JP2012036827A - Sirocco fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sirocco fan that can reduce noise generated by a leak flow.SOLUTION: The sirocco fan 31 is arranged so that the axial one-end side of a rotating shaft A in an impeller 13 opposes an intake 17. At least part of a communication part 25 located at the one-end side among clearances of blades 11 is located outside the radial direction rather than the end of the impeller 13 side in a bell mouth 19. An air flow resistance member 27 in which a plurality of substantially-uniform holes are formed almost all over the member is arranged on a passage of the leak flow M in which air flowing out to the outside of the radial direction from the impeller 13 flows again into the clearances of the blades 11 via the communication part 25.

Description

  The present invention relates to the structure of a sirocco fan.

  Conventionally, for example, a sirocco fan has been used as a blower of an air conditioner. The sirocco fan includes an impeller that is rotated by a fan motor and a scroll casing that houses the impeller. This impeller has a plurality of blades arranged along the circumferential direction. The casing includes an accommodation space in which the impeller is accommodated, a bell mouth that is opposed to the impeller on one end side in the axial direction to form an air suction port, and guides the air to the impeller, and the impeller And an air outlet through which air that has flowed out radially outward from the air is blown out. The air guided by the bell mouth flows into the impeller from the one end side, travels toward the other end side, passes through the gap between the blades, and flows out to the outside in the radial direction of the impeller (for example, Patent Documents). 1).

JP 2009-281198 A

  In general, a sirocco fan is often used at a high specific speed (ns = 400 to 900), and some vibration occurs in the impeller when the impeller rotates. Therefore, in order to prevent the impeller from coming into contact with the bell mouth during rotation, the end portion on the one end side of the impeller is disposed with a relatively large distance from the bell mouth. In other words, the impeller communicates with the outside of the impeller in the axial direction at a gap (communication portion) between the blades at the end portion on the front side in the axial direction, and a large gap exists between the communication portion and the casing. I'm open.

  Therefore, in such a sirocco fan, a leakage flow in which a part of the air flowing out from the impeller radially outwards re-enters the impeller through the communication portion is likely to occur, and this leakage flow causes noise.

  Therefore, the present invention has been made in view of such points, and an object of the present invention is to provide a sirocco fan that can reduce noise caused by leakage flow.

  The sirocco fan of the present invention includes an impeller (13) and a casing (23). The impeller (13) is rotatable around the rotation axis (A), and a plurality of blades (11) are arranged in the circumferential direction. The casing (23) is a bell mouth (15) in which an accommodation space (15) in which the impeller (13) is accommodated, and an inlet (17) for allowing air to flow into the accommodation space (15). 19) and a blower outlet (21) for blowing the air in the accommodation space (15) to the outside. One end of the impeller (13) in the axial direction of the rotating shaft (A) is disposed so as to face the suction port (17). Of the gap between the blades (11), at least a part of the communication portion (25) located on the one end side is more radially outward than the end on the impeller (13) side of the bell mouth (19). positioned. A plurality of substantially uniform holes are formed on the path of the leakage flow in which the air flowing out from the impeller (13) to the outside in the radial direction re-enters the gap between the blades (11) through the communication portion (25). Is provided with an airflow resistance member (27) provided substantially throughout.

  In this configuration, the airflow resistance member (on the path of the leakage flow in which the air flowing out from the impeller (13) to the outside in the radial direction re-enters the gap between the blades (11) through the communication portion (25). 27) is provided, noise caused by the leakage flow can be reduced.

  The reason why the noise is reduced is considered as follows. In other words, the airflow resistance member (27) is provided with a plurality of substantially uniform holes over substantially the whole, and is disposed on the path of the leakage flow, so that it becomes a resistance when the leakage flow passes. Therefore, compared with the case where the airflow resistance member (27) is not provided, it is considered that the inflow amount of the leakage flow that re-enters the impeller (13) can be reduced. In addition, the leakage flow is a turbulent flow in which the flow direction and the flow velocity are unstable. However, the leakage flow is trickled by passing through the airflow resistance member (27) provided with a plurality of substantially uniform holes throughout the entire area. The Thereby, it is considered that the leakage flow is rectified into a more stable flow by uniformizing the flow direction and flow velocity to some extent. As described above, it is considered that the noise caused by the leakage flow can be reduced by reducing the inflow amount of the leakage flow and rectifying the leakage flow.

  Further, when the inflow amount of the leakage flow is reduced, the loss is reduced by that amount, and the reduction of the static pressure due to the leakage flow is suppressed.

