JP2002005090A - Centrifugal fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the loss of energy of air flow when the air is running in the casing of centrifugal fan. SOLUTION: In this centrifugal fan 1, a number of raised portions 40 are put on the inner face 36 of a voluted casing 10 which contains an impeller 11. The raised portions 40 stabilize the air flow running near by the raised portions and to made the air flow as in the form of turbulence in boundary layer, so as to protect development of the boundary layer. As a result, the loss of energy is reduced. The raised portions 40 include raised lines 41 and 42 which extend to the directions crossing to the streamline, The raised lines are formed on the whole region of an inner face 27 of a peripheral wall 31. So the structure of the centrifugal fan is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal fan used for blowing air in, for example, a heat exchange type ventilator.

[0002]

2. Description of the Related Art Generally, a centrifugal fan has a cylindrical impeller and a casing that accommodates the impeller, collects an air flow sent from the impeller, and guides the air flow to an outlet. The inner surface of this casing is formed with a smooth surface.

[0003]

Incidentally, in the centrifugal fan, phenomena such as a decrease in the amount of air blown out, a decrease in the static pressure at the air outlet, and an increase in the blowing noise may occur. This is because
It is conceivable that the energy loss when the air flow flows along the inner surface of the casing is large. Then, an object of the present invention is to solve the above-mentioned technical problems and to provide a centrifugal fan that can suppress energy loss due to the inner surface of the casing.

[0004]

According to the first aspect of the present invention, in a centrifugal fan accommodating an impeller in a spiral casing, a large number of projections are provided on the inner surface of the casing. To provide a centrifugal fan.
ADVANTAGE OF THE INVENTION According to this invention, the energy loss of the flow along a casing inner surface, for example, an air flow, can be suppressed. It is considered that the reason for this is that the development of the boundary layer, which is a region where the flow velocity is low and causes energy loss, is suppressed by the protrusion.

[0005] Here, the projection only has to protrude from the inner surface of the casing around the projection. For example, the protrusion
In addition to a projection composed of a relatively convex inner portion that is surrounded by an inner surface that is a relatively concave portion, it also includes a ridge that is sandwiched on both sides by an inner surface that is a relatively concave portion. According to a second aspect of the present invention, there is provided the centrifugal fan according to the first aspect, wherein the protrusion includes a ridge extending in a direction intersecting with the streamline.

According to the present invention, the effect of the projection can be obtained continuously in the extending direction of the ridge, so that the energy loss can be further suppressed. Here, the above-mentioned streamline is a streamline in the vicinity of the ridge, and is a streamline of the flow inward of the casing from the tip of the ridge. According to a third aspect of the present invention, there is provided the centrifugal fan according to the first aspect, wherein the projection includes a ridge extending in a direction substantially orthogonal to a streamline.

According to the present invention, the orthogonal ridge can prevent the generation of the air flow along the extending direction of the ridge in addition to the operation and effect according to the second aspect, so that the energy loss due to the air flow can be reduced. Occurrence can be prevented. As a result, the invention according to claim 4, which can further suppress energy loss, is characterized in that, in the centrifugal fan according to claim 1, the projection includes a ridge extending parallel to the rotation center axis of the impeller. Centrifugal fan.

According to the present invention, the ridge extending parallel to the rotation center axis intersects the streamline, so that the effect of claim 2 can be obtained similarly. In addition, when the ridge parallel to the rotation center axis is formed integrally with the inner surface of the casing, for example, the shape of the inner surface can be simplified and the casing can be easily formed. According to a fifth aspect of the present invention, there is provided the centrifugal fan according to any one of the first to fourth aspects, wherein an inner surface of the casing includes an inner surface of a peripheral wall facing an outer periphery of the impeller. provide.

