JP5550319B2 - Multiblade centrifugal fan and air conditioner using the same - Google Patents

Description

  The present invention relates to a multiblade centrifugal fan that can be widely applied to air conditioners for buildings and automobiles, and an air conditioner using the same.

  A multiblade centrifugal fan having a configuration in which an impeller having a plurality of fan blades is rotatably provided in a scroll-shaped fan casing is widely used as a fan for blowing air in a refrigeration, air-conditioning or ventilation device. . When the airflow blown from the multiblade centrifugal fan is led to a heat exchange unit or the like provided on the downstream side via a duct or the like, the ratio of the heat exchanger area to the blowout port area of the multiblade centrifugal fan is large, And if the distance between both is small, the cross-sectional area of a duct must be expanded rapidly. Normally, a diffuser portion whose flow passage cross-sectional area is rapidly enlarged is installed at the outlet of the fan casing by integrally molding or integrally connecting it, and the airflow is expanded along the wall surface.

  The distance between the heat exchanger and the multi-blade centrifugal fan is required to be as small as possible in order to reduce the size of the air conditioner and the like, and in many cases, the distance cannot be secured sufficiently. Therefore, even if a diffuser is used, depending on the air volume, the airflow cannot be sufficiently diffused, and the airflow blown out at high speed may be supplied to the heat exchanger without being diffused much. The wind speed distribution with respect to the air will deteriorate, and the ventilation resistance will increase. As a result, the operation noise becomes high, the fan power is forced to increase, and the heat exchange performance in the heat exchanger is degraded.

  Therefore, as shown in Patent Document 1, by forming a concave enlarged portion on the flow passage wall surface where the flow passage is suddenly enlarged and generating a vortex therein, the outer edge of the vortex is formed. Measures are taken such as inducing the flow to the flow path, expanding the air flow so as to follow the rapidly expanding flow path wall surface, and improving the wind speed distribution on the downstream side.

Japanese Patent No. 3158543 (see FIGS. 1 to 4)

  However, as shown in Patent Document 1, if the air volume is within an appropriate range, by forming an appropriate vortex in the concave enlarged portion, the air flow is induced along the vortex and the air flow is applied to the wall surface. Although it can be enlarged so as to be attached, there is a problem that the desired effect cannot be obtained when the air volume changes.

  That is, when the air volume is reduced, the flow is easily separated due to the influence of a small eddy current generated at the entrance of the concave expansion portion, and the air flow is difficult to expand. On the other hand, when the air volume becomes relatively large, the vortex becomes larger than the concave enlarged portion, and the eddy current cannot be settled in the concave enlarged portion, so that the vortex is not stabilized and the flow turbulence is promoted. There was a problem such as.

  The present invention has been made in view of such circumstances, and is a multiblade centrifugal fan capable of smoothly expanding an airflow at a diffuser portion and promoting uniform air velocity distribution on the downstream side. And it aims at providing the air conditioner using the same.

In order to solve the above-described problems, the multiblade centrifugal fan of the present invention and the air conditioner using the same employ the following means.
That is, the multiblade centrifugal fan according to the present invention is the multiblade centrifugal fan in which the diffuser portion whose flow path is rapidly enlarged is integrally formed or integrally connected to the outlet of the fan casing. A plurality of projections for generating vertical vortices having a surface inclined at a predetermined angle with respect to the air flow direction are provided on the wall surface at a position where the flow path of the first gas begins to expand rapidly.

  According to the present invention, for generating a vertical vortex having a surface inclined at a predetermined angle with respect to the airflow direction on a wall surface at a position where a flow path of a diffuser portion provided in a blower outlet of a fan casing starts to rapidly expand. Since a plurality of protrusions are provided, a plurality of longitudinal vortices can be generated near the wall surface at a position where the flow path begins to expand rapidly via a plurality of protrusions for generating a vertical vortex. By attracting a part of the high energy flow to the low energy flow flowing in the vicinity of the wall surface, the separation due to the development of the boundary layer in the diffuser portion can be suppressed. Therefore, it is possible to smoothly expand the air flow along the diffuser section, promote uniform air velocity distribution for the heat exchanger etc. provided on the downstream side, reduce ventilation resistance and operating noise, heat exchange performance The improvement etc. can be aimed at.

