JPH08284894A - Centrifugal blower - Google Patents

Abstract

PURPOSE: To provide a centrifugal blower capable of exhibiting its high static pressure. CONSTITUTION: A turbulence control plate 20 is installed so as to be set up in and around a nose part 18 in a casing 13 and at the side of an inner circumferential part of a blade piece 15 in a multiblade centrifugal fan 12. This turbulence control plate 20 is made into a form extending along the radial direction of this multiblade centrifugal fan 12 in a state of being approached to be blade piece 15. Supposing that high static pressure is added to a centrifugal blower, and such an air current as flowing back to the inner circumferential part side from the outer circumferential part side of the fan 12, what is known as a turbulent flow is produced, this turbulence is weakened and abated to some extent by the control plate 20, so that high static pressure can be exhibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal fan having a multi-blade centrifugal fan and a spiral casing surrounding the multi-blade centrifugal fan.

[0002]

2. Description of the Related Art A conventional structure of a centrifugal blower of this type is shown in FIGS. 9 and 10, the centrifugal blower includes a multi-blade centrifugal fan 2 which is rotationally driven by a motor 1 and a spiral casing 3 which is provided so as to surround the multi-blade centrifugal fan 2. There is. Among them, the multi-blade centrifugal fan 2 is configured by arranging a large number of blade pieces 5 extending in the axial direction on the outer peripheral portion of the main plate 4 in a cylindrical shape. Further, the casing 3 has an intake port 6 at a portion corresponding to the suction side of the multi-blade centrifugal fan 2, a nose portion 7 at a winding start tip portion of the casing 3, and further outward from the nose portion 7. It has an exhaust port 8 that opens.

In this structure, when the multi-blade centrifugal fan 2 is rotated by the motor 1 in the direction of arrow A in FIG. 9, the air blown by the multi-blade centrifugal fan 2 causes the air outside the casing 3 to come from the intake port 6. The air is sucked into the casing 3 and discharged in the circumferential direction of the multi-blade centrifugal fan 2 as shown by the arrow B, and the discharged air is collected by the casing 3 and discharged from the exhaust port 8. .

[0004]

By the way, in the above-mentioned conventional structure, when a high static pressure is applied to the centrifugal blower, as shown by an arrow C in FIG. 9, in the vicinity of the nose portion 7 in the casing 3, A so-called turbulent flow, which is a reverse flow from the outer peripheral side to the inner peripheral side of the multi-blade centrifugal fan 2, is generated, so that the static pressure is suppressed and a high static pressure cannot be exerted. there were.

Therefore, an object of the present invention is to provide a centrifugal blower capable of exerting a high static pressure.

[0006]

In order to achieve the above-mentioned object, the first means of the present invention has a large number of blades on the outer peripheral portion thereof and sucks air from the axial direction by being rotated. And a multi-blade centrifugal fan that discharges in the circumferential direction, and is provided so as to surround the multi-blade centrifugal fan.The multi-blade centrifugal fan has an intake port and a nose portion at a portion corresponding to the suction side. A spiral casing that collects the air discharged from the blade centrifugal fan and discharges it from an exhaust port, and the casing so as to be arranged in the vicinity of the nose portion and on the inner peripheral side of the blade piece in the multi-blade centrifugal fan. And a turbulence suppressing plate extending in the radial direction of the multi-blade centrifugal fan in a state of being close to the blade pieces.

In this case, the turbulent flow suppressing plate is arranged within an angle range of 0 to 30 degrees from the straight line connecting the rotation center of the multi-blade centrifugal fan and the tip of the nose portion toward the rotation direction side of the multi-blade centrifugal fan. It is preferable (second means), and the radial dimension of the turbulence suppressing plate is set to the inner radius of the blade piece between the rotation center of the multi-blade centrifugal fan and the end portion on the inner peripheral side of the blade piece. 30 to 50
It is preferable to set it within the range of% (third means).
Furthermore, the relationship between the axial dimension H of the blade piece and the dimension h of the axial gap between the axial tip of the turbulence suppressing plate and the main plate of the multi-blade centrifugal fan, h / H is 0.5. It is preferable to set as follows (fourth means).