  Further, the air (main flow) that is guided by the bell mouth (19) and flows into the impeller (13) interferes with the leak flow in the gap between the vanes (11), but the inflow amount of the leak flow Since the turbulence of the main flow caused by the interference is reduced by reducing the flow rate and rectifying the leakage flow, the aerodynamic characteristics of the fan can be expected to be improved.

  In the sirocco fan, the airflow resistance member (27) may be fixed to the impeller (13) so as to cover the communication portion (25). In this configuration, since the airflow resistance member (27) is fixed to the impeller (13) so as to cover the communication portion (25), the leakage flow is rectified by the airflow resistance member (27). Immediately after that, it flows again into the gap between the blades (11) through the communication portion (25). Therefore, as compared with the case where the airflow resistance member (27) is provided at a position away from the communication portion (25), a more stable leakage flow can be re-flowed into the gap between the blades (11). it can.

  Moreover, when the said airflow resistance member (27) is being fixed to the said impeller (13) so that the said communication part (25) may be covered, the edge part by the side of the impeller (13) in the said bellmouth (19) is In the radial direction, the communicating portion (25) may be located between the radially inner end portion and the radially outer end portion of the communicating portion (25).

  In this configuration, the end portion on the impeller (13) side of the bell mouth (19) is, in the radial direction, the end portion on the inner side in the radial direction of the communication portion (25) and the communication portion (25). Located between the radially outer ends. Therefore, in this configuration, not only the leakage flow but also a part of the air (main flow) guided to the bell mouth (19) flows into the communication portion (25).

  In such a form, if the airflow resistance member (27) is not provided in the communication part (25), the leakage flow flowing into the communication part (25) and a part of the main flow are not rectified. There is a risk that noise due to mutual interference will increase.

  On the other hand, in this configuration, both the leakage flow and a part of the main flow pass through the airflow resistance member (27) and are rectified, and then flow into the impeller (13) to join together. Therefore, noise caused by the interference Can be reduced.

  In the sirocco fan, the casing (23) includes the bell mouth (19) and has a front surface (231) extending in a direction perpendicular to the rotation axis (A), and the air flow The resistance member (27) may be formed in a cylindrical shape, and one end thereof may be fixed to the inner surface of the front portion (231) so as to surround the bell mouth (19).

  Moreover, when the said airflow resistance member (27) is cylindrical, the other end part of the said airflow resistance member (27) exists in the position which adjoins the edge part of the said radial direction outer side in the said communication part (25). Is preferred. In this configuration, since the airflow resistance member (27) can cover most of the leakage flow path, the amount of leakage flow that flows into the communication portion (25) without passing through the airflow resistance member (27) is further reduced. can do. Therefore, the noise reduction effect resulting from the leakage flow can be further enhanced.

  Moreover, when the said airflow resistance member (27) is cylindrical, it is preferable that the outer diameter of the other end part of the said airflow resistance member (27) is larger than the outer diameter of the said impeller (13). In this configuration, the airflow resistance member (27) can be used even when there is a rotational shake during rotation of the impeller (13) or a slight misalignment (center misalignment) during assembly of the impeller (13). Can be prevented from contacting the impeller (13).

  Furthermore, it is preferable that the airflow resistance member (27) is disposed so as to surround the communication portion (25) from the outside in the radial direction.

  When the other end portion of the airflow resistance member (27) is at a position facing the communication portion (25) in the axial direction, the other end portion of the airflow resistance member (27) and the impeller are avoided in order to avoid mutual contact. Since it is necessary to provide some gap in the axial direction between (13) and a part of the leakage flow through the gap, it re-flows into the gap between the blades (11).

  On the other hand, in this configuration, since the airflow resistance member (27) is disposed so as to surround the communication portion (25) from the outside in the radial direction, the flow direction of the leakage flow is defined in the axial direction. It can be almost covered by (27). Thereby, since the quantity of the leakage flow which flows into a communicating part (25) without passing an airflow resistance member (27) can be made smaller, the noise reduction effect can be heightened more.

  Further, when the airflow resistance member (27) is cylindrical, the airflow resistance member (27) may have a substantially truncated cone shape whose outer diameter increases from the one end to the other end. Good. In this configuration, the airflow resistance member (27) having a substantially frustoconical shape has an effect of suppressing contact with the impeller (13), and further, compared to the airflow resistance member (27) having a substantially constant outer diameter. Thus, the effect of reducing the amount of leakage flow and the effect of suppressing the turbulence of the air flow by trickling the leakage flow can be further enhanced. That is, the airflow resistance member (27) having a substantially frustoconical shape as compared with the airflow resistance member (27) having a substantially constant outer diameter increases the area of the side surface even if the axial length is the same. Can do. Accordingly, the area through which the leakage flow passes can be increased as compared with the airflow resistance member (27) having a substantially constant outer diameter, thereby increasing the effect of increasing the leakage flow resistance and reducing the amount of leakage flow. In addition, the effect of suppressing the turbulence of the air flow by trickling the leakage flow can be enhanced.

