WO2011121773A1

WO2011121773A1 - Multi-blade blower

Info

Publication number: WO2011121773A1
Application number: PCT/JP2010/055929
Authority: WO
Inventors: 一輝岡本; 仁菊地; 健一迫田
Original assignee: 三菱電機株式会社
Priority date: 2010-03-31
Filing date: 2010-03-31
Publication date: 2011-10-06

Abstract

A blower having reduced noise and improved blowing performance which are efficiently achieved using a low-cost simple shape. A multi-blade blower (1) includes a multi-blade impeller (3) and a scroll casing (4) and blows air, which is sucked from the inlet, from the outlet (10) by the rotation of the multi-blade impeller (3). The inner diameter-side end of a shroud (7) and the front end of a bell-mouth have overlap sections which overlap each other in the circumferential direction of the rotating shaft of a motor. The distance between the upper wall surface of the scroll casing (4) and the shroud (7) continuously increases from the inner diameter-side end of the shroud (7) toward the outer diameter-side end thereof. The outer diameter (D2) of the shroud (7) is greater than the outer diameter (D1) of the multi-blade impeller (3) at the blade portion thereof.

Description

Multi-blade blower

The present invention relates to a multi-blade fan for air conditioning.

Conventionally, a multiblade blower collects air blown from an impeller using a scroll casing having a predetermined spread, and further converts the dynamic pressure component of the flow into a static pressure component by expanding the flow path. I am letting. On the other hand, inside the multiblade blower, an air flow is generated along the wall surface of the scroll casing, and part of the air leaks to the outside through the gap between the impeller and the bell mouth, or becomes a circulating flow and the blade tip of the impeller. There is a problem that it interferes with or interferes with the air current blown through between the blades of the impeller (hereinafter referred to as the blade-to-blade). These have adverse effects such as deterioration of noise of the multiblade fan and deterioration of the air blowing characteristics.

For such problems, the blade tip of the impeller and the bell mouth are overlapped so as not to cause air leakage (see Patent Document 1), or an obstacle wall is provided so that the circulating flow does not flow around the blade tip. A device for improving the performance of the blower has been devised by changing the air flow in the blower by a method such as (see Patent Document 2). In addition, a method of adjusting the balance of the impeller by using a shroud provided as strength reinforcement on the blade tip side is also disclosed (see Patent Document 3).

JP 2008-101537 A Japanese Utility Model Publication No. 62-173600 JP 2009-185750 A

In the conventional multi-blade fan, by changing the air flow in the blower by devising various shapes, air leakage is reduced or interference between the circulating flow and the blade tip of the impeller is improved, and the performance of the blower is improved. Has been. However, as in the invention described in Patent Document 1 and the invention described in Patent Document 3, the upper wall surface of the bell mouth or the scroll casing is brought close to the blade tip of the impeller, and the upper wall surface of the bell mouth or the scroll casing and the impeller. If the distance between the two is reduced, the effective volume of the scroll casing is reduced. Further, as in the invention described in Patent Document 2, when the position where the circulating flow flows is changed by providing an obstacle wall or the like, the circulating flow is newly added in the region where the scroll casing is effectively functioning because the air originally flows. As a result, the effective volume of the scroll casing is reduced. When the effective volume of the scroll casing is reduced, the effect of static pressure recovery by the scroll casing is weakened, resulting in a problem that the blowing performance of the blower is lowered.

Furthermore, there is also a problem that the performance of the blower is lowered due to collision or interference between the airflow that circulates in the blower along the wall surface of the scroll casing and the flow blown through the blades of the impeller.

The present invention has been made in view of the above, and an object of the present invention is to obtain a blower that can efficiently achieve noise reduction and improvement of blowing performance with a simple and low-cost shape.

