inscribed as the marking 41 indicating left and the sign “
” is inscribed on the not-shown other side of the disc face 13 b as the marking 41 indicating right.
In this embodiment, the air-blowing fan 13 includes the two impellers 13 a connected together through their respective disc faces 13 b. If the impellers 13 a are mounted on the rotation shaft 32 in a wrong direction, the air is blown in the opposite direction. That is, if the impellers 13 a are mounted on the rotation shaft 32 in a wrong direction, the impellers 13 a rotate in the opposite direction to the intended rotation direction. Hence, the air is not sucked in a face perpendicular to the rotation direction of the impellers 13 a. On the contrary, the air is blown out of the face. In order to avoid such a problem, the marking 41 is inscribed on the disc face 13 b to distinguish between the right and the left. In this embodiment, a part of a mold for the impeller 13 a serves as an insert for inscribing the marking 41, so that the marking 41 is inscribed simultaneously when the impeller 13 a is molded.
As described above, the marking 41 is inscribed on the disc face 13 b of the impeller 13 a. Thus, when mounting the air-blowing fan 13 on the rotation shaft 32, a manufacturing worker can identify the left or the light of the impeller 13 a by simply looking at the marking 41. Such a feature can reduce the risk that the manufacturing worker would inadvertently switch the right and the left when mounting the impeller 13 a.
Moreover, the feature can reduce such a risk of inadvertently switching the right and the left in the mounting not only in the manufacturing but also in re-assembling the impeller 13 a and the rotation shaft 32 dismounted for repair and inspection after the manufacturing of the blowing device.
Hence, the feature makes it possible to clearly distinguish the difference between the right and the left of the impeller 13 a when the impeller 13 a is mounted on the rotation shaft 32 in manufacturing or repair and inspection of the blowing device, compared with a case of identifying whether the right and the left are inadvertently switched once the rotation shaft 32 and driven. Thus, the feature saves the trouble of mounting the impeller 13 a on the rotation shaft 32 again after they have already been assembled together.
Note that, in the example illustrated in FIG. 7, the marking 41 is represented in, but is not limited to, Chinese characters “
” and “
” respectively equivalent to the left and the right in English words. Alternatively, English words “Right” and “Left” may be respectively inscribed on the right and the left of the disc face 13 b. Moreover pairs “
(Right)” and “
(Left)” may be respectively inscribed on the right and the left of the disc face 13 b.
Furthermore, depending on an assembly process, the impellers can be mounted not in the horizontal right-left direction but in the vertical up-down direction. Hence, the marking 41 may identify the vertical direction.
That is, the marking 41 may be any given marking as long as the worker does not inadvertently switch the right and the left (up and down) when securing the impellers 13 a to the rotation shaft 32. Other than the above inscription visually recognizable, the marking 41 may be embossed (not shown) on a portion of the disc face 13 b or the impeller 13 a, so that the user can feel the embossed marking 41 to identify the right and the left (up and down).
Furthermore, in the above example, two markings are inscribed or formed to identify the right and the left (up and down) of the two impellers 13 a. Alternatively, the marking 41 may be inscribed or formed on at least one of the two impellers 13 a because if the right and the left (up and down) are identified for one of the impellers 13 a, the right and the left (up and down) for the other impeller 13 a are also identified.
As can be seen, the marking 41 is provided to at least one of the two impellers 13 a to identify the direction in which the impellers 13 a are mounted on the rotation shaft 32. Such a feature makes it possible to reduce the risk of mounting the impellers 13 a on the rotation shaft 32 in the wrong rotation direction.
Note that the marking 41 is formed using, but not limited to, an insert with a mold for manufacturing the impellers 13 a. The marking 41 may be either stamped or attached in the form of a sticker on the disc face 13 b after the impellers 13 a are manufactured.
In addition, the two impellers 13 a of the air-blowing fan 13 are formed horizontally symmetrically, contributing to component sharing. Such a feature makes it possible to reduce manufacturing costs.