  Furthermore, the multiblade centrifugal fan of the present invention is characterized in that, in the above-described multiblade centrifugal fan, the projection is a plate-like projection that stands vertically on the wall surface.

  According to the present invention, since the vertical vortex generating projection is a plate-like projection that is erected vertically on the wall surface, the vertical vortex is generated when the air current passes over the upper edge of the plate-like projection. The separation due to the development of the boundary layer in the diffuser portion can be suppressed through the continuously generated vertical vortex. Therefore, the airflow can be smoothly expanded along the diffuser portion, and the wind speed distribution on the downstream side can be made uniform.

  In the multiblade centrifugal fan of the present invention, in the multiblade centrifugal fan, the height of the plate-like protrusion from the wall surface to the upper end is gradually increased toward the downstream side in the airflow direction. And

  According to the present invention, since the height from the wall surface to the upper end is gradually increased toward the downstream side in the airflow direction, the plate-shaped protrusion is configured so that the upper end is gradually increased toward the downstream side. It is possible to continuously generate longitudinal vortices that gradually increase through the layer, and to reliably suppress separation due to the development of the boundary layer in the diffuser section through the more stable and strong longitudinal vortex generated in the multilayer shape. it can. Thereby, airflow can be smoothly expanded stably along a diffuser part, and the wind speed distribution in the downstream can be made more uniform.

  Further, in the multiblade centrifugal fan of the present invention, in any one of the multiblade centrifugal fans described above, the inclination angle θ of the inclined surface with respect to the airflow direction of the protrusion is in a range of 20 ° to 60 °. Features.

  According to the present invention, since the inclination angle θ with respect to the airflow direction of the inclined surface of the protrusion is in the range of 20 ° to 60 °, the longitudinal vortex flow through the protrusion while moderately suppressing an increase in ventilation resistance due to the protrusion. By generating this, peeling due to the development of the boundary layer in the diffuser portion can be reliably suppressed. Accordingly, it is possible to smoothly expand the air flow along the diffuser portion while suppressing the deterioration of the fan performance, and to uniform the wind speed distribution on the downstream side.

  Further, the multiblade centrifugal fan according to the present invention is the multiblade centrifugal fan in which the diffuser portion whose flow path is rapidly enlarged is integrally formed or integrally connected to the outlet of the fan casing. On the wall surface at the position where the flow path of the pipe begins to expand rapidly, the triangle has a peak that is the maximum height on the upstream side in the airflow direction, the height is gradually decreased toward the downstream side, and the width is gradually increased A plurality of conical-shaped projections for generating vertical vortices are provided.

  According to the present invention, on the wall surface at the position where the flow path of the diffuser portion provided in the blower outlet of the fan casing begins to expand rapidly, the top portion which is the maximum height on the upstream side in the airflow direction has the downstream side. Since there are a plurality of triangular pyramid-shaped projections for generating vertical vortices whose height is gradually decreased and the width is gradually increased, a triangular pyramid is formed in the vicinity of the wall surface at the position where the flow path starts to expand rapidly. A plurality of vertical vortex flows can be generated through a plurality of vertical vortex generating projections, and a part of the high energy flow is attracted to the low energy flow flowing near the wall surface via the vertical vortex flow. Further, separation due to the development of the boundary layer in the diffuser portion can be suppressed. Therefore, it is possible to smoothly expand the air flow along the diffuser section, promote uniform air velocity distribution for the heat exchanger etc. provided on the downstream side, reduce ventilation resistance and operating noise, heat exchange performance The improvement etc. can be aimed at. In particular, by forming the protrusions in a triangular pyramid shape, a pair of left and right vertical vortex flows can be generated from one protrusion, and a vertical vortex flow can be efficiently generated by a small number of protrusions, and separation due to the development of the boundary layer is suppressed. be able to. Accordingly, it is possible to smoothly increase the air flow along the diffuser portion and to uniform the air velocity distribution on the downstream side thereof while suppressing an increase in the ventilation resistance due to the protrusion and suppressing a decrease in fan performance. Further, the moldability of the protrusion can be improved, and the strength of the protrusion itself can be sufficiently secured.

  Furthermore, the multiblade centrifugal fan of the present invention is characterized in that, in the multiblade centrifugal fan, the apex angle α of the triangular pyramid-shaped protrusion is in the range of 30 ° to 90 °.

