JP3487238B2 - Bell mouth structure of blower - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a structure of a bell mouth portion of a blower.

[0002]

2. Description of the Related Art For example, in an axial blower such as a propeller fan or a centrifugal blower such as a turbo fan, the air on the suction side is smoothly guided to the blowout side in accordance with an impeller for blowing air to reduce the amount of leakage. There is a bell mouth to reduce.

The structure of the conventional bell mouth portion of each of these blowers is shown in FIGS. 9, 10 and 11, respectively.

First, FIGS. 9 and 10 show the structure of a bell mouth portion of a propeller fan 1 which is an example of an axial flow type blower, 2 is an impeller for blowing air of the propeller fan 1, and 3 is the impeller. It is a bell mouth provided on the outer peripheral side of 2 through a predetermined gap S. The impeller 2 includes a hub 2a fixed to a motor shaft (not shown) and a plurality of blades 2b, 2 integrally formed on the outer periphery of the hub 2a with a predetermined blade angle at a predetermined interval.
It consists of b ...

Further, the bell mouth 3 has an air suction opening 3 on its inner peripheral side which is open to the air suction side with a predetermined radius of curvature.
a, a fan guide opening 3b having a predetermined width and extending in the air blowing direction from the air suction opening 3a, and an air blowing opening from the fan guide opening 3b to the air blowing side with a predetermined radius of curvature. It has the airflow guide part continuous with the opening 3c for use. The end of the air outlet 3c is attached to the partition plate 4 having a vertical wall structure, for example.

In this case, in a general bell mouth, as shown in, for example, FIGS. 9 and 10, the air suction opening 3a thereof is provided.
The so-called axisymmetric shape is used in which the height and the radius of curvature of the entire airflow guide portion from the above to the air outlet 3c are constant.

By the way, the bell mouth 3 is generally made of synthetic resin or metal. From the viewpoint of reducing aerodynamic noise during air blowing, the bell mouth 3 extends from the air suction opening 3a to the air blowing opening 3c. By making the shape of the airflow guide surface (peripheral surface shape) a combination of a curved surface having a predetermined radius of curvature and a flat surface as described above, the airflow that flows into the fan guide opening 3b from the air intake opening 3a side. The state and the airflow state flowing out from the fan guide opening 3b toward the air blowing opening 3c are made as smooth as possible without disturbance.

Next, FIG. 11 shows a structure of a bell mouth portion of a turbofan 10 as an example of a centrifugal blower.

In the figure, reference numeral 11 is an impeller for blowing air from the turbofan 10. The impeller 11 is a hub 11a fixed to a drive shaft 20a of a motor 20 and air in the centrifugal direction inside the impeller 11. The other end side shroud 11b forming the suction port
And a large number of moving blades 11c, 11c ... Are arranged in parallel in the circumferential direction at a predetermined blade angle and a predetermined blade interval. On the other hand, the end portion 1 of the shroud 11b on the air suction port side
A downstream side air outlet side end portion of the bell mouth 13 is fitted in the inside of the inside 2 with a predetermined gap so as to be relatively rotatable.

The bell mouth 13 is the impeller 1 for blowing air.
In order to allow the air from the blower body side air suction port to smoothly flow into the impeller 10 centrifugal direction toward the air suction port side end portion 12 of the shroud 11b forming the air suction port of No. 1, as shown in the figure. In addition, an air flow guide portion including an air flow inlet portion 13b and an air flow outlet portion 13c having a predetermined radius of curvature, which extends from the attachment edge portion 13a to the blower body and whose opening diameter is gradually reduced from the air flow upstream side to the air flow downstream side. It is configured to have. The shape of the impeller 11 corresponds to the shroud 11b of the blower impeller 11.
By smoothly guiding the air on the suction side in the centrifugal direction on the suction side on the suction side, the aerodynamic noise generated during air blowing is reduced as much as possible.

[0011]

As described above, by making the bellmouth shape of both the axial flow type centrifugal fan and the centrifugal blower close to the ideal airflow guide shape, the turbulence of the airflow in the outer peripheral portion of the impeller and the suction portion is reduced. The amount is reduced to reduce aerodynamic noise.

However, the aerodynamic noise generated in the bell mouth portion is caused by the fine turbulence of the air flow caused by the relationship with each blade part rotating when the impeller rotates and the interference with the air flow guide surface, that is, the pressure fluctuation. There is also aerodynamic noise, and the aerodynamic noise cannot always be sufficiently reduced only by improving the bell mouth shape as described above.

