WO2016170580A1

WO2016170580A1 - Centrifugal blower

Info

Publication number: WO2016170580A1
Application number: PCT/JP2015/062007
Authority: WO
Inventors: 一輝岡本; 慶二郎山口; 柏原　秀明
Original assignee: 三菱電機株式会社
Priority date: 2015-04-20
Filing date: 2015-04-20
Publication date: 2016-10-27
Also published as: JP6486459B2; JPWO2016170580A1

Abstract

A centrifugal blower is provided with: a scroll casing having formed therein a suction opening and a discharge opening; an impeller (3) provided within the scroll casing; and a drive motor for rotating the impeller about a rotation axis. The impeller (3) has a disk-shaped main plate (5) rotating about the rotation axis and has a plurality of blades (6) raised from the outer periphery of the main plate (5). When the rotation axis-side ends of the blades (6) are defined as the inner peripheral ends thereof and the ends of the blades (6) opposite the rotation axis are defined as the outer peripheral ends thereof, the outer diameter d of the main plate (5) is smaller than the outer diameter D of the circle formed by connecting the outer peripheral ends of the plurality of blades (6). Each of the blades (6) is provided with a plurality of protrusions (11) formed arranged from the inner peripheral end toward the outer peripheral end.

Description

Centrifugal blower

The present invention relates to a centrifugal blower that blows air by rotating an impeller.

A centrifugal blower in which an impeller rotating around a rotation shaft is accommodated in a scroll casing is used. The impeller is formed with a plurality of wings, and air is blown out through the wings between the wings. When the flow velocity of the air passing between the blades increases, the air may be separated from the blade surface and noise may be generated. Therefore, in order to suppress separation of air passing between the blades from the blade surface, as shown in Patent Document 1, a protrusion may be formed on the blade surface.

Japanese Patent No. 2669448

However, the formation of protrusions on the blade surface may lead to an increase in pressure loss and a decrease in air passage cross-sectional area due to an increase in blade thickness, which may reduce the blowing performance.

The present invention has been made in view of the above, and it is an object of the present invention to provide a blower capable of improving the blowing performance while suppressing the generation of noise by forming protrusions on the blade surface.

In order to solve the above-described problems and achieve the object, the present invention provides a scroll casing in which a suction port and an outlet are formed, an impeller provided inside the scroll casing, and an impeller around a rotating shaft. The impeller includes a disk-shaped main plate that rotates about a rotation shaft, and a plurality of blades that are erected on the outer periphery of the main plate. Of these, when the end on the rotating shaft side is the inner peripheral end and the end on the opposite side of the rotating shaft is the outer peripheral end, the outer diameter D of the main plate is larger than the outer diameter D of the circle connecting the outer peripheral ends of the plurality of blades. The outer diameter d is smaller, and the blade is provided with a plurality of protrusions formed side by side from the inner peripheral end toward the outer peripheral end.

The centrifugal blower according to the present invention has an effect of improving the air blowing performance while suppressing the generation of noise by forming protrusions on the blade surface.

The figure which looked at the centrifugal blower concerning Embodiment 1 of the present invention from the inlet side. FIG. 2 is a cross-sectional view of the centrifugal blower according to the first embodiment, and is a cross-sectional view taken along the line AA shown in FIG. FIG. 3 is a cross-sectional view of the centrifugal blower according to the first embodiment, and is a cross-sectional view taken along line BB shown in FIG. FIG. 3 is a cross-sectional view of the centrifugal blower according to the first embodiment, and is a cross-sectional view taken along the line CC in FIG. The figure which looked at the impeller in Embodiment 1 from the surface side of the main plate The perspective view which looked at the impeller in Embodiment 1 from the back surface side of the main plate It is the elements on larger scale of the impeller in Embodiment 1, Comprising: The figure which expanded the E section of FIG. FIG. 8 is a cross-sectional view of the wing according to the first embodiment, and is a cross-sectional view taken along the line FF shown in FIG. Sectional drawing of the centrifugal blower concerning Embodiment 2 of this invention. FIG. 10 is a cross-sectional view of the centrifugal fan according to the second embodiment, and is a cross-sectional view taken along the line GG shown in FIG. It is the elements on larger scale of the centrifugal blower concerning Embodiment 2, Comprising: The figure which expanded the H section shown in FIG. It is the elements on larger scale of the centrifugal blower concerning Embodiment 2, Comprising: The figure which expanded the I section shown in FIG. The figure which showed the relationship between the fan efficiency and air volume of the centrifugal blower concerning Embodiment 2. The figure which showed the relationship between the specific noise and air volume of the centrifugal blower concerning Embodiment 2. The figure which shows the modification of the wing | blade in Embodiment 2.

