JP2017160807A - Air blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-blade air blower capable of restricting reverse flow of air near a tongue part and improving air blowing efficiency.SOLUTION: A multi-blade air blower 1 comprises a scroll casing 2 including: a base plate 21; a plurality of blades 22 fixed to the base plate 21; an impeller 3 for blowing out gas sucked from one end side in an axial direction from among the plurality of blades 22 toward outside in a radial direction; a ventilation passage 12a storing the impeller 3 and formed around the impeller 3 with a tongue part 10 being applied as a starting point; a discharging port 15 arranged at a terminal end of the ventilation passage 12a; a suction port 14 formed at one end side in the axial direction in respect to the impeller 3; and a bell mouth 14b arranged around the suction port 14 and extending up to an inner diameter of the impeller 3. The scroll casing 2 has a shield plate 16 of the bell mouth 14b extending from an end edge 14a of the bell mouth 14b toward the base plate 21 in an axial direction up to a position near the base plate 21 in a range from above a line of the bell mouth 14b connecting the tongue part 10 with a rotating shaft A of the impeller 3 up to a specified position in a rotating direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a blower used for an air conditioner.

  Conventionally, as a blower used in an air conditioner, a multiblade blower having an impeller having a plurality of blades around a rotating shaft and a scroll casing in which the impeller is housed and a spiral air passage is formed. Is known (see, for example, Patent Document 1).

  The scroll casing of such a multiblade blower is provided with a suction port on one end side in the axial direction of the rotating shaft of the impeller. As the impeller rotates, air is sucked from the suction port into the scroll casing. The sucked air is sucked into the impeller and blown out between the plurality of blades outward in the radial direction of the impeller. The air blown to the outside in the radial direction of the impeller is rectified while decelerating in the ventilation path, and is discharged from a discharge port provided at the end of the ventilation path.

  The side wall of the scroll casing is provided with a tongue that is the starting point of the spiral shape of the ventilation path at a position closest to the outer peripheral portion of the impeller. The tongue is provided in the upstream part of the ventilation path, and has a role of dividing the flow of air in the rotation direction of the impeller and the flow of air in the discharge direction from the downstream part of the ventilation path toward the discharge port.

Japanese Patent Laid-Open No. 11-132196

  When the air sucked from the suction port by the rotation of the impeller is blown into the ventilation path through the impeller, the gap between the impeller and the tongue portion in the ventilation path is narrow, so that the vicinity of the tongue portion becomes high pressure. In addition, in the vicinity of the tongue portion, a part of the air flowing in the downstream portion passes between the tongue portion and the impeller and re-flows into the upstream portion, so that the pressure is likely to be further increased. As a result, a backflow from the ventilation path into the impeller tends to occur near the tongue, which can cause a reduction in blowing efficiency. Therefore, in Patent Document 1, suction is performed in the axial direction of the rotating shaft of the impeller by extending a portion near the tongue portion of the bell mouth around the suction port toward the other end side (substrate side) in the axial direction. A structure that blocks the mouth area is described.

  However, since the velocity of the air blown out from the impeller is higher on the substrate side than on the suction port side, the pressure on the substrate side increases near the tongue in the ventilation path, and the backflow of air is caused by the rotation of the impeller. It occurs more strongly in a region on the substrate side opposite to the suction port side in the axial direction than in a region on the suction port side in the axial direction of the shaft. Therefore, there has been a problem that it is difficult to sufficiently suppress the reduction in the blowing efficiency only by preventing the backflow of air in the vicinity of the tongue portion in the vicinity of the tongue portion.

  In view of the circumstances as described above, an object of the present invention is to provide a blower that can suppress a decrease in blowing efficiency due to a backflow of air on the substrate side in the vicinity of the tongue.

