JP2012211576A - Centrifugal air blower and air conditioner with the same - Google Patents

Abstract

A centrifugal blower capable of suppressing a decrease in fan efficiency due to a leakage flow is provided.
A bell mouth 25 has a flare portion 221 whose inner diameter and outer diameter become smaller from the front F in the axial direction toward the rear R, and a rear R in the axial direction A than the flare 221 and has an air suction port. And a straight portion 222 that is inserted into the shroud with a predetermined gap between the peripheral portion and the inner diameter and the outer diameter are constant in the axial direction A. The flare portion 221 has a plurality of wall portions 27 that are arranged at predetermined intervals along the circumferential direction of the outer peripheral surface 25s and rise from the outer peripheral surface 25s. Each wall portion 27 extends along the outer peripheral surface 25s from the front F in the axial direction A toward the rear R so as to be substantially parallel to the axial direction A and the radial direction of the bell mouth 25.
[Selection] Figure 4

Description

  The present invention relates to a centrifugal blower and an air conditioner including the same.

  Conventionally, for example, a centrifugal blower is used as a blower of an indoor unit of an air conditioner. In this centrifugal blower, when the fan motor is driven and the impeller rotates, air is sucked into the housing of the indoor unit from the suction port of the indoor unit. The sucked air is guided by the bell mouth to the air inlet of the shroud. Hereinafter, the air flow guided to the air suction port by the bell mouth is referred to as a main flow.

  This mainstream air is sent to the outside in the radial direction by a plurality of blades arranged in the circumferential direction between the hub and the shroud, and most of the air is blown into the room through the blowout port of the indoor unit. The part circulates toward the bell mouth through the space between the outer peripheral surface of the shroud and the housing in the indoor unit, and joins the main stream again through the gap between the bell mouth and the shroud. Hereinafter, the air flow that circulates as described above and merges with the main flow through the gap is referred to as a leakage flow (circulation flow). When a leakage flow in which a part of the main flow branches is generated in this way, the amount of air blown into the room is reduced by that amount, so that the fan efficiency is lowered.

  For example, Patent Literature 1 discloses a centrifugal blower in which a large number of grooves are provided on the outer surface of a bell mouth (fan guide) in order to suppress a decrease in fan efficiency. In this centrifugal blower, the leakage flow that circulates toward the bell mouth through the space between the outer peripheral surface of the shroud and the casing is introduced into the gap between the bell mouth and the shroud through the groove (Patent Document). 1 paragraph numbers 0024 and 0052, see FIGS. 5 and 6). Patent Document 1 describes that since the leakage flow is guided by the groove as described above and becomes a stable flow, it is possible to suppress a decrease in the blowing performance due to the fluctuation of the leakage flow.

JP 2001-3899 A

  By the way, in the centrifugal blower described in Patent Document 1, it is considered that a part of the air in the leakage flow needs to enter the inside of the groove in order for the leakage flow to be guided by the groove to become a stable flow.

  However, since the air flowing around the groove at a high speed easily passes through the vicinity of the groove rather than entering the groove, the effect of guiding the air through the groove is not necessarily sufficient. Therefore, further improvement in fan efficiency is desired in the centrifugal fan.

  Then, this invention is made | formed in view of this point, The place made into the objective is providing the centrifugal air blower which can suppress the fall of the fan efficiency resulting from a leak flow.

  (1) The centrifugal blower of the present invention includes an impeller (23) and a bell mouth (25). The impeller (23) is arranged on the inner surface of the shroud (19) along the circumferential direction of the air suction port (19a), and a shroud (19) having a circular air suction port (19a). A plurality of blades (21). The impeller (23) is fixed to the rotating shaft (13) of the fan motor (11). The bell mouth (25) is disposed in front of the shroud (19) in the axial direction (F) of the rotating shaft (13).