Hereinafter, a centrifugal blower according to an embodiment of 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 1 FIG.
FIG. 1 is a view of a centrifugal blower according to a first embodiment of the present invention as viewed from the suction port side. FIG. 2 is a cross-sectional view of the centrifugal fan according to the first embodiment, and is a cross-sectional view taken along the line AA shown in FIG. FIG. 3 is a cross-sectional view of the centrifugal blower according to the first embodiment, and is a cross-sectional view taken along the line BB shown in FIG. 4 is a cross-sectional view of the centrifugal fan according to the first embodiment, and is a cross-sectional view taken along the line CC shown in FIG.

The centrifugal blower 1 includes a drive motor 2, an impeller 3, and a scroll casing 4. The scroll casing 4 is formed with a suction port 8 and an air outlet 9, and an air passage 13 that connects the suction port 8 and the air outlet 9 is formed inside. A tongue 10 is provided in the air passage 13.

FIG. 5 is a view of the impeller 3 according to the first embodiment as viewed from the surface 5b side of the main plate 5. FIG. FIG. 6 is a perspective view of the impeller 3 according to the first embodiment when viewed from the back surface 5 a side of the main plate 5. The impeller 3 includes a disk-shaped main plate 5 and a plurality of wings 6 erected along the outer periphery of the surface 5b of the main plate. The main plate 5 is rotated about the rotation shaft 15 by the drive motor 2. As the main plate 5 rotates, the entire impeller 3 including the blades 6 rotates around the rotation shaft 15. In the following description, the end on the rotating shaft 15 side of the blade 6 is referred to as an inner peripheral end, and the end on the opposite side of the rotating shaft 15 is referred to as an outer peripheral end.

An annular reinforcing member 7 is attached to the outer peripheral end of the blade 6. A convex portion 12 is provided on the bottom surface 4a of the scroll casing 4 facing the back surface 5a of the main plate 5 so that the gap between the main plate 5 and the back surface 5a is constant. As shown in FIG. 5, in the impeller 3, the outer diameter d of the main plate 5 is smaller than the outer diameter D of the circle connecting the outer peripheral ends of the blades 6. In the following description, the outer diameter D of the circle connecting the outer peripheral ends of the blade 6 is also referred to as the outer diameter D of the blade 6.

FIG. 7 is a partially enlarged view of the impeller 3 in the first embodiment, and is an enlarged view of a portion E in FIG. FIG. 8 is a cross-sectional view of blade 6 according to Embodiment 1, and is a cross-sectional view taken along the line FF shown in FIG. On the surface of the blade 6, a plurality of protrusions 11 are provided that are arranged side by side from the inner peripheral end toward the outer peripheral end. As shown in FIG. 8, the protrusion 11 is formed in a range that does not reach the end 6 b on the opposite side of the main plate 5 from the end 6 a on the main plate 5 side in the direction along the rotation axis 15. Specifically, the protrusion 11 is formed in a range in the vicinity of the main plate 5. More specifically, the protrusion 11 is formed in a range between the back surface 5a and the front surface 5b of the main plate 5.

Here, in the centrifugal blower 1, as shown in FIGS. 2 and 3, the air sucked from the suction port 8 is blown out into the scroll casing 4 through the impeller 3. Therefore, the air sucked from the suction port 8 is sucked along the rotating shaft 15, and then the direction of travel is bent and blown into the scroll casing 4 from between the blades 6.

