WO2014167707A1

WO2014167707A1 - Centrifugal fan

Info

Publication number: WO2014167707A1
Application number: PCT/JP2013/061042
Authority: WO
Inventors: 一輝岡本; 青木　普道; 雄大小崎; 千景門井
Original assignee: 三菱電機株式会社
Priority date: 2013-04-12
Filing date: 2013-04-12
Publication date: 2014-10-16
Also published as: JP6058125B2; CN205089681U; JPWO2014167707A1

Abstract

A centrifugal fan wherein an annular expansion section that projects toward an impeller wheel is disposed on a scroll casing bottom wall face facing the impeller wheel, and an airflow inlet section through which air flows is formed in a portion of the expansion section.

Description

Centrifugal blower

The present invention relates to the structure of a centrifugal fan provided with a scroll casing, particularly for ventilation and air conditioning.

A centrifugal blower equipped with a scroll casing having a predetermined expansion ratio in the airflow direction in the air passage cross-sectional area collects the dynamic pressure of the air blown out from the impeller at the scroll casing and moves toward the air outlet. By gradually expanding the pressure, static pressure recovery is performed to convert dynamic pressure into static pressure. Therefore, the static pressure is highest in the vicinity of the blower outlet of the blower. On the other hand, since the effect of recovering the static pressure by the scroll casing is small in a region where the air passage cross-sectional area is narrow with the tongue portion partitioning the blower outlet and the air passage in the blower as a boundary, the static pressure is low. That is, due to the configuration of the centrifugal blower, the largest internal pressure difference occurs at the tongue.

Since the air flowing in the vicinity of the air outlet has a high static pressure, a part of the flow is not blown out from the air outlet, and a reverse flow is generated into the blower air passage having a low static pressure. In particular, it tends to flow backward from the blower air passage through the back side of the impeller main plate (the gap between the impeller and the scroll casing) toward the axial center of the drive motor having a weak flow. Similarly, the flow that collides with the tongue wall surface may enter the back side of the main plate of the impeller.

As shown in FIG. 11, the centrifugal blower as the prior art has a uniform flow between the impeller and the bottom wall of the scroll casing facing the impeller in the backflow of the impeller main plate. The direction of air inflow is not uniquely determined and is unstable. And as FIG. 12 shows, the flow which entered the main plate back side of the impeller easily flows out from the back side of the impeller to the air passage inside the blower again without passing through the opening of the main plate of the impeller. Become. Therefore, the direction in which the air flows out is not uniquely determined and becomes unstable.

In another conventional technique, the position and size of the opening provided on the main plate of the impeller are devised by using the flow of air that enters the back side of the main plate of the impeller as described above. The improvement of the blower which made the flow of air around this drive motor and reduced the blowing noise while cooling the drive motor has been made (for example, see Patent Document 1).

JP 2012-13035 A (refer to claim 1)

In a centrifugal blower equipped with a scroll casing, the air flowing in the vicinity of the outlet has a high static pressure, so a part of the flow enters the back side of the main plate of the impeller. At this time, in the conventional centrifugal blower, since the shape of the gap formed by the main plate of the impeller and the bottom wall surface of the scroll casing is uniform, the impeller main plate can be back from any direction around the impeller. And air enters. As a result, the direction in which the air flows is not uniquely determined and becomes unstable, and the turbulence of the air flow and the pressure fluctuation increase, which may have adverse effects such as a decrease in blowing performance, an increase in noise, and occurrence of surging. In addition, air that has entered the back side of the main plate of the impeller may flow out from the back side of the main plate of the impeller to the air passage inside the blower again without flowing around the drive motor. There was a problem that the cooling effect of the drive motor could not be obtained sufficiently.

The present invention has been made to solve such conventional problems, and rectifies the flow of air on the back side of the main plate of the impeller by using a simple and inexpensive means, and the turbulence and pressure of the airflow An object of the present invention is to provide a centrifugal blower that reduces fluctuations and improves the blowing noise performance. It is another object of the present invention to provide a centrifugal blower that facilitates the flow of air to the surface side (suction port side) of the impeller main plate and further enhances the cooling effect of the drive motor.