  According to the present invention, since the apex angle α of the triangular pyramid-shaped protrusion is in the range of 30 ° to 90 °, the protrusion is adjusted while suppressing the increase in ventilation resistance due to the triangular pyramid-shaped protrusion to an appropriate range. By generating the longitudinal vortex through the separation, separation due to the development of the boundary layer in the diffuser portion can be reliably suppressed. Accordingly, it is possible to smoothly expand the air flow along the diffuser portion while suppressing the decrease in fan performance to the minimum, and to make the air velocity distribution on the downstream side uniform.

  Furthermore, the multiblade centrifugal fan of the present invention is the above-described multiblade centrifugal fan, wherein the plurality of protrusions are arranged in a staggered manner on the wall surface, and the protrusions on the downstream side are gradually enlarged. It is characterized by that.

  According to the present invention, the plurality of protrusions are arranged in a staggered manner on the wall surface, and the protrusions on the downstream side are gradually enlarged, so even if the number of protrusions is increased to increase the number of vertical vortexes generated, A plurality of vertical vortex flows can be prevented from interfering with each other, and even when the boundary layer develops due to the expansion of the flow path, the vertical vortex flows are generated one after another by the enlarged protrusion on the downstream side, The development of the boundary layer can be suppressed. Therefore, the air flow can be expanded and flowed easily along the wall surface of the diffuser portion, and the wind speed distribution on the downstream side can be made more uniform.

  Furthermore, the multiblade centrifugal fan according to the present invention is the multiblade centrifugal fan in which the diffuser portion whose flow path is rapidly enlarged is integrally formed or integrally connected to the outlet of the fan casing. A plurality of vertical vortex generating grooves extending in the airflow direction from the upstream to the downstream of the position are provided on the wall surface of the position where the flow path of the first part begins to expand rapidly.

  According to the present invention, on the wall surface of the position where the flow path of the diffuser portion provided at the outlet of the fan casing begins to expand rapidly, the longitudinal vortex generation is extended in the airflow direction from upstream to downstream of the position. Since there are a plurality of grooves, a plurality of vertical vortex flows are generated in the vicinity of the wall surface before and after the position where the flow path begins to expand rapidly, via a plurality of vertical vortex generation grooves extending in the airflow direction. Suppressing delamination due to the development of the boundary layer in the diffuser by attracting a part of the high energy flow to the low energy flow flowing in the vicinity of the wall surface through the plurality of vertical vortex flows. Can do. Therefore, it is possible to smoothly expand the air flow along the diffuser section, promote uniform air velocity distribution for the heat exchanger etc. provided on the downstream side, reduce ventilation resistance and operating noise, heat exchange performance The improvement etc. can be aimed at. Further, since vertical vortices are generated by the grooves, there is no increase in ventilation resistance due to the vertical vortex generation means, and it is possible to eliminate a decrease in fan performance due to an increase in pressure loss.

  Furthermore, the multiblade centrifugal fan of the present invention is characterized in that, in the multiblade centrifugal fan, the groove has a rectangular or inverted triangular cross-sectional shape.

  According to the present invention, since the cross-sectional shape of the groove for generating the vertical vortex is a rectangular shape or an inverted triangle shape, when the air current flows into the rectangular shape or the inverted triangle shape groove, the edge portions are successively formed. The vertical vortex can be generated, and the vertical vortex can suppress separation due to the development of the boundary layer in the diffuser portion. Therefore, the airflow can be smoothly expanded along the diffuser portion, and the wind speed distribution on the downstream side can be made uniform. Moreover, the cross-sectional secondary moment of a flow-path wall can be enlarged by the groove | channel of a plurality of rectangular shape or an inverted triangular shape, and ensuring of the intensity | strength of the flow-path wall of a diffuser part can be made easy.

  Furthermore, the multiblade centrifugal fan of the present invention is the above-described multiblade centrifugal fan, wherein the groove has a depth and / or pitch that is increased at a position where the flow path of the diffuser portion begins to expand rapidly. It is characterized by being.

  According to the present invention, the depth and / or pitch of the grooves for generating the vertical vortex is increased at the position where the flow path of the diffuser portion begins to expand rapidly. Depending on the development, the longitudinal vortex generated can be increased by increasing the depth and / or pitch of the groove for generating the vertical vortex. Therefore, the airflow can be effectively and stably expanded smoothly along the diffuser portion, and the wind speed distribution on the downstream side can be made more uniform.