And most preferably, the turbulence suppressing plate is
The multi-blade centrifugal fan is arranged at a position of about 15 degrees from the straight line connecting the center of rotation of the multi-blade centrifugal fan and the tip of the nose to the rotation direction side of the multi-blade centrifugal fan. Is set to about 40% of the inner radius of the winglet between the center of rotation of the wing and the end of the winglet on the inner peripheral side, and the turbulent flow suppressing plate has a large axial tip portion and a large amount. It is preferable to set the relationship between the dimension h of the axial gap between the blade centrifugal fan and the main plate and the axial dimension H of the blade piece so that h / H is about 0.1 (fifth means). . In addition, it is also preferable that the turbulent flow suppressing plate is formed integrally with the casing (sixth means).

[0009]

According to the first means, a high static pressure is applied to the centrifugal blower, and an air flow that flows backward from the outer peripheral side to the inner peripheral side of the multi-blade centrifugal fan in the vicinity of the nose portion in the casing,
Even if so-called turbulent flow occurs, the turbulent flow hits the turbulence suppressing plate and the momentum is weakened.
Turbulence can be reduced and high static pressure can be exerted.

Further, when a low static pressure is applied to the centrifugal blower, the air flow when air is discharged from the multi-blade centrifugal fan flows from the inner peripheral side to the outer peripheral side of the multi-blade centrifugal fan in the radial direction. Since the turbulence suppressing plate is provided so as to extend in the radial direction of the multi-blade centrifugal fan, the turbulence suppressing plate hardly interferes with the air flow by the multi-blade centrifugal fan. In this case, it is possible to prevent the air volume from decreasing and the noise from increasing as much as possible.

Then, the turbulence suppressing plate is arranged within an angle range of 0 to 30 degrees from the straight line connecting the center of rotation of the multi-blade centrifugal fan and the tip of the nose to the rotation direction side of the multi-blade centrifugal fan. (Second means), the radial dimension of the turbulence suppressing plate is 30 to 50% of the inner radius of the blade piece in the multi-blade centrifugal fan
(Third means), the dimension h of the axial gap between the axial tip of the turbulence suppressing plate and the main plate of the multi-blade centrifugal fan, and the axial dimension H of the blade piece. Relationship with h / H
Is set to 0.5 or less (fourth means)
In addition, the turbulent flow generated near the nose portion in the casing can be effectively weakened by the turbulent flow suppression plate, and as is clear from the experimental results (see FIGS. 5, 6, and 7), It becomes possible to obtain a high static pressure.

Further, as in the fifth means, the turbulence suppressing plate is provided at about 15 degrees from the straight line connecting the center of rotation of the multi-blade centrifugal fan and the tip of the nose to the rotation direction side of the multi-blade centrifugal fan. The turbulent flow suppressing plate is arranged at a position such that the radial dimension of the turbulent flow suppressing plate is about 40% of the inner circumference radius of the blade piece in the multi-blade centrifugal fan, and the axial tip end portion of the turbulent flow suppressing plate is set. When the relationship between the dimension h of the axial gap between the blade and the main plate of the multi-blade centrifugal fan and the dimension H of the blade pieces in the axial direction is set so that h / H is about 0.1, the disturbance is The generation of the flow can be suppressed more effectively, and as is clear from the experimental results (see FIGS. 5, 6, and 7), a higher static pressure can be obtained. When the turbulent flow suppressing plate is formed integrally with the casing, there is an advantage that the number of parts and the number of assembling steps can be reduced as compared with the case where a turbulent flow suppressing plate that is separate from the turbulent flow suppressing plate is attached to the casing.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First, in FIGS. 1 and 2, the centrifugal blower is composed of a multi-blade centrifugal fan 12 that is rotationally driven by a motor 11, and a spiral casing 13 provided so as to surround the multi-blade centrifugal fan 12. Has been done. Of these, the multi-blade centrifugal fan 12 is configured by arranging a large number of blade pieces 15 extending in the axial direction in a cylindrical shape on the outer peripheral portion of a disc-shaped main plate 14. Each wing piece 1
A ring-shaped side plate 16 is provided at an end portion (right end portion in FIG. 2) opposite to the main plate 14 side of FIG. Also,
The casing 13 has an intake port 17 composed of a bell mouth at a portion corresponding to the suction side of the multi-blade centrifugal fan 12, and has a nose portion 18 at the winding start tip of the casing 3.
And an exhaust port 19 that opens outward from the nose portion 18.

