JP3315925B2 - Centrifugal fan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal fan suitable for reducing a discharge pressure loss at a discharge port of a casing.

[0002]

2. Description of the Related Art In a casing structure of a centrifugal fan in which a ventilation path to a discharge port is relatively short, the cross section of the passage rapidly expands near the discharge port, so that turbulent flow of discharge air is likely to occur, and Improvements have been made to accommodate pressure, wind speed and volume reductions. The technique disclosed in Japanese Patent Application Laid-Open No. H9-228997 discloses a technique in which a tapered surface extending toward the nose is formed inside the casing opposite to the nose of the discharge port, or the end of the discharge port is connected to the tapered surface. By forming a tapered surface that expands toward the edge and providing a rectifying plate facing this tapered surface, rectification and pressure drop of the discharge air at the discharge port is suppressed, and improvements are made to increase the wind speed and air volume. ing.

FIG. 9 is a front view of the above-mentioned conventional centrifugal fan, and FIG. 10 is a side view showing the casing of FIG.
The arrow R indicates the direction of rotation of the impeller 4. In order to suppress a decrease in pressure near the discharge port 9 of the casing 1 and a decrease in fan characteristics, a tapered portion 5 is provided to reduce the sectional area of the discharge port 9. That is, the taper 5a toward the nose 10 and the taper 5b toward the edge of the discharge port 9 are formed, and the cross-sectional shape of the ventilation passage 8 is changed to improve the fan characteristics.

[0004]

In the above prior art, in order to improve the fan characteristics by increasing the wind speed and air volume, the taper 5a, 5b is gently formed to provide a ventilation passage near the edge of the discharge port 9. 8, the cross-sectional area is uniformly reduced, but an increase in the flow resistance of the pressurized air inside the casing 1 is unavoidable, and there is room for further improvement in terms of uniform wind speed distribution. Is believed to have left.

[0005]

In the centrifugal fan casing according to the present invention, the sum of the heights of the two walls is one of the distance between the side walls near the side wall near the discharge port facing the outer peripheral edge of the impeller. / 2, or at a height reaching a part close to the side of the impeller where one of the side walls faces one of the side walls, the air flow path expands toward the discharge port side in any case. To form a triangular pyramidal projection having two surfaces,
The one ridge line of the triangular pyramid-shaped projection forms an ascending gradient in a direction substantially perpendicular to the discharge port, and among the intersection lines between the triangular pyramid-shaped projection and the side wall, an intersection line near the center axis of the impeller. Is formed so as to be parallel to the tangent line of the outer diameter of the impeller to form a rectifying guide. Such a casing of the centrifugal fan can reduce the resistance to the flow of the discharge air in the vicinity of the discharge port edge and efficiently rectify the discharge air without impairing the discharge pressure.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A centrifugal fan according to the present invention will be described with reference to an embodiment. <First Embodiment> FIG. 1 is a front view of a first embodiment of a centrifugal fan provided with a rectifying guide according to the present invention, and FIG. 2 is a side view thereof. The casing described in the claims is a casing obtained by integrating the casing 1 and the casing cover 2 in the present embodiment. That is, the present embodiment shows the case where the rectifying guides are provided on both the casing 1 and the casing cover 2. In FIG. 1, a casing 1 and a casing cover 2 which are arranged to face each other so as to cover the impeller 4 are provided with a ventilation passage on an inner surface close to the discharge port 9,
A triangular pyramid-shaped projection 3 is formed so as to function as a rectifying guide. That is, the triangular pyramid-shaped projections 3 serving as the rectifying guide are shown in FIGS. 3 to 5 provided on the casing 1 and shown in FIGS. 6 to 8 provided on the casing cover 2 side. The arrow R indicates the direction of rotation of the impeller 4.

As shown in FIG. 4, the triangular pyramid-shaped projections 3 are formed and arranged in the vicinity of the discharge port 9 and close to the outer diameter of the impeller 4, and diverge toward the direction of the discharge port 9. As described above, a rectifying guide having the first surface 3a and the second surface 3b is formed to reduce and suppress additional resistance to the airflow flowing through the ventilation passage 8 toward the discharge port 9.

That is, one of the three ridges of the triangular pyramid-shaped projection 3 serving as a rectifying guide forms a direction substantially perpendicular to the discharge opening surface of the discharge port 9, and forms an ascending gradient in the direction of the discharge port 9. are doing.

Further, among the intersections formed by the triangular pyramid-shaped projections 3 and the surface of the side wall 11a or the surface of the side wall 11b, the intersection near the center axis of the impeller 4 is the impeller 4
It is preferable that they are arranged so as to be parallel to a tangent to the outer diameter.