For this reason, as a method of absorbing the pressure fluctuation, for example, the airflow guide surface of the bell mouth is formed of a porous material, but in the case of this structure, the surface is rough and not smooth. However, there is a problem that dust easily adheres, dust accumulates on the surface of the porous material with the lapse of operating time, the holes are clogged, and the effect disappears.

The present invention has been made to solve such a problem, and at least a main part of the bell mouth is a hollow cylindrical body or a hollow closed cross-section structure, and the air flow guide portion thereof is configured. By providing a large number of small holes communicating with the outside for absorbing pressure fluctuations , the dust is less likely to adhere, and the adhered dust is sucked into the inside through the small holes. Thus, it is an object of the present invention to provide a bellmouth structure of a blower having a pressure fluctuation absorbing structure in which the pressure fluctuation absorbing effect does not disappear for a long period of time even with the lapse of operating time.

[0015]

In order to achieve the above-mentioned object, each invention of the present application is provided with the following problem solving means.

(1) Invention of Claim 1 This invention is a bell mouth of a blower which is provided corresponding to the outer periphery of the impeller 2 for blowing and guides the air on the suction side of the impeller 2 to the blowing side. 3 and has a hollow cylindrical structure, and a large number of small holes 34 for absorbing pressure fluctuations in the inner peripheral wall 32 forming the airflow guide portions 3a, 3b, 3c. , 34 ... provided, the number of small holes 34,
34 ... through the inner hollow space 33 through the external air passage S
It is characterized by communicating with.

Therefore, in this structure, at least the inner peripheral wall 32 is made of synthetic resin, metal, or the like, whereby the airflow guide surfaces of the airflow guide portions 3a, 3b, 3c can be formed smoothly, and dust can be removed. Can be made difficult to adhere and absorb the above pressure fluctuations.
No number of dust that has entered the small holes 34, 34 in ... that circle stopped in the plurality of small holes 34, 34 ... part to, become sucked into the inner space 33.

Therefore, unlike the case of the conventional porous member, the surface of the small hole portion is not clogged due to the accumulation of dust, and the pressure fluctuation absorbing effect does not disappear, and the impeller is rotated for a long period of time. The pressure fluctuation absorbing effect can be maintained.

(2) Invention of Claim 2 This invention is a blower which is provided corresponding to the shroud 11b of the impeller 11 for blowing, and which guides the air on the suction side of the impeller 11 in the blowing direction on the suction side. Of the bell mouth, the portion corresponding to the air flow guide portions 13b and 13c is formed in a closed cross-section structure with a hollow inside, and the pressure fluctuation is absorbed in the inner peripheral wall 15 portion constituting the air flow guide portions 13b and 13c. A large number of small holes 16, 16 ...
· The provided is characterized in that communicates the interior hollow space 17 to the outside air passage W through the multiplicity of small holes 16, 16 ....

Therefore, in this structure, by forming at least the inner peripheral wall 32 portion with synthetic resin, metal, or the like, the airflow guide surfaces of the airflow guide portions 13b and 13c can be formed smoothly, and dust adheres thereto. The pressure fluctuation can be absorbed and
No dust has entered that circle stopped in the plurality of small holes 16, 16 ... part on a number of small holes 16, 16 in ... of order, so sucked into the inner space 17.

Therefore, unlike the case of the conventional porous member, the surface of the small hole portion is not clogged due to the accumulation of dust and the pressure fluctuation absorbing effect does not disappear, and the impeller rotation is performed for a long time. The pressure fluctuation absorbing effect can be maintained.

(3) Invention of Claim 3 This invention is the structure of the invention described in claim 1 above.
A partition wall 35 for partitioning the internal hollow space 33 into a high pressure side region and a low pressure side region is provided in the internal hollow space 33.

By providing the partition wall 35 in this way, it is possible to cut backflow from the high pressure outlet side to the low pressure inlet side in the internal hollow space 33, so that turbulence can be further reduced. become.

(4) Invention of Claim 4 This invention is the structure of the invention described in claim 1 or 2, wherein the sound absorbing material 36, 1 is provided in the internal hollow space 33, 17.
It is characterized by being filled with 9.

When the sound absorbing materials 36 and 19 are filled in this way, in the case of the invention of claim 1, the backflow from the high pressure outlet side to the low pressure suction side is surely performed over the partition wall 35 as described above. While the aerodynamic noise generated can be prevented, the generated aerodynamic noise is more effectively absorbed without causing resonance.