The casing 13 near the intake port 17
As shown in FIG. 3, the mounting portion 20 a at the base end of the turbulent flow suppression plate 20 having a flat plate shape is attached to the outer surface of the with a screw 21. The turbulence suppressing plate 20 has a tip portion inserted into the casing 13 through the intake port 17, and as shown in FIG. 1, is located in the vicinity of the nose portion 18 and on the inner circumference of the blade piece 15 in the multi-blade centrifugal fan 12. The multi-blade centrifugal fan 12 is arranged so as to be inserted and disposed on the side of the blade and extends in the radial direction of the multi-blade centrifugal fan 12 while being close to the inner peripheral portion of the blade piece 15.

Now, the installation conditions of the turbulence suppressing plate 20 will be described in more detail. First, the turbulence suppressing plate 20
In FIG. 1, an angle θ from a straight line A connecting the rotation center O of the multi-blade centrifugal fan 12 and the tip of the nose portion 18 of the casing 13, specifically, the straight line A to the multi-blade centrifugal fan 1
The position within the range of 0 to 30 degrees toward the rotation direction of 2 (direction of arrow B) is preferable, and the position is more preferably about 15 degrees.

Further, the radial dimension a of the turbulence suppressing plate 20 is
Ratio (a / D) between the center O of rotation of the multi-blade centrifugal fan 12 and the end of the blade 15 on the inner peripheral side relative to the inner peripheral radius D of the blade.
Is preferably set to fall within the range of 30 to 50%, more preferably set to a / D of about 40%.

Further, in FIG. 2, the dimension h of the axial gap between the tip of the turbulence suppressing plate 20 in the axial direction and the main plate 14 of the multi-blade centrifugal fan 12 and the blade piece 15 in the multi-blade centrifugal fan 12 are shown. It is preferable that h / H is set to 0.5 or less, and more preferably, h / H is set to about 0.1.

In the above structure, when the multi-blade centrifugal fan 12 is rotated by the motor 11 in the direction of arrow B in FIG. 1, the air blown by the multi-blade centrifugal fan 12 causes the air outside the casing 13 to enter the intake port. 17 to casing 13
Inhaled into the multi-blade centrifugal fan 2 as indicated by arrow C.
Is discharged in the circumferential direction of, and the discharged air is collected by the casing 13 and discharged from the exhaust port 19.

Therefore, a high static pressure is applied to the centrifugal blower, and a so-called turbulent flow is generated near the nose portion 18 in the casing 13 so as to flow backward from the outer peripheral side to the inner peripheral side of the multiblade centrifugal fan 12. Even if it does (see arrow E of the chain double-dashed line in FIG. 1), the turbulent flow hits the turbulent flow suppression plate 20 and the momentum is weakened. As a result, the turbulent flow can be reduced, and as shown in FIG. , It becomes possible to exert a higher static pressure than the conventional example.

Here, FIG. 5 is a characteristic diagram showing the relationship between the angle θ indicating the arrangement position of the turbulence suppressing plate 20 and the full-closed static pressure Ps in the installation conditions of the turbulent suppressing plate 20. Horizontal axis angle θ
In the figure, a plus (+) indicates the rotation direction side of the multi-blade centrifugal fan 12 (arrow B side) from the straight line A, and a minus (-) indicates a side opposite to the rotation direction of the multi-blade centrifugal fan 12 (arrow arrow). The side opposite to B) is shown. In FIG. 5, a characteristic line S1 shown by a solid line shows a case where the above-mentioned h / H ratio is 0.1 and a / D is 40%, and a characteristic line S2 shown by a broken line shows a h / H ratio. Is 0.5 and a / D is 50%, and the characteristic line S3 indicated by a chain double-dashed line is h
A case where the ratio of / H is 0.5 and a / D is 30% is shown.

As is clear from FIG. 5, the static pressure is high when the angle θ indicating the position of the turbulent flow suppressing plate 20 is within the range of 0 to +30 degrees, and the static pressure is at about 15 degrees. It can be seen that the static pressure is highest when. Also, the characteristic line S1
However, it can be seen that the static pressure is higher than the other characteristic lines S2 and S3.

FIG. 6 is a characteristic diagram showing the relationship between the a / D ratio of the installation conditions of the turbulence suppressing plate 20 and the total closing static pressure Ps. In FIG. 6, the characteristic line T1 shown by the solid line shows the case where the h / H ratio is 0.1 and the angle θ is +15 degrees, and the characteristic line T2 shown by the broken line shows that the h / H ratio is 0. .5 and the angle θ is +30 degrees, and the characteristic line T3 indicated by the chain double-dashed line shows the case where the h / H ratio is 0.5 and the angle θ is 0 degrees.

