JPH06101696A - Centrifugal blower - Google Patents

Abstract

PURPOSE:To provide a centrifugal blower for restraining reduction of the blowing efficiency and rise of produced sound pressure level respectively due to the deviation between the design blade output angle and proper outlet angle when an impeller is used at a motional point under high static pressure requirement different from a design motional point. CONSTITUTION:An elastic blade plate 7 made of a material having elastic modulus smaller than that of a blade plate 6 at the blade outlet side of the blade plate 6 of an impeller 5 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeller of a centrifugal blower used for a blower such as an air conditioner.

[0002]

2. Description of the Related Art In recent years, blowers such as air conditioners have been required to reduce noise as their living standards have improved. The optimal design of the corner is made.

The impeller of the above-mentioned conventional centrifugal blower will be described below with reference to the drawings.

FIG. 6 shows the structure of an impeller of a conventional centrifugal blower. In the drawing, reference numeral 1 denotes an impeller, which is composed of a plurality of vane plates 2, a main plate 3 to which the vane plate 2 is fixed, and a side plate 4 fixed to an end face of the vane plate 2 on the side opposite to the main plate.

FIG. 7 shows an impeller 1 of the centrifugal blower shown in FIG.
2 is a cross-sectional view taken along the line AA ′ orthogonal to the rotation axis of FIG. β1 indicates the blade outlet angle.

The operation of the impeller of the centrifugal blower configured as described above will be described below.

First, when the impeller 1 is rotated by the driving force of an electric motor (not shown), air is introduced into the impeller 1 through a suction bell mouth (not shown), and the air flows between the plurality of vanes 2. When passing, static pressure and dynamic pressure are added and the air is discharged from the impeller 1 to the outside to perform air blowing.

At this time, the blade outlet angle is designed to be the blade outlet angle β1 which is suitable for the operating point where the impeller 1 is used.
As a result, when the centrifugal blower is used at the designed operating point, the blowing efficiency is good and the generated sound pressure level can be lowered.

[0009]

However, in the above-mentioned configuration, the impeller 1 is used at an operating point different from the designed operating point due to clogging of the filter of the air conditioner and installation of options such as a high-performance filter. In such a case, the blade outlet angle β1 that is optimized at the design operating point has a large deviation from the trajectory of the airflow that passes between the plurality of blade plates 2 and is discharged, and the blowing efficiency sharply decreases, There is a problem that the generated sound pressure level becomes high.

In view of the above-mentioned problems, the present invention suppresses a decrease in air blowing efficiency and an increase in generated sound pressure level without replacing the impeller when the impeller is used at an operating point different from the designed operating point. It is intended to provide a centrifugal blower capable of

[0011]

In order to solve this problem, an impeller of a centrifugal fan according to the present invention comprises a plurality of vane plates,
An elastic blade plate composed of a main plate to which the blade plate is fixed and a side plate fixed to an end surface of the blade plate opposite to the main plate, and made of a material having a smaller elastic coefficient than the blade plate on the blade outlet side of the blade plate. Is provided.

Still another aspect of the present invention is such that the cross section of the elastic blade plate cut along each plane perpendicular to the rotary shaft of the impeller is gradually reduced from the main plate toward the side plate.

[0013]

In the present invention, since the elastic blade plate made of a material having a smaller elastic coefficient than the blade plate is provided on the blade outlet side of the blade plate, when the blade wheel is used at a point other than the designed operating point, The rotation speed changes, and as a result, the centrifugal force acting on the elastic blade plate changes and the blade outlet angle changes, which reduces the deviation between the blade outlet angle and the trajectory of the airflow discharged between the blade plates. , It suppresses the decrease of the ventilation efficiency and the increase of the generated sound pressure level.

In another aspect of the invention, since the cross section of the elastic blade plate cut along each plane perpendicular to the rotary shaft of the impeller is formed so as to gradually decrease from the main plate toward the side plate, the amount of change in the blade outlet angle is reduced. Can be set at each position perpendicular to the axis of rotation of the impeller, and the deviation between the blade outlet angle at each cross section and the trajectory of the air flow discharged between multiple vanes is reduced to reduce the ventilation efficiency and generate noise. Further increase in pressure level can be suppressed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In addition, in order to avoid duplication, the same components as those of the conventional example will be denoted by the same reference numerals and description thereof will be omitted.

FIG. 1 shows the structure of an impeller of a centrifugal blower according to the first embodiment of the present invention.

In the figure, reference numeral 5 denotes an impeller of a centrifugal blower, which is composed of a plurality of vanes 6 and a main plate 3 to which the vanes 6 are fixed, and a side plate 4 fixed to an end face of the vanes 6 opposite to the main plate.
An elastic blade plate 7 made of a material having an elastic coefficient smaller than that of the blade plate 6 is provided on the blade outlet side of the blade plate 6. Also, 8
Is an electric motor for rotating the impeller 5.