In order to solve the above-described problems and achieve the object, the present invention includes a main plate that is rotationally driven by a motor, a plurality of blades that are arranged at predetermined intervals in the circumferential direction on the outer peripheral portion of the main plate, A multi-blade impeller having an annular shroud that maintains an interval on a side opposite to a side connected to each main plate of the blades at a predetermined interval, and an air suction port, which faces the air suction port A scroll casing having a casing main body in which the multi-blade impeller is housed, a bell mouth protruding to the inside of the casing main body around the air inlet, and an air outlet provided on the outer peripheral portion of the casing main body, , And a multi-blade blower that blows out air sucked from the air suction port from the air blow-out port by rotation of the multi-blade impeller. The space between the wall surface on the air inlet side of the casing body and the shroud continuously increases from the inner diameter side end of the shroud toward the outer diameter side end. The multi-blade impeller is characterized in that the outer diameter of the shroud is larger than the outer diameter of the blade portion.

The multiblade blower according to the present invention has the effect that the shroud plays the role of air leakage prevention and a rectifying plate, so that the noise reduction and the improvement of the air blowing performance can be efficiently obtained with a low-cost simple shape.

FIG. 1 is a cross-sectional view of the multi-blade fan according to the embodiment of the present invention as viewed from the axial direction of the rotating shaft. FIG. 2 is a cross-sectional view in which the radial direction of the rotating shaft of the multiblade fan according to the embodiment of the present invention is a viewpoint. FIG. 3 is a cross-sectional view with the radial direction of the rotating shaft of a conventional multiblade fan as a viewpoint. FIG. 4 is an enlarged view of the vicinity of a blade end portion of a multiblade impeller of a conventional multiblade fan. FIG. 5 is an enlarged view of the vicinity of the blade end portion of the multi-blade impeller of the multi-blade fan according to the embodiment of the present invention. FIG. 6 is a diagram showing the relationship between the noise characteristics of the multiblade fan and the ratio of the outer diameter of the shroud and the outer diameter of the multiblade impeller at the blade portion. FIG. 7A is a diagram illustrating an example of a tongue portion provided with a recess. FIG. 7B is a diagram illustrating an example of a tongue portion provided with a stepped portion. FIG. 7C is a diagram illustrating an example of a tongue portion provided with a stepped portion. FIG. 8A is a diagram illustrating an example of the shape of the main plate. FIG. 8-2 is a diagram illustrating an example of the shape of the main plate. FIG. 9A is a diagram illustrating an example of the shape of the shroud. FIG. 9B is a diagram illustrating an example of the shape of the shroud. FIG. 9C is a diagram illustrating an example of the shape of the shroud. FIG. 10 is a diagram showing the air blowing characteristics of the multiblade fan according to the present embodiment and the conventional multiblade fan. FIG. 11 is a diagram illustrating noise characteristics of the multiblade fan according to the present embodiment and the conventional multiblade fan.

Hereinafter, embodiments of a multiblade fan according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a cross-sectional view of the multi-blade fan according to the embodiment of the present invention as viewed from the axial direction of the rotating shaft. 2 is a cross-sectional view of the multiblade fan according to the embodiment of the present invention taken along the line II-II in FIG. 1 (a cross-sectional view with the radial direction of the rotating shaft as a viewpoint). As shown in FIGS. 1 and 2, the multiblade blower 1 includes a drive motor 2, a multiblade impeller 3, and a scroll casing 4. The multi-blade impeller 3 is attached to the rotary shaft of the drive motor 2 and is driven to rotate, and a cylindrical ridge is fixed to the main plate 5 at one end and the front side of the main plate 5 is open. A large number of blades 6 fixed to the outer peripheral portion of the main plate 5 at a predetermined mounting angle at equal intervals in the circumferential direction are provided. A shroud 7 is provided at the other end of the blade 6, and the other end of the blade 6 is fixed at equal intervals in the circumferential direction by the shroud 7. The scroll casing 4 includes a casing body having a suction port 8 on the upper wall surface 4 a and a spiral air flow path around the multi-blade impeller 3, and a bell protruding toward the lower wall surface 4 b around the suction port 8. A part of the air flow along the outer periphery of the casing 9 is located between the mouse 9, the air outlet 10 that protrudes from the outer periphery of the casing body and communicates with the air flow path, and the casing body and the air outlet 10. And a tongue 11 for diverting and leading to the outlet 10.