  The bell mouth (25) has a flare portion (221) and a straight portion (222). The flare portion (221) has an inner diameter and an outer diameter that decrease from the front (F) to the rear (R) in the axial direction. The straight portion (222) is positioned rearward (R) in the axial direction than the flare portion (221), and a predetermined gap is provided between the straight portion (222) and the peripheral edge portion (19e) of the air suction port (19a). The inner diameter and the outer diameter are constant in the axial direction.

  The flare portion (221) has a plurality of wall portions (27) that are arranged at predetermined intervals along the circumferential direction of the outer peripheral surface (25s) and stand up from the outer peripheral surface (25s). Each wall portion (27) has the outer peripheral surface (25s) from the front (F) to the rear (R) in the axial direction so as to be substantially parallel to the axial direction and the radial direction of the bell mouth (25). It extends along.

  In this configuration, since the bell mouth (25) has a plurality of wall portions (27), the wall portion (27) serves as a leakage flow resistance, and the amount of leakage flow can be reduced. Moreover, since the direction of the leakage flow can be made closer to the direction of the main flow, it is possible to suppress the main flow from being disturbed when the leakage flow joins the main flow. Thereby, the fall of fan efficiency can be suppressed. In addition, a noise reduction effect can be expected. Specifically, it is as follows.

  That is, the mainstream air guided to the air suction port (19a) of the shroud (19) by the bell mouth (25) is mainly in the axial direction of the rotating shaft (13) in the vicinity of the air suction port (19a). It flows in the direction along. On the other hand, the leakage flow in the conventional centrifugal blower is affected by the air flow in the rotation direction caused by the rotation of the shroud (19) and is directed to the direction inclined from the axial direction of the rotation shaft (13) to the rotation direction. Flowing. In this way, in the vicinity of the air suction port (19a) where the main flow and the leakage flow merge, the directions of the main flow and the leakage flow are greatly different, so when the leakage flow merges with the main flow, the main flow is disturbed by the leakage flow. As a result, fan efficiency is reduced.

  On the other hand, in the configuration of the present invention, the outer peripheral surface of the bell mouth (25) from the front (F) to the rear (R) in the axial direction so that the wall (27) is substantially parallel to the axial direction and the radial direction ( 25s). That is, the air flow path (29) sandwiched between the adjacent wall portions (27) faces in the direction along the axial direction. This air flow path (29) is a space in which both sides and the bottom are surrounded by the adjacent wall portion (27) and the outer peripheral surface (25s) of the bell mouth (25). The inlet and outlet of the leak flow into the are open and unobstructed. Therefore, since the leakage flow can be reliably guided and circulated in the air flow path (29) between the adjacent wall portions (27), an excellent effect of guiding the leakage flow can be obtained.

  In the course of the leakage flow flowing in the inclined direction reaching the wall (27) and passing through the air flow path (29) between the adjacent wall portions (27), the air flow path (29) corrects the direction of leakage flow in the axial direction. Therefore, compared to the case where the plurality of wall portions (27) are not provided, the resistance that air receives during circulation increases. Thereby, the quantity of the leakage flow branched from the main flow can be reduced. Moreover, in the vicinity of the air suction port (19a), the flow direction of the leakage flow rectified by the air flow path (29) is close to the axial direction, which is the main flow direction. Therefore, when the leakage flow merges with the main flow in the vicinity of the air suction port (19a), the degree of interference of the leakage flow with the main flow is reduced. Therefore, it is possible to suppress a decrease in fan efficiency due to the leakage flow.

  In this configuration, since the straight portion (222) is provided at the rear (R) of the flare portion (221), the flare portion (221) and the straight portion (222) are integrally formed as shown below. It becomes possible.

  (2) In the centrifugal blower, it is preferable that the flare portion (221) and the straight portion (222) are integrally formed.