  When the airflow resistance member (27) is cylindrical, the airflow resistance member (27) may have a corrugated cross section. In this configuration, the airflow resistance member (27) having a corrugated cross section has a larger side area than the airflow resistance member (27) having a substantially constant outer diameter even if the axial length is the same. can do. Thereby, the said effect similar to the case of the substantially frustoconical airflow resistance member (27) can be acquired.

  Moreover, when the said airflow resistance member (27) is cylindrical, the said casing (23) has the space | interval of the inner surface and the outer end part of the said radial direction in the said impeller (13) in the said circumferential direction. The airflow has a spiral shape that gradually increases along the gap, and the amount of inflow of the leaking flow that re-enters the gap between the blades (11) corresponds to the tendency of the different drift depending on the position in the circumferential direction. The magnitude | size of the resistance of the said airflow resistance member (27) at the time of passing may be set according to the position of the said circumferential direction. When the casing (23) has the spiral shape, the amount of leakage flow inflow tends to vary depending on the position in the circumferential direction. Therefore, in this configuration, the magnitude of the resistance of the airflow resistance member (27) when the airflow passes is set according to the position in the circumferential direction so as to correspond to the tendency of the drift. The difference in the inflow amount in the circumferential direction is reduced. Thereby, since the inflow amount of the leakage flow can be made uniform to some extent also in the circumferential direction, the noise reduction effect can be further enhanced.

  Specific examples of the airflow resistance member (27) include forms such as a mesh structure and a lattice structure. In the case of the mesh structure, it is preferable to have a mesh of 30 mesh to 70 mesh. Thereby, the noise reduction effect can be further enhanced.

  As described above, according to the present invention, it is possible to provide a centrifugal blower that can reduce noise caused by the leakage flow.

It is a top view which shows the sirocco fan which concerns on 1st Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. It is the top view which expanded a part of impeller of the said sirocco fan. It is sectional drawing which shows the modification of the sirocco fan which concerns on 1st Embodiment. It is sectional drawing which shows the sirocco fan which concerns on 2nd Embodiment of this invention. (A) And (B) is a perspective view which shows the airflow resistance member of the sirocco fan which concerns on 2nd Embodiment, respectively. (A) is sectional drawing which shows the modification 1 of the sirocco fan which concerns on 2nd Embodiment, (B) is sectional drawing which shows the other modification 2 of the sirocco fan which concerns on 2nd Embodiment. (A) is sectional drawing which shows the modification 3 of the sirocco fan which concerns on 2nd Embodiment, (B) is sectional drawing which shows the other modification 4 of the sirocco fan which concerns on 2nd Embodiment. (A) And (B) is a perspective view which shows the other example of the said airflow resistance member, respectively. It is a graph showing the relationship between an air volume and specific noise.

  Hereinafter, a sirocco fan according to an embodiment of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
As shown in FIGS. 1 and 2, the sirocco fan 10 according to the first embodiment includes a spiral casing (scroll casing) 23 and an impeller 13 accommodated in the casing 23. The impeller 13 is connected to a motor (not shown), and rotates in the rotation direction D around the rotation axis A in the casing 23 by driving the motor.

  The casing 23 includes an accommodation space 15 in which the impeller 13 is accommodated, a bell mouth 19 in which a suction port 17 for allowing air to flow into the accommodation space 15 is formed, and air in the accommodation space 15 is blown out to the outside. It has the blower outlet 21 for making it.

  The casing 23 includes a front plate (front portion) 231 disposed on the front side F in the axial direction of the rotation axis A of the impeller 13, a back plate 233 disposed on the back side R, the front plate 231, and the back. And a side plate (body plate) 235 disposed between the face plates 233. In the casing 23, parts other than the suction port 17 and the blower outlet 21 are closed by the front plate 231, the back plate 233 and the side plate 235. The bell mouth 19 is formed on the front plate 231 and faces a portion on one end side F (front side F) of the impeller 13 in the axial direction of the rotation axis A.

  The casing 23 has a substantially cylindrical casing body 23a formed so as to surround the impeller 13, and a discharge pipe portion that protrudes from the casing body 23a toward the outlet 21 and is formed in a cylindrical shape having a substantially rectangular cross section. 23b. As shown in FIG. 1, a boundary portion (tongue portion) 237 between the discharge pipe portion 23b and the casing main body 23a forms an acute angle in a plan view between the side plate 235 of the discharge pipe portion 23b and the side plate 235 of the casing main body 23a. So connected. The distance between the inner surface of the side plate 235 in the casing 23 and the radially outer end of the impeller 13 gradually increases along the rotational direction D from the tongue 237.