  In order to achieve the above object, a blower of the present invention includes a substrate and a plurality of blades arranged in a cylindrical shape along the outer periphery of the substrate with a rotation axis perpendicular to the substrate as a center and attached to the substrate. An impeller including the above-described impeller, a ventilation path formed around the impeller with a tongue as a starting point, a discharge port provided at the end of the ventilation path, and the impeller A scroll casing having a suction port formed on the one end side or both ends in the axial direction of the rotating shaft and a bell mouth around the suction port and extending to the inner diameter of the impeller. The scroll casing is located in a range from a line connecting the tongue portion and the rotation shaft of the impeller to a predetermined position in the rotation direction of the bell mouth from the edge of the bell mouth toward the substrate side. A shielding plate extending to the vicinity of the substrate;

  According to this configuration, the bell mouth has a shielding plate extending near the impeller substrate in the vicinity of the tongue portion, thereby suppressing the backflow of air near the tongue portion generated on the substrate side and improving the blowing efficiency. be able to.

  In the blower of the present invention, the predetermined position may be between 90 degrees and 100 degrees in the rotation direction with respect to the tongue.

  In this case, since the length of the shielding plate extends from the tongue portion to 25% or more of the entire circumference of the scroll casing, the shielding plate can suppress the backflow of air near the substrate.

  In the blower of the present invention, the width of the shielding plate in the circumferential direction may be wider on the substrate side than on the suction port side.

  In this case, it is possible to easily prevent the backflow of air in the vicinity of the impeller substrate while suppressing a decrease in the outflow amount of air to the ventilation path by the shielding plate on the suction port side.

  In the blower of the present invention, the shielding plate has a convex portion that protrudes radially inward from the suction port side toward the substrate side on the inner peripheral side, and the circumferential direction from the convex portion. You may have the inclination guide surface which guides gas toward the both sides of the said tongue part.

  In this case, the air flow in the vicinity of the tongue can be guided to the direction away from the tongue in the circumferential direction on the substrate side of the impeller and sent out to the ventilation path. Can be improved.

  In the multiblade fan of the present invention, the scroll casing may have an outer peripheral wall located on the radially outer side of the impeller. In the range where the outer peripheral wall faces the shielding plate along the rotation direction of the impeller from the tongue portion, the distance from the rotation shaft is set to the same constant distance as the distance from the rotation shaft to the tongue portion. , Formed concentrically with the impeller. Further, the outer peripheral wall is formed so as to increase the distance from the rotation shaft toward the rotation direction of the impeller from the end point of the range facing the shielding plate in the rotation direction of the impeller. .

  In this case, the upstream portion near the tongue portion of the ventilation path is a flow path having a narrow cross section and a constant width, thereby increasing resistance to re-inflow of air on the discharge port side that may occur near the tongue portion to the upstream portion. And re-inflow can be suppressed. Moreover, according to this structure, it can prevent that the problem that the pressure in a ventilation path will become low by providing a shielding board, for example, and it can prevent blowing efficiency falling.

  By this invention, the backflow of the air which arises on the board | substrate side among the tongue parts can be suppressed, and ventilation efficiency can be improved.

The disassembled perspective view of the multiblade fan which concerns on 1st Embodiment. The exploded view seen from the front of the multiblade fan concerning a 1st embodiment. Sectional drawing perpendicular | vertical to the axial direction of a rotating shaft of the multiblade fan which concerns on 1st Embodiment. The front view of the multiblade fan which concerns on 1st Embodiment. The perspective view for demonstrating the shape of the scroll casing of the multiblade fan which concerns on 2nd Embodiment. The front view of the multiblade fan which concerns on 2nd Embodiment. The enlarged view of the shielding board in FIG. 6A. The front view of the multiblade fan which concerns on 3rd Embodiment. The enlarged view of the shielding board in FIG. 7A. The side view which looked at the shielding board shown to FIG. 7B in the arrow C direction of the figure. The perspective view of the shielding board shown to FIG. 7B. Sectional drawing for demonstrating the flow of gas of the multiblade fan which concerns on 3rd Embodiment. Sectional drawing of the multiblade fan which concerns on 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
(overall structure)
FIG. 1 is an exploded perspective view of the multiblade fan 1 according to the first embodiment of the present invention, and FIG. 2 shows the exploded multiblade fan 1 shown in FIG. 1 from the front (in the direction of arrow B). FIG. 3 is a cross-sectional view of the multiblade fan 1 perpendicular to the axial direction of the rotation axis A of the impeller 3, and FIG. 4 is a schematic front view of the multiblade fan 1 viewed from the same direction as FIG. It is. In FIG. 4, the illustration of the impeller 3 is omitted, and a region where the impeller 3 is arranged is indicated by a one-dot chain line. Moreover, in FIG. 4, the external appearance of the scroll casing 2 is simplified and shown.