  In this configuration, since the flare portion (221) and the straight portion (222) are integrally formed, the manufacturing cost can be reduced. The flared portion (27) of the bell mouth (25) has a plurality of wall portions (27), but the rear (R) portion of the flared portion (221) is a straight portion (222). For example, the bell mouth (25) can be integrally formed at a low cost by a molding means such as injection molding using a pair of molds arranged to face each other in the axial direction.

  (3) In the centrifugal blower, the standing height from the outer peripheral surface (25s) of the flare portion (221) at the front end (27f) of each wall portion (27) is as follows. It is preferable that the height of the flare portion (221) is larger than the standing height from the outer peripheral surface (25s) of the rear (R) end portion (27r) of 27).

  In this configuration, the wall portion can catch a large amount of leakage flow at the rear end portion where the standing height is large and guide it to the air flow path, while the front end portion where the standing height is small. The contact with the peripheral edge of the air inlet of the shroud can be suppressed.

  (4) In the centrifugal blower, the height of each wall portion (27) from the outer peripheral surface (25s) of the flare portion (221) is from the rear (R) end portion (27r) to the front (F) It is preferable that it gradually increases toward the end (27f).

  In this configuration, since the standing height of each wall portion changes smoothly, the air flow in the air flow path becomes smoother.

  (5) In the centrifugal blower, the rear (R) end (27r) of each wall (27) has a front height (F) from the outer peripheral surface (25s) of the flare (221). The peripheral surface (19e) of the air suction port (19a) is an inclined surface facing the inclined surface of the wall (27). Is preferred.

  In this configuration, the rear end portion of each wall portion and the peripheral edge portion of the air suction port are the inclined surfaces facing each other, so that the wall portion can be extended to the vicinity of the shroud and each other during rotation. Can be prevented from contacting.

  (6) In the centrifugal fan, the axially rear (R) end of each wall (27) is in a radial direction with respect to the axially forward (F) end of the shroud (19). It is preferable that it is located in the position which opposes or its vicinity.

  In this configuration, the axially rearward (R) end of each wall portion (27) is opposed to the axially forward (F) end of the shroud (19) in a radial direction or Since it is located in the vicinity thereof, the leakage flow can be guided to the air suction port (19a) of the shroud (19) or to the vicinity of the air suction port (19a). Thereby, the fall of the fan efficiency resulting from a leak flow can further be suppressed.

  (7) In the centrifugal blower, the axially rear (R) end of each wall (27) is more forward than the axially forward (F) end of the shroud (19) (F ).

  In this configuration, the axially rearward (R) end of each wall (27) is positioned forward (F) relative to the axially forward (F) end of the shroud (19). Therefore, it can prevent that each wall part (27) contacts a shroud (19).

  (8) Since the air conditioner of the present invention includes the centrifugal blower, it is possible to suppress a decrease in fan efficiency due to leakage flow.

  As described above, according to the present invention, it is possible to suppress a decrease in fan efficiency due to leakage flow.

It is sectional drawing which shows the indoor unit provided with the centrifugal blower which concerns on one Embodiment of this invention. It is a bottom view which shows the positional relationship of the impeller in the said indoor unit, a heat exchanger, and a blower outlet. It is a perspective view which shows the impeller of the said centrifugal blower. It is a side view which shows the bell mouth of the said centrifugal blower. It is a top view which shows the bell mouth of the said centrifugal blower. It is the side view to which a part of FIG. 4 was expanded. It is sectional drawing to which some centrifugal fans were expanded. It is sectional drawing which showed the positional relationship of the shroud of the said impeller, and the said bellmouth. Fig. 2 shows a method of molding the bell mouth, wherein (A) is a side view showing a state where a molding die is closed before molding or during molding, and (B) is a molding die after molding. It is a side view which shows the state which opened. (A) is sectional drawing which shows the flow of the air in the said centrifugal blower, (B) is sectional drawing which shows the flow of the air in the modification of the said centrifugal blower.