  The bell mouth 19 has a substantially circular inlet 17 for sucking air into the casing 23 and plays a role of guiding the air to the impeller 13. As shown in FIG. 2, the inner peripheral surface of the bell mouth 19 has a curved shape whose inner diameter decreases from the front side F toward the back side R. Similarly, the outer peripheral surface of the bell mouth 19 has a curved shape whose outer diameter decreases from the front side F toward the back side R.

  The impeller 13 includes a disk-shaped main plate 35 disposed to face the back plate 233 of the casing 23, a plurality of forward-facing blades 11 arranged along the rotation direction D, and the front F side of these blades 11. And a ring portion 33 connected to the end portion. An unillustrated motor is connected to the main plate 35. An end portion on the back side R of each blade 11 is connected to the main plate 35. The ring portion 33 is an annular member for connecting and reinforcing the end portions on the front side F of the blades 11. The length (blade chord length) from the leading edge to the trailing edge of each blade 11 is substantially constant in the axial direction of the rotation axis A. The chord length may gradually increase from the front side F to the back side R.

  When the impeller 13 is rotated by the motor, air is sucked into the casing 23 from the bell mouth 19 as shown by a one-dot chain line in FIG. The sucked air flows into the impeller 13 from the front side F in the axial direction of the rotary shaft A toward the back side R along the axial direction, passes through the gap between the blades 11 and radially outside. Flows out from the impeller 13. The outflowed air moves inside the casing body 23a of the casing 23 along the rotation direction D, and is discharged from the outlet 21 of the discharge pipe portion 23b.

  As shown in FIGS. 2 and 3, the impeller 13 has a communication portion 25 that is a gap between the blades 11 at the end portion on the front side F in the axial direction and communicates with the outside of the impeller 13 in the axial direction. ing. In the first embodiment, the communication portion 25 is located on the outer side in the radial direction from the end portion 19a on the back side R of the bell mouth 19 (see FIG. 2). Therefore, in the sirocco fan 31, a leakage flow M is generated in which a part of the air that has flowed out of the radial direction from the impeller 13 re-enters the impeller 13 through the communication portion 25.

  The sirocco fan 31 has an annular airflow resistance member 27 provided at an end portion on the front side F of the impeller 13. The airflow resistance member 27 is fixed to the end portion on the front side F of the impeller 13 so as to cover almost the entire communication portion 25. Therefore, most of the leakage flow M passes through the airflow resistance member 27 and flows again into the gap between the blades 11 of the impeller 13. The method for fixing the airflow resistance member 27 to the end portion on the front side F of the impeller 13 is not particularly limited. You may fix using another member of illustration omitted.

  The airflow resistance member 27 has a network structure in which a plurality of substantially uniform holes are formed over substantially the whole. A method for producing such an airflow resistance member 27 is not particularly limited, and examples thereof include a method in which a plurality of fine wires made of a metal such as stainless steel, a synthetic resin, or the like are knitted in a net shape and joined.

  The fineness of the airflow resistance member 27 is preferably 10 mesh or more, more preferably 30 mesh or more, and further preferably about 30 mesh to 70 mesh. When the fineness of the airflow resistance member 27 is 30 mesh or more, a particularly remarkable effect of reducing the blowing sound is obtained. The mesh represents the number of eyes per inch.

  Further, the thickness of the airflow resistance member 27 is preferably reduced in order to enhance the effect of reducing the blowing sound. The thickness of the airflow resistance member 27 is preferably 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.25 mm or less. Therefore, it is preferable to select a thin wire having a small diameter so that the thickness of the airflow resistance member 27 falls within the above range as the thin wire constituting the airflow resistance member 27.

  When the relationship between the air volume and the specific noise of the sirocco fan 31 of the first embodiment provided with the airflow resistance member 27 and the conventional sirocco fan is compared, for example, as shown in the graph of FIG. It turns out that occurs. In this comparative test, a net having a mesh size of 60 mesh in the vertical direction and a mesh size of 40 mesh in the horizontal direction was used as the airflow resistance member 27. The airflow resistance member 27 had a thickness of about 0.098 mm. Moreover, the conventional sirocco fan as a comparative example used the thing with the structure similar to FIG. 2 except the airflow resistance member 27 being not provided. As shown in the graph of FIG. 10, it can be seen that the sirocco fan 31 of this embodiment provided with the airflow resistance member 27 has an excellent noise reduction effect as compared with the conventional sirocco fan.