For comparison, FIG. 3 shows a cross-sectional view with the radial direction of the rotating shaft of a conventional multiblade fan as a viewpoint. The conventional multiblade blower 21 includes a drive motor 22, a multiblade impeller 23, and a scroll casing 24. The multiblade impeller 23 includes a main plate 25 and a plurality of blades 26. Further, the scroll casing 24 includes a suction port 28 and a bell mouth 29, and an air outlet and a tongue not shown in FIG. These are the same as the members of the same name in the multiblade blower 1 according to the present embodiment.

1 and FIG. 2 is different from the conventional multiblade fan shown in FIG. 3 in that a shroud 7 is provided and the shape of the blade 6 is different.

As shown in FIG. 2, the multiblade blower 1 has an upper end portion of the shroud 7 and a lower end portion of the bell mouth 9 overlapping (overlapping) in the radial direction of the rotation shaft of the drive motor 2.

Further, the shroud 7 is moved from the suction port 8 side toward the main plate 5 side so that the distance between the upper wall surface 4a of the scroll casing 4 and the bell mouth 9 and the shroud 7 increases toward the outer diameter direction of the shroud 7. The shape is inclined in the radial direction. The blade length of the multiblade impeller 3 has a blade length B2 on the outer diameter side shorter than the blade length B1 on the inner diameter side, corresponding to the shape of the shroud 7. On the other hand, as shown in FIG. 3, in the conventional multiblade fan, the blades 26 have a rectangular shape.

Furthermore, as shown in FIG. 1, the outer diameter D2 of the shroud 7 is larger than the outer diameter D1 of the multi-blade impeller 3 at the blade 6 part.

FIG. 4 is an enlarged view of the vicinity of the blade end portion of the multi-blade impeller 23 of the conventional multi-blade fan 21. FIG. 5 is an enlarged view of the vicinity of the blade end portion of the multi-blade impeller 3 of the multi-blade fan 1 according to the present embodiment. As shown in FIG. 4, in the conventional multi-blade fan 21, the circulating flow X flowing along the upper wall surface 24 a of the scroll casing 24 passes through the clearance between the multi-blade impeller 23 and the bell mouth 29 from the suction port 28. It leaks to the outside (FIG. 4, airflow X1), passes between the blades of the multiblade impeller 23, interferes with the blade tip of the multiblade impeller 23 (FIG. 4, airflow X2), and the outer periphery of the multiblade impeller 23 The characteristics of the multiblade fan 21 are adversely affected by colliding with or interfering with the airflow Y that flows in the vicinity and blows out through the blades of the multiblade impeller 23 (FIG. 4, airflow X3).

On the other hand, as shown in FIG. 5, the multiblade blower 1 according to the present embodiment has a structure in which the upper end portion of the shroud 7 and the lower end portion of the bell mouth 9 overlap in the radial direction of the rotating shaft. Is less likely to leak (airflow X1 in FIG. 4 can be suppressed). Further, by covering the blade tip of the multi-blade impeller 3 with the shroud 7, air flows along the shroud 7 on the blade tip side as shown by the airflow X4 in FIG. It becomes difficult to interfere with the end (the airflow X2 in FIG. 4 can be suppressed). Further, since the blade length of the multi-blade impeller 3 is shortened on the outer diameter side and the space on the blade tip side is widened, the airflow passing through the blade tip side of the multi-blade impeller 3 is diffused and the bending is also gentle. As a result, the flow velocity is also reduced, and turbulence in the airflow can be reduced.

Furthermore, the outer diameter of the shroud 7 is made larger than the outer diameter of the multi-blade impeller 3 at the blade 6 portion, so that the airflow Y and the shroud 7 blown out between the blades of the multi-blade impeller 3 are reduced. The airflow X4 flowing out along the outer side of the multi-blade impeller 3 is separated and blocked by the shroud 7 on the outer side of the outer periphery of the multi-blade impeller 3, and both are less likely to collide or interfere with each other. That is, the shroud 7 serves as a “rectifying plate” that rectifies the circulating flow, so that the airflow Y blown out between the blades of the multi-blade impeller 3 flows smoothly without being obstructed.