Also in the case of the second aspect of the present invention, the aerodynamic noise generated is not resonated and is more effectively absorbed.

(5) Invention of Claim 5 In the invention according to claim 1, 2, 3 or 4, the bell mouths 3, 13 are provided with bell mouth main bodies 31, 14 and an inner peripheral wall 32. , 15 side are respectively constituted by separate members and are integrated by being combined with each other.

In this way, the bell mouth main body 31, 14 side and the inner peripheral wall 32, 15 portion corresponding to the air flow guide portions 3a to 3c, 13b, 13c are respectively constituted by separate members,
When the bell mouth structures are combined and integrated with each other, molding of each bell mouth structure with a synthetic resin becomes easy.

[0029]

As a result of the above, according to the present invention, it is possible to provide a blower having a low aerodynamic noise and a high blowing performance at a low cost.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) FIG. 1 shows a bell mouth structure of a blower according to Embodiment 1 of the present invention.

FIG. 1 shows the structure of a bell mouth portion of a propeller fan 1 which is an example of an axial flow type blower. Reference numeral 2 is a blower impeller of the propeller fan 1, and 3 is an outer peripheral side of the impeller 2. The bell mouth is provided via a predetermined gap S that is a part of the air passage. The impeller 2 comprises a hub 2a fixed to a motor shaft (not shown), and a plurality of blades 2b, 2b, ... Formed integrally on the outer periphery of the hub 2a with a predetermined blade angle at a predetermined interval. ing. Bell mouse 3
Is formed of, for example, a synthetic resin material into a substantially cylindrical body structure having a hollow interior as a whole, and the air flow guide portion on the inner peripheral side thereof has an air suction opening portion 3a opened to the air suction side with a predetermined radius of curvature, and A fan guide opening portion 3b having a predetermined width extending from the air suction opening portion 3a in the air blowing direction, and an air blowing opening portion 3c opened from the fan guide opening portion 3b to the air blowing side with a predetermined curvature radius. And an airflow guide section that is continuous with the above. The upper end portion on the side of the air blowing opening 3c is, for example, a partition plate 4 having a vertical wall structure.
Installed on.

More specifically, the bell mouth 3 having the substantially cylindrical body structure is formed of the synthetic resin and the bell mouth main body 31 of the substantially semi-cylindrical structure which is located on the upper side and is also formed of the synthetic resin. At the same time, the inner peripheral wall of the substantially semi-cylindrical structure that is located on the lower side and constitutes the above-mentioned airflow guide portion that is fitted integrally with the bell mouth main body 31 from below so as to form the internal hollow space 33 The member 32 and the member 32 are separate from each other, and the inner peripheral wall member 32 of the latter is
A large number of small holes 3 that connect the internal hollow space 33 and the external blower passage (S) to each other from the air intake opening 3a constituting the air flow guide portion to the air blowing opening 3c.
4, 34 ... Are provided. Further, the front end side of the bell mouth main body 31 has a circular arc surface 31b from the outer side to the inner side in the radial direction, and the air flow guide action thereof causes a wide range of inflow from the outer peripheral side in the radial direction of the bell mouth 3. The incoming air is made to smoothly flow around to the air intake opening 3a side. Further, at the upper part of the rear end side of the bell mouth main body 31, an edge 3 for attaching to the partition plate 4
1a is integrally formed and is fixedly supported by the partition plate 4 via the mounting edge portion 31a.

Also in the case of the bell mouth 3 of this embodiment, as in the case of a general bell mouth, the entire cylinder diameter from the air suction opening 3a to the air blowing opening 3c (high And the radius of curvature is constant in the circumferential direction, so-called axisymmetric shape is used.

As described above, the bell mouth 3 of the present embodiment is made of, for example, a synthetic resin material in a substantially cylindrical body structure, and from the viewpoint of reducing aerodynamic noise during air blowing, the air in the air flow guide portion is The airflow guide surface shape (inner peripheral surface shape) from the suction opening 3a to the air blowing opening 3c
Is a combination shape of the curved surface (3a, 3c) having a predetermined radius of curvature and the flat surface (3b) as described above,
From the air intake opening 3a side to the fan guide opening 3b
The airflow state flowing into the airflow state and the airflow state flowing out from the fan guide opening portion 3b toward the air blowout opening portion 3c are made as smooth as possible without disturbance.

However, in the aerodynamic noise generated in the bell mouth 3 portion, the minute turbulence of the airflow and the airflow guide portion caused by the relationship with the respective blade portions 2b, 2b, ... Which rotate when the impeller 2 rotates. Interference with the airflow guide surfaces (3a-3c),
That is, there is also aerodynamic noise due to pressure fluctuation, and the aerodynamic noise cannot be sufficiently reduced only by improving the bell mouth shape as described above.