  The presence of the airflow resistance member 27 not only increases the airflow resistance with respect to the leakage flow M and reduces the amount of the leakage flow M, but also the leakage flow B itself is finely and evenly trickled and rectified to obtain a uniform flow velocity. It will flow without disturbance, so the flow will be stable. As a result, the fan efficiency is improved and the leakage flow M smoothly flows back into the gap between the blades 11. Accordingly, interference between the conventional leakage flow M and the main flow flowing into the casing along the bell mouth 19 is also suppressed. Therefore, compared with the conventional sirocco fan, ventilation performance improves and ventilation sound is reduced.

  FIG. 4 is a cross-sectional view showing a modification of the sirocco fan according to the first embodiment. In this modification, the end portion 19a on the impeller 13 side of the bell mouth 19 is located between the radially inner end portion 25b and the outer end portion 25a of the communication portion 25 in the radial direction. Yes.

  More specifically, it is as follows. A distance R2 from the rotation axis A to the radially inner end of the end portion 19a of the bell mouth 19, and a distance R3 from the rotation axis A to the radially outer end of the end portion 19a of the bell mouth 19 Is larger than the distance R1 from the rotation axis A to the radially inner end of the blade 11 (the trailing edge of the blade 11). The distance R2 and the distance R3 are smaller than the distance R4 from the rotation axis A to the radially outer end of the blade 11 (the leading edge of the blade 11).

  Therefore, in this modification, not only the leakage flow M but also a part of the air (main flow S) guided by the bell mouth 19 and flowing into the casing 23 flows into the communication portion 25. A part of the main flow S and the leakage flow M pass through the airflow resistance member 27. Accordingly, both of the leakage flow M and the main flow S pass through the airflow resistance member 27 and are rectified, and then flow into the gap between the blades 11 and merge.

Second Embodiment
As shown in FIGS. 5 and 6A, the sirocco fan 31 of the second embodiment includes a cylindrical airflow resistance member 27. The airflow resistance member 27 has the same mesh structure as the airflow resistance member 27 of the first embodiment. 6B, the airflow resistance member 27 is fixed to the frame body 271 along the frame body 271 and the frame body 271 assembled vertically and horizontally so as to form a cylindrical skeleton. It may be constituted by a cylindrical net portion 272.

  As shown in FIG. 5, the airflow resistance member 27 has one end portion on the front side F fixed to the inner surface 231 a of the front plate 231 of the casing 23. The airflow resistance member 27 is disposed so as to surround the end 19a on the rear side R of the bell mouth 19 over the entire circumference of the bell mouth 19 in the circumferential direction.

  An end portion 27 a on the back surface side R of the airflow resistance member 27 is located at a position close to the radially outer end portion 25 a of the communication portion 25. Therefore, most of the leakage flow M passes through the airflow resistance member 27 and re-enters into the gap between the blades 11 from the communication portion 25. An end portion 27 a on the rear side R of the airflow resistance member 27 is located at a position facing the radially outer end portion 25 a of the communication portion 25 in the axial direction of the rotation axis A.

  Here, the “close position” refers to the back side R of the airflow resistance member 27 when the impeller 13 rotates, taking into account the tolerances and errors of each part in the machine design, the vibration during rotation of the impeller 13, and the like. The end portion 27a of the casing 23 is not in contact with the impeller 13, and most of the gap between the inner surface 231a of the front plate 231 of the casing 23 and the radially outer end portion 25a of the communicating portion 25 of the impeller 13 is airflow. The position where the resistance member 27 can cover is said.

  In the casing 23 of the second embodiment, the distance between the inner surface of the side plate 235 and the radially outer end of the impeller 13 gradually increases from the tongue 237 along the rotational direction D (circumferential direction). Therefore, in this sirocco fan 31, the amount of inflow of the leakage flow M that re-enters into the gap between the blades 11 may vary depending on the position in the rotational direction D. The magnitude of the resistance of the airflow resistance member 27 (resistance when the airflow passes) can also be set according to the position in the rotational direction D so as to correspond to this tendency of drift.

  Specifically, for example, when the leakage flow unevenness (non-uniform flow) increases from the tongue portion 237 of the casing 23 in the rotational direction D, for example, the resistance of the airflow resistance member 27 is reduced to the tongue portion. A configuration in which the position gradually increases from the position corresponding to 237 toward the rotation direction D can be exemplified. In order to change the resistance of the airflow resistance member 27 for each part, for example, means such as changing the fineness of the mesh of the airflow resistance member 27 for each part or changing the thickness of the airflow resistance member 27 for each part can be exemplified.