A centrifugal blower according to the present invention is a centrifugal blower including a scroll casing, an impeller that is arranged in a ring shape with a plurality of blades arranged in an annular shape, and a drive motor that drives the impeller, The scroll casing bottom wall surface facing the impeller is provided with an annular bulging portion protruding toward the impeller side, and an airflow inflow portion through which an airflow flows is formed in a part of the bulging portion. .

According to the present invention, air entering the back side of the main plate of the impeller is formed by forming an airflow inflow portion on the bottom wall surface of the scroll casing. Since the air flows uniquely and stably from the outlet side toward the axial center of the drive motor, it is possible to obtain a blower in which blowing noise is reduced and the cooling effect of the drive motor is further enhanced.

It is a top view of the centrifugal blower according to Embodiment 1 of the present invention. It is the longitudinal cross-sectional view (X1-'X1) which looked at the centrifugal blower of FIG. 1 from the direction which cross | intersects a rotating shaft. It is the cross-sectional view (Y-'Y) which looked at the centrifugal air blower of FIG. 2 from the axial direction. It is the cross-sectional view (Z-'Z) which looked at the centrifugal blower of Drawing 2 from the axial direction. It is an example of the shape of the baffle plate provided in a scroll casing bottom wall surface. It is an example of the shape of the guide plate provided in a scroll casing bottom wall surface. It is a top view of the centrifugal blower which concerns on Embodiment 2 of this invention. It is the longitudinal cross-sectional view (X2-'X2) which looked at the centrifugal blower of FIG. 7 from the direction which cross | intersects a rotating shaft. It is a graph which shows the ventilation performance in the centrifugal blower of embodiment which implemented this invention. It is a graph which shows the noise performance in the centrifugal blower of embodiment which implemented this invention. It is a cross-sectional view of the centrifugal blower of the conventional form. It is a longitudinal cross-sectional view of the centrifugal blower of the conventional form.

Embodiment 1 FIG.
FIG. 1 is a top view of a centrifugal blower according to Embodiment 1 of the present invention.
FIG. 2 is a longitudinal sectional view (X1-'X1) of the centrifugal blower of FIG. 1 as seen from the direction intersecting the rotation axis.
FIG. 3 is a cross-sectional view (Y-'Y) seen from the axial direction of the centrifugal fan of FIG.
FIG. 4 is also a cross-sectional view (Z-'Z).
FIG. 5 is a shape example of a baffle plate provided on the bottom wall surface of the scroll casing.
FIG. 6 is a shape example of a guide plate provided on the bottom wall surface of the scroll casing.

As shown in FIGS. 1 to 4, the centrifugal blower 1 includes a drive motor 2, an impeller 3, and a scroll casing 4. The impeller 3 includes a main plate 6 provided with a plurality of openings 5, a plurality of blades 7, and an annular member 8 for reinforcement. The scroll casing 4 includes a flow path having a predetermined expansion ratio in the airflow direction in the air passage cross-sectional area, and includes a suction port 9 on the upper surface, and an air outlet 10 and a tongue portion 11 on the side surface.

The scroll casing 4 is provided with an annular bulging portion 4b projecting toward the impeller 3 on the scroll casing bottom wall surface 4a facing the impeller 3. As shown in FIG. 2, in the centrifugal blower 1, the impeller 3 holds a predetermined gap with the bulging portion 4 b of the scroll casing 4 so that it can be rotated by the drive motor 2. Further, as shown in FIG. 4, a concave portion 12 through which air can flow is formed in the bulging portion 4 b on the outlet 10 side of the scroll casing 4. Therefore, the bulging portion 4b has a shape in which a part of the annular shape is cut off by the concave portion.