FIG. 2 shows an impeller 5 of the centrifugal blower shown in FIG.
3 is a cross-sectional view taken along line BB ′ orthogonal to the rotation axis of FIG. The blade outlet angle β1 is designed to a value suitable for the operating point where the impeller 5 is normally used.

The operation of the centrifugal blower configured as above will be described below. First, when the impeller 5 is rotated by the driving force of the electric motor 8, air is introduced into the impeller 5 through the suction bell mouth (not shown), and static pressure is generated when passing between the plural vane plates 6. Dynamic pressure is applied and the air is discharged from the impeller 5 to serve as a blower.

Here, the blade plate 6 is provided on the blade outlet side of the blade plate 6.
Since the elastic vane plate 7 made of a material having a smaller elastic coefficient is provided, when the impeller 5 is used at an operating point under a high static pressure condition different from the design operating point, the impeller 5 of the centrifugal blower is used.
From the aerodynamic characteristics of the above, the axial load on the induction type electric motor 8 is reduced. Here, if the voltage applied to the electric motor 8 is constant, due to the torque characteristics of the electric motor 8, the rotational speed of the electric motor 8 increases as the axial load decreases, and as a result, the rotational speed of the impeller 5 increases and the elastic blade plate A centrifugal force in the radial direction, which is larger than the design rotation speed, acts on the center of gravity of 7.

Therefore, the elastic blade plate 7 is deformed in the same direction as the rotation direction, and the blade outlet angle becomes larger than the designed outlet angle β1 and becomes a large blade outlet angle β1 'adapted to a high static pressure operating point condition. As a result, the force applied to the fluid passing between the blade plates 6 in the radial direction increases, and the turbulence due to the deviation between the blade outlet angle β1 ′ and the trajectory of the airflow discharged between the blade plates 6 is generated. It reduces the generation of air, and suppresses the reduction of the ventilation efficiency and the increase of the generated sound pressure level.

As described above, according to this embodiment, the blade plate 6
When the impeller 5 is used at an operating point under a high static pressure condition different from the design operating point, by providing the elastic blade plate 7 on the blade outlet side of the blade outlet angle of the blade outlet angle larger than the design blade outlet angle β1. By changing to β1 ′, it is possible to suppress the reduction of the ventilation efficiency and the increase of the generated sound pressure level.

Therefore, it is possible to suppress an increase in energy required to drive the impeller 5 and suppress generation of turbulent noise energy generated at the outlet of the blade plate 6.

The second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows a structure of an impeller of a centrifugal blower according to a second embodiment of the present invention.

In the figure, 9 is an impeller of a centrifugal blower, and a plurality of vanes 10 and a main plate 3 to which the vanes 10 are fixed.
An elastic blade plate 11 made of a material having a smaller elastic coefficient than that of the blade plate 10 is provided on the blade outlet side of the blade plate 10. The elastic blade plate 11 is formed such that a cross section cut along each plane orthogonal to the rotation axis of the impeller 9 becomes gradually smaller from the main plate 3 to the side plate 4. Further, 12 is an electric motor for rotating the impeller 9.

FIG. 4 shows an impeller 9 of the centrifugal blower shown in FIG.
6 is a cross-sectional view taken along line CC ′ in the vicinity of the side plate 4 orthogonal to the rotation axis of FIG. The blade outlet angle β2 is designed to a value suitable for the operating point in which the impeller 9 is used.

FIG. 5 shows an impeller 9 of the centrifugal blower shown in FIG.
3 is a cross-sectional view taken along line DD ′ of the vicinity of the main plate 3 orthogonal to the rotation axis of FIG. The blade outlet angle β3 is designed to a value suitable for the operating point where the impeller 9 is used.

The operation of the centrifugal blower configured as described above will be described below. First, when the impeller 9 is rotated by the driving force of the electric motor 12, air is introduced into the impeller 9 through a suction bell mouth (not shown), and static pressure is generated when passing between the plurality of vanes 10. Dynamic pressure is applied and the air is discharged from the impeller 9 to serve as an air blower.

Here, since the elastic blade plate 11 is provided on the blade outlet side of the blade plate 10, when the impeller 9 is used at an operating point under a high static pressure condition different from the designed operating point, the blade of the centrifugal blower is used. Due to the aerodynamic characteristics of the vehicle 9, the axial load on the induction type electric motor 12 is reduced. Here, if the voltage applied to the electric motor 12 is constant, due to the torque characteristics of the electric motor 12, the rotational speed of the electric motor 12 increases as the axial load decreases, and as a result, the rotational speed of the impeller 9 increases, and the elastic blade plate. A centrifugal force in the radial direction, which is larger than the designed rotation speed, acts on the center of gravity of 11. Therefore, the elastic blade plate 11 is deformed in the same direction as the rotation direction.