For this reason, as a method for absorbing the pressure fluctuation, for example, the airflow guide surface of the bell mouth 3 is formed of a porous material. In the case of this structure, the operation is performed as already described. There is a problem that dust adheres to and accumulates on the surface of the porous material with the lapse of time, clogging the pores, and losing its effect.

Therefore, in the present embodiment, as described above, the bell mouth 3 is formed in a substantially cylindrical structure having a hollow inside, and the inner peripheral wall 32 portion forming the air flow guide portions (3a to 3c) thereof. Are provided with a large number of small holes 34, 34 ... Through the small holes 34, 34.
Is communicated with the external ventilation passage (S).

Therefore, in this structure, unlike the conventional porous member, the air flow guide portion (3) is made of, for example, a synthetic resin material.
Since it becomes possible to smoothly form the airflow guide surface itself of a to 3c), it is possible to prevent dust from adhering to the air flow guide surface itself, and the inside is hollow so that the large number of small holes 34, 34. .. communicates with the inside hollow space 33, so that dust that has entered the large number of small holes 34, 34 ... Does not stop at the small holes 34, 34. It is sucked into the inner space 33.

Therefore, unlike the case of the conventional porous member, the surface of the small hole portion is not clogged due to the accumulation of dust and the pressure fluctuation absorbing effect does not disappear, and the impeller is rotated for a long period of time. The pressure fluctuation absorbing effect can be maintained.

Further, in the configuration of the present embodiment, the bell mouth 3 has a bell mouth main body 31 having a concave groove portion and a lid-like air flow guide portion (which covers the concave groove portion of the bell mouth main body 31 as shown in FIG. 2 with the inner peripheral wall member 32 on the 3a to 3c) side
It is composed of separate members of a set, and they are combined with each other to be, for example, fitted and integrated.

As described above, when the bell mouth body 31 and the inner peripheral wall member 32 on the air flow guide portion (3a to 3c) side are formed by separate members and are combined with each other to be fitted and integrated, a synthetic resin molding is performed. In this case, it is sufficient to mold each of them individually, so that molding with a synthetic resin becomes easy regardless of the structure.

As a result, according to the bellmouth structure of the blower of the present embodiment, it is possible to provide an axial flow blower such as a propeller fan having a low aerodynamic noise and a high blow performance at low cost. .

Second Embodiment Next, FIG. 2 shows a bell mouth structure of a blower according to a second embodiment of the present invention.

In this embodiment, the bell mouth structure of the blower of the above-described first embodiment is adopted as a basic structure, and the internal hollow space 33 has the internal hollow space 33 in the high pressure side region and the low pressure side region. It is characterized in that a partition wall 35 made of synthetic resin for partitioning into and is provided.

When the impeller 2 rotates, the suction side of the impeller 2 becomes a low pressure region, while the blow side becomes a high pressure region.

Therefore, when the inner hollow space 33 of the bell mouth 3 is communicated with the external air passage, the space 33 is formed.
In the inside, a backflow is generated from the outlet side toward the inlet side, the airflow is disturbed on both the outlet side and the inlet side, the ventilation efficiency is reduced, and new aerodynamic noise is likely to occur.

However, when the partition wall 35 is provided as described above, it is possible to cut the flow of the reverse flow from the high pressure outlet side to the low pressure inlet side in the internal hollow space 33, thereby further reducing turbulence. Will be able to solve such problems.

(Embodiment 3) Next, FIG. 3 shows a bell mouth structure of a blower according to Embodiment 3 of the present invention.

The present embodiment is characterized in that the bell mouth structure of the blower of the above-mentioned first embodiment is adopted as a basic constitution, and the sound absorbing material 36 is further filled in the internal hollow space 33 thereof. .

When the sound absorbing material 36 is filled in this way, it is possible to reliably prevent the backflow from the high pressure outlet side to the low pressure suction side above the partition wall 35, while the sound absorbing material 36 is filled. By adjusting the sound absorption frequency characteristics of 36 to the frequency band of the generated aerodynamic noise, the generated aerodynamic noise can be absorbed particularly effectively without causing resonance.

(Fourth Embodiment) Next, FIGS. 4 to 6 show a bell mouth structure of a blower according to a fourth embodiment of the present invention.