  Furthermore, the air conditioner according to the present invention is characterized in that any one of the above-described multiblade centrifugal fans is mounted as a fan for blowing air.

  According to the present invention, since any one of the above-described multiblade centrifugal fans is mounted as an air blowing fan mounted on the air conditioner, as described above, the airflow fan approaches the downstream side of the multiblade centrifugal fan. Therefore, it is possible to promote further uniformization of the wind speed distribution with respect to the heat exchangers arranged in this manner. Therefore, it is possible to reduce operation noise and fan power and improve heat exchange performance, thereby contributing to further reduction in noise and performance of the air conditioner.

  According to the multiblade centrifugal fan of the present invention, it is possible to generate a plurality of vertical vortex flows through a plurality of vertical vortex generating protrusions or grooves in the vicinity of the wall surface at a position where the flow path starts to expand rapidly. By attracting a part of the high energy flow to the low energy flow near the wall surface via the vortex, it is possible to suppress separation due to the development of the boundary layer in the diffuser, and therefore smooth along the diffuser. The air flow can be expanded to the same, and the uniform wind speed distribution can be promoted for the heat exchanger or the like provided on the downstream side thereof, the ventilation resistance and operation noise can be reduced, and the heat exchange performance can be improved. .

  According to the air conditioner of the present invention, it is possible to promote the further uniformization of the wind speed distribution with respect to the heat exchanger disposed close to the downstream side of the multiblade centrifugal fan. Therefore, it is possible to improve the heat exchange performance and contribute to further reduction in noise and performance of the air conditioner.

It is one side view of the state where the multiblade centrifugal fan concerning a 1st embodiment of the present invention was connected to the heat exchange unit of an air harmony machine. It is a perspective view of the state which connected the multiblade centrifugal fan shown in FIG. 1 to the heat exchange unit of the air conditioner. It is the side view (A) of the diffuser part of the multiblade centrifugal fan shown in FIG. 1, and its perspective view (B). It is a perspective view of the diffuser part of the multiblade centrifugal fan concerning 2nd Embodiment of this invention. It is a top view of a diffuser part of a multiblade centrifugal fan concerning a 3rd embodiment of the present invention. It is the side view (A) of the diffuser part of the multiblade centrifugal fan concerning 4th Embodiment of this invention, its perspective view (B), and top view (C). It is a perspective view of the diffuser part of the multiblade centrifugal fan concerning 5th Embodiment of this invention. It is the perspective view (A) of the diffuser part of the multiblade centrifugal fan concerning 6th Embodiment of this invention, and its aa sectional drawing (B). They are the perspective view (A) of the modification of the diffuser part of the multiblade centrifugal fan concerning 6th Embodiment shown in FIG. 8, and its bb sectional drawing (B).

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a side view showing a state in which the multiblade centrifugal fan according to the first embodiment of the present invention is connected to a heat exchange unit of an air conditioner, and FIG. 2 is a perspective view thereof. Yes.
The multiblade centrifugal fan 1 includes a scroll-shaped fan casing 2 formed of a resin material. The fan casing 2 is provided with an air inlet 3 having a bell mouth on the upper surface, and an outlet 5 is extended in a tangential direction from the upstream side of the nose portion 4.

  Inside the fan casing 2, an impeller 6 having a large number of blades is rotatably supported via a rotating shaft of a motor (not shown) installed on the bottom side. The blower outlet 5 of the fan casing 2 is provided with a diffuser portion 7 whose flow path cross-sectional area is rapidly enlarged by being integrally formed or integrally connected. The multiblade centrifugal fan 1 is connected to a heat exchange unit 9 including a heat exchanger 8 disposed on the downstream side through the diffuser unit 7.

  The multi-blade centrifugal fan 1 is disposed close to the side of the heat exchange unit 9, and the air velocity blown from the blower outlet 5 having a relatively small area is blown to the heat exchanger 8 having a large area ratio. It is necessary to supply the flow abruptly so that the distribution is uniform. For this reason, the multi-blade centrifugal fan 1 and the heat exchange unit 9 are connected via the diffuser portion 7 in which the flow path is rapidly expanded, but the flow path is rapidly expanded regardless of the amount of air flow. It is difficult to guide the flow to the heat exchanger 8 side by suppressing the separation of the flow at the part and diffusing the air flow so as to always follow the wall surface of the diffuser part 7.