Further, the elastic blade plate 11 has a cross section taken along each plane perpendicular to the rotation axis of the impeller 9 and gradually decreases from the main plate 3 to the side plate 4, so that the blade plate 10 near the side plate 4 is reduced. Since the cross section is small, the amount of deformation of the elastic blade plate 11 due to the change in centrifugal force is large, and the blade outlet angle β2 largely changes to the blade outlet angle β2 ′. Since the cross section of the vane plate 10 near the main plate 3 is large, the amount of deformation of the elastic vane plate 11 due to the change in centrifugal force is small, and the vane outlet angle β3 changes to a vane outlet angle β3 ′.

Therefore, when the impeller 9 is used under an operating point condition where the static pressure is higher than the design operating point, the airflow passing between the vane plates 10 near the side plate 4 sharply decreases, and the vane outlet angle is large. The vane outlet angle that changes and the airflow passing between the vane plates 10 near the main plate 3 does not change greatly can be changed to a small value.

Thus, the amount of change in the blade outlet angle at each position orthogonal to the rotation axis of the impeller 9 is adapted to the change in the air flow, so that the fluid passing between the blade plates 10 is radially moved. The applied force is greatly increased, and the occurrence of turbulence due to the deviation between the outlet angle of the blade and the trajectory of the airflow discharged between the blades 10 is further reduced, which further reduces the ventilation efficiency and raises the generated sound pressure level. Suppress.

As described above, according to this embodiment, the blade plate 1
The elastic blade plate 11 is provided on the blade outlet side of
By forming the cross section of No. 1 so as to become gradually smaller from the main plate to the side plate in each plane orthogonal to the rotation axis of the impeller 9, the impeller 9 is operated at a high static pressure operating point different from the design operating point. When used, the blade outlet angle near the side plate 3 where the passing air flow is greatly reduced is changed to a blade outlet angle β2 ′ from the design blade outlet angle β2 so that the blade outlet angle near the main plate 4 where the passing air flow does not change greatly. By changing the blade outlet angle β3 ′ from the designed blade outlet angle β3 to be smaller, it is possible to further suppress the reduction of the blowing efficiency and the increase of the generated sound pressure level.

Therefore, it is possible to suppress an increase in energy required to drive the impeller 10 and to greatly suppress the generation of turbulent noise energy generated at the outlet of the blade plate 6.

[0035]

As described above, according to the present invention, a plurality of vanes, a main plate to which the vanes are fixed, and a side plate fixed to an end face of the vanes opposite to the main plate constitute an impeller, and the vanes are provided. By providing an elastic vane plate made of a material having a smaller elastic coefficient than the vane plate on the vane outlet side of the plate, when the vane wheel is used at an operating point under a high static pressure condition different from the designed operating point, the vane outlet By changing the angle to a blade outlet angle larger than the designed blade outlet angle, it is possible to suppress lowering of the blowing efficiency and increase of the generated sound pressure level.

Furthermore, the cross section of the elastic blade plate cut along each plane perpendicular to the axis of rotation of the impeller is formed so as to gradually decrease from the main plate toward the side plate, so that the impeller is designed and operated. When used at operating points under different high static pressure conditions, the blade outlet angle near the side plate is changed greatly, and the blade outlet angle near the main plate is changed slightly to reduce the ventilation efficiency and raise the generated sound pressure level. It can be further suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view of an impeller of a centrifugal blower according to a first embodiment of the present invention.

2 is a cross-sectional view of the main part of the impeller of the centrifugal blower of FIG. 1 taken along the line BB ′.

FIG. 3 is a sectional view of an impeller of a centrifugal blower according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of the main part of the impeller of the centrifugal blower shown in FIG.

5 is a cross-sectional view of the impeller of the centrifugal blower shown in FIG. 3, taken along the line DD ′.

FIG. 6 is a cross-sectional view of a conventional centrifugal blower.

7 is a cross-sectional view of the main part of the impeller of the centrifugal blower of FIG. 6 taken along the line AA ′.

[Explanation of symbols]

 3 main plate 4 side plate 5 impeller 6 impeller plate 7 elastic impeller plate 9 impeller 10 impeller plate 11 elastic impeller plate β1, β1 ′ impeller exit angle β2, β2 ′ impeller exit angle β3, β3 ′ impeller exit angle

Claims (2)

[Claims] 1. A vane wheel is composed of a plurality of vanes, a main plate to which the vanes are fixed, and a side plate fixed to an end face of the vanes opposite to the main plate. A centrifugal blower provided with an elastic blade made of a material having a smaller elastic coefficient than the blade. 2. The centrifugal blower according to claim 1, wherein a cross section of the elastic blade plate cut along each plane orthogonal to the rotation axis of the impeller is gradually reduced from the main plate toward the side plate.