According to the present invention, the above-described energy loss, which tends to increase on the inner surface of the peripheral wall, can be suppressed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A centrifugal fan according to a first embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional front view schematically showing a centrifugal fan and a motor according to the first embodiment of the present invention. FIG. 2 is a sectional side view of the centrifugal fan of FIG. The centrifugal fan 1 has an impeller 11 that is rotatably supported, and a spiral casing 10 that houses the impeller 11. The casing 10 is formed with a suction port 13 for sucking air and a blowout port 15 for blowing out an air flow. The centrifugal fan 1 constitutes a centrifugal blower together with the motor 2 that drives the impeller 11. The impeller 11 is driven by a motor 2 arranged in a direction in which a rotation center axis 17 extends, is driven and connected to a rotation shaft 3 of the motor 2, and is rotatably supported by a bearing (not shown) of the motor 2. I have.

The impeller 11 has a substantially cylindrical shape.
The axis of the cylinder is arranged so as to coincide with the rotation center axis 17. The impeller 11 includes an annular plate 21 disposed at one end in the axial direction, a disk 22 disposed at the other end in the axial direction substantially parallel to the annular plate 21, and an annular plate Board 21
And a large number of blades 24 connecting the two. Annular plate 2
An opening through which air passes is formed in the central portion of 1. A motor 2 for rotational driving is provided at the center of the disk 22.
A boss 28 to which the rotary shaft 3 is fitted is provided.
The large number of blades 24 are arranged in a circle around the rotation center axis 17. Each blade 24 has the same shape, for example,
It is formed in a known sirocco type.

The casing 10 has a substantially spiral peripheral wall 31.
And two side walls 32 connected to the peripheral wall 31 and arranged at both ends in the axial direction. On one side wall 32,
The above-described suction port 13 is formed. The peripheral wall 31 has a peripheral surface portion 33 formed of a substantially circular surface having a substantially arc-shaped cross section, and a substantially flat first planar portion extending from one end of the peripheral surface portion 33 in the circumferential direction to the tangential direction of the peripheral surface portion 33 at this one end. 34 and the peripheral surface part 33
And a substantially flat second flat portion 35 extending from the other end in the circumferential direction to face the first flat portion 34.

The circumferential surface portion 33 has a radial dimension increasing from the rotation center axis from the upstream side to the downstream side in the direction of air flow. Inner surface 36 of casing 10
Includes an inner surface 37 of the peripheral wall 31 and an inner surface 38 of the side wall 32. The inner surface 36 is a surface along which the airflow from the outer periphery 25 of the impeller 11 flows, and is a surface downstream of the impeller 11. In the centrifugal fan 1 of the present invention, a large number of projections 40 are provided on the inner surface 36 of the casing 10. Thereby, the energy loss of the air flow on the inner surface 36 of the casing 10 can be reduced.

In the first embodiment of the present invention, a plurality of projections 4
0 is the inner surface 37 of the peripheral wall 31 of the inner surface 36 of the casing 10.
Are formed integrally. Further, the plurality of projections 40 include a plurality of protrusions 41 extending in parallel with the rotation center axis 17 of the impeller 11. Each ridge 41 extends in a direction (see arrow C1) crossing the streamline (see arrow F). Ridge 41
Are formed integrally with each part of the peripheral wall 31, that is, the peripheral surface part 33, the first plane part 34, and the second plane part 35. The ridge 41 on the peripheral surface 33 protrudes from the inner surface 37 that forms a substantially circumferential surface of the peripheral surface 33. In addition, the ridges 41 on the first flat portion 34 and the second flat portion 35 protrude from the substantially flat inner surface 37. The inner surface 37 of the casing 10 is formed by the inner surface 37 of each portion of the peripheral wall 31 and the ridge 41.
6 is formed.

The ridge 41 has a substantially semicircular cross-sectional shape cut in the axial direction. Each of the ridges 41 extends between the side walls 32 so as to extend in the axial direction and parallel to each other. Each of the protrusions 41 is arranged at a predetermined interval between adjacent protrusions 41 so that the projections and depressions are continuously formed along the streamline direction by the large number of protrusions 40. The predetermined interval is the same between the ridges 41, but may be different.

The projections 40 are sized to reliably change the air flow in the casing 10 from laminar to turbulent. For example, the protrusion height of each projection 40 from the inner surface 36 of the casing 10 is preferably set in a range of 0.3 mm or more and 3.0 mm or less,
For example, the protrusion height is approximately 1 mm. Here, if the protrusion height is higher than 3.0 mm, the energy loss may be rather increased. On the other hand, if the protrusion height is lower than 0.3 mm, it is difficult to obtain the effect of suppressing energy loss.