  Therefore, in the present embodiment, as shown in FIGS. 3A and 3B, on the wall surface 7A at the position where the flow path of the diffuser portion 7 starts to expand rapidly, only a predetermined angle θ with respect to the airflow direction. A configuration is adopted in which a plurality of rectangular vortex generating plate-like protrusions 10 having inclined surfaces are provided at appropriate intervals in the width direction.

  Thus, by providing a plurality of plate-like protrusions 10 for generating vertical vortices at appropriate intervals on the wall surface 7A at the position where the flow path of the diffuser portion 7 starts to expand rapidly, the position where the flow path starts to expand rapidly. The airflow flowing in the vicinity of the wall surface 7A collides with the inclined surface of the plate-like protrusion 10, and the vertical vortex S is continuously generated one after another over the upper edge. This longitudinal vortex S is generated from each of the plurality of plate-like protrusions 10, and a layer of the longitudinal vortex S is formed along the wall surface 7 </ b> A in a region downstream of the plate-like protrusions 10.

  A boundary at a portion where the flow path of the diffuser portion 7 rapidly expands by attracting a part of the high energy flow (main flow) Q to the low energy flow flowing in the vicinity of the wall surface 7A by the plurality of vertical vortex flows S. Peeling due to layer development can be suppressed. Therefore, it is possible to smoothly expand the air flow along the wall surface of the diffuser portion 7, to promote uniform wind speed distribution with respect to the heat exchanger 8 provided on the downstream side thereof, and to reduce the ventilation resistance and operation sound. The heat exchange performance can be improved.

  In addition, since the vertical vortex generated by the plate-like protrusion 10 can be stably generated regardless of the air volume, the air flow can be stably supplied regardless of the air volume. 7A can be expanded along the line 7A. Therefore, the wind speed distribution on the downstream side can be surely made uniform.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
This embodiment differs from the first embodiment described above in the shape of the plate-like protrusion 11 for generating a vertical vortex. Since other points are the same as those in the first embodiment, description thereof will be omitted.
In the present embodiment, as shown in FIG. 4, the plate-like protrusions 11 for generating vertical vortices are such that the height from the wall surface 7A to the upper end 11A of the diffuser portion 7 is gradually increased toward the downstream side in the airflow direction. The triangular plate-like protrusion 11 is provided.

  In this way, by using the triangular plate-like projections 11 whose height of the upper end 11A is gradually increased toward the downstream side in the air flow direction, the upper end 11A is continuously generated when the upper end edge is overcome. The vertical vortex S can be gradually increased to be generated in multiple layers. And the peeling by the development of the boundary layer in the diffuser part 7 can be suppressed through the more stable strong longitudinal vortex S generated in this multilayer shape. Therefore, the airflow can be smoothly and stably expanded along the diffuser portion 7, and the wind speed distribution on the downstream side can be made more uniform.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
This embodiment differs from the first and second embodiments described above in that the inclination angle θ with respect to the airflow direction of the plate-like protrusions 10 and 11 for generating vertical vortices is specified. Since other points are the same as those in the first and second embodiments, description thereof will be omitted.
In the present embodiment, as shown in FIG. 5, the inclination angle θ with respect to the airflow direction of the plate-like protrusions 10 and 11 for generating vertical vortices provided on the wall surface 7A of the diffuser portion 7 is 20 ° or more and 60 ° or less. Is set in the range.

  As described above, by setting the inclination angle θ of the plate-like protrusions 10 and 11 with respect to the airflow direction to a range of 20 ° to 60 °, the increase in the ventilation resistance due to the plate-like protrusions 10 and 11 is moderately suppressed. By generating the vertical vortex S through the protrusions 10 and 11 as described above, separation due to the development of the boundary layer in the diffuser portion 7 can be reliably suppressed. Therefore, while suppressing a decrease in fan performance due to an increase in ventilation resistance, the airflow can be smoothly expanded along the diffuser portion 7, and the wind speed distribution on the downstream side can be made uniform.

