JPH08135596A - Impeller for centrifugal blower - Google Patents

Abstract

PURPOSE: To reduce the turbulent nose of a one side suction type centrifugal blower impeller by intensifying air blowout in radial direction in a portion from a suction side end for certain distance, thereby suppressing recirculation flow in a casing and reducing an eddy. CONSTITUTION: In a one side suction type, by being held with an end ring 21 and an annular ring 23 so as to form side face of a cylinder of the impeller 2 from an end 2b for certain distance. Plural plate type blades 25 are similarly installed so as to form side face in the remaining portion of the cylinder of the impeller 2. Outlet angle of blades 24 between extension direction at outlet side end and direction opposite to circumferential speed vector of blades 24 is set to be smaller than outlet angle of blades 25 in the remaining portion. At least in the remaining portion, outlet angle of blade 25 is larger than 90 deg. so as to be sirocco type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeller for a centrifugal blower used in a blower of an air conditioner. In particular, the present invention relates to improvement of a sirocco type impeller (referred to as "sirocco fan") having an outlet angle of blades larger than 90 degrees.

[0002]

2. Description of the Related Art Conventionally, a sirocco fan has been frequently used in the above-mentioned centrifugal blower, but on the other hand, improvement in blowing efficiency and noise reduction are required. Therefore, the special fair 4
There is a sirocco fan in which the longitudinal direction of the blade is inclined with respect to the axial direction of the impeller as disclosed in Japanese Patent No. 54078. According to this sirocco fan, the discharge air is blown out in a direction orthogonal to the axial direction of the impeller when viewed in a cross section along the axial direction of the impeller. As a result, there was some effect, but insufficient, on the improvement of ventilation efficiency and noise reduction.

[0003]

On the other hand, as a result of the research conducted by the present applicant, it was found that the following phenomenon occurred in the sirocco fan. That is, in the size of the velocity (referred to as “outlet velocity”) of the air (referred to as “outlet air”) flowing out from the outlet-side end of the impeller constituting the impeller, the impeller is located near the outlet of the casing. The exit velocity from a portion of the vehicle close to the suction side end has almost no radial component (see FIG. 6). That is, the air blowing from the portion near the suction side end was weak.

FIG. 6 is a graph showing the outlet velocity at a position near the discharge port. The vertical axis indicates the outlet velocity, the size of the arrow indicates the size of the radial component, and the upward direction indicates the outside.
The downward direction indicates the inward direction, and the horizontal axis indicates the axial position with the right side of the drawing as the suction side. From the above phenomenon, in the part on the suction side of the impeller, the outflow air is not efficiently blown out, so a recirculation flow that circulates with the impeller inside the casing occurs, and this recirculation flow increases the blowing efficiency of the sirocco fan. It is thought that it is decreasing. Further, since the blowout is weak, vortices are generated, and as a result, turbulent noise may be generated.

By the way, in the above-mentioned conventional technique, the effect of reducing the noise is insufficient because the air is weakly blown out near the suction side end of the impeller. It is thought that Therefore, the purpose of the present invention is to
An object of the present invention is to provide an impeller for a centrifugal blower, which solves the above-mentioned technical problems and makes use of the characteristics of a sirocco fan while suppressing the generation of recirculation flow and turbulent noise.

[0006]

In order to achieve the above object, the impeller for a centrifugal blower according to claim 1 is a one-suction type impeller for a centrifugal blower in which one end is closed and air is sucked in from the other end. In the part from the other end to the predetermined distance, the outlet angle formed by the direction in which the outlet side end of the blade extends and the direction opposite to the direction of the circumferential velocity vector of the blade is
It is set to be smaller than the outlet angle of the remaining portion, and at least the remaining portion has the blade outlet angle of 9
It is characterized in that it is formed in a sirocco type having a size larger than 0 degree.