In this centrifugal blower 1, when the impeller 3 rotates, the air blown out from the impeller 3 is recovered in dynamic pressure in the flow passage of the scroll casing 4 having a predetermined expansion rate in the airflow cross-sectional area in the airflow direction, It blows out from the blower outlet 10 with the static pressure recovery effect | action which converts a dynamic pressure into a static pressure toward the blower outlet 10. FIG. Therefore, the static pressure is highest on the outlet 10 side of the centrifugal blower 1.

On the other hand, since the static pressure recovery effect by the scroll casing 4 is small in a region where the cross-sectional area of the air passage is narrow with the tongue portion 11 partitioning the air outlet 10 of the centrifugal blower 1 and the air passage in the air blower as a boundary, the static pressure is low. That is, due to the configuration of the centrifugal blower 1, the largest internal pressure difference occurs at the tongue 11.

Then, since the air flowing in the vicinity of the air outlet 10 has a high static pressure, a part of the flow is not blown out from the air outlet 10 to the outside, and a reverse flow is generated in the blower air passage having a low static pressure. In particular, it flows backward from the blower air passage through the back surface 6a side of the main plate 6 of the impeller 3 (the gap between the impeller 3 and the bulging portion 4b of the scroll casing) toward the axial center of the drive motor 2 where the flow is weak. Is likely to occur. Similarly, the flow that collides with the wall surface of the tongue portion 11 may enter the back surface 6a side of the main plate 6 of the impeller 3 in the same manner.

The centrifugal blower 1 according to Embodiment 1 of the present invention is such that the expansion of the scroll casing bottom wall surface 4a is such that the gap between the back surface 6a of the main plate 6 of the impeller 3 and the bulging portion 4b of the scroll casing bottom wall surface 4a is locally expanded. A recessed portion 12 is provided in the protruding portion 4b. Therefore, the flow of air that tends to enter the back surface 6 a side (the gap between the impeller 3 and the scroll casing 4) of the impeller 3 is concentrated in the vicinity of the recess 12.

Moreover, the centrifugal blower 1 provided with the scroll casing 4 as described above has a high static pressure in the vicinity of the air outlet 10 due to its structure. Therefore, as shown in FIG. 4, by providing a recess 12 in the bulging portion 4 b of the scroll casing bottom wall surface 4 a in the vicinity of the outlet 10 of the centrifugal blower 1, the rear plate 6 a side of the main plate 6 of the impeller 3 is moved toward the rear surface 6 a side. The incoming flow is more likely to be concentrated near the recess 12. The concave portion 12 has a function of uniquely determining the air flow direction by serving as an inlet for the flow of air entering the back surface 6a of the impeller 3.

That is, as shown in FIG. 2, the backflow of air entering the back surface 6a side of the main plate 6 of the impeller 3 is stably formed. Part of this flow flows from the outlet 10 toward the axial center of the drive motor 2 and eventually flows through the opening 5 of the main plate 6 to the surface 6b side of the main plate 6 of the impeller 3. A is formed. By forming this stable circulation flow A, the blowing noise can be reduced and the cooling effect of the drive motor can be further enhanced.

Further, as shown in FIG. 5, as another means for facilitating the flow of the air entering the back surface 6 a side of the main plate 6 of the impeller 3 from the outlet 10 side of the scroll casing 4, A baffle plate 13 that obstructs the flow of air entering the back surface 6a side of the main plate 6 of the impeller 3 except in the vicinity of the blowout port 10 may be provided upright.

The baffle plate 13 is provided in a scroll casing bottom wall surface 4a facing the outer peripheral edge of the impeller 3 in an annular shape protruding toward the impeller 3 side. And since the baffle plate 13 is provided except the blower outlet 10 side, this opening part 5 plays the role of the inflow port which introduces the high static pressure air near the blower outlet 10 to the back surface 6a side of the impeller 3. Fulfill. Therefore, it has the function of uniquely determining the direction of air flow, like the recess 12 of the bulging portion 4b.

Further, as shown in FIG. 6, in order to further enhance the cooling effect of the drive motor 2, the air that has entered the back surface 6 a side of the main plate 6 of the impeller 3 flows stably toward the axial center direction of the drive motor 2. As described above, the guide plate 14 may be provided on the scroll casing bottom wall surface 4a.