  FIG. 7A is a cross-sectional view showing Modification 1 of the sirocco fan according to the second embodiment. The airflow resistance member 27 of the first modification has a cylindrical shape as described above. In the airflow resistance member 27, the outer diameter of the end portion 27 a on the rear side R is larger than the outer diameter of the impeller 13. The end portion 27a on the back surface side R is located on the back surface side R with respect to the end portion on the front side F of each blade 11 of the impeller 13 (the end portion 25a of the communication portion 25).

  Thus, since the airflow resistance member 27 is disposed so as to surround the communication portion 25 from the outside in the radial direction, the radially outer side of the inner surface 231a of the front plate 231 of the casing 23 and the communication portion 25 of the impeller 13. It is possible to cover almost the entire gap between the end 25a of the first and second ends 25a. That is, in the form shown in FIG. 7, more of the gaps can be covered than in the form shown in FIG. Thereby, since the quantity of the leakage flow M which flows into the communication part 25 without passing the airflow resistance member 27 can be made smaller, the noise reduction effect can be further enhanced.

  FIG. 7B is a cross-sectional view showing a second modification of the sirocco fan according to the second embodiment. The airflow resistance member 27 of the second modification has a substantially truncated cone shape whose outer diameter increases from the front side F toward the back side R. As described above, the airflow resistance member 27 of Modification 2 has a substantially truncated cone shape, and thus the side surface is inclined with respect to the axial direction of the rotation axis A. Therefore, as compared with the airflow resistance member 27 having a substantially constant outer diameter as shown in FIG. 7A, the airflow resistance member 20 of the second modification has an airflow resistance member even if the axial length is the same. 27 area (side area) can be increased. Thereby, in the modification 2, the effect of reducing the amount of leakage flow and the effect of rectifying the leakage flow can be further improved.

  FIG. 8A is a cross-sectional view showing Modification 3 of the sirocco fan according to the second embodiment. FIG. 8B is a cross-sectional view showing another modification 4 of the sirocco fan according to the second embodiment.

  The airflow resistance member 20 of Modification 3 has a corrugated cross section, and the airflow resistance member 20 of Modification 4 has a curved cross section, so that the airflow resistance member has a substantially constant outer diameter as shown in FIG. Compared to 20, the airflow resistance member 27 of the modified examples 3 and 4 can increase the area (side surface area) of the airflow resistance member 27 even if the axial length is the same. Thereby, in the modified examples 3 and 4, the effect of reducing the amount of leakage flow and the effect of rectifying the leakage flow can be further improved.

  FIG. 9A is a perspective view showing another example of the airflow resistance member. FIG. 9B is a perspective view showing still another example of the airflow resistance member. The airflow resistance member 27 shown in FIG. 9A is a cylindrical mesh member having a mesh structure in which a plurality of thin linear bodies X and a plurality of thin linear bodies Y made of synthetic resin or metal are knitted. For example, the mesh member is reinforced by a frame body 271 shown in FIG. As shown in FIG. 9B, the airflow resistance member 27 has a lattice structure obtained by molding a synthetic resin, for example. The airflow resistance member 27 includes a plurality of vertical lattices 273 and a plurality of horizontal lattices 274, and the plurality of gaps are formed by the lattices 273 and 274.

<Outline of Embodiment>
The above embodiment is summarized as follows.

  In the sirocco fan, the airflow resistance member 27 is disposed on the path of the leakage flow M in which the air that flows out of the radial direction from the impeller 13 re-enters the gap between the blades 11 through the communication portion 25. Therefore, noise caused by the leakage flow can be reduced. Further, since the airflow resistance member 27 is provided, the inflow amount of the leakage flow M is reduced, the loss is reduced correspondingly, and the decrease in static pressure due to the leakage flow is suppressed.

  Further, the air (main flow) that is guided by the bell mouth 19 and flows into the impeller 13 interferes with the leakage flow in the gap between the blades 11, but the inflow amount of the leakage flow M is reduced and the leakage flow is reduced. Since M is rectified, mainstream turbulence due to the interference is reduced, so that improvement of aerodynamic characteristics of the fan can be expected.

  In the sirocco fan 31, the position where the airflow resistance member 27 is disposed may be on the path of the leakage flow M. Specific examples are as follows.

  For example, like the sirocco fan 31 of the first embodiment, the airflow resistance member 27 may be fixed to the impeller 13 so as to cover the communication portion 25.

  In this configuration, since the airflow resistance member 27 is fixed to the impeller 13 so as to cover the communication portion 25, the leakage flow M flows between the blades 11 through the communication portion 25 immediately after being rectified by the airflow resistance member 27. Re-enter the gap. Therefore, as compared with the case where the airflow resistance member 27 is provided at a position away from the communication portion 25, a more stable leakage flow can be re-entered into the gap between the blades 11.

