JPH09195997A - Centrifugal blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniform wind velocity distribution so as to reduce noise by providing with a suction direction changing piece which is positioned on the suction port outer peripheral part of an opposite direction to the diffuser of a casing, and for straightening suction flow in a blower axial direction. SOLUTION: In a spiral casing 2 provided with a suction bell-mouth 3 in which a sirocco fan 1, a suction direction changing piece 7 is arranged on a part of a suction port circumference. Flow by the suction changing piece 7 is straightened in the axial direction of the sirocco fan 1 on the straight line part of the suction direction changing piece 7 so as to show it by B, and it becomes flow for changing the direction to 90 degree in a radial direction in the vicinity of a holding ring 6 suffering the influence of centrifugal force by flow on a circular arc surface. At this time, the flow becomes the same flow as prior flow A on a position which is not provided with the suction direction changing piece 7. As a result, the flow-in position of a fan differs in the axial direction of the sirocco fan 1, and thereby, a fan flow-in wind velocity distribution is unified more than that of a prior art.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art The structure of a conventional general centrifugal blower will be described with reference to FIG. The sirocco fan 1 having blades arranged in parallel with the rotation axis between the boss portion 5 and the retaining ring 6,
It is housed in a spiral casing 2 equipped with a suction bell mouth 3 and driven by a motor 4.

The most basic conventional centrifugal blower is disclosed in Japanese Utility Model Laid-Open No. 57-134398. As shown in FIG. 8, a plurality of guide vanes are provided on the surface of the spiral casing 2 having a suction port so that the suction flow can flow in an orderly manner.

[0004]

Since the conventional centrifugal blower is constructed as described above, the air flowing in from the suction bell mouth has a distribution depending on the fan inflow speed in the axial direction of the sirocco fan. As a result, there is a problem that the air volume is reduced and the noise when passing between the blades is deteriorated.

Further, in the double-sided suction structure, when the suction pressure loss is different on both sides, a pressure difference occurs inside the two sirocco fans. As a result, there is a problem that the distribution of blown-air velocity at the outlet of the sirocco fan becomes non-uniform on the left and right, leading to a decrease in air volume, and the pressure difference inside the sirocco fan disturbs the merging portions from the left and right fans, which worsens noise. It was

Further, there is a problem that the flow blown from the sirocco fan is severely disturbed on the back side of the suction bell mouth curved in an arc shape, and the noise is deteriorated.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to obtain a centrifugal air blower capable of obtaining a large air volume and reducing noise by making the wind velocity distribution uniform. With the goal.

[0008]

According to a first aspect of the present invention, there is provided a centrifugal blower having a spiral casing, the centrifugal blower being located at an outer peripheral portion of a suction port in a direction opposite to a blowout port of the casing and having a suction flow. It is characterized by including a suction direction changing piece for rectifying the direction.

A centrifugal blower according to a second aspect of the present invention is a centrifugal blower having double-sided suction ports, characterized in that pressure balance holes for pressure balance are provided in boss portions of the left and right sirocco fans.

A centrifugal blower according to a third aspect of the present invention is a centrifugal blower having a curved suction bell mouth, and has a curved surface from the vicinity of the sirocco fan holding ring portion located at the end of the sirocco fan to the side surface of the casing having the suction port. A rectifying piece is provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. Hereinafter, Embodiment 1 of the present invention will be described with reference to FIG.
A description will be given based on FIGS. 2 and 3. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. A sirocco fan 1 having blades arranged in parallel with the axis of rotation between the boss portion 5 and the retaining ring 6 is sucked and is housed in a spiral casing 2 having a bell mouth 3. A suction direction changing piece 7 is provided in a part of the vicinity of the suction port of the spiral casing 2.

The conventional suction flow flows in along the arc surface of the suction bell mouth 3 as shown by an arrow A in FIG.
The centrifugal force generated by the flow on the arc surface causes the flow toward the center of the sirocco fan. Then, after passing through the retaining ring 6, the flow turns 90 ° in the radial direction of the sirocco fan. At this time, the flow from the entire circumference of the suction port was concentrated at a position where the fan inflow position was away from the retaining ring 6 in the sirocco fan axial direction, and the fan inflow air velocity distribution was non-uniform.

However, the flow due to the suction direction changing piece 7 is rectified in the axial direction of the sirocco fan at the straight part of the suction direction changing piece 7 as shown by the solid arrow B, and the centrifugal force due to the flow on the arc surface is eliminated. In the vicinity of the holding ring 6, the flow changes its direction by 90 ° in the radial direction. At this time,
Where there is no suction direction changing piece 7 at the suction port, the flow is the same as that of the conventional arrow A, so the fan inflow position differs in the sirocco fan axial direction, and the fan inflow air velocity distribution becomes more uniform than in the conventional case.

Therefore, the distribution of the inflow speed of the fan in the axial direction of the sirocco fan is made uniform, so that the passing air speed between the blades is reduced and the noise is reduced.

The suction direction changing piece 7 is located on the suction outer peripheral portion in the direction opposite to the air outlet, and the size thereof is the suction peripheral portion 60.
° to 120 ° and a width of 5 mm to 30 mm. The shape has a modification as shown in FIG.