  As shown in FIG. 1, the multiblade fan 1 includes a scroll casing 2, an impeller 3, a motor 4, and the like.

  The scroll casing 2 includes a bottom plate 11, side plates 12, and a top plate 13. The bottom plate 11, the side plate 12 and the top plate 13 accommodate the impeller 3, and are configured to form a spiral air passage 12a around the impeller 3 as shown in FIG. 3, and the end of the air passage 12a. Is configured to have a discharge port 15 formed therein. The bottom plate 11 is formed in a flat plate shape, and a hole (not shown) through which the shaft 4a of the motor 4 is inserted is formed at the center. The top plate 13 has an outer shape that corresponds to the outer shape of the bottom plate 11. A suction port 14 for sucking gas (for example, air) into the scroll casing 2 is provided at the center of the top plate 13.

  The tongue 10 is closest to the impeller 3 and becomes the starting point of the ventilation path 12a. The ventilation path 12a is provided around the impeller 3 so that the width increases from the position facing the tongue 10 toward the rotation direction of the impeller 3. More specifically, the side plate 12 of the scroll casing 2 is formed so as to move away from the peripheral surface of the impeller 3 from the position facing the tongue 10 toward the rotation direction of the impeller 3. In the ventilation path 12a around the impeller 3, the width of the ventilation path 12a on the line connecting the tip of the tongue 10 and the rotation axis A of the impeller 3 is the smallest. In the ventilation path 12a around the impeller 3, a region from a line connecting the tip of the tongue 10 and the rotation axis A of the impeller 3 to a predetermined position in the rotation direction is referred to as an “upstream portion”. . When the tongue portion is 0 degree (reference) and the entire circumference of the scroll casing 2 is 360 degrees, the predetermined position is between 90 degrees and 100 degrees with respect to the rotation direction. This upstream portion is a region where gas easily flows back to the impeller 3 from the substrate 21 side of the ventilation path 12a.

  The ventilation path 12 a is provided around the impeller 3 with the tongue 10 as a starting point, and also has a linear flow path toward the discharge port 15. Most of the gas circulating around the ventilation path 12 a around the impeller 3 is discharged from the discharge port 15 through the linear flow path, but a part of the gas passes through the ventilation path 12 a of the portion facing the tongue portion 10. Then, it flows again into the upstream portion in the ventilation path 12a around the impeller 3.

  The top plate 13 is provided with a suction port 14 surrounded by a bell mouth 14b. In FIG. 3, the shape of the bell mouth 14 b around the suction port 14 as viewed from the direction of the rotation axis A is represented by a one-dot chain line. As shown in FIG. 3, the suction port 14 (a region surrounded by the end edge 14 a at the tip of the bell mouth 14 b) is located on the inner peripheral side with respect to the blade 22 of the impeller 3. The suction port 14 (the region surrounded by the edge 14a at the tip of the bell mouth 14b) and the impeller 3 have a concentric relationship with each other when viewed in the rotation axis A direction of the impeller 3.

  As shown in FIGS. 1 to 3, the impeller 3 includes a disk-shaped substrate 21, a plurality of blades 22, a connection ring 23, and an impeller shaft 21 a. One end of each of the plurality of blades 22 is supported by the peripheral edge of the disk-shaped substrate 21 and is disposed at a predetermined interval in the circumferential direction. The other ends of the plurality of blades 22 are connected to each other by a connection ring 23. The impeller shaft 21 a is coaxially connected to the shaft 4 a of the motor 4, and is rotated integrally with the shaft 4 a of the motor 4 when the shaft 4 a of the motor 4 is rotated by driving the motor 4.