  Hereinafter, a centrifugal blower 51 and an air conditioner 31 including the centrifugal blower 51 according to an embodiment of the present invention will be described with reference to the drawings.

<Overall structure of air conditioner>
As shown in FIG. 1, the air conditioner 31 according to the present embodiment is a ceiling-embedded cassette indoor unit. The air conditioner 31 includes a substantially rectangular parallelepiped housing 33 embedded in an opening provided in the ceiling, and a decorative panel 47 attached to the lower portion of the housing 33. The decorative panel 47 is slightly larger in plan view than the housing 33 and is exposed to the room in a state of covering the opening of the ceiling. The decorative panel 47 has a rectangular suction grill 39 provided in the center thereof, and four elongated rectangular outlets 37 provided along each side of the suction grill 39.

  The air conditioner 31 includes a centrifugal blower (turbo fan) 51, a fan motor 11, a heat exchanger 43, a drain pan 45, an air filter 41, and the like in a housing 33. Centrifugal blower 51 includes an impeller 23 and a bell mouth 25. The fan motor 11 is fixed to the approximate center of the top plate of the housing 33. The rotation shaft 13 of the fan motor 11 extends downward.

  As shown in FIGS. 1 and 2, the heat exchanger 43 has a flat shape with a small thickness. The heat exchanger 43 is disposed so as to surround the periphery of the impeller 23 in a state where it rises upward from a dish-shaped drain pan 45 extending along the lower end portion thereof. The drain pan 45 stores water droplets generated in the heat exchanger 43. The stored water is discharged through a drainage path (not shown).

  The air filter 41 has a size that covers the inlet of the bell mouth 25, and is provided along the suction grill 39 between the bell mouth 25 and the suction grill 39. The air filter 41 captures dust in the air when the air sucked into the housing 33 from the suction grill 39 passes through the air filter 41.

  As shown in FIGS. 1 to 3, the impeller 23 includes a hub 15, a shroud 19, and a plurality of blades 21. The hub 15 is fixed to the lower end portion of the rotating shaft 13 of the fan motor 11. The hub 15 has a circular shape centered on the rotation shaft 13 in plan view.

  The shroud 19 is disposed to face the front F in the axial direction A of the rotary shaft 13 with respect to the hub 15. The shroud 19 has an air suction port 19 a that opens in a circle around the rotation shaft 13. The outer diameter of the shroud 19 increases from the front F toward the rear R.

  The plurality of blades 21 are arranged between the hub 15 and the shroud 19 at a predetermined interval along the circumferential direction of the air suction port 19a. The front F end of each blade 21 is joined to the inner surface of the shroud 19. The rear R end of each blade 21 is joined to the hub 15. Each blade 21 is a backward blade that is inclined in the direction opposite to the rotation direction (backward) with respect to the radial direction of the hub 15.

<Bellmouth structure>
As shown in FIG. 1, the bell mouth 25 is disposed to face the front F in the axial direction A with respect to the shroud 19. As shown in FIGS. 4 and 5, the bell mouth 25 includes a bell mouth main body 22 and a flange portion 24. The flange portion 24 is a portion projecting radially outward from the peripheral edge of the front F of the bell mouth main body 22. The bell mouth 25 is made of, for example, a synthetic resin or a metal.

  The bell mouth main body 22 includes a flare portion 221 and a straight portion 222. The flare portion 221 is a portion where the inner diameter and the outer diameter become smaller from the front F in the axial direction A toward the rear R. The straight portion 222 is located rearward R in the axial direction A with respect to the flare portion 221, and has a constant inner diameter and outer diameter in the axial direction A. The straight part 222 is integrally formed with the flare part 221 by a method described later, for example.

  The bell mouth main body 22 has a through hole 25a penetrating in the front-rear direction. The outer peripheral surface 25 s of the bell mouth 25 (the outer peripheral surface 25 s of the bell mouth main body 22) has a curved shape in which the outer diameter decreases from the front F toward the rear R in the region of the flare portion 221. In the region, the outer diameter is almost constant.