Embodiment 2 The second embodiment of the present invention will be described below with reference to FIG. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. A sirocco fan 1 having blades arranged in parallel with the axis of rotation between the boss portion 5 and the retaining ring 6 is sucked and is housed in a spiral casing 2 having a bell mouth 3. A plurality of pressure balancing holes 8 for pressure balancing are provided in the boss portion 5.

In the conventional boss shape, when the suction pressure loss is greatly different on both sides, a left and right fan blowout wind speed difference occurs, and the flow is drawn toward the higher wind speed, further increasing the wind speed difference. For this reason, noise was generated where the flows with large wind speed differences merged, and the blowing efficiency from the sirocco fan outlet was non-uniform, resulting in poor blowing efficiency.

However, the pressure balance hole 8 is formed in the boss portion.
Is provided, the pressure in the left and right fans is made uniform through the pressure balance hole 8 from the higher pressure side to the lower pressure side. Therefore, the difference between the left and right fan blowing wind speeds is reduced.

Therefore, the distribution of the blowing air velocity at the outlets of the sirocco fans becomes uniform on the left and right, so that the blowing efficiency is improved, and the turbulence at the merging portions of the blowing from the left and right fans is reduced, so that noise reduction is achieved.

Embodiment 3 The third embodiment of the present invention will be described below with reference to FIG. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. A sirocco fan 1 having blades arranged in parallel with the rotation axis between the boss portion 5 and the retaining ring 6 is sucked and is housed in a spiral casing 2 having a bell mouth 3. A curved straightening piece 9 is provided from the holding ring portion 6 to the side surface portion of the casing 2 having a suction port.

As shown by the arrow A in FIG. 5, the flow of air blown from the fan in the vicinity of the retaining ring 6 of the related art is disturbed because the flow becomes unstable in the space behind the suction bell mouth 3. However, the flow by the rectifying piece 9 flows along the rectifying piece 9 as shown by the arrow B, becomes a stable flow, and turbulence is reduced.

Therefore, the noise due to the turbulence of the flow on the back side of the suction bell mouth 3 curved in an arc shape can be reduced.

The rectifying piece 9 is integrally positioned inside the casing rather than the side surface of the retaining ring 6, and there is a modified example as shown in FIG.

[0024]

The centrifugal fan according to the first aspect of the present invention is a centrifugal fan having a spiral casing, which is located at the outer peripheral portion of the suction port in the direction opposite to the outlet of the casing and rectifies the suction flow in the axial direction of the blower. Since the configuration is provided with the suction direction changing piece, the inflow wind velocity distribution is made uniform in the blower axial direction, so that the air velocity passing between the blades is reduced and noise can be reduced.

The centrifugal blower according to claim 2 is a centrifugal blower having a double-sided suction port, and pressure balance holes for pressure balance are provided in the boss portions of the left and right sirocco fans.
The blowing air velocity distribution at the outlets of the sirocco fans becomes uniform on the left and right, improving the blowing efficiency, and reducing the turbulence at the merging portions of the blowing from the left and right fans, thus achieving low noise.

A centrifugal blower according to a third aspect of the present invention is a centrifugal blower having a curved suction bell mouth, and has a curved surface from the vicinity of the sirocco fan holding ring portion located at the end of the sirocco fan to the side surface of the casing having the suction port. Since the rectifying piece is provided, the flow in the space behind the suction bell mouth is stabilized.

[Brief description of the drawings]

1 is a perspective view of a centrifugal fan according to Embodiment 1 of the present invention.

FIG. 2 is a vertical cross-sectional view of the centrifugal fan according to the first embodiment of the present invention.

FIG. 3 is a vertical sectional view of a centrifugal fan according to a modification of the first embodiment of the present invention.

FIG. 4 is a perspective view of a boss portion of a centrifugal blower according to Embodiment 2 of the present invention.

FIG. 5 is a vertical sectional view of a centrifugal fan according to a third embodiment of the present invention.

FIG. 6 is a vertical cross-sectional view of a centrifugal fan according to a modification of the third embodiment of the present invention.

FIG. 7 is a perspective view of a conventional centrifugal blower.

FIG. 8 is a perspective view of another conventional centrifugal blower.

[Explanation of symbols]

1 sirocco fan, 2 spiral casing, 3 suction bell mouth, 5 boss, 6 retaining ring, 7 suction direction changing piece, 8 pressure balancing hole, 9 straightening piece.

Claims (3)

[Claims] 1. A centrifugal blower having a spiral casing, comprising a suction direction changing piece which is located at an outer peripheral portion of a suction port in a direction opposite to an outlet of the casing and rectifies the suction flow in the axial direction of the blower. Centrifugal blower characterized by. 2. A centrifugal blower having a double-sided suction port, wherein pressure balance holes for pressure balance are provided in the boss portions of the left and right sirocco fans. 3. A centrifugal blower having a curved suction bell mouth, wherein a curved straightening piece is provided from the vicinity of the sirocco fan holding ring portion located at the end of the sirocco fan to the side surface of the casing having the suction port. A characteristic centrifugal blower.