(Configuration of shielding plate 16)
As shown in FIGS. 1 to 4, in the present embodiment, the edge 14 a at the tip of the bell mouth 14 b faces the upstream portion from the edge 14 a of the bell mouth 14 b to the vicinity of the substrate 21. An extended shielding plate 16 is provided. More specifically, the maximum length L ₁ , which is the distance from the edge 14 a of the suction port 14 to the lower end 163 closest to the substrate 21 of the shielding plate 16, is from the edge 14 a of the suction port 14 to the substrate 21. The distance L ₀ is, for example, 80% or more and 90% or less.

  Thus, by providing the shielding plate 16 in the range from the edge 14a of the suction port 14 to the vicinity of the substrate 21, the gas flow from the ventilation path 12a facing the vicinity of the tongue portion 10 to the impeller 3 is blocked. . Thereby, the backflow of the gas from the ventilation path 12a by the side of the board | substrate 21 to the inner side of the impeller 3 can be suppressed effectively in the tongue part 10 vicinity. As a result, the air blowing efficiency of the multiblade fan 1 can be improved.

Here, the gap between the lower end portion 163 of the shielding plate 16 and the substrate 21 is to avoid interference between the lower end portion 163 of the shielding plate 16 and the substrate 21 due to blurring in the direction of the rotation axis A that occurs when the impeller 3 rotates. Necessary gap. Therefore, the position of the lower end 163 of the shielding plate 16 in the direction of the rotation axis A of the impeller 3 is as close as possible to the surface of the substrate 21 as long as interference between the lower end 163 of the shielding plate 16 and the substrate 21 does not occur. You may let me. Accordingly, in case that blurring does not occur at the time of rotation, the maximum length _{L 1} in the rotation axis A of the shielding plate 16 is 90% to 100% of the distance _{L 0} from the edge 14a of the inlet 14 to the substrate 21 It may be less.

  The shielding plate 16 is a range from a position facing the tongue portion 10 of the suction port 14 to a predetermined position in the rotational direction of the impeller 3 in the circumferential direction of the suction port 14, that is, an upstream portion of the ventilation path 12a. Is provided in a range (from 0 to 90 degrees). For example, the position of the end portion 161 in the rotation direction of the impeller 3 in the shielding plate 16 is a position facing the upstream portion of the ventilation path 12a where the backflow of gas from the ventilation path 12a to the impeller 3 can occur. Set to Further, the position of the end portion 162 of the shielding plate 16 in the direction opposite to the rotation direction of the impeller 3 is set to a position facing the tongue portion 10.

[Second Embodiment]
FIG. 5 is a perspective view for explaining the shape of the scroll casing 102 of the multiblade fan 101 according to the second embodiment of the present invention.

In the configuration of the multiblade fan 101 according to the second embodiment, the shape of the shielding plate 17 is different from the shape of the shielding plate 16 in the first embodiment.
In addition, in FIG. 5, since it aims at mainly showing the shape of the scroll casing 102, illustration of the impeller 3 is abbreviate | omitted.

  6A is a front view of the multi-blade fan 101, and FIG. 6B is a front view of the shielding plate 17 of the multi-blade fan 101.

  As shown in FIGS. 5 and 6A, the shielding plate 17 is provided on the side of the substrate 21 with respect to the narrow width portion 17a extending from the end edge 14a of the bell mouth 14b, and is sucked into the narrow width portion 17a. An enlarged portion 17b having a wide shape along the circumferential direction of the mouth 14 is provided. Thus, the width of the shielding plate 17 in the circumferential direction of the suction port 14 is wider on the substrate 21 side than on the suction port 14 side.

  The enlarged portion 17b of the shielding plate 17 is provided in the upstream portion in the same manner as the shielding plate 16 of the first embodiment. For example, the enlarged portion 17b has an end portion 171 in the rotating direction of the impeller 3 in the enlarged portion 17b at an upstream portion of the vent passage 12a in which a backflow from the vent passage 12a to the impeller 3 can occur near the substrate 21. Of these, it is arranged at a position facing the downstream side. Further, the enlarged portion 17 b is arranged on a line where an end portion 172 of the enlarged portion 17 b in the direction opposite to the rotation direction of the impeller 3 connects the tip of the tongue 10 and the rotation axis A of the impeller 3.