  Further, when the airflow resistance member 27 is fixed to the impeller 13 so as to cover the communication portion 25, the end portion on the impeller 13 side in the bell mouth 19 is the same as in the modified example of the first embodiment. In the radial direction, the communicating portion 25 may be located between the radially inner end portion and the communicating portion 25 on the radially outer end portion.

  In this configuration, the end on the impeller 13 side of the bell mouth 19 is between the radially inner end of the communicating portion 25 and the radially outer end of the communicating portion 25 in the radial direction. positioned. Therefore, in this configuration, not only the leakage flow but also part of the air (main flow) guided to the bell mouth 19 flows into the communication portion 25.

  In such a configuration, if the airflow resistance member 27 is not provided in the communication portion 25, the leakage flow flowing into the communication portion 25 and a part of the main flow are not rectified, and thus are caused by mutual interference. Noise may increase.

  On the other hand, in this configuration, both the leakage flow and a part of the main flow pass through the airflow resistance member 27 and are rectified, and then flow into the impeller 13 to be joined, thereby reducing noise caused by the interference. Can do.

  Further, like the sirocco fan 31 of the second embodiment, the casing 23 is provided with a bell mouth 19 and has a front portion 29 that extends in a direction orthogonal to the rotation axis A. In addition to being formed in a cylindrical shape, one end portion thereof may be fixed to the inner surface of the front surface portion 29 so as to surround the bell mouth 19.

  When the airflow resistance member 27 is cylindrical, the other end portion of the airflow resistance member 27 is preferably in a position close to the radially outer end portion of the communication portion 25.

  In this configuration, since the airflow resistance member 27 can cover most of the leakage flow path, the amount of leakage flow that flows into the communication portion 25 without passing through the airflow resistance member 27 can be further reduced. Therefore, the noise reduction effect resulting from the leakage flow can be further enhanced.

  When the airflow resistance member 27 is cylindrical, the outer diameter of the other end portion of the airflow resistance member 27 is larger than the outer diameter of the impeller 13 as in Modifications 1 and 2 of the second embodiment. It is preferable.

  In this configuration, the airflow resistance member 27 is in contact with the impeller 13 even when there is a rotational shake during the rotation of the impeller 13 or a slight misalignment (center misalignment) during the assembly of the impeller 13. Can be suppressed.

  Further, in the sirocco fan 31 of the second embodiment, the airflow resistance member 27 is preferably disposed so as to surround the communication portion 25 from the outside in the radial direction.

  When the other end portion of the airflow resistance member 27 is in a position facing the communication portion 25 in the axial direction, in order to avoid mutual contact, between the other end portion of the airflow resistance member 27 and the impeller 13, Since it is necessary to provide a gap that is vacant in the axial direction, a part of the leakage flow passes through the gap and flows again into the gap between the blades 11.

  On the other hand, in this configuration, since the airflow resistance member 27 is disposed so as to surround the communication portion 25 from the outside in the radial direction, the airflow resistance member 27 substantially covers the leakage flow path in the axial direction. it can. Thereby, since the quantity of the leakage flow which flows into the communication part 25 without passing the airflow resistance member 27 can be made smaller, the noise reduction effect can be further enhanced.

  Further, when the airflow resistance member 27 is cylindrical, the airflow resistance member 27 has a substantially truncated cone whose outer diameter increases from the one end to the other end, as in Modification 2 of the second embodiment. You may have a shape.

  In this configuration, the airflow resistance member 27 having a substantially frustoconical shape has an effect of suppressing the contact with the impeller 13 and, in addition, the amount of leakage flow compared to the airflow resistance member 27 having a substantially constant outer diameter. And the effect of suppressing the turbulence of the air flow by trickling the leakage flow. That is, the airflow resistance member 27 having a substantially truncated cone shape as compared with the airflow resistance member 27 having a substantially constant outer diameter can increase the area of the side surface even when the axial length is the same. Thereby, since the area through which the leak flow passes can be increased as compared with the airflow resistance member 27 having a substantially constant outer diameter, the effect of increasing the leak flow resistance and reducing the amount of the leak flow can be enhanced. In addition, the effect of suppressing the turbulence of the air flow by trickling the leakage flow can be enhanced.

  Further, when the airflow resistance member 27 is cylindrical, the airflow resistance member 27 may have a corrugated cross section, as in Modification 3 of the second embodiment.

  In this configuration, the airflow resistance member 27 having a corrugated cross section can have a larger side area even when the axial length is the same as that of the airflow resistance member 27 having a substantially constant outer diameter. . Thereby, the same effect as the case of the airflow resistance member 27 having a substantially truncated cone shape can be obtained.