  As shown in FIG. 1, the straight portion 222 is inserted into the shroud 19 from the air suction port 19a with a predetermined gap provided between the straight portion 222 and the peripheral edge portion 19e of the air suction port 19a. Thereby, the bell mouth 25 can guide the air sucked from the front F toward the rear R through the through hole 25 a to the air suction port 19 a of the shroud 19.

  4-6, the flare part 221 has the several wall part 27 arranged at predetermined intervals along the circumferential direction of the outer peripheral surface 25s. Each wall portion 27 stands (is erected) from the outer peripheral surface 25 s of the flare portion 221. Each wall portion 27 extends along the outer peripheral surface 25 s from the front F in the axial direction A toward the rear R so as to be substantially parallel to the axial direction A and the radial direction of the bell mouth 25.

  As shown in FIG. 6, the bell mouth 25 has a plurality of air flow paths 29 surrounded on three sides by adjacent wall portions 27, 27 and an outer peripheral surface 25s. The air flow path 29 faces in the direction along the axial direction A. The air channel 29 is surrounded on both sides and bottom by the adjacent wall 27 and the outer peripheral surface 25s of the bell mouth 25, but the inlet and outlet of the leak flow into the air channel 29 are open. There is nothing to block. Accordingly, the leakage flow is reliably guided to the inlet of the air flow path 29 between the wall portions 27 and guided in the air flow path 29 from the front F toward the rear R.

  A rear R end (rear end) 27r of each wall 27 is located at a position facing the end of the front F of the shroud 19 in the axial direction A in the radial direction or in the vicinity thereof. The rear end portion 27r of each wall portion 27 may be positioned in front F of the front F end portion of the shroud 19 in the axial direction A.

  As shown in FIGS. 7 and 8, the standing height from the outer peripheral surface 25 s of each wall portion 27 gradually increases from the rear end portion 27 r toward the front F end portion (front end portion) 27 f. Each wall portion 27 has a standing height Hf at the front end portion 27f larger than a standing height Hr at the rear end portion 27r. The standing height Hr and the standing height Hf are not particularly limited. For example, the standing height Hr is about 1 mm to 10 mm, and the standing height Hf is about 3 mm to 20 mm. it can.

  As shown in FIGS. 6 and 8, the rear end portion 27 r of each wall portion 27 is an inclined surface inclined with respect to the axial direction A. In this inclined surface, the standing height from the outer peripheral surface 25 s gradually decreases from the front F toward the rear R.

  On the other hand, as shown in FIG. 8, the peripheral edge portion 19 e of the air suction port 19 a is an inclined surface inclined with respect to the axial direction A. The inclined surface of the peripheral edge portion 19e is provided to face the inclined surface of the rear end portion 27r of each wall portion 27. In other words, the tip of the rear end portion 27r of each wall portion 27 is provided at a position (substantially the same height) that substantially faces the tip end of the peripheral edge portion 19e that is the end portion of the front F of the shroud 19 in the radial direction. . Both the inclined surface of the peripheral edge portion 19e and the inclined surface of the end portion 27r of the wall portion 27 are inclined so that the rear R is located on the inner side in the radial direction than the front F. As described above, since the end portions are formed by the inclined surfaces, the rear end portion 27r of each wall portion 27 can be extended to a position facing the peripheral edge portion 19e of the shroud 19 or the vicinity thereof.

  Next, the flow of air in the centrifugal blower 51 will be described. As shown in FIG. 8, the mainstream S air guided to the air suction port 19a of the shroud 19 by the bell mouth body 22 of the bell mouth 25 is mainly the rotating shaft 13 of the shroud 19 in the vicinity of the air suction port 19a. In the direction along the axial direction A.