As shown in FIG. 6A, also in this embodiment, the shielding plate 17 extends from the end edge 14 a of the suction port 14 to the vicinity of the substrate 21 in the axial direction of the rotation axis A. In this embodiment, the distance to the lower end portion 173 closest to the substrate 21 of the enlarged portion 17b from the edge 14a of the suction port 14, the maximum length L ₁ in the rotation axis A of the shielding plate 17, the first embodiment The same length as in the case of is set.

  As shown in FIG. 6B, in the present embodiment, the narrow portion 17a of the shielding plate 17 has a portion on the suction port 14 side of the shielding plate 17 cut out from both sides in the circumferential direction toward the center of the shielding plate 17. It is formed in such a shape.

  Since the shielding plate 17 for suppressing the backflow of the gas on the substrate 21 side in the vicinity of the tongue portion 10 is provided between the suction port 14 and the ventilation path 12a in the gas flow direction, the shielding plate 17 is used. If it becomes too large, there may be a demerit that the cross-sectional area of the flow path for suction is reduced and the amount of suction is reduced. In particular, the backflow of the gas on the suction port 14 side is smaller than the backflow of the gas on the substrate 21 side, and there is a demerit due to a reduction in the suction amount. On the other hand, in the present embodiment, the shielding plate 17 is configured such that the width in the circumferential direction of the suction port 14 is wider on the substrate 21 side than the suction port 14 side, thereby shielding on the suction port 14 side. It is possible to easily prevent the backflow of the gas in the vicinity of the substrate 21 of the impeller 3 while suppressing a decrease in the amount of gas sucked by the plate 17.

  In addition, the shape of the shielding board 17 is not restricted to what was shown to FIG. 6B. For example, the narrow portion 17a may have a shape in which only the end 171 side in the rotation direction of the impeller 3 in the circumferential direction of the portion on the suction port 14 side of the shielding plate 17 is cut out. Alternatively, the narrow portion 17a may have a shape in which only the end 172 side opposite to the above in the circumferential direction of the portion on the suction port 14 side of the shielding plate 17 is cut out. Further, the shape is not limited to the shape having the small width portion 17a and the enlarged portion 17b. For example, the shape in which the width in the circumferential direction of the shielding plate 17 gradually spreads from the suction port 14 side toward the substrate 21 side may be used. .

[Third Embodiment]
FIG. 7A is a front view of the multiblade fan 201 according to the third embodiment of the present invention, and FIG. 7B is a front view of the shielding plate 18 of the multiblade fan 201. 8A is a side view of the shielding plate 18 viewed in the direction of arrow C in FIG. 7B, and FIG. 8B is a perspective view. FIG. 9 is a cross-sectional view of the multiblade fan 201 perpendicular to the axial direction of the rotation axis A, and an arrow F indicates the flow of gas due to the provision of the shielding plate 18 of the present embodiment.

  The configuration of the multiblade fan 201 according to the third embodiment is different from that of the first and second embodiments in the shape of the shielding plate 18.

  As shown in FIG. 7A to FIG. 9, in this embodiment, the shielding plate 18 protrudes toward the inner side with respect to the suction port 14 and toward the radially inner side from the suction port 14 side toward the substrate 21 side. And the inclined guide surface 18b that guides gas toward both sides of the tongue portion 10 in the circumferential direction of the suction port 14 from the convex portion 18a.

As shown in FIGS. 7A and 9, the extending range of the shielding plate 18 in the vicinity of the tongue portion 10 of the scroll casing 202 in the multiblade fan 201 is basically the same as in the first embodiment. The positions of the end portions 181 and 182 in the circumferential direction of the shielding plate 18 are the same as the positions of the end portions 161 and 162 of the shielding plate 16 of the first embodiment. Although not shown, also in this embodiment, the distance from the edge 14a of the inlet 14 to the lower end portion 183 of the shield plate 18, the maximum length L ₁ in the rotation axis A of the shielding plate 18, the The same length as in the case of one embodiment is set. The shielding plate 18 in the present embodiment is different from the shielding plate 16 in the first embodiment in that a convex portion 18a and an inclined guide surface 18b are formed on the inner peripheral side thereof.