  At this time, when the inclination angle θ with respect to the airflow direction of the plate-like protrusions 10 and 11 is less than 20 °, the generation of the longitudinal vortex S is insufficient, and a part of the high energy flow (main flow) Q is sufficiently near the wall surface 7A. It cannot be attracted to and the separation due to the development of the boundary layer cannot be sufficiently suppressed. When the inclination angle θ exceeds 60 °, the vortex generated when the air current collides with the inclined surfaces of the plate-like protrusions 10 and 11 and climbs over the upper edge thereof becomes a horizontal vortex. This horizontal vortex disturbs the main flow and causes an increase in draft resistance, which is not preferable.

  In the first to third embodiments described above, as shown in FIG. 5, the plurality of plate-like protrusions 10, 11 arranged on the left and right sides of the center in the flow path width direction are arranged in opposite directions. Of course, all the plate-like protrusions 10 and 11 may be arranged to be inclined in the same direction.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The present embodiment differs from the first to third embodiments described above in that the vertical vortex generating projection 12 has a triangular pyramid shape. Since other points are the same as those in the first to third embodiments, the description thereof will be omitted.
In this embodiment, as shown in FIGS. 6 (A), (B), and (C), the maximum height is set on the upstream side in the airflow direction on the wall surface 7A at the position where the flow path of the diffuser portion 7 starts to expand rapidly. A configuration is adopted in which a plurality of triangular pyramid-shaped projections 12 for generating vertical vortices having a top portion, which is gradually reduced toward the downstream side, and whose width is gradually increased, are provided.

  As shown in FIG. 6C, the triangular pyramid-shaped protrusion 12 has an apex angle α that is directed to the upstream side in the airflow direction in a range of 30 ° to 90 °. On the wall surface 7 </ b> A, they are arranged at equal intervals substantially in a horizontal line.

  In this way, on the wall surface 7A at the position where the flow path of the diffuser portion 7 starts to rapidly expand, it has a top portion that is the maximum height on the upstream side in the airflow direction, and the height is gradually reduced toward the downstream side, By providing a plurality of triangular pyramid-shaped vertical vortex generating protrusions 12 whose widths are gradually increased, a plurality of triangular pyramid-shaped vertical vortex generating protrusions are provided in the vicinity of the wall surface 7A at a position where the flow path starts to expand rapidly. A plurality of vertical vortex flows S can be generated via the protrusions 12, and by attracting a part of the high energy flow (main flow) Q to the low energy flow flowing in the vicinity of the wall surface via the vertical vortex flows S, Separation due to the development of the boundary layer in the diffuser portion 7 can be suppressed.

  Therefore, according to this embodiment, the same effects as those of the above-described embodiments can be obtained. In particular, since the vertical vortex generating projections 12 have a triangular pyramid shape, a pair of left and right vertical vortex flows S can be generated from one projection 12, and the vertical vortex flows S can be efficiently generated by a small number of projections 12. Separation due to the development of the boundary layer can be suppressed. Accordingly, it is possible to smoothly increase the airflow along the diffuser portion 7 and make the air velocity distribution on the downstream side uniform while suppressing an increase in ventilation resistance due to the protrusion 12 and suppressing a decrease in fan performance. Further, the moldability of the protrusion 12 can be improved, and the strength of the protrusion 12 itself can be sufficiently secured.

  Furthermore, since the apex angle α of the triangular pyramid-shaped protrusion 12 is set in a range of 30 ° to 90 °, the protrusion 12 is adjusted while suppressing an increase in ventilation resistance due to the triangular pyramid-shaped protrusion 12 within an appropriate range. Thus, the vertical vortex S can be generated, and separation due to the development of the boundary layer in the diffuser portion 7 can be reliably suppressed. Therefore, the airflow can be smoothly expanded along the diffuser portion 7 while minimizing the decrease in fan performance due to the increase in ventilation resistance, and the air velocity distribution on the downstream side can be made uniform.