The shape of the guide plate 14 may be any shape as long as the airflow can be guided toward the axial center of the drive motor 2, such as an arcuate standing portion shape as shown in FIG. Can also be selected.

Embodiment 2. FIG.
In the first embodiment, in the vicinity of the air outlet 10 of the centrifugal blower 1, the flow entering the back surface 6a side of the main plate 6 of the impeller 3 is concentrated in the vicinity of the concave portion 12, and the concave portion 12 is an air flow inlet. However, in the second embodiment, the outlet of the air flow that has entered the back surface 6a side of the main plate 6 of the impeller 3 has been shown. Is the configuration of the centrifugal blower 1 that uniquely determines the air flow direction. This will be described with reference to FIGS.

FIG. 7 is a top view of the centrifugal blower according to Embodiment 2 of the present invention.
FIG. 8 is a longitudinal sectional view (X2-'X2) of the centrifugal blower of FIG. 7 as seen from the direction intersecting the rotation axis.
As shown in FIGS. 7 and 8, the centrifugal blower 1 according to the second embodiment has a bowl-like shape on the case wall surface 2 a of the drive motor 2, which is symmetric with respect to the rotation axis of the drive motor 2 with respect to the outlet 10. The rectifying guide 15 is provided. The rectifying guide 15 is not provided on the outlet 10 side of the scroll casing 4. That is, the rectifying guide 15 of the present embodiment is installed at a position corresponding to the bulging portion 4b and the baffle plate 13 in the first embodiment.

Therefore, the flow of air that has entered the back surface 6 a side of the main plate 6 of the impeller 3 passes through the periphery of the drive motor 2, and then is guided by the rectifying guide 15 and passes through the opening 5 of the main plate 6 of the impeller 3. It becomes easy to flow out to the surface 6b side of the impeller 3. That is, the rectifying guide 15 and the opening 5 of the main plate 6 stably serve as an outlet for the flow of air that has entered the back surface 6a side of the main plate 6 of the impeller 3 so that the direction of air flow is unique. Has a function to be determined.

Thus, in the centrifugal blower 1 of the second embodiment, the outflow direction of the air that has entered the back surface 6a side of the main plate 6 of the impeller 3 can be stabilized, so the axial center of the drive motor 2 from the vicinity of the outlet 10 The air flow toward the direction can be uniquely determined. Further, by stabilizing the outflow direction of the air, the air that has entered the back surface 6 a side of the main plate 6 of the impeller 3 flows out to the surface 6 a side of the impeller 3 through the opening 5 of the main plate 6 of the impeller 3. This facilitates the flow of air around the drive motor 2. That is, the cooling effect of the drive motor 2 can be further enhanced by forming an air path through which air flows around the drive motor 2.

Further, in order to obtain a cooling effect of the drive motor 2 without deteriorating the pressure loss in the air passage, the rectifying guide is provided on the case wall surface 2a of the drive motor 2 on the side symmetrical to the rotation axis of the drive motor 2 with respect to the outlet 10. A cooling fin having 15 may be attached.

Since both the air flow adjusting means of the first embodiment and the second embodiment described above correspond to the shape change of only a specific part of the blower instead of the whole blower according to the internal pressure difference of the blower, the performance of the blower is improved. Is efficient. Moreover, an inexpensive drive motor can be used by further enhancing the cooling effect of the drive motor. Or a cheaper blower can be realized by minimizing the number of cooling fins.

Next, FIG. 9 is a graph comparing the air blowing characteristics of the centrifugal fan according to the embodiment of the present invention and the conventional centrifugal fan. A broken line is a blowing characteristic of a centrifugal fan having a conventional shape. A thin solid line is a blowing characteristic of a centrifugal blower that employs a configuration in which the flow entering the back surface 6a side of the main plate 6 of the impeller 3 of the first embodiment is concentrated in the airflow inflow portion. The thick solid line represents the flow of air that has entered the back surface 6a side of the main plate 6 of the impeller 3 in the configuration of the first embodiment and the flow guide 15 and the opening 5 of the main plate 6 of the second embodiment. It is the ventilation characteristic of the centrifugal blower 1 which employ | adopted both the structures which formed the outflow port.