The casing 1 on which the projections 40 are formed.
The zero inner surface 36 includes an inner surface 37 of the peripheral wall 31 facing the outer periphery 25 of the impeller 11. The ridge 41 is formed on the inner surface 3 of the peripheral wall 31.
7 is formed on the entire surface. This is preferable because energy loss can be reliably reduced. Further, the projection 40 is omitted on the inner surface 38 of the side wall 32, whereby the shape of the casing 10 can be simplified and the effect of suppressing energy loss can be sufficiently obtained. Because the side wall 32
The air flow near the inner surface of tends to be turbulent from the beginning, the boundary layer is stable, and the effect of suppressing the energy loss when the projection 40 is provided on the side wall 32 is reduced when the projection 40 is provided on the peripheral wall 31. This is because it is low. In addition, the protrusion 40 may be provided on the side wall 32 as in the second embodiment.

A predetermined direction predetermined by the motor 2, for example,
It is driven counterclockwise in FIG. Accordingly, the impeller 11 rotates in the same direction. The air is blown out of the outlet 15 through the flow path in the casing 10 from the inlet 13 (see arrow F). The impeller 11 rotates to apply centrifugal force to the air around the blades 24 to move the air. As a result, air flows from the suction port 13 to the impeller 11
Sucked inside. The air flow sent from the outer periphery 25 of the impeller 11 is collected by the casing 10 and flows toward the outlet 15 along the inner surface 36 of the casing 10. The air flow is directed radially outward in the casing 10, along the axial direction away from the suction port 13, and in the circumferential direction along the direction of the circumferential velocity vector of the impeller 11. Flows along. This air flow flows in a direction intersecting with each ridge 41 parallel to the rotation center axis 17.

Further, it is more preferable that the above-mentioned ridge 41 is inclined as in the second embodiment described below so as to be substantially perpendicular to the streamline. The second embodiment is different from the first embodiment in the following points, and the other points are configured in the same manner, and the same reference numerals are given and the description is omitted. The same applies to other embodiments described below. In the second embodiment, as shown in FIGS. 3 and 4,
The numerous projections 40 include a number of protrusions 42 formed on the inner surface 37 of the peripheral wall 31 of the casing 10 and an inner surface 3 of the side wall 32.
8 and a large number of projections 44 formed on the substrate. Ridge 42
Is a predetermined angle with respect to the rotation center axis 17 (see the angle E).
, And extends in a direction (see arrow C2) substantially perpendicular to the streamline (see arrow F).

The ridge 42 differs from the ridge 41 of the first embodiment in the following points. In addition, about the point which is not specifically described, it is assumed that it is comprised similarly to the ridge 41. The predetermined angle of the ridge 42 is, for example, approximately 45 degrees.
The inclination of the ridge 42 is such that the portion of the ridge 42 on the side far from the suction port 13 has a larger airflow near the ridge 42 than the portion of the ridge 42 near the suction port 13. It is set to be in the rear of the direction. This makes it easier for the streamline and the ridge 42 to cross at right angles.

If the ridges 42 on the inner surface 37 of the peripheral wall 31 are all inclined in the same direction, the ridges 42 on the inner surface of the second flat portion 35 have a smaller angle with the streamline. Therefore, as shown by a chain line in FIG. 4, the inclination of the ridge 42 on the inner surface of the second flat portion 35 is reversed at the same angle as the inclination of the ridge 42 on the peripheral surface portion 33 and the first flat portion 34. It may be oriented. The projections 44 are formed on both side walls 32, in particular, radially outside the outer periphery 25 of the impeller 11. The protrusion 44 is formed in a hemispherical shape.

In the third embodiment, as shown in FIG. 5, the centrifugal fan 1 is of a double suction type that can suction air from both left and right sides, which are both sides in the axial direction. The centrifugal fan 1 includes a pair of left and right suction impellers 11 in which a pair of annular plates 21 substantially parallel to each other and a disk 22 partitioning between the annular plates 21 on the left and right sides are connected by a large number of blades 24 arranged in a circle.
And a casing 10 that accommodates the impeller 11 and has a pair of suction ports 13 at both ends in the axial direction. The pair of suction ports 13 are formed corresponding to the pair of annular plates 21.