  Here, when the apex angle α of the triangular pyramid-shaped protrusion 12 is less than 30 °, the vertical vortex S is not sufficiently generated, and a part of the high energy flow (main flow) Q is sufficiently provided in the vicinity of the wall surface 7A. It cannot be attracted, and peeling due to the development of the boundary layer cannot be sufficiently suppressed. When the apex angle α exceeds 90 °, the vortex generated when the air current collides with the triangular pyramid-shaped protrusion 12 and gets over it becomes a horizontal vortex. This horizontal vortex disturbs the main flow and causes an increase in draft resistance, which is not preferable.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG.
This embodiment is different from the above-described fourth embodiment in the arrangement configuration of the vertical vortex generating projections 12 having a triangular pyramid shape. Since other points are the same as those in the fourth embodiment, description thereof will be omitted.
In the present embodiment, a plurality of vertical vortex generating projections 12 having a triangular pyramid shape are arranged in two rows on the front and back on the wall surface 7A at a position where the flow path of the diffuser portion 7 starts to expand rapidly as shown in FIG. Arranged in a staggered manner, the protrusions 12 arranged on the downstream side are gradually enlarged. The protrusions 12 may be arranged in a staggered manner in three or more rows.

  In this way, the plurality of vertical vortex generating protrusions 12 are arranged in a staggered manner on the wall surface 7A in the front and rear directions, and the protrusions 12 on the downstream side are gradually increased in size so that the number of vertical vortex generating protrusions 12 is increased. Even when the number of generated vertical vortex flows S is increased by increasing the number of vertical vortex flows S, a plurality of vertical vortex flows S can be prevented from interfering with each other, and the boundary layer develops due to the expansion of the flow path in the diffuser section 7. Even in this case, the longitudinal vortex S can be generated one after another by the enlarged protrusion 12 on the downstream side, and the development of the boundary layer can be suppressed. For this reason, it is possible to make the airflow expand along the wall surface of the diffuser portion 7 and to make it easier to flow, and to make the wind speed distribution on the downstream side more uniform.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described with reference to FIGS.
This embodiment is different from the first to fifth embodiments described above in that a groove is provided for generating a vertical vortex instead of a protrusion. Since the other points are the same as those in the first to fifth embodiments, the description thereof will be omitted.
In this embodiment, a plurality of grooves for generating vertical vortices extending in the airflow direction from the upstream side to the downstream side of the wall surface 7A at the position where the flow path of the diffuser portion 7 starts to expand rapidly, that is, FIG. As shown in (A) and (B), a plurality of grooves 13 having a rectangular cross section, or as shown in FIGS. 9 (A) and (B), a plurality of grooves having an inverted triangular cross section. The groove 14 is provided.

  The rectangular groove 13 or the inverted triangular groove 14 may be a groove having a constant depth and / or pitch, but at a position where the flow path of the diffuser portion 7 begins to expand rapidly, the depth and Alternatively, the pitch may be increased.

  Thus, on the wall surface 7A at the position where the flow path of the diffuser portion 7 begins to suddenly expand, the groove 13 or the inverted triangular shape of the rectangular cross section for generating the vertical vortex extending in the airflow direction from the upstream to the downstream of the position. By adopting a configuration in which a plurality of grooves 14 having a shape cross section are provided, a plurality of grooves 13 and 14 extending in the airflow direction are provided in the vicinity of the wall surface 7A before and after the position where the flow path starts to expand rapidly. A plurality of longitudinal vortices S can be generated. That is, when the airflow flows into the grooves 13 and 14 having a rectangular or inverted triangular cross section, the vertical vortex S is generated one after another at the edge portion, and the vicinity of the wall surface 7A is passed through the plurality of vertical vortex flows S. By attracting a part of the high energy flow (main flow) Q with respect to the low energy flow flowing through, separation due to the development of the boundary layer in the diffuser portion 7 can be suppressed.

  Therefore, according to the present embodiment, as in the above-described embodiments, the airflow can be smoothly expanded along the diffuser portion 7, and the wind speed distribution with respect to the heat exchanger 8 or the like provided on the downstream side is uniform. The reduction of ventilation resistance and operation noise, improvement of heat exchange performance, etc. can be achieved. Further, since the vertical vortex S is generated by the grooves 13, 14, there is no increase in ventilation resistance due to the vertical vortex generating means, and a decrease in fan performance due to an increase in pressure loss can be eliminated.

  Furthermore, by using a plurality of rectangular or inverted triangular grooves 13 and 14 as the vertical vortex generating means, the cross-sectional secondary moment of the channel wall can be increased, and the strength of the channel wall of the diffuser portion 7 can be increased. Ensuring can be facilitated. Further, by increasing the depth and / or pitch of the grooves 13 and 14 at a position where the flow path of the diffuser portion 7 starts to expand rapidly, the occurrence occurs according to the development of the boundary layer due to the expansion of the flow path in the diffuser portion 7. The vertical vortex S to be generated can be increased. For this reason, the airflow can be effectively and stably expanded smoothly along the diffuser portion 7, and the wind speed distribution on the downstream side can be made more uniform.