The present embodiment is different from the above-mentioned first to third embodiments in that it has a bell mouth structure when a centrifugal blower is adopted as the blower.

That is, FIGS. 4 to 6 show the structure of a turbo fan similar to that shown in FIG. 11 as an example of the centrifugal blower.

In the figure, reference numeral 11 is an impeller for blowing the turbo fan, and the impeller 11 forms a hub 11a fixed to the drive shaft of the motor and an air suction port in the impeller centrifugal direction. A large number of moving blades 11c, 11c ... Are arranged side by side in the circumferential direction with a predetermined blade angle and a predetermined blade interval between the other end side shroud 11b. On the other hand, in the air suction port side end 12 of the shroud 11b, the downstream side air outlet 13c side end of the bell mouth 13 is fitted with a predetermined gap so as to be relatively rotatable with a predetermined dimension.

The bell mouth 13 is the impeller 1 for blowing air.
The air from the air suction port side of the blower main body with respect to the air suction port side end portion 12 of the shroud 11b forming the air suction port of No. 1 is directed in the impeller 10 in the centrifugal direction (blowing direction).
As an air flow guide portion for smoothly flowing in toward the fan, as shown in the figure, an air flow having a predetermined radius of curvature that extends from the attachment edge portion 13a to the blower body and has a gradually reduced opening diameter from the air flow upstream side to the downstream side. It has an inlet portion 13b and an air outlet portion 13c. The shape thereof corresponds to the shroud 11b of the blower impeller 11, and smoothly guides the air on the suction side of the impeller 11 in the blow-out side centrifugal direction on the suction side to reduce aerodynamic noise generated during blowing. We try to reduce it as much as possible.

Then, from the air inlet portion 13b to the air outlet portion 13c forming at least the air flow guide portion.
The portion is formed in a closed cross-section structure with a hollow inside, and the air flow inlet portion 13b and the air flow outlet portion 13 of the air flow guide portion are formed.
A large number of small holes 16, 16 ... Are provided in the inner peripheral wall 15 portion which is continuously formed with c, and the large number of small holes 16, 16 ...
It is characterized in that the internal hollow space 17 formed on the inside via the is communicated with the external blowing passage W.

Therefore, in this structure, unlike the conventional porous material, the airflow guide surfaces of the airflow guide portions (13b, 13c) can be smoothly formed of synthetic resin or the like.
It is possible to prevent dust from adhering to the inside of the internal hollow space 17, and the dust that has entered the large number of small holes 16, 16 ... Does not stop at the small holes 16, 16 ... Will be sucked into.

Therefore, unlike the case of the conventional porous member, the surface of the small hole portion is not clogged due to the accumulation of dust and the pressure fluctuation absorbing effect does not disappear, and the impeller rotation is performed for a long time. The pressure fluctuation absorbing effect can be maintained.

The bell mouth 13 has a bell mouth main body 14 having a concave groove portion as in the first to third embodiments, and a lid-like air flow guide for covering the concave groove portion of the bell mouth main body 14. Since the inner peripheral wall member 15 on the side of the surfaces 13b and 13c is composed of separate members and is combined and integrated with each other, molding with a synthetic resin becomes easy regardless of the structure.

As a result, according to the bellmouth structure of the blower of the present embodiment, it is possible to provide a centrifugal blower such as a turbo fan having low aerodynamic noise and high blow performance at low cost.

(Fifth Embodiment) Next, FIG. 7 shows a bell mouth structure of a blower according to a fifth embodiment of the present invention.

This embodiment adopts the bell mouth structure of the blower of the above-mentioned Embodiment 4 as a basic structure, and the same hollow absorption space as that of the above-mentioned Embodiment 3 is absorbed in the internal hollow space 17. It is characterized by being filled with the material 19.

In this way, the sound absorbing material 1 is placed in the inner hollow space 17.
When 9 is filled, the generated aerodynamic noise does not resonate and is more effectively absorbed.

(Sixth Embodiment) Next, FIG. 8 shows a bell mouth structure of a blower according to a sixth embodiment of the present invention.

This embodiment adopts the bell mouth structure of the blower of the above-mentioned Embodiment 4 as a basic structure, and further has the same hollow and small hole structure on the outer peripheral side as on the inner peripheral side. The feature is that it is provided.

If such a configuration is adopted, in addition to the aerodynamic noise reduction effect similar to that of the above-described fourth embodiment, the aerodynamic noise due to the leakage flow on the outer peripheral side of the bell mouth 13 which is a peculiar reduction to the turbofan is also generated. With the same pressure fluctuation absorption effect,
The absorption can be effectively reduced.