SUMMARY

A sirocco fan according to a first aspect of the present invention includes the impeller 13 a including the boss 31 for securing the rotation shaft 32 transmitting rotational force of a motor (the driving motor 33), the impeller 13 a rotating to suck air from a direction in parallel with the rotation shaft 32, and to eject the air from the rotation face 13 d of the impeller 13 a, wherein the boss 31 is formed to protrude outward from the end face 13 c of the impeller 13 a sucking the air, and is provided with the screw hole 31 a opening, on a side face of a protruding portion of the boss 31, for fastening the rotation shaft 32 with a screw.
In the above configuration, the boss for securing the rotation shaft transmitting rotational force of the motor is formed to protrude outward from the end face of the impeller sucking the air. The boss is provided with the screw hole opening, on the side face of a protruding portion of the boss, for fastening the rotation shaft with a screw. Thanks to the features, a blade of the impeller does not have to be partially notched or removed in order to pass a screw through the screw hole, opening on a side face of the boss, when the rotation shaft is fastened with the screw, unlike the case when the boss is formed inward in relation to the air-sucking end face of the impeller.
Such features make it possible to reduce a decrease in a volume of the air when a blade of the impeller is partially notched or removed.
In addition, a mold for forming the impeller does not have to be shaped into a complex shape, unlike the case where a blade of the impeller is to be partially notched or removed.
In the sirocco fan, of a second aspect of the present invention, according to the first aspect, the impeller 13 a may include two impellers 13 a each having a face (the disc face 13 b) across from the end face 13 c sucking the air, and connected together through the face, and the screw hole 31 a opening on the boss 31 of one of the two impellers 13 a and the screw hole 31 a opening on the boss 31 of another one of the two impellers 13 a may be provided not in a single plane.
In the above configuration, when two impellers are connected together, the screws tightening the rotation shaft on the bosses for the two impellers are provided not in a single plane, thereby reducing an imbalance of weight distribution due the weight of the screws. Such a feature contributes to stable rotation of the two impeller.
In the sirocco fan, of a third aspect of the present invention, according to the second aspect, the screw hole 31 a opening on the boss 31 of one of the two impellers 13 a and the screw hole 31 a opening on the boss 31 of the other one of the two impellers 13 a may shift 180° from each other in a rotation direction of the rotation shaft 32.
In the above configuration, the screw hole opening on the boss of one of the two impellers and the screw hole opening on the boss of the other one of the two impellers shift 180° from each other in the rotation direction of the rotation shaft. Accordingly, the screws tightening the rotation shaft on the bosses for the two impellers are provided not in a single plane, and are positioned to shift 180° from each other in the rotation direction of the rotation shaft, thereby reducing an imbalance of weight distribution due the weight of the screws. Such a feature contributes to stable rotation of the two impeller.
In the sirocco fan, of a fourth aspect of the present invention, according to the second or third aspect, at least one of the two impellers 13 a may include the marking 41 identifying a direction in which the rotation shaft 32 is mounted.
When a typical sirocco fan rotates in a wrong direction, the air is not sucked in a face perpendicular to the rotation direction of the impellers. On the contrary, the air is blown out of the face. In order to avoid such a problem, the impellers need to be secured to the rotation shaft not to rotate in the wrong direction.
As can be seen, the marking is provided to at least one of the impellers to identify the direction in which the impellers are mounted on the rotation shaft. Such a feature makes it possible to reduce the risk of mounting the impellers on the rotation shaft in the wrong rotation direction.
In the sirocco fan, of a fifth aspect of the present invention, according to any one of the first to fourth aspects, the boss may be made of aluminum.
In the above configuration, the bosses are made of aluminum, contributing to reducing the weight of the sirocco fan as a whole.
A blowing device of a sixth aspect of the present invention includes the sirocco fan (the air-blowing fan 13) according to any one of the second to fifth aspects, the sirocco fan (the air-blowing fan 13) including a plurality of sirocco fans (the air-blowing fans 13) rotatably connected together in series.
Such a configuration allows the blowing device to supply a sufficient volume of air.
An air conditioner of a seventh aspect of the present invention includes the sirocco fan (the air-blowing fan 13), according to any one of the first to fifth aspects, serving as a blowing device.
In the above configuration, the air to be obtained is larger in volume and higher in pressure compared with a case of using a cross-flow fan as the air-blowing fan. In the use of an HEPA filter for air purification, such a feature makes it possible to ensure a sufficient volume of the air (a sufficient volume of the air to be sucked).
The present invention shall not be limited to the embodiments described above, and can be modified in various manners within the scope of claims. The technical aspects disclosed in different embodiments are to be appropriately combined together to implement an embodiment. Such an embodiment shall be included within the technical scope of the present invention. Moreover, the technical aspects disclosed in each embodiment are combined to achieve a new technical feature.

REFERENCE SIGNS LIST

13 Air-Blowing Fan (Sirocco Fan)
13 a Impeller
13 b Disc Face
13 c End Face
13 d Rotation Face
31 Boss
31 a Screw Hole
32 Rotation Shaft
33 Driving Motor (Motor)
35 Joint
41 Marking

Claims

1. A sirocco fan comprising

an impeller including a boss for securing a rotation shaft transmitting rotational force of a motor, the impeller being configured to rotate to suck air from a direction in parallel with the rotation shaft, and to eject the air from a rotation face of the impeller, wherein

the boss is formed to protrude outward from an end face of the impeller sucking the air, and is provided with a screw hole opening, on a side face of a protruding portion of the boss, for fastening the rotation shaft with a screw.

2. The sirocco fan according to claim 1, wherein

the impeller includes two impellers each having a face across from the end face sucking the air, and connected together through the face, and

the screw hole opening on the boss of one of the two impellers and the screw hole opening on the boss of an other one of the two impellers are provided not in a single plane.

3. The sirocco fan according to claim 2, wherein

the screw hole opening on the boss of one of the two impellers and the screw hole opening on the boss of the other one of the two impellers shift 180° from each other in a rotation direction of the rotation shaft.

4. The sirocco fan according to claim 2, wherein

at least one of the two impellers includes a marking identifying a direction in which the rotation shaft is mounted.

5. The sirocco fan according to claim 1, wherein

the boss is made of aluminum.

6. A blowing device comprising

the sirocco fan according to claim 2, the sirocco fan including a plurality of sirocco fans rotatably connected together in series.

7. An air conditioner comprising

the sirocco fan, according to claim 1, serving as a blowing device.