  With reference to FIG. 7A-FIG. 9, the convex-shaped part 18a and the inclination guide surface 18b are demonstrated. On the inner surface of the shielding plate 18, the convex portion 18 a extends from a position in the middle from the suction port 14 toward the substrate 21 side to the lower end portion 183, and toward the radially inward side toward the lower end portion 183 on the substrate 21 side. It is formed in the shape of a ridge line protruding so as to be inclined. Two inclined guide surfaces 18b formed in a shape inclined downward from the convex portion 18a toward both sides in the circumferential direction are provided. Each of the inclined guide surfaces 18b has a shape capable of guiding the gas flow from the convex portion 18a in the circumferential direction, and includes one or more curved surfaces or planes.

  Further, as shown in FIG. 7B, the gas flow is more efficiently guided on the end portion 182 side in the circumferential direction of the inclined guide surface 18b provided on the end portion 182 side in the vicinity of the tongue portion 10 of the shielding plate 18. Therefore, the sub guide surface 18c, which is a surface formed in a direction different from the direction of the inclined guide surface 18b, may be provided. For example, it is conceivable that the gas flow toward the discharge port 15 side of the tongue 10 along the inclined guide surface 18b merges with the gas flow in the linear flow path toward the discharge port 15 of the ventilation path 12a. . Therefore, by providing the sub guide surface 18c in a region downstream of the inclined guide surface 18b in the guide direction, it is possible to appropriately adjust the gas flow and to relieve turbulent vortices that may be generated by the gas merging.

  As shown in FIG. 9, in this embodiment, a convex portion 18a and an inclined guide surface 18b are provided on the inner peripheral surface of the shielding plate 18 provided in the vicinity of the tongue portion 10 where gas backflow is likely to occur. As a result, the gas flow branches off at the convex portion 18a and is guided in the direction of arrow F along the inclined guide surfaces 18b on both sides thereof.

  Thereby, the flow of the gas sucked from the suction port 14 can be guided in the circumferential direction toward both sides 181 and 182 of the tongue portion 10 in a direction away from the tongue portion 10. That is, the gas on the inner peripheral side of the impeller 3 can be sent to the ventilation path 12a after being guided to a position where the backflow of gas is less likely to occur compared to the vicinity of the tongue portion 10. Therefore, it is possible to effectively suppress the backflow and improve the blowing efficiency.

[Fourth Embodiment]
FIG. 10 is a cross-sectional view of a multiblade fan 301 according to the fourth embodiment of the present invention.
In the scroll casing 302 of the multiblade blower 301 of the present embodiment, the shape of the side plate 312 (outer peripheral wall) located on the radially outer side of the impeller 3 is different from that of the first embodiment.

  On the other hand, the shielding plate 16 in the present embodiment is substantially the same as that in the first embodiment, and the position and range in which the shielding plate 16 is provided are the same as those in the first embodiment.

  As shown in FIG. 10, the side plate 312 of the scroll casing 302 has a cross section of the air passage 12 a that starts to expand at a position facing the end 161 of the shielding plate 16 (the end in the rotational direction of the impeller 3) in the radial direction. An enlargement start point 316 is set. The side plate 312 is formed concentrically with the impeller 3 in a range from the tongue portion 310 to the expansion start point 316 in the rotation direction of the impeller 3, that is, a range facing the shielding plate 16. In this range, the distance from the rotation axis A (the center of the axis 4a) to the side plate 312 is maintained at the same distance as the distance r from the rotation axis A to the tongue portion 310. As a result, an upstream portion from the tongue portion 310 to the expansion start point 316 is followed by an air passage 312 a having a minimum width of a portion corresponding to the tongue portion 310. The location where the minimum width ventilation path 312a continues is the upstream portion 312aa of the ventilation path 312a.