When the centrifugal blower 1 is used with a large air volume, that is, when used on the open side, a strong inertial force acts on the air flow. Since the air sucked from the suction port 8 is bent in the traveling direction, a biased velocity distribution is formed between the blades 6 such that the main plate 5 side becomes larger due to the inertial force.

In the centrifugal blower 1 according to the first embodiment, since the outer diameter d of the main plate 5 is smaller than the outer diameter D of the blades 6, the traveling direction of the air flowing between the blades 6 is not bent and the main plate 5 is not bent. The heading flow passes to the back surface 5 a side of the main plate 5 without colliding with the main plate 5. As described above, when the outer diameter d of the main plate 5 and the outer diameter D of the blade 6 are made equal, the portion blocked by the main plate 5 is made a part of the air path by reducing the outer diameter d of the main plate 5. Air can be allowed to pass through. Thereby, expansion of an airway cross-sectional area can be aimed at and reduction of flow loss and improvement of ventilation performance can be expected. Moreover, noise can be reduced by suppressing the collision of air with the main plate 5.

Also, as shown in FIG. 7, by providing a plurality of protrusions 11 on the surface of the blade 6, the flow of air on the surface of the blade 6 is disturbed, and separation of the flow hardly occurs. Flow separation is more likely to occur as the flow velocity increases, but by forming protrusions 11 in the vicinity of the main plate 5 where the velocity distribution becomes large when used with a large air flow, the flow separation is effectively suppressed, and centrifugal separation is achieved. It is possible to improve the blowing performance of the blower 1 and reduce noise. It should be noted that flow separation is unlikely to occur in a portion away from the main plate 5 where the flow velocity is difficult to increase. Therefore, in the centrifugal blower 1 according to the first embodiment, the protrusion 11 is not formed on a portion of the blade 6 that is away from the main plate 5, that is, on a portion where peeling is difficult to occur. Therefore, an air passage area is ensured between the blades 6 and an increase in pressure loss can be suppressed. Thereby, the ventilation performance of the centrifugal blower 1 can be improved.

In addition, when the centrifugal blower 1 is used at a medium air volume that requires a certain level of static pressure, the inertial force is weakened due to a decrease in the flow velocity, and thus an average speed distribution is obtained between the blades 6. Therefore, the air passing from between the blades 6 to the back surface 5a side of the main plate 5 decreases. Since the protrusion 11 provided on the surface of the blade 6 is around the main plate 5, the centrifugal blower 1 can be reduced and the blowing performance can be improved without obstructing the flow between the blades 6.

Embodiment 2. FIG.
FIG. 9 is a cross-sectional view of the centrifugal blower according to the second embodiment of the present invention. FIG. 10 is a cross-sectional view of the centrifugal fan according to the second embodiment and is a cross-sectional view taken along the line GG shown in FIG. FIG. 11 is a partial enlarged cross-sectional view of the centrifugal blower according to the second embodiment, and is an enlarged view of the portion H shown in FIG. 9. FIG. 12 is a partial enlarged cross-sectional view of the centrifugal blower according to the second embodiment, and is an enlarged view of a portion I shown in FIG. 9. In addition, about the structure similar to the said Embodiment 1, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

In the centrifugal blower 21 according to the second embodiment, the clearance between the bottom surface 4a of the scroll casing 4 and the main plate 5 is greater than the interval h1 at the portion on the opposite side of the air outlet 9 across the rotation shaft 15. The interval h2 at the portion between 15 and the air outlet 9 is larger. That is, as shown in FIGS. 9, 10, and 12, the convex portion 12 is not formed in a portion between the rotating shaft 15 and the air outlet 9.

The centrifugal blower 21 has the largest air passage cross-sectional area of the scroll casing 4 in front of the air outlet 9, so that the air flow speed is increased in front of the air outlet 9. Therefore, between the rotating shaft 15 and the blower outlet 9, an even stronger inertial force acts on the flow, thereby increasing the deviation of the velocity distribution toward the main plate 5.