As is apparent from FIG. 6, the ratio (a of the radial dimension a of the turbulence suppressing plate 20 to the inner radius D of the blade piece (a
It is understood that the static pressure is high when / D) is in the range of 30 to 50%, and the static pressure is highest when it is approximately 40%. Further, it can be seen that the characteristic line T1 has a higher static pressure as a whole than the other characteristic lines T2 and T3.

FIG. 7 is a characteristic diagram showing the relationship between the ratio h / H and the full-closed static pressure Ps in the installation conditions of the turbulence suppressing plate 20. In FIG. 7, the characteristic line U1 shown by the solid line is
The characteristic line U2 indicated by a broken line is the case where a / D is 40% and the angle θ is +15 degrees, and the case where a / D is 30% and the angle θ is 0 degrees is indicated by a two-dot chain line. Characteristic line U3
Indicates the case where a / D is 50% and the angle θ is 30 degrees.

As is apparent from FIG. 7, when the h / H ratio is 0.5 or less, the static pressure is high, especially about 0.
It can be seen that when the value is 1, the static pressure is high. Also, the characteristic line U1
However, the static pressure is higher than the other characteristic lines U2 and U3.

Therefore, in these FIG. 5 to FIG.
As the installation conditions of the turbulence suppressing plate 20, the angle θ is arranged at a position of about +15 degrees, the a / D ratio is set to about 40%, and the h / H ratio is set to about 0.1. It can be seen that the case of setting so as to be most preferable. Moreover, in this case, a high static pressure can be exhibited with a simple structure in which the turbulent flow suppressing plate 20 is provided in the casing 13.

When a low static pressure is applied to the centrifugal blower, the air flow when air is discharged from the multi-blade centrifugal fan 12 is along the radial direction from the inner peripheral side to the outer peripheral side of the multi-blade centrifugal fan 12. In this case, since the turbulent flow suppressing plate 20 is provided so as to extend in the radial direction of the multi-blade centrifugal fan 12, the turbulent flow suppressing plate 20 prevents the air flow by the multi-blade centrifugal fan 12. Therefore, it is possible to prevent the air volume from decreasing and the noise from increasing in such a case as much as possible. This can be understood from the fact that in FIG. 4, even if the static pressure becomes low (even when the static pressure becomes close to 0), the air volume Q is almost the same as that of the conventional example, so that the air volume does not decrease.

FIG. 8 shows a second embodiment of the present invention. This second embodiment differs from the above-mentioned first embodiment in the following points. That is, the casing 13 is made of synthetic resin, and the turbulent flow suppressing plate 22 is integrally formed on the casing 13.

In the case of such a structure, there is an advantage that the number of parts can be reduced and the number of assembling steps can be reduced as compared with the case where the turbulent flow suppressing plate 20 which is a separate body is attached to the casing 13.

The turbulent flow suppressing plates 20 and 22 are not limited to the flat plate shape, and may be bent to have a slightly arcuate shape. it can.

[0031]

According to the centrifugal blower of the present invention, by providing the turbulence suppressing plate so as to be arranged in the vicinity of the nose portion of the casing and on the inner peripheral side of the blade of the multi-blade centrifugal fan, Even if a high static pressure is applied to the centrifugal blower and turbulent flow occurs in the vicinity of the nose in the casing, the turbulent flow can be weakened and reduced by the turbulence suppressing plate, and as a result, high static pressure can be exerted. Like
Further, since the turbulence suppressing plate is provided along the radial direction of the multi-blade centrifugal fan, the turbulence suppressing plate hardly interferes with the air flow by the multi-blade centrifugal fan when the static pressure is low. In such a case, it is possible to prevent the air volume from decreasing and the noise from increasing. In addition, this can be achieved with a simple structure in which the turbulent flow suppressing plate is provided.

Then, the turbulence suppressing plate is arranged within an angle range of 0 to 30 degrees from the straight line connecting the center of rotation of the multi-blade centrifugal fan and the tip of the nose to the rotation direction side of the multi-blade centrifugal fan. , The radial dimension of the turbulence suppressing plate is set within the range of 30 to 50% with respect to the inner radius of the blade piece in the multi-blade centrifugal fan, or the axial tip of the turbulence suppressing plate and the multi-blade centrifugal are set. When the relationship between the dimension h of the axial gap between the fan and the main plate and the axial dimension H of the blade is set so that h / H is 0.5 or less, the nose portion in the casing is The turbulent flow generated in the vicinity can be effectively weakened by the turbulent flow suppression plate, and a higher static pressure can be obtained.