A projection 40 is formed on the inner surface 37 of the peripheral wall 31 of the casing 10. The protrusion 40 includes a pair of ridges 42 having a substantially V shape. The pair of protrusions 42 are arranged in the axial direction, are connected at adjacent ends in the axial direction, and are inclined at the same angle in opposite directions to the rotation center axis 17. The V-shaped top formed by the pair of ridges 42 is
It is upstream of the V-shaped open part in the flow direction. The pair of projections 42 and the suction port 13 on the side close thereto are arranged in the same manner as the relationship between the projections 42 and the suction port 13 of the second embodiment.

When the impeller 11 rotates, an air flow is blown from the outer periphery 25 of the impeller 11. At this time, the flow direction of the air flow in the axial direction is opposite to the right side and the left side of the disk 22 disposed at a substantially intermediate portion in the axial direction so as to face the disk 22 and face each other. The airflows on the left and right sides in the axial direction flow so as to cross each pair of the ridges 42 at substantially right angles. As described above, according to each embodiment of the present invention, the energy loss when the airflow flows along the inner surface of the casing 10 can be suppressed by the large number of protrusions 40 provided on the inner surface 36 of the casing 10.

It is considered that this is because the development of the boundary layer, which is a region where the flow velocity is low, which causes energy loss, is suppressed by the protrusion 40. That is, the projections 40 cause turbulence in the boundary layer, and the turbulence makes it harder for the air flow to separate on the inner surface of the casing 10 as compared with the laminar flow. As a result, the development of the boundary layer due to the occurrence of peeling can be suppressed. Therefore, it is possible to suppress energy loss due to a decrease in the flow velocity in the boundary layer. On the other hand, there is a concern about energy loss due to the generation of turbulence. However, since the projections 40 generate turbulence only near the inner surface of the casing 10, it is considered that the energy loss due to turbulence is extremely small.
After all, it is considered that the energy loss can be suppressed when viewed as the whole of the centrifugal fan 1.

Since the energy loss can be suppressed as described above, the amount of air blown from the centrifugal fan 1 can be kept large, the wind pressure at the outlet can be kept high, and the operating noise can be suppressed low. Here, the protrusion 40 may be protruded from the inner surface 36 of the casing 10 surrounding the protrusion, for example, the inner surface 37 of the peripheral wall 32. More specifically, the protrusions 40 extend in a direction perpendicular to the streamlines above the inner surfaces 36 of the casing 10 on both sides of the protrusions 40 along the direction along the streamlines near the protrusions 40. Along the inner side of the casing 10. For example, the protrusions 40 include the above-described protrusions 44 that are surrounded by the inner surface 38 that is a relatively concave portion and that are formed of relative convex portions, and the protrusions that are sandwiched on both sides by the inner surface 37 that is a relatively concave portion. 41 and 42, which are collectively referred to. Further, the projection 40 may be formed integrally with the casing 10 or may be formed separately from the casing 10. In addition, the protrusion 40 does not include a peripheral edge portion of the concave portion formed on the inner surface 36 and which does not protrude from an adjacent portion outside the peripheral edge portion when viewed from the concave portion.

The above-mentioned streamline is a streamline near the ridge and is a streamline inside the casing than the tip of the ridge. Further, as shown in each embodiment, the protrusions 41 and 42 extending in the direction intersecting with the streamline can obtain the effect of the projection 40 continuously in the extending direction, so that the energy loss is further suppressed. it can. In particular, as shown in the second embodiment, the ridge 42 extending in a direction substantially perpendicular to the streamline has the same operation and effect as the ridge 41 extending in the direction intersecting the streamline, and in addition, extends the ridge 42. Since the generation of the air flow along the direction can be prevented, the generation of energy loss due to the air flow can be prevented. As a result, energy loss can be further suppressed.