As described above, the gap between the bottom surface 4a of the scroll casing 4 and the main plate 5 is more than the distance h1 between the rotation shaft 15 and the portion on the opposite side of the air outlet 9 with the rotation shaft 15 interposed therebetween. By increasing the distance h2 at the intermediate portion, air easily passes from between the blades 6 toward the back surface 5a side of the main plate 5 at the portion between the rotary shaft 15 and the outlet 9. Become.

As a result, the local rapid increase in flow velocity can be mitigated. Further, the separation of the flow is suppressed by the protrusions 11 provided on the surface of the blade 6. On the other hand, in the portion on the opposite side of the air outlet 9 across the rotary shaft 15, in order to suppress the air from flowing into the gap between the bottom surface 4a of the scroll casing 4 and the main plate 5, the air blowing performance of the blower is deteriorated. The gap between the bottom surface 4a of the scroll casing 4 and the main plate 5 is narrowed.

Further, the air that has passed from between the blades 6 toward the back surface 5a side of the main plate 5 flows in the vicinity of the bottom surface 4a of the scroll casing 4, and the entire air passage 13 can be used effectively, and the air blowing performance. Can be improved.

FIG. 13 is a diagram showing the relationship between the fan efficiency and the air volume of the centrifugal blower 21 according to the second embodiment. FIG. 14 is a diagram illustrating the relationship between the specific noise and the air volume of the centrifugal blower 21 according to the second embodiment. 13 and 14 also show the relationship between the fan efficiency and the air volume and the relationship between the specific noise and the air volume of the conventional centrifugal blower. Here, the centrifugal blower of the conventional example is a centrifugal blower in which no protrusion is formed on the blade, and the outer diameter d of the main plate is equal to the outer diameter of the blade.

Here, the fan efficiency η of the centrifugal fan is calculated based on the following formula (1), and the specific noise K is calculated based on the following formula (2).

Here, P: total pressure [Pa], Q: air volume [m ³ / min], L: shaft output [W], SPL: noise level [dB], g: gravitational acceleration.

As shown in FIGS. 13 and 14, the centrifugal blower 21 according to the second embodiment has characteristics of maximum fan efficiency +2 pt and −1.0 dB while suppressing a decrease in the blowing performance as compared with the conventional centrifugal blower. Improvement effect was obtained.

In the first and second embodiments, the single suction centrifugal fan is illustrated, but the present invention is not limited to this, and the present invention can also be applied to a double suction centrifugal fan. Further, the present invention is not limited to a blower for ventilation and air conditioning, and can be applied to devices for other purposes.

FIG. 15 is a view showing a modification of the wing 6 in the second embodiment. As shown in FIG. 15, the size and shape of the protrusion 11 may be different for each protrusion 11. Further, the size and shape of the protrusion 11 may be varied in the wing 6 in the first embodiment.

The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1,21 Centrifugal blower, 2 drive motor, 3 impeller, 4 scroll casing, 4a bottom surface, 5 main plate, 5a back surface, 5b surface, 6 blades, 6a, 6b end, 8 suction port, 9 air outlet, 10 tongue , 11 protrusions, 12 protrusions, 13 air paths, 15 rotation axes.

Claims

A scroll casing formed with a suction port and an air outlet;
An impeller provided inside the scroll casing;
A centrifugal blower comprising: a drive motor that rotates the impeller about a rotation axis;
The impeller has a disk-shaped main plate that rotates about the rotation axis, and a plurality of blades that are erected on the outer periphery of the main plate,
Outer diameter of a circle connecting the outer peripheral ends of the plurality of blades when the end on the rotary shaft side is an inner peripheral end and the opposite end of the rotary shaft is an outer peripheral end among the blades. The outer diameter d of the main plate is smaller than D,
The centrifugal fan according to claim 1, wherein the wing is provided with a plurality of protrusions formed side by side from the inner peripheral end toward the outer peripheral end.
The said protrusion is formed in the range which does not reach the edge part on the opposite side of the said main board from the edge part of the said main board in the direction along the said rotating shaft among the said wing | blades. Centrifugal blower.
The gap between the main plate and the scroll casing is larger in a portion between the rotary shaft and the blower outlet than a portion on the opposite side of the blower outlet across the rotary shaft. Item 3. The centrifugal blower according to item 1 or 2.