As shown in the graph of FIG. 9, the blowing characteristics of the solid blower 1 and the centrifugal blower 1 having both the first and second embodiments are more solid than the conventional centrifugal blower having a broken line in almost the entire region. It can be seen that it has improved.

FIG. 10 is a graph comparing the noise characteristics of the centrifugal fan 1 according to the embodiment of the present invention and a conventional centrifugal fan. In the noise characteristics as well, the noise characteristics of the solid blower according to the first embodiment and the centrifugal fan having the shapes adopting both the first and second embodiments are improved as compared with the conventional blower of FIG. I understand that.
When the centrifugal blower 1 having the shape adopting both the first and second embodiments, which is the best mode of the present invention, was implemented, a noise reduction effect of about −1.5 dB was obtained in comparison with the same air volume.

In the present invention, air that has entered the back surface 6a side of the main plate 6 of the impeller 3 by combining either or both of the airflow adjusting means of the first and second embodiments described above is impeller 3. A circulation flow A is formed which flows through the opening 5 of the main plate 6 and flows toward the surface 6 b of the main plate 6 of the impeller 3. Therefore, the turbulence noise performance can be improved by reducing the turbulence of air flow and pressure fluctuation on the back surface 6a side of the main plate 6 of the impeller 3. Further, air can easily flow out to the surface 6 a side (suction port side) of the main plate 6 of the impeller 3, and a centrifugal blower that further enhances the cooling effect of the drive motor 2 can be obtained.

In the above-described embodiment, the present invention is applied to the centrifugal fan provided with the scroll casing. However, the present invention is not limited to this, and can be applied to a multi-blade fan using a multi-blade impeller.

In the above-described embodiment, the present invention is applied to a blower for ventilation and air conditioning. However, the present invention is not limited to this and can be applied to other devices.

1 Centrifugal blower, 2 drive motor, 2a case wall, 3 impeller, 4 scroll casing, 4a scroll casing bottom wall, 4b bulge, 5 opening, 6 main plate, 6a back, 6b surface, 7 blades, 8 annular members (Wing reinforcing member), 9 inlet, 10 outlet, 11 tongue, 12 recess, 13 baffle plate, 14 guide plate, 15 rectifier guide.

Claims

A centrifugal blower comprising: a scroll casing; an impeller that is arranged in a ring shape with a plurality of blades accommodated in the scroll casing; and a drive motor that drives the impeller,
The scroll casing bottom wall surface facing the impeller is provided with an annular bulging portion protruding toward the impeller side, and an airflow inflow portion through which an airflow flows is formed in a part of the bulging portion. And centrifugal blower.
The centrifugal air blower according to claim 1, wherein the airflow inflow portion is a recess provided in the bulging portion.
The centrifugal blower according to claim 2, wherein the concave portion is provided on an outlet side of the scroll casing.
The centrifugal blower according to claim 2 or 3, wherein the concave portion is provided on a tongue side of the scroll casing.
The centrifugal blower according to any one of claims 1 to 4, wherein the drive motor includes a case, and a rectifying guide for guiding an airflow is provided on a case wall surface of the case.
6. The centrifugal blower according to claim 5, wherein the rectifying guide is disposed on the case wall surface that is symmetrical to the rotational axis of the drive motor with respect to the outlet of the scroll casing.
The centrifugal air blower according to claim 5 or 6, wherein the rectifying guide is disposed corresponding to a portion excluding the air flow inflow portion provided on the bottom wall surface of the scroll casing.
The centrifugal blower according to any one of claims 1 to 7, wherein a guide plate for guiding the airflow is provided on the bottom wall surface of the scroll casing at the airflow inflow portion.