  The side plate 312 is formed so as to increase the distance from the rotation axis A toward the rotation direction of the impeller 3 from the expansion start point 316 that is the end point of the range facing the shielding plate 16. That is, the side plate 312 is formed so as to move away from the circumferential surface of the impeller 3 as it goes from the expansion start point 316 toward the rotation direction of the impeller 3. Thereby, the ventilation path 312a is provided in the circumference | surroundings of the impeller 3 so that a cross section may spread as it goes to the rotation direction of the impeller 3 from the position corresponding to the expansion start point 316. The part where this ventilation path 312a is expanded becomes the downstream part 312ab of the ventilation path 312a.

  In this embodiment, the side plate 312 of the scroll casing 302 is formed in this way, and the upstream portion 312aa from the tongue portion 310 to the expansion start point 316 of the ventilation path 312a is a flow path having a narrow constant cross-sectional area. From the position of the tongue 310 to the expansion start point 316, resistance to the flow of gas from the impeller 3 toward the ventilation path 312a increases. Thereby, it can suppress that the gas by the side of the discharge outlet 15 which may arise in the tongue part 310 vicinity flows back into the upstream part of the ventilation path 312a.

  For example, depending on the shape of the ventilation path, a shield plate may be provided at a position where the ventilation path is enlarged, which may cause a low pressure region in the ventilation path. If a low-pressure area occurs in the ventilation path, gas is drawn in the direction opposite to the rotation direction, or the amount of re-inflow of the gas on the discharge port side to the upstream part is increased. There is a risk that. In the multiblade blower 301 of the present embodiment, the ventilation path 312a is not enlarged on the rotational direction side of the impeller 3 with respect to the range in which the side plate 312 of the scroll casing 302 faces the shielding plate 16, Therefore, it is possible to prevent the pressure from being lowered due to the expansion of the ventilation path 312a, and it is possible to prevent the air blowing efficiency from being lowered.

As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, various changes, such as a double suction fan, can be added.

1, 101, 201 Multiblade blower 2, 102, 202 Scroll casing 3 Impeller 10 Tongue 11 Bottom plate 12a Ventilation path 14 Suction port 14a Edges 16, 17, 18 Shield plate 17b Enlarged portion 18a Convex portion 18b Inclined guide surface 21 Substrate 22 Blade A Rotating shaft

Claims (5)

An impeller having a substrate and a plurality of blades attached to the substrate and arranged in a cylindrical shape along an outer periphery of the substrate around a rotation axis perpendicular to the substrate;
An air passage that houses the impeller and is formed around the impeller with a tongue as a starting point, a discharge port provided at the end of the air passage, and an axial direction of the rotation shaft with respect to the impeller A scroll casing having a suction port formed on one end side or both ends thereof, and a bell mouth around the suction port and extending to the inner diameter of the impeller,
With
The scroll casing includes the bell mouth in a range from a line connecting the tongue portion and the rotation shaft of the impeller to a predetermined position in a rotation direction from the edge of the bell mouth toward the substrate side. A blower comprising a shielding plate extending to the vicinity of a substrate.   The blower according to claim 1, wherein the predetermined position is between 90 degrees and 100 degrees in a rotation direction with respect to the tongue portion. The blower according to claim 1,
The blower characterized in that the width of the shielding plate in the circumferential direction is wider on the substrate side than on the suction port side. The blower according to claim 1 or 2,
The shielding plate has a convex portion projecting radially inward from the suction port side toward the substrate side on the inner peripheral side, and on both sides of the tongue portion in the circumferential direction from the convex portion. An air blower having an inclined guide surface for guiding gas toward the air. The multi-blade fan according to any one of claims 1 to 4,
The scroll casing has an outer peripheral wall located on the radially outer side of the impeller,
The outer peripheral wall is
In the range facing the shielding plate along the rotation direction of the impeller from the tongue, the distance from the rotation shaft is set to the same constant distance as the distance from the rotation shaft to the tongue, and the impeller Formed concentrically,
A blower characterized in that a distance from the rotation shaft is increased from an end point of a range facing the shielding plate in the rotation direction of the impeller toward the rotation direction of the impeller.

Images