Further, as shown in FIG. 1, the distance between the side walls of the casing 1 and the casing cover 2 is C, the height from the side wall 11a of the casing 1 to the apex of the triangular pyramid-shaped projection 3 is A, and similarly, , Side wall surface 11 of casing cover 2
If the height from b is B, it is desirable that C ≧ 2 (A + B). That is, the sum of the heights of the rectifying guide 3 on the casing 1 side and the rectifying guide 3 on the casing cover 2 side facing the casing 1 is 1/1 / the inner surface distance between the side wall 11a of the casing 1 and the side wall 11b of the casing cover 2. Setting it to 2 or less is effective in reducing the resistance of the discharge airflow and preventing loss of the discharge pressure.

The triangular pyramid-shaped projections 3 provided as the rectifying guides are provided so as to be close to the outer peripheral edge of the impeller 4, but the shapes of the casing 1 and the casing cover 2 and the structure of the impeller 4 In some cases, the positions to be formed and arranged on the side wall 11a of the casing 1 and the side wall 11b of the casing cover 2 can have some allowance. Furthermore, the triangular pyramid-shaped protrusions 3, 3 do not necessarily need to be arranged so as to be identically opposed on both the casing 1 side and the casing cover 2 side.

<Embodiment 2> Even if the triangular pyramid-shaped projections 3 are arranged on only one of the casing 1 and the casing cover 2, the first embodiment can be realized if the structural requirements of claim 1 are satisfied. As a result, an effect as a rectifying guide can be obtained.

<Embodiment 3> A triangular pyramid-shaped projection of the present invention is one in which three surfaces constituting the projection have a gentle concave or convex surface, or are formed in a triangular pyramid shape by combining a flat, concave and convex surface. Embodiment 3 includes a rectifying guide of a modified type as described above, whereby the speed and direction of the air flow are appropriately adjusted according to the target specification. can do. The curved surface according to claim 4 includes a concave surface or a convex surface as described above.

[0014]

According to the above configuration, the centrifugal fan of the present invention reduces the resistance of the discharge airflow near the discharge port edge and provides an efficient rectifying effect without causing a loss in discharge pressure. Can be.

[Brief description of the drawings]

FIG. 1 is a front view of a first embodiment of a centrifugal fan according to the present invention.

FIG. 2 is a side view of the centrifugal fan of FIG.

FIG. 3 is a front view showing a casing of the first and second embodiments of the centrifugal fan according to the present invention.

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a sectional view taken along line BB of FIG. 4;

FIG. 6 is a front view showing a casing according to the first and second embodiments of the centrifugal fan according to the present invention.

FIG. 7 is a side view of FIG. 6;

FIG. 8 is a sectional view taken along line AA of FIG. 7;

FIG. 9 is a front view of a conventional centrifugal fan.

FIG. 10 is a side view showing a casing of the centrifugal fan of FIG. 9;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Casing 2 ... Casing cover 3 ... Triangular pyramid-shaped protrusion 4 ... Impeller 3a ... 1st taper surface 3b ... 2nd taper surface 3c ... 3rd
Tapered surface 5 ... Tapered portion 5a ... Nose side tapered surface 5b ... Discharge side tapered surface 6 ... Rectifying plate 7 ... Casing suction port 8 ... Ventilation path 9 ... Discharge port 10 ... Nose 11 ... Side wall 11a ... Casing side wall 11b ... Casing cover side wall 12 casing cover inlet

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F04D 29/44 F04D 17/16 F04D 29/66

Claims (4)

(57) [Claims] 1. A spiral-shaped casing, an impeller housed in the casing, and a ventilation path formed in a circumferential space between the impeller and the casing, wherein the ventilation path has a spiral shape. A centrifugal fan configured to gradually expand from a suction port side of the center of the shape toward a discharge port side of the casing, a triangular pyramid-shaped projection provided on the ventilation path and standing on at least one side wall of the casing. The one ridge line of the triangular pyramid-shaped projection forms an ascending gradient in a direction substantially perpendicular to the discharge port, and the impeller of the intersection line between the triangular pyramid-shaped projection and the side wall is provided. A centrifugal fan characterized in that an intersection line on the side closer to the central axis is formed in parallel with a tangent to the outer diameter of the impeller. 2. A triangular pyramid-shaped projection of the rectifying guide is provided on each of both side walls of the casing facing the impeller, and a sum of heights of the two triangular pyramid-shaped projections is a distance between the two side walls. 2. The centrifugal fan according to claim 1, wherein the height is set so as not to exceed 1/2 of the dimension. 3. The rectifying guide according to claim 1, wherein a vertex of the triangular pyramid-shaped projection provided on one of the side walls of the casing is provided close to a side surface of the impeller. The centrifugal fan as described. 4. The surface forming the triangular pyramid-shaped projection is a flat surface,
The centrifugal fan according to any one of claims 1 to 3, wherein the centrifugal fan includes a curved surface or a combination of a flat surface and a curved surface.