As described above, by widening the gap in the vicinity of the blade tip side of the multiblade impeller 3, the circulating flow generated in the multiblade fan 1 can be rectified and suppressed, and the characteristics of the multiblade fan 1 can be improved. Since the blade length of the multi-blade impeller 3 that contributes to the air blowing performance is adjusted to be short, it is necessary to make the shape compatible with both.

The optimum dimensions and shape regarding the blade length are the same as the conditions disclosed in International Publication No. 2008/093390. That is, the dimension of the shroud 7 is added to the blade 6 of the multi-blade impeller 3 in which the blade length B2 on the outer diameter side is 0.75 × B1 ≦ B2 ≦ 0.95 × B1 with respect to the blade length B1 on the inner diameter side. It is good to install with matching shapes. More preferably, the size and shape of the shroud 7 should be matched with the blades 6 of the multi-blade impeller 3 where B2 = 0.8 × B1.

Further, as shown in FIG. 5, the multiblade blower 1 according to the present embodiment increases the outer diameter of the shroud 7 to increase the airflow X4 flowing out along the shroud 7 and the blades of the multiblade impeller 3. The airflow Y blown out through is divided and cut off to improve the characteristics of the multiblade blower 1. FIG. 6 is a diagram showing the relationship between the noise characteristic of the multiblade fan 1 with respect to the ratio D2 / D1 between the outer diameter D2 of the shroud 7 of the multiblade impeller 3 and the outer diameter D1 of the blade 6. As shown in FIG. 6, when D2 / D1 is large, the noise characteristics of the multiblade fan 1 can be improved. That is, the noise characteristics of the multiblade fan 1 can be improved by extending the shroud 7 so that the outer diameter D2 of the shroud 7 is increased. In order to obtain a noise reduction effect (−1 dB or more), the outer diameter D1 of the multiblade impeller 3 at the blade 6 portion is 1.1 × D1 ≦ D2 with respect to the outer diameter D2 of the shroud 7. In addition, the shape of the shroud 7 may be determined. On the other hand, in the case of 1.2 × D1 <D2, the dimension is generally such that the shroud 7 and the tongue 11 collide. Therefore, in general, it is preferable that the shape of the shroud 7 is 1.1 × D1 ≦ D2 ≦ 1.2 × D1. However, it goes without saying that 1.2 × D1 <D2 as long as the shroud 7 and the tongue 11 do not collide.

Note that the side surface of the scroll casing 4 and the multi-blade impeller 3 can be rotated so that the multi-blade impeller 3 can rotate even when the shroud 7 and the tongue 11 are prevented from colliding and the outer diameter D2 of the shroud 7 is increased. It is also possible to devise the place where the distance to the point is closest, that is, the shape of the tongue 11. For example, as shown in FIGS. 7-1 to 7-3, the tongue portion 11 has a recess or a step portion so that the outer diameter side end portion of the shroud 7 of the multi-blade impeller 3 and the tongue portion 11 do not collide with each other. Etc. may be provided. By setting it as such a shape, the outer diameter D2 of the shroud 7 can be enlarged without enlarging the multiblade fan 1. FIG. Thereby, the noise characteristic of the multiblade fan 1 can be improved.

Furthermore, when the multiblade impeller 3 provided with the shroud 7 is formed by die machining, the shape of the main plate 5 of the multiblade impeller 3 may be devised so that the die can be simply cut in one direction. For example, the main plate 5 of the multi-blade impeller 3 may have a shape in which only a portion obtained by projecting the shroud 7 onto the surface of the main plate 5 is cut out. In other words, it is preferable that the shroud 7 and the main plate 5 do not overlap in the axial direction of the rotation shaft of the drive motor 2 as shown in FIGS. By forming the main plate 5 in such a shape, the mold used for forming the multiblade impeller 3 forms a space in the shape of the multiblade impeller 3 only by abutting the convex part and the concave part. This makes it easy to assemble the mold and remove the mold after molding. Thereby, the manufacturing cost of the multiblade fan 1 can be reduced.