  In the conventional centrifugal blower that does not have the wall 27, the leakage flow M1 is caused by the shroud 19 rotating in the rotation direction K in the vicinity of the air suction port 19a as indicated by the broken arrow M1. The air flows in the direction inclined from the axial direction A to the rotational direction K by being influenced by the air flow to K. Therefore, when this leakage flow M1 merges with the main flow S, the flow of the main flow S is disturbed by the leakage flow M1, resulting in an increase in blowing sound and a decrease in fan efficiency.

  On the other hand, in the centrifugal blower 51 of the present embodiment, the leak flow M is along the air flow path 29 surrounded by the adjacent wall portion 27 and the outer peripheral surface 25 s of the bell mouth main body 22 as indicated by the one-dot chain line arrow M. Then, it is guided from the front F to the rear R, and passes through a gap between the rear R end of the bell mouth body 22 and the front F end of the shroud 19. The leakage flow M that has passed through the gap is corrected so that the flow direction approaches the axial direction A in the vicinity of the air suction port 19a as compared with the conventional case. Accordingly, interference when the leakage flow M joins the main flow S is suppressed.

  Next, a method for manufacturing the bell mouth 25 will be described by taking as an example the case where the bell mouth 25 is made of synthetic resin.

  As shown in FIGS. 9A and 9B, the bell mouth main body 22 and the flange portion 24 are injection-molded using an upper mold 61 and a lower mold 62. The upper mold 61 has a shape along the shape of the inner peripheral surface of the flare portion 221, the inner peripheral surface of the straight portion 222, and the upper surface of the flange portion 24. The lower mold 62 has a shape along the shape of the outer peripheral surface 25 s of the flare portion 221, the plurality of wall portions 27, the outer peripheral surface of the straight portion 222, and the lower surface of the flange portion 24. The upper mold 61 and the lower mold 62 are slidable in a direction in which they are separated from each other (vertical direction).

  As shown in FIG. 9A, when the mold 61 and the mold 62 are in a state of being closest to each other, a space having the same shape as the flare portion 221 and the flange portion 24 is formed inside and melted in this space. Resin is injected. Thereafter, as shown in FIG. 9B, the molds 61 and 62 slide in a direction away from each other, and the molded body is taken out. The molded body is a bell mouth 25 in which a flare portion 221, a straight portion 222, and a flange portion 24 are integrally formed, and a plurality of wall portions 27 are formed on the outer peripheral surface 25s of the flare portion 221.

<Outline of Embodiment>
This embodiment is summarized as follows.

  (1) In the present embodiment, since the bell mouth 25 has a plurality of wall portions 27, the wall portion 27 serves as a resistance to leakage flow, and the amount of leakage flow can be reduced. Moreover, since the direction of the leakage flow can be made closer to the direction of the main flow, it is possible to suppress the main flow from being disturbed when the leakage flow joins the main flow. Thereby, the fall of fan efficiency can be suppressed and the noise reduction effect can also be expected.

  In the present embodiment, a straight portion 222 is provided at the rear R of the flare portion 221. For example, as shown in FIGS. 10 (A) and 10 (B), in the centrifugal blower 51, some air flow may occur in the vicinity of the inner peripheral surface of the shroud 19 to generate vortices W1 and W2. Since such vortices W1 and W2 affect the fan efficiency, it is preferable to suppress the generation thereof. The degree of vortex generation is related to the structure of the centrifugal blower 51, particularly the length of the bell mouth 25 in the axial direction A and the length of the shroud 19 in the axial direction A.

  The length h1 in the axial direction A of the bell mouth 25 in the centrifugal blower 51 shown in FIG. 10 (A) is larger than the length h3 in the axial direction A of the bell mouth 25 in the centrifugal blower 51 shown in FIG. 10 (B). Further, the length h2 of the shroud 19 in the axial direction A of the centrifugal blower 51 shown in FIG. 10A is larger than the length h4 of the shroud 19 in the axial direction A of the centrifugal blower 51 shown in FIG. In such a case, in the centrifugal blower 51 shown in FIG. 10 (A), the change in the direction of the airflow is gentler than that in the centrifugal blower 51 shown in FIG. 10 (B), so in the vicinity of the inner peripheral surface of the shroud 19. There is a tendency for airflow to be less likely to occur. Therefore, the vortex W1 in the centrifugal blower 51 shown in FIG. 10A tends to be smaller than the vortex W2 in the centrifugal blower 51 shown in FIG. 10B.