Further, the impeller for a centrifugal blower according to a second aspect is the impeller for a centrifugal blower according to the first aspect, wherein a portion from the other end to a predetermined distance has radial blades extending in a radial direction. It is characterized in that it is formed in a mold. Further, the impeller for a centrifugal blower according to claim 3 is a double-suction type centrifugal impeller for a centrifugal blower in which a central portion in the axial direction is closed and air is sucked in from both ends, in a portion from each end to a predetermined distance. The outlet angle formed by the direction in which the outlet side end of the blade extends and the direction opposite to the direction of the circumferential velocity vector of the blade is set smaller than the outlet angle in the remaining portion including the central portion, At least the remaining portion is characterized by being formed in a sirocco shape in which the outlet angle of the blade is larger than 90 degrees.

Further, an impeller for a centrifugal blower according to a fourth aspect is the impeller for a centrifugal blower according to the third aspect, wherein the blade extends radially along a radial direction in a portion from each end to a predetermined distance. It is characterized in that each is formed in a mold.

[0009]

In general, in a centrifugal blower impeller, when the so-called outlet angle (for example, shown by the angle Ds in FIG. 4) becomes smaller, the magnitude of the radial component of the absolute velocity of the outflow air (the "outlet radial velocity"). It is known to grow. Therefore, in the configuration of claim 1,
By setting the outlet angle in a portion up to the predetermined distance from the other end of the impeller to be relatively smaller than the remaining portion, the outflow radial velocity of the portion up to the predetermined distance is
It becomes larger than when the exit angle is not made small.

Conventionally, at the portion of the outlet of the blade near the end on the suction side, there is almost no outflow radial velocity, and it is difficult for air to be blown out. On the other hand, in the present invention, the outflow radial velocity becomes large in the portion up to the predetermined distance from the other end, which is the end on the suction side, and the air is blown out strongly from this portion. Therefore, the recirculation flow in the casing is less likely to occur, the vortices are reduced, and the turbulent noise is reduced.

Further, according to the configuration of the invention according to the second aspect, in addition to the operation according to the first aspect, a partially simple blade shape is adopted, so that the impeller can be easily manufactured.
Further, in the configuration of claim 3, the outlet angle at each portion from each end of the impeller to the predetermined distance is set to be relatively smaller than that at the remaining portion, so that the predetermined distance up to the predetermined distance can be obtained. The outflow radial velocity of the portion is larger than that when the outlet angle is not reduced. Therefore, as a result of the air blowout in the radial direction becoming stronger in each part from each end of the impeller to a predetermined distance, recirculation flow and turbulent noise can be reduced.

Further, according to the structure of the invention according to claim 4, in addition to the function described in claim 3, a partially simple blade shape is adopted, so that the impeller can be easily manufactured.

[0013]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. FIG. 1 is a partial cross-sectional front view showing an outline of a centrifugal blower using an impeller for a centrifugal blower according to an embodiment of the present invention. FIG. 2 is a side view of a cross section taken along the line AA of FIG. 1 and 2, a main configuration of a general centrifugal blower is a casing 1 having a shape of a spiral chamber, and an impeller 2 which is housed in the casing and is formed into a rotatable substantially cylindrical cage. Consists of.

The casing 1 is formed in a hollow, substantially columnar shape, and has a protruding portion 11 on its side surface. The overhang portion 11 is provided with a discharge port 12 for discharging air. A motor 3 is provided on one end surface 16 of the casing 1,
An air inlet 14 is provided on the other end surface 15. The impeller 2 is a one-suction type impeller in which one end 2a of the cylinder is closed and air is sucked in from the other end 2b.
A disk-shaped end plate 22 is provided at one end 2a thereof, and an annular end ring 21 is provided at the other end 2b thereof. Then, a plurality of plate-shaped blades 24 are formed by the end ring 21 and the annular ring 23 so as to form the side surface of the cylinder of the impeller 2 at a portion from the other end 2b to a predetermined distance (L in FIG. 1). It is sandwiched by and is evenly arranged on the same circumference. Further, a plurality of plate-shaped blades 25 are provided so as to form the side surface of the remaining part of the cylinder of the impeller 2.
Are sandwiched between the end plate 22 and the ring 23, and are evenly arranged on the same circumference. It should be noted that FIG. 2 shows only part of the blades 24 and 25.