Further, the turbulent flow suppressing plate is arranged at a position of about 15 degrees from the straight line connecting the center of rotation of the multi-blade centrifugal fan and the tip of the nose to the rotation direction side of the multi-blade centrifugal fan to suppress turbulent flow. The radial dimension of the plate is set to be about 40% of the inner peripheral radius of the blade in the multi-blade centrifugal fan, and the axial tip of the turbulence suppressing plate and the main plate of the multi-blade centrifugal fan are set. When the relationship between the dimension h of the axial gap between and the axial dimension H of the winglet is set so that h / H is about 0.1,
The generation of turbulence can be suppressed more effectively, and a higher static pressure can be obtained. When the turbulent flow suppression plate is formed integrally with the casing, compared to the case where a turbulent flow suppression plate separate from this is attached to the casing,
There is an advantage that the number of parts and the number of assembling steps can be reduced.

[Brief description of drawings]

FIG. 1 is an overall sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a portion corresponding to line XX in FIG.

FIG. 3 is an exploded perspective view of a main part

FIG. 4 is a characteristic diagram showing a relationship between air volume and static pressure.

FIG. 5 is a characteristic diagram showing the relationship between the angle θ and the fully closed static pressure.

FIG. 6 is a characteristic diagram showing the relationship between a / D ratio and full-closed static pressure.

FIG. 7 is a characteristic diagram showing a relationship between h / H ratio and full-closed static pressure.

FIG. 8 is a perspective view of a main part showing a second embodiment of the present invention.

9 is a view corresponding to FIG. 1 showing a conventional configuration.

FIG. 10 is a view corresponding to FIG.

[Explanation of symbols]

Reference numeral 11 is a motor, 12 is a multi-blade centrifugal fan, 13 is a casing, 14 is a main plate, 15 is a blade piece, 17 is an intake port, 18 is a nose portion, 19 is an exhaust port, 20 is a turbulence suppressing plate, and 22 is a turbulent flow. It is a suppression plate.

Claims (6)

[Claims] 1. A multi-blade centrifugal fan which has a large number of blades on its outer peripheral portion and sucks air from the axial direction and discharges it in the circumferential direction when it is rotated, and surrounds this multi-blade centrifugal fan. And a nose portion having a suction port in a portion corresponding to the suction side of the multi-blade centrifugal fan, and a spiral casing that collects the air discharged from the multi-blade centrifugal fan and discharges it from the exhaust port, Provided in the casing so as to be arranged in the vicinity of the nose portion and on the inner peripheral side of the blade in the multi-blade centrifugal fan, and along the radial direction of the multi-blade centrifugal fan in a state of being close to the blade. A centrifugal blower comprising an extending turbulence suppressing plate. 2. The turbulence suppressing plate is arranged within an angle range of 0 to 30 degrees from the straight line connecting the center of rotation of the multi-blade centrifugal fan and the tip of the nose portion toward the rotation direction side of the multi-blade centrifugal fan. The centrifugal blower according to claim 1, characterized in that. 3. The radial dimension of the turbulence suppressing plate is 30 to 50% of the inner circumference radius of the blade between the rotation center of the multi-blade centrifugal fan and the end on the inner circumference side of the blade. The centrifugal blower according to claim 1, wherein the centrifugal blower is set within a range. 4. The relationship between the axial dimension H of the blade and the dimension h of the axial gap between the tip of the turbulence suppressing plate in the axial direction and the main plate of the multi-blade centrifugal fan is expressed by h / H. The centrifugal blower according to claim 1, wherein the centrifugal blower is set to be 0.5 or less. 5. The turbulence suppressing plate is arranged at a position of about 15 degrees from the straight line connecting the center of rotation of the multi-blade centrifugal fan and the tip of the nose to the rotation direction side of the multi-blade centrifugal fan, The radial dimension of the plate is set to be about 40% of the inner radius of the blade between the center of rotation of the multi-blade centrifugal fan and the end of the blade on the inner peripheral side, and The relationship between the axial dimension H of the blade and the dimension h of the axial gap between the axial tip of the flow suppression plate and the main plate of the multi-blade centrifugal fan, h / H is about 0.1. The centrifugal blower according to claim 1, wherein the centrifugal blower is set as follows. 6. The centrifugal blower according to claim 1, wherein the turbulence suppressing plate is formed integrally with the casing.