  Therefore, in the centrifugal blower 51 shown in FIG. 10A with a relatively small vortex W1, by providing the straight part 222 at the rear R of the flare part 221, the cost can be reduced by integral molding as shown in the following (2). However, the generation of the vortex W1 is also suppressed to a small level.

  (2) In this embodiment, since the flare part 221 and the straight part 222 are integrally molded, manufacturing cost can be reduced. The flared portion 221 of the bell mouth 25 has a plurality of wall portions 27. Since the rear portion R of the flared portion 221 is the straight portion 222, for example, a pair of gold plates arranged opposite to each other in the axial direction. The bell mouth 25 can be integrally formed at a low cost by molding means such as injection molding using a mold.

  (3) In the present embodiment, the standing height from the outer peripheral surface 25s of the flare portion 221 at the front end portion 27f of each wall portion 27 is the outer peripheral surface of the flare portion 221 at the rear end portion 27r of each wall portion 27. Since each wall portion 27 can catch a large amount of leakage flow at the rear end portion where the standing height is large and guide it to the air flow path, while it is larger than the standing height from 25 s. Contact with the peripheral edge portion 19e of the air inlet 19a of the shroud 19 can be suppressed at the front end portion where the installation height is small.

  (4) In the present embodiment, the standing height of each wall portion 27 from the outer peripheral surface 25s of the flare portion 221 gradually increases from the rear end portion 27r toward the front end portion 27f. Since the standing height of the air flow changes smoothly, the air flow in the air flow path 29 becomes smoother.

  (5) In the present embodiment, the rear end portion 27r of each wall portion 27 is an inclined surface in which the standing height from the outer peripheral surface 25s of the flare portion 221 gradually decreases from the front F toward the rear R. Since the peripheral edge portion 19e of the air suction port 19a is an inclined surface facing the inclined surface of the wall portion 27, each wall portion 27 can be extended to the vicinity of the shroud 19 and contact each other during rotation. Can be suppressed.

  (6) In this embodiment, the rear end portion 27r of each wall portion 27 is located at a position facing the front end (F) in the axial direction A of the shroud 19 in the radial direction or in the vicinity thereof. Therefore, the leakage flow can be guided to the air suction port 19a of the shroud 19 or to the vicinity of the air suction port 19a. Thereby, the fall of the fan efficiency resulting from a leak flow can further be suppressed.

  (7) In the present embodiment, the rear end portion 27r of each wall portion 27 is located in front F of the end portion of the shroud 19 in the axial direction, so that each wall portion 27 is connected to the shroud 19. Contact can be prevented.

<Other embodiments>
As mentioned above, although embodiment of this invention was described, this invention is not limited to each said embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the meaning.

  For example, in the above-described embodiment, the case where the flare portion and the straight portion are integrally formed is illustrated, but these may be joined to each other after being separately molded.

  Moreover, in the said embodiment, although the form which increased the said standing height of each wall part gradually from back to front was illustrated, the said standing height was increased stepwise from back to front. May be. Moreover, the said standing height of each wall part may be constant from back to front, and may decrease toward the front from the back.

  Moreover, in the said embodiment, the rear-end part of each wall part is an inclined surface from which the said standing height reduces gradually toward the back from the said front, The said peripheral part of the said air inlet is the said wall part However, the present invention is not limited to this example. The rear end portion of each wall portion may be a surface perpendicular to the axial direction instead of an inclined surface. Similarly, the peripheral edge portion of the air suction port may be a surface perpendicular to the axial direction.