The inner diameters of the end ring 21 and the ring 23 are such that the blades 24 and 25 are designed to facilitate the intake of air.
Is set to be larger than the inner diameter of the inner circumference. 3 and 4 show sectional shapes of the blades 24 and 25 in a section orthogonal to the axis of the impeller 2. 3 and 4 are cross-sectional views of the blade 24 and the blade 25.

The blade 24 has a substantially rectangular cross-sectional shape, and the long side 24a of the rectangle is arranged along the radial direction of the impeller 2. In the outer diameter side end portion 24b which is the air outlet side end portion of the blade 24, the long side 24a extends in the direction (arrow V).
Indicated by fr. ) And the circumferential velocity vector of the blade 24 (indicated by the arrow Vvr) in the opposite direction is the outlet angle (indicated by the angle Dr). That is, the blade 24
Constitutes a radial type impeller having an exit angle of 90 degrees.

Further, the blade 25 has a sectional shape obtained by curving the sectional shape of the blade 24, and the center of curvature of the curvature is on the rotation direction (arrow B) side of the impeller 2 with respect to the blade. The curved shape is as follows, that is, the position on the curved long side 25a is the blade 25.
The direction of the tangent line at the above position gradually changes from the radial direction of the impeller 2 to the tangential direction as it approaches the outer diameter side end 25b from the inner diameter side end. In the outer diameter side end 25b of the blade 25, the direction of the tangent line of the long side 25a (arrow Vf
Denote by s. ) And the circumferential velocity vector of the blade 25 (arrow V
Indicated by vs. The angle formed by the direction opposite to the direction of () is the outlet angle (indicated by angle Ds). The blades 25 constitute a known sirocco fan whose outlet angle is larger than 90 degrees.

The length of the blade 24 in the axial direction, that is, the above-mentioned predetermined distance L is approximately W from the other end 2b with respect to the axial length of the impeller 2 (W in FIG. 1). It is preferably set to a length of 20 to 40 percent. If the length L of the blade 24 is less than 20% of W, the effect of increasing the velocity of the outflow air, which will be described later, cannot be sufficiently obtained. If the length L of the blade 24 is greater than 40%,
The characteristics of the sirocco fan with a large outlet angle may be impaired.

The impeller 2 is provided so that its axis is parallel to the axial direction of the casing 1 and the end ring 21 faces the suction port 14. Further, the impeller 2 has a motor 3 connected to the end plate 22 and is rotationally driven in one direction (arrow B in FIG. 2) about the axis of the impeller 2.
Next, the operation of the impeller 2 will be described. When the impeller 2 is rotationally driven by the motor 3, the air between the blades 24 and 25 is pushed by the centrifugal force from the ends of the blades along the blades in the outer peripheral direction. The air flowing out from the ends of the blades at this time will be described with reference to FIG. 5 in comparison with the following comparative example.

FIG. 5 is an explanatory view showing the magnitude of the radial direction component of the outlet velocity of the blade when the impeller of the centrifugal blower is different according to the axial direction. (A) is a case of a comparative example, (b) is a case of this example. The vertical axis of each figure shows the magnitude of the speed, and the horizontal axis shows the position of the impeller in the axial direction, with the suction port side (the other end) on the left side in the drawing. The comparative example is a case where a conventional sirocco type impeller is used instead of the impeller 2 of the present example, and the outlet angle of the blade is set to be the same as that of the blade 25. The other parts are the same except for the configuration in which the outlet angles of the blades are different.

In FIG. 5, the speed of the blade 24 of this embodiment is higher than the speed of the same portion in the comparative example. In addition, the speed of the blades 25 of the present embodiment is substantially the same as the speed of the same portion in the comparative example. On the other hand, with respect to the entire flow of the impeller, in this embodiment, there is little difference in the magnitude of the velocity in many parts of the axial position of the blade, and it is more uniform than in the comparative example. . It is considered that this is a result of an increase in the speed of the blade 24.