Further, as shown in FIG. 9A, the end portion on the outer diameter side of the shroud 7 is shaped to be bent toward the suction port 8 side with respect to the radial direction of the rotating shaft of the drive motor 2, thereby allowing the multiblade impeller. The airflow Y blown out between the three blades 3 and the airflow X4 flowing out along the shroud 7 may be kept away from each other to avoid a collision and interference between them, and to have a rectifying function for reducing noise.

Further, as shown in FIG. 9-2, an uneven shape is provided on the inclined surface of the shroud 7, or a notch shape is provided on the end surface of the shroud 7 as shown in FIG. A small turbulence may be given to the flowing airflow X4 to suppress separation of the airflow, and a turbulent flow control function for further reducing noise may be provided. In the present embodiment, the outer diameter D2 of the shroud 7 is larger than the outer diameter D1 of the multi-blade impeller 3 in the portion of the blade 6, so that the shroud is also in the region outside the outer periphery of the multi-blade impeller 3. These functions can be added to 7, and further noise reduction and improvement of the air blowing performance can be achieved as compared with the conventional multiblade fan.

FIG. 10 is a diagram showing the air blowing characteristics of the multiblade fan 1 according to the present embodiment and the conventional multiblade fan. FIG. 11 is a diagram illustrating noise characteristics of the multiblade fan 1 according to the present embodiment and the conventional multiblade fan. Here, the flow coefficient φ, the fan efficiency η _T , and the specific noise K _T are expressed by the following formulas (1) to (3). 10 and 11, (a) is a multi-blade impeller 3 according to the present embodiment, (b) is a conventional multi-blade impeller without a shroud, and (c) is a shroud from the suction port side to the main plate side. As the shape to be inclined toward the outer diameter direction, the air blowing characteristic and the noise characteristic when using a conventional multiblade impeller in which the outer diameter of the shroud is the outer diameter at the blade portion are shown.

Q: Air flow [m ³ / min] D: Blade outer diameter [m] B: Blade length [m] N: Speed [rpm]
P _T : Total pressure [Pa] PW: Shaft power [W] SPL _A : Noise characteristics (A characteristics) [dB]

As shown in FIGS. 10 and 11, the multiblade fan 1 according to the present embodiment has improved air blowing characteristics and noise characteristics as compared with the conventional multiblade fan. In particular, when the multiblade impeller 3 of B2 = 0.8 × B1 was used, a maximum noise reduction effect of about −1.5 dB was obtained in comparison with the same air volume.

As described above, in the multiblade fan 1 according to the present embodiment, the upper end portion of the shroud 7 overlaps the lower end portion of the bell mouth 9 in the radial direction of the rotating shaft, and the upper wall surface 4a of the scroll casing 4 and the bell The shape of the shroud 7 is inclined in the outer diameter direction from the suction port 8 side toward the main plate 5 side so that the distance between the mouse 9 and the shroud 7 is increased. Further, the blade length of the multiblade impeller 3 corresponds to the shape of the shroud 7 and is configured such that the blade length on the outer diameter side is shorter than the blade length on the inner diameter side. By setting it as such a structure, the airflow along the wall surface of the scroll casing 4 becomes difficult to leak outside from the clearance gap between the multiblade impeller 3 and the bellmouth 9. FIG. Further, by covering the blade tip with the shroud 7, the circulating flow generated in the multiblade fan 1 and the blade tip of the multiblade impeller 3 do not interfere with each other. Furthermore, since the blade length of the multi-blade impeller 3 is shortened on the outer diameter side and the gap between the upper wall surface 4a of the bell mouth 9 or the scroll casing 4 and the multi-blade impeller 3 is widened, the circulation flow becomes gentle. , Turbulence of airflow can be reduced.