In this case, of course, it is possible to fill the inside hollow spaces 17, 17 both inside and outside with the same sound absorbing material 19 as in the fifth embodiment.

(Other Embodiments) Furthermore, the bell mouth 3, 1 in each of the above embodiments
Bellmouth body 31, 14 and inner peripheral wall member 32 of 3,
Needless to say, 15 may be formed of a metal having a higher degree of smoothness instead of the above-mentioned synthetic resin, for example.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a bellmouth structure of a blower according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a bellmouth structure of a blower according to Embodiment 2 of the present invention.

FIG. 3 is a cross-sectional view showing a bellmouth structure of a blower according to Embodiment 3 of the present invention.

FIG. 4 is a partial cross-sectional view showing a bellmouth structure of a blower according to a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a configuration of a bellmouth structure main part of the blower according to Embodiment 4 of the present invention.

FIG. 6 is a cross-sectional view showing the operation of the bellmouth structure of the blower according to Embodiment 4 of the present invention.

FIG. 7 is a sectional view showing a configuration of a main part of a bell mouth structure of a blower according to a fifth embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a configuration of a main part of a bell mouth structure of a blower according to a sixth embodiment of the present invention.

FIG. 9 is a partially cutaway perspective view showing a bell mouth structure of a blower according to a first conventional example.

FIG. 10 is a cross-sectional view showing a bellmouth structure of the blower according to the first conventional example.

FIG. 11 is a cross-sectional view showing a bell mouth structure of a blower according to a second conventional example.

[Explanation of symbols]

1 is a propeller fan, 2 is an impeller, 2a is a hub, 2b is a blade, 3 is a bell mouth, 3a is an air suction opening, 3b
Is a fan guide port, 3c is an air blowing opening, 4 is a partition plate, 10 is a turbofan, 11 is an impeller, 11a is a hub, 11b is a shroud, 11c is a blade, 12 is an air suction port side end, 13 is a bell mouth, 13a is a mounting edge, 1
3b is an air inlet, 13c is an air outlet, 14 is a bell mouth main body, 15 is a bell mouth inner peripheral wall member, 16 is a small hole, 17 is an internal hollow space, 19 is a sound absorbing material, 31 is a bell mouth main body, 32 is a bellmouth inner peripheral wall member, 33, 33
Reference numerals a and 33b are internal hollow spaces, 34 is a small hole, and 36 is a sound absorbing material.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 3-202699 (JP, A) JP 10-227299 (JP, A) JP 4-191500 (JP, A) JP 4- 265500 (JP, A) JP 64-60799 (JP, A) JP 2000-27798 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04D 29/54 F04D 29 / 44

Claims (5)

(57) [Claims] 1. A bell mouth (3) of a blower, which is provided corresponding to the outer periphery of an impeller (2) for blowing air and guides air on the suction side of the impeller (2) to the blowing side. , The inside of which is formed into a hollow cylindrical structure, and the air flow guide portion (3
a), (3b), (3c) and a number of small holes (34) for absorbing pressure fluctuations in the inner peripheral wall (32) portion,
(34) a ... provided, the large number of small holes (34), (3
4) A bell mouth structure of a blower, characterized in that the internal hollow space (33) is communicated with the external blower passage (S) via. 2. A bell mouth of a blower (corresponding to a shroud (11b) of an impeller (11) for blowing air, which guides air on the suction side of the impeller (11) in the blowing direction on the suction side ( 13), the portions corresponding to the air flow guide portions (13b), (13c) are formed in a closed cross-section structure having a hollow inside, and the air flow guide portions (13)
b), pressure is applied to the inner peripheral wall (15) that constitutes (13c)
A large number of small holes (16), (16) for absorbing fluctuations
The provided ..., the large number of small holes (16), (16) via a ... blower, characterized in that communicates the interior hollow space (17) to the outside air passage (W) bellmouth structure . 3. A partition wall (35) for partitioning the internal hollow space (33) into a high pressure side region and a low pressure side region is provided in the internal hollow space (33). The bellmouth structure of the blower according to 1. 4. A bell mouth structure for a blower according to claim 1, wherein the inner hollow spaces (33), (17) are filled with sound absorbing materials (36), (19). . 5. The bell mouths (3), (13) are provided on the bell mouth main body (31), (14) side and the inner peripheral walls (32), (1).
5. The bell mouth structure of the blower according to claim 1, wherein the side and the side 5) are formed by separate members and are integrated by being combined with each other.