As described above, conventionally, in the portion near the suction side end of the blade outlet, there was almost no outflow radial velocity and it was difficult to blow air, whereas in the present embodiment, the suction side blade was used. In the portion 24, the outflow diameter velocity becomes large, and the air is blown out strongly from this portion. Therefore, the recirculation flow in the casing 1 is less likely to occur,
In addition, vortices are reduced and turbulent noise can be reduced.

Further, since the air blowout becomes strong, the flow from the outlet of the blade is made more uniform with respect to the axial position. As a result, the generation of the spiral flow in the casing due to the non-uniformity with respect to the axial position is also suppressed, and the turbulent noise due to this is also reduced. Further, since the blades 24 are formed in a radial type extending in the radial direction, the partial blade shape is partially simplified, which facilitates the manufacture of the impeller. Further, it is easier than manufacturing the blade having the shape described in the conventional art.

Regarding the aerodynamic performance such as a large circumferential component of the absolute velocity of the outflow air from the blade inlet portion to the outlet portion, generally, the portion near the axial center of the impeller 2 is And the influence on the whole of the suction side part is small. That is, since the part near the center is a sirocco type, its characteristics are fully utilized, and
By changing the suction side portion from the sirocco type to the radial type, the aerodynamic performance in that portion is slightly reduced, but the overall aerodynamic performance is hardly affected. On the other hand, if the suction side part is changed from the sirocco type to the radial type, the recirculation flow in that part is reduced, and the overall aerodynamic performance is expected to be improved. Therefore, considering the above-mentioned advantages and disadvantages and the degree of influence, the overall aerodynamic performance is considered to be equivalent to the conventional one.

In the embodiment of the present invention, the one-end suction type impeller for centrifugal blowers in which one end 2a of the impeller 2 is closed and air is sucked in from the other end 2b has been described. It can also be applied to a double-suction type impeller for a centrifugal blower that is closed and sucks air from both ends. In this case, in the part from the both ends of the impeller 2 to the predetermined distance,
The portion composed of the blades 25 may be arranged, and the portion composed of the blades 24 may be arranged between them. Since the effect of the present invention is obtained at both ends of the impeller, a larger effect is obtained than when the present invention is applied to a single suction type impeller for a centrifugal blower. Further, a member similar to the end plate 22 of the embodiment of the present invention may be provided at the center of the impeller 2. In addition, the portion formed by the blades 25 may be only one side instead of both ends.

In the embodiment of the present invention, the outlet angle is 9
As a 0-degree radial type impeller, instead of the blade 24, as shown in FIG. 7, a blade 26 having an inlet side end 26c curved in the rotation direction (arrow B) may be used. The entrance angle Dri of the blade 26 is set to be smaller than 90 degrees. In this case, the blade 24 having an inlet angle of 90 degrees
Compared with the above case, the blade 26 can obtain a large total pressure increase between the inlet and the outlet of the air. Where the entrance angle Dri
Is the direction in which the inlet side end 26c of the blade 26 extends (arrow V
fr) and the circumferential velocity vector of the blade 26 (arrow Vvr
It is an angle formed with the direction i). The angle Dr, the arrow Vfr, and the arrow Vvr at the outlet-side end portion 26b of the blade 26 are the same as those in FIG. 3, and thus the description thereof is omitted.

Further, in the embodiment of the present invention, the outlet angle of the blade 24 on the suction side is set to 90 degrees, but the invention is not limited to this. For example, the outlet angle of the blade 24 on the suction side is
It may be set smaller than 90 degrees to form a so-called turbo-type impeller, or conversely may be set larger than 90 degrees to form a so-called sirocco-type impeller.