Furthermore, in the multiblade fan 1 according to the present embodiment, the multiblade impeller 3 is configured such that the outer diameter D2 of the shroud 7 is larger than the outer diameter D1 of the multiblade impeller 3 at the blade 6 portion. Has been. With such a configuration, the airflow blown out between the blades of the multiblade impeller 3 and the airflow along the shroud 7 are separated by the shroud 7 on the outer side of the outer periphery of the multiblade impeller 3. Therefore, both of them are less likely to collide or interfere with each other, and the performance of the multiblade fan 1 can be improved. That is, the shroud 7 serves as a rectifying plate that rectifies the circulating flow. Since the shroud 7 plays a role of preventing air leakage and a current plate, it is possible to efficiently reduce noise and improve air blowing performance with a low-cost simple shape.

The multiblade blower 1 according to the present embodiment increases the distance between the upper wall surface 4a of the scroll casing 4 and the bell mouth 9 and the multiblade impeller 3 by devising the shape of the shroud 7 of the multiblade impeller 3. On the other hand, the circulating flow generated in the multiblade fan 1 is guided or rectified into this space, and the noise reduction and the improvement of the air blowing performance of the multiblade fan 1 are realized. That is, since the shroud 7 functions as both an air leakage prevention and a current plate, the effects of reducing noise and improving air blowing performance can be obtained at a low cost with a simple shape. Energy saving can be realized by improving the blowing performance.

In the above embodiment, the multi-blade fan for air conditioning is taken as an example, but the present invention is not limited to this and can be applied to other devices. Moreover, in the said embodiment, although the single suction type multi-blade fan was taken as an example, this invention is not limited to this, It is also possible to apply to a double suction type multi-blade fan.

As described above, the multiblade blower according to the present invention is useful as a blower for a ventilation device, an air conditioner or the like installed in a house, a school, a hospital, an office, or the like where quietness is required.

DESCRIPTION OF SYMBOLS 1 Multiblade fan 2 Drive motor 3 Multiblade impeller 4 Scroll casing 4a Upper wall surface of scroll casing 4b Lower wall surface of scroll casing 5 Main plate 6 Blade 7 Shroud 8 Suction port 9 Bell mouth 10 Outlet 11 Tongue

Claims

A main plate that is rotationally driven by a motor, a plurality of blades arranged at predetermined intervals in the circumferential direction on the outer periphery of the main plate, and a space on the side opposite to the side of each of the blades connected to the main plate A multi-blade impeller having an annular shroud for maintaining
A casing main body having an air suction port, in which the multi-blade impeller is accommodated so as to face the air suction port, a bell mouth protruding toward the inner side of the casing main body around the air suction port, and the casing A scroll casing having an air outlet provided on the outer periphery of the main body;
A multi-blade blower that blows out air sucked from the air suction port from the air outlet by rotation of the multi-blade impeller,
An end portion on the inner diameter side of the shroud and a tip portion of the bell mouth have an overlap portion that overlaps in the circumferential direction of the rotation shaft of the motor,
The space between the wall surface on the air inlet side of the casing body and the shroud continuously increases from the inner diameter side end of the shroud toward the outer diameter side end.
In the multiblade impeller, the outer diameter of the shroud is larger than the outer diameter of the blade portion.
The multiblade fan according to claim 1, wherein the shroud is inclined so that an outer diameter side is close to the main plate.
Each of the blades has a blade length on the outer diameter side of the multi-blade impeller that is not less than 0.75 times and not more than 0.95 times a blade length on the inner diameter side of the multi-blade impeller. The multiblade fan according to claim 1 or 2.
The scroll casing has a tongue portion that diverts a part of the air flow along the outer peripheral portion of the casing body and guides it to the air outlet.
The multi-blade fan according to any one of claims 1 to 3, wherein the tongue portion includes a concave portion or a step portion at a location facing an end portion on the outer diameter side of the shroud.
The multiblade fan according to any one of claims 1 to 4, wherein an end of the shroud on the outer diameter side is warped toward the air suction port.
The multi-blade blower according to any one of claims 1 to 5, wherein the shroud is provided with irregularities on a surface of the casing body that faces the wall surface on the air suction port side.
The multi-blade fan according to any one of claims 1 to 6, wherein the shroud includes a notch at an end portion on an outer diameter side.