  Moreover, in the said embodiment, when the front-end | tip of the rear-end part of each wall part is provided in the position (substantially the same height) which opposes the front-end | tip of the peripheral part which is the edge part ahead of a shroud in radial direction. However, the present invention is not limited to this. The rear end portion of each wall portion may be provided in front of or behind the front end portion of the shroud.

  Moreover, in the said embodiment, although the case where the centrifugal air blower was used for the ceiling embedded type cassette indoor unit was illustrated, it can be used for other types of indoor units, and for other uses other than the air conditioner. It can also be used.

DESCRIPTION OF SYMBOLS 11 Fan motor 13 Rotating shaft 15 Hub 17 Air suction port 19 Shroud 19a Air suction port 19e Peripheral part of air suction port 21 Blade 22 Bell mouth main body 221 Flare part 222 Straight part 23 Impeller 24 Flange part 25 Bell mouth 25a Through hole 25s Bellmouth outer peripheral surface 26 Belt portion 27 Wall portion 27f Wall portion front end portion 27r Wall portion rear end portion 29 Air flow path 31 Indoor unit A Axial direction of fan motor rotation shaft F Forward R Rear

Claims (8)

A shroud (19) having an air suction port (19a) that opens in a circle, and a plurality of blades (21) arranged on the inner surface of the shroud (19) along the circumferential direction of the air suction port (19a). An impeller (23) fixed to the rotating shaft (13) of the fan motor (11),
A bell mouth (25) disposed forward (F) in the axial direction of the rotating shaft (13) rather than the shroud (19), and
The bell mouth (25)
A flare portion (221) in which the inner diameter and the outer diameter decrease from the front (F) in the axial direction toward the rear (R),
The shroud (19) is located behind the flare portion (221) in the axial direction (R), and a predetermined gap is provided between the air suction port (19a) and a peripheral edge portion (19e). A straight portion (222) inserted inside and having an inner diameter and an outer diameter constant in the axial direction,
The flare portion (221) has a plurality of wall portions (27) that are arranged at predetermined intervals along the circumferential direction of the outer peripheral surface (25s) and rise from the outer peripheral surface (25s),
Each wall portion (27) has the outer peripheral surface (25s) from the front (F) to the rear (R) in the axial direction so as to be substantially parallel to the axial direction and the radial direction of the bell mouth (25). A centrifugal blower that extends along.   The centrifugal blower according to claim 1, wherein the flare portion (221) and the straight portion (222) are integrally formed.   The standing height from the outer peripheral surface (25s) of the flare portion (221) at the front end (27f) of each wall portion (27) is the rear (R) of each wall portion (27). The centrifugal fan according to claim 1 or 2, wherein the height of the flare portion (221) at the end portion (27r) is larger than the standing height from the outer peripheral surface (25s).   The erected height of each wall portion (27) from the outer peripheral surface (25s) of the flare portion (221) is from the rear (R) end portion (27r) to the front (F) end portion (27f). The centrifugal blower according to claim 3, which gradually increases. The rear (R) end (27r) of each wall (27) has a standing height from the outer peripheral surface (25s) of the flare (221) from the front (F) to the rear (R). A slope that gradually decreases,
The centrifugal blower according to any one of claims 1 to 4, wherein the peripheral edge portion (19e) of the air suction port (19a) is an inclined surface facing the inclined surface of the wall portion (27).   The axially rearward (R) end of each wall (27) is at or near a position facing the axially forward (F) end of the shroud (19) in the radial direction. The centrifugal blower according to claim 1, wherein the centrifugal blower is located.   The axially rear (R) end of each wall (27) is positioned forward (F) relative to the axially forward (F) end of the shroud (19). Item 7. The centrifugal blower according to Item 6.   The air conditioner provided with the centrifugal blower of any one of Claims 1-7.

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