  In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, in the above-described embodiment, the configuration example in which the diffuser portion 7 is integrally formed with or integrally connected to the fan casing 2 has been described. However, the fan casing 2 is generally configured to be vertically divided into two parts, and the lower side. The upper casing and the lower diffuser section may be integrally formed, the upper diffuser section may be manufactured separately, and integrated with the upper fan casing by connection.

  Further, the projection for generating the vertical vortex described in the first to fifth embodiments and the groove for generating the vertical vortex described in the sixth embodiment may be combined. A vortex generating groove may be provided on the upstream side of the position where the flow path of the diffuser portion 7 begins to expand rapidly, and a vertical vortex generating protrusion may be provided on the downstream side thereof.

  Furthermore, the plurality of vertical vortex generating protrusions or grooves are not necessarily required to have a uniform size, and the plurality of protrusions or grooves may have different sizes depending on the wind speed distribution in the diffuser section. Thus, separation due to the development of the boundary layer in the diffuser portion can be finely controlled and suppressed according to the wind speed distribution.

DESCRIPTION OF SYMBOLS 1 Multi-blade centrifugal fan 2 Fan casing 5 Outlet 7 Diffuser part 7A Wall surface 10,11 of diffuser part 11A Projection 11A Upper end of protrusion 12 Triangular pyramid-shaped protrusion 13 Rectangular groove 14 Inverted triangular groove θ Plate-like protrusion Inclination angle α Vertex angle S of triangular pyramid-shaped projections

Claims (11)

In the multiblade centrifugal fan in which the diffuser part whose flow path is rapidly expanded is integrally formed or integrally connected to the outlet of the fan casing,
A multi-blade characterized in that a plurality of projections for generating vertical vortices having a surface inclined at a predetermined angle with respect to the airflow direction are provided on a wall surface at a position where the flow path of the diffuser portion starts to rapidly expand. Centrifugal fan.   The multi-blade centrifugal fan according to claim 1, wherein the protrusion is a plate-like protrusion that is vertically provided on the wall surface.   The multiblade centrifugal fan according to claim 2, wherein the plate-like projections are gradually increased in height from the wall surface to the upper end toward the downstream side in the airflow direction.   4. The multiblade centrifugal fan according to claim 1, wherein an inclination angle θ of the protrusion with respect to the airflow direction of the inclined surface is in a range of 20 ° to 60 °. 5. In the multiblade centrifugal fan in which the diffuser part whose flow path is rapidly expanded is integrally formed or integrally connected to the outlet of the fan casing,
On the wall surface at the position where the flow path of the diffuser section begins to expand rapidly, it has a top portion that is the maximum height on the upstream side in the airflow direction, the height is gradually decreased toward the downstream side, and the width is gradually increased. A multi-blade centrifugal fan comprising a plurality of triangular pyramid-shaped projections for generating vertical vortices.   The multiblade centrifugal fan according to claim 5, wherein the apex angle α of the triangular pyramid-shaped protrusion is in a range of 30 ° to 90 °.   The multi-blade centrifugal fan according to any one of claims 1 to 6, wherein the plurality of protrusions are arranged in a zigzag pattern on the wall surface, and the protrusions on the downstream side are gradually enlarged. In the multiblade centrifugal fan in which the diffuser part whose flow path is rapidly expanded is integrally formed or integrally connected to the outlet of the fan casing,
A plurality of grooves for generating vertical vortices extending in the airflow direction from upstream to downstream of the position are provided on a wall surface at a position where the flow path of the diffuser portion starts to rapidly expand. Wing centrifugal fan.   The multi-blade centrifugal fan according to claim 8, wherein the groove has a rectangular or inverted triangular cross-sectional shape.   10. The multiblade centrifugal fan according to claim 8, wherein the groove has a depth and / or a pitch that is increased at a position where the flow path of the diffuser portion starts to expand rapidly. An air conditioner in which the multiblade centrifugal fan according to any one of claims 1 to 10 is mounted as a fan for blowing air.

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