Further, the embodiment of the present invention is characterized in that the outlet angle of the impeller 2 is made smaller at a portion at a predetermined distance from the end portion on the suction portion side than at other portions. The shape and arrangement of the blades other than this feature are not limited.
In addition, various design changes can be made without changing the gist of the present invention.

[0029]

According to the invention of claim 1, the following effects can be obtained. That is, in the one-suction type impeller for a centrifugal blower, air is strongly blown out in the radial direction in a portion up to a predetermined distance from the suction side end. Therefore, the recirculation flow in the casing can be made less likely to occur, and vortices can be reduced to reduce turbulent noise. Since the parts other than the above are configured as a sirocco fan, the characteristics of the sirocco fan can be exhibited as the entire impeller.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, an impeller can be easily manufactured.
According to the invention of claim 3, the following effects can be obtained. That is, in the double suction impeller for a centrifugal blower, the recirculation flow and the vortex can be reduced in each part from each end to a predetermined distance, and the turbulent noise can be reduced. In addition, the characteristics of a sirocco fan can be exhibited as the entire impeller.

According to the invention of claim 4, in addition to the effect of the invention of claim 3, an impeller can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional front view showing an outline of a centrifugal blower using an impeller for a centrifugal blower according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view taken along the line AA of FIG.

FIG. 3 is a blade 24 cut by a plane orthogonal to the axis of the impeller 2.
FIG.

FIG. 4 is a blade 25 cut by a plane orthogonal to the axis of the impeller 2.
FIG.

FIG. 5 is a graph showing the relationship between the axial position of the impeller and the radial component of the blade exit velocity (indicated simply as velocity in the figure), where (a) shows a comparative example and (b) shows This embodiment is shown.

FIG. 6 is a graph showing an outlet speed of a conventional sirocco fan at a position near a discharge port of outflow air, in which the vertical axis represents the outlet speed, and the size of an arrow represents the size of a radial component; The upward direction indicates the outward direction, and the downward direction indicates the inward direction, and the horizontal axis indicates the axial position with the right side of the drawing as the suction side.

FIG. 7 is an enlarged sectional view of an essential part of a blade 26 according to another embodiment of the present invention, taken along a plane orthogonal to the axis of the impeller 2.

[Explanation of symbols]

 1 ... Casing 2 ... Impeller 2a ... One end 2b ... The other end 24, 25 ... Blade angle Ds, Dr ... Exit angle L ... Predetermined distance

Claims (4)

[Claims] 1. A one-suction suction impeller (2) for a centrifugal blower in which one end (2a) is closed and air is sucked in from the other end (2b), and a predetermined distance (L) from the other end (2b). In the part up to
The direction in which the outlet end (24b) of the blade (24) extends (arrow Vf
r) and the circumferential velocity vector (arrow Vvr) of the blade (24) in the opposite direction to each other, the exit angle (Dr) is set smaller than the exit angle (Ds) in the remaining portion, and at least The rest of the above is the exit angle (Ds) of the blade (25)
An impeller for a centrifugal blower, characterized in that it is formed in a sirocco shape with an angle larger than 90 degrees. 2. The impeller for a centrifugal blower according to claim 1, wherein a portion from the other end (2b) to a predetermined distance (L) is a blade (2
An impeller for a centrifugal blower, characterized in that 4) is formed in a radial type extending in the radial direction. 3. A double-suction type impeller for a centrifugal blower, in which a central portion in the axial direction is closed and air is sucked in from both end portions, extends from the end portion on the outlet side of the blade at a portion up to a predetermined distance from each end portion. Direction and the direction opposite to the direction of the circumferential velocity vector of the blade are set to be smaller than the outlet angle in the remaining portion including the central portion, and at least the remaining portion is An impeller for a centrifugal blower, which is formed in a sirocco shape with an outlet angle larger than 90 degrees. 4. An impeller for a centrifugal blower according to claim 3, wherein a portion from each of the end portions to a predetermined distance is formed in a radial type in which the blade extends in the radial direction. Impeller for centrifugal blowers.