  Further, in the sirocco fan 31 of the second embodiment, the airflow passes so that the inflow amount of the leaking flow that re-inflows into the gap between the blades 11 corresponds to the tendency of different drift depending on the position in the circumferential direction. The magnitude of the resistance of the airflow resistance member 27 when doing so may be set according to the position in the circumferential direction.

  In this configuration, the inflow in the circumferential direction is set by setting the magnitude of the resistance of the airflow resistance member 27 when the airflow passes in accordance with the position in the circumferential direction so as to correspond to the tendency of the drift. The amount difference is reduced. Thereby, since the inflow amount of the leakage flow can be made uniform to some extent also in the circumferential direction, the noise reduction effect can be further enhanced.

  Specific examples of the airflow resistance member 27 include forms such as a mesh structure and a lattice structure. In the case of the mesh structure, it is preferable to have a mesh of 30 mesh to 70 mesh. Thereby, the noise reduction effect can be further enhanced.

  As mentioned above, although each embodiment of this invention was described, this invention is not limited to each said embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the meaning.

DESCRIPTION OF SYMBOLS 11 Blade 13 Impeller 15 Accommodating space 17 Suction port 19 Bell mouth 21 Outlet 23 Casing 231 Front plate 233 Back plate 235 Side plate 25 Communication part 27 Airflow resistance member 31 Sirocco fan A Rotating shaft F Front side in the axial direction of the rotating shaft R Back side of the axis of rotation D

Claims (14)

An impeller (13) that is rotatable about a rotation axis (A) and in which a plurality of blades (11) are arranged in a circumferential direction;
A storage space (15) in which the impeller (13) is stored; a bell mouth (19) in which a suction port (17) for allowing air to flow into the storage space (15) is formed; and the storage space (15) a casing (23) having a blow-out opening (21) for blowing the air in the outside to the outside,
A sirocco fan disposed so that one end side in the axial direction of the rotating shaft (A) in the impeller (13) faces the suction port (17);
Of the gap between the blades (11), at least a part of the communication portion (25) located on the one end side is more radially outward than the end on the impeller (13) side of the bell mouth (19). Located
A plurality of substantially uniform holes are formed on the path of the leakage flow in which the air flowing out from the impeller (13) to the outside in the radial direction re-enters the gap between the blades (11) through the communication portion (25). A sirocco fan in which an airflow resistance member (27) provided substantially throughout is disposed.   The sirocco fan according to claim 1, wherein the airflow resistance member (27) is fixed to the impeller (13) so as to cover the communication portion (25).   The end of the bell mouth (19) on the side of the impeller (13) is, in the radial direction, the end in the radial direction of the communication part (25) and the radial direction of the communication part (25) The sirocco fan according to claim 2, which is located between outer ends. The casing (23) has a front portion (231) in which the bell mouth (19) is disposed and extends in a direction perpendicular to the rotation axis (A),
The airflow resistance member (27) is formed in a cylindrical shape, and one end thereof is fixed to the inner surface of the front portion (231) and is disposed so as to surround the bell mouth (19). The sirocco fan according to claim 1.   The sirocco fan according to claim 4, wherein the other end portion of the airflow resistance member (27) is in a position close to an outer end portion in the radial direction of the communication portion (25).   The sirocco fan according to claim 4 or 5, wherein an outer diameter of the other end portion of the airflow resistance member (27) is larger than an outer diameter of the impeller (13).   The sirocco fan according to claim 6, wherein the airflow resistance member (27) is disposed so as to surround the communication portion (25) from the outside in the radial direction.   The sirocco fan according to any one of claims 4 to 7, wherein the airflow resistance member (27) has a substantially truncated cone shape with an outer diameter increasing from the one end portion toward the other end portion.   The sirocco fan according to any one of claims 4 to 7, wherein the airflow resistance member (27) has a corrugated cross section. The casing (23) has a spiral shape in which the distance between the inner side surface and the radially outer end of the impeller (13) gradually increases along the circumferential direction,
The airflow resistance member (27) when the airflow passes so that the inflow amount of the leaking flow that re-enters into the gap between the blades (11) corresponds to the tendency of different drift depending on the position in the circumferential direction. The sirocco fan according to any one of claims 4 to 9, wherein a magnitude of the resistance is set according to a position in the circumferential direction.   The sirocco fan according to any one of claims 1 to 10, wherein the airflow resistance member (27) has a mesh structure.   The sirocco fan according to claim 11, wherein the mesh structure has a mesh of 30 mesh to 70 mesh.   The sirocco fan according to any one of claims 1 to 10, wherein the airflow resistance member (27) has a lattice structure. The sirocco fan according to any one of claims 1 to 13, wherein the airflow resistance member (27) reduces a passing amount of the leakage flow and rectifies the leakage flow.

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