Further, as shown in the first embodiment, the ridge 41 extending parallel to the rotation center axis 17 of the impeller 11 intersects with the streamline, so that the above-described operation and effect can be obtained similarly.
In addition, for example, when the ridge 41 parallel to the rotation center axis 17 is formed integrally with the inner surface 36 of the casing 10, the shape of the inner surface 36 can be simplified, and the casing 10 can be easily formed. Further, as shown in each embodiment, the projections 40 formed on the inner surface 37 of the peripheral wall 31 facing the outer periphery 25 of the impeller 11 can suppress the above-described energy loss that tends to increase on the inner surface 37 of the peripheral wall 31. This is preferable because the suppression effect can be increased.

Further, in order to suppress energy loss, a simple structure in which the projection 40 is provided on the inner surface 36 of the casing 10 is sufficient, and an increase in cost can be suppressed. The shape of the protrusion 40 may be, for example, a hemispherical shape such as the protrusion 44 of the second embodiment, a conical or pyramid-shaped protrusion 40, or a straight line parallel to each other shown in each embodiment. In addition to the ridges 41 and 42, the ridge may be a curved ridge, and the ridge may have a semicircular cross-section, a polygon such as a triangle or a rectangle, or a corner or a corner thereof. It may be formed by a smooth curve.

The shape of the blade 24 is not particularly limited as long as it can form the centrifugal impeller 11. For example, the blade 24 has an outlet formed by a direction in which the outlet side end of the blade 24 extends (see arrow V1 in FIG. 2) and a direction opposite to the direction of the circumferential velocity vector of the blade 24 (see arrow V2 in FIG. 2). The sirocco type in which the angle (see the angle D) is larger than 90 degrees may be used, the radial type in which the above-mentioned exit angle is 90 degrees may be used, and the turbo type in which the above-mentioned exit angle is smaller than 90 degrees may be used. Is also good.

The above-described centrifugal fan 1 is a general term for a sirocco fan having blades of a sirocco type, a radial fan having blades of a radial type, and a turbo fan having blades of a turbo type. The present invention can be applied to any of a sirocco fan, a radial fan, and a turbo fan.
In particular, when the blades 24 are of the sirocco type, the centrifugal fan 1 can be further reduced in noise in combination with the quietness which is an advantage of the sirocco type blades.

In addition, various design changes can be made without changing the gist of the present invention.

[Brief description of the drawings]

FIG. 1 is a sectional front view schematically showing a centrifugal fan and a motor according to a first embodiment of the present invention.

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

FIG. 3 is a sectional front view schematically showing a centrifugal fan and a motor according to a second embodiment of the present invention.

FIG. 4 is an exploded view of the casing shown in FIG. 3, in which corresponding parts are denoted by A to D.

FIG. 5 is a sectional front view schematically showing a centrifugal fan and a motor according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Centrifugal fan 10 Casing 11 Impeller 17 Center axis of rotation 24 Blade 25 Outer periphery of impeller 31 Peripheral wall 36 Inner surface of casing 37 Inner surface of peripheral wall 40 Projection 41, 42 Ridge 44 Projection C1 Direction crossing streamline C2 Streamline and approximately Orthogonal direction F streamline

Claims (5)

[Claims] 1. A centrifugal fan (1) for accommodating an impeller (11) in a spiral casing (10), wherein a large number of projections (40) are provided on an inner surface (36) of the casing (10). And centrifugal fan. 2. The centrifugal fan (1) according to claim 1, wherein the projection (40) includes a ridge (41, 42) extending in a direction (C1) intersecting with the streamline (F). Features a centrifugal fan. 3. The centrifugal fan (1) according to claim 1, wherein said projection (40) includes a ridge (42) extending in a direction (C2) substantially orthogonal to the streamline (F). And centrifugal fan. 4. The centrifugal fan (1) according to claim 1, wherein said projection (40) includes a ridge (41) extending parallel to the rotation center axis (17) of the impeller (11). Features a centrifugal fan. 5. The centrifugal fan (1) according to any one of claims 1 to 4, wherein an inner surface (36) of the casing (10) has an outer periphery (2) of the impeller (10).
A centrifugal fan including an inner surface (37) of a peripheral wall (31) opposed to 5).