JP6634929B2 - Centrifugal blower - Google Patents

Description

  The present invention relates to a centrifugal blower that discharges air sucked from one axial end of a rotating shaft toward a radial outside of the rotating shaft.

  2. Description of the Related Art Conventionally, a centrifugal blower has been proposed in which a leakage flow from a gap between a shroud and a bell mouth in a centrifugal fan is reduced to reduce separation noise of a blade negative pressure surface due to interference with a main flow (for example, see Patent Document 1). This Patent Document 1 discloses a configuration in which a labyrinth seal portion is provided along a rotation direction at a portion of a blade negative pressure surface region of a shroud at an air suction side end facing a bell mouth.

JP 2001-115991 A

  According to the study of the present inventors, in the configuration disclosed in Patent Document 1, the shroud is located on the outer peripheral side of the bellmouth, and a step is formed between the bellmouth and the shroud. Therefore, the airflow along the inner surface of the bellmouth is separated at the downstream end of the airflow of the bellmouth and does not flow along the inner surface of the shroud. This causes turbulence in the airflow flowing from the bellmouth surface to the vicinity of the fan shroud. Such a turbulence grows as it proceeds downstream of the air flow of the fan, and causes factors such as an increase in noise and a decrease in air blowing efficiency.

  In view of the above, an object of the present invention is to provide a centrifugal blower capable of reducing noise and improving air blowing efficiency.

  The invention according to claim 1 is directed to a centrifugal blower that discharges air sucked from one end side of the rotating shaft (20) in the axial direction (AX) toward the outside in the radial direction (RD) of the rotating shaft.

  In order to achieve the above object, the invention according to claim 1 includes a plurality of blades (31) radially arranged with respect to the axis (CL) of the rotation shaft, and one end side of the plurality of blades in the axial direction. A cylindrical impeller (3) having an annular side plate (32) for connecting the parts and rotating about the axis of the rotating shaft; and an impeller which accommodates the impeller and is located at a position close to the side plate. A casing (4) in which a bell mouth-shaped air suction portion (41) for guiding air to the inside is formed.

The air suction portion has a downstream end (411) that constitutes an end on the downstream side of the air flow, and an inner wall (412) that constitutes a radially inner wall of the rotating shaft. The side plate has an upstream end portion (321) that constitutes an end portion on the upstream side of the air flow, and an inner plate surface portion (323) that constitutes a plate surface radially inside the rotary shaft. The diameter of the inner plate surface portion increases from one end side to the other end side in the axial direction of the rotation shaft.

  Further, the air suction portion and the side plate are arranged such that the downstream end and the upstream end are spaced apart in the axial direction of the rotary shaft in at least a part of the rotary shaft in the rotation direction (CD). And the difference between the diameter (Db) of the minimum diameter portion on the inner wall surface portion and the diameter (Ds) of the minimum diameter portion on the inner plate surface portion is set to be equal to or less than the thickness of the side plate. .

  As described above, in at least a part of the air suction portion and the side plate, the difference in diameter between the minimum diameters of the inner wall surface portion of the air suction portion and the inner plate surface portion of the side plate is set to be equal to or less than the thickness of the side plate. The inner wall surface of the portion and the inner plate surface of the side plate have substantially no steps. Thereby, the air flowing along the air suction portion easily flows smoothly to the side plate side. Therefore, it is possible to realize a centrifugal blower capable of reducing noise and improving blowing efficiency. Note that the bell mouth-shaped air suction part means an air suction part whose diameter is increased in a trumpet shape toward the air flow upstream side.

  The reference numerals in parentheses of each means described in this section and in the claims show an example of a correspondence relationship with specific means described in the embodiment described later.

It is a typical axial sectional view of the centrifugal blower of a 1st embodiment. It is an expanded sectional view of an important section including a side plate of a centrifugal blower of a 1st embodiment. It is an axial sectional view showing the flow of air in the centrifugal blower of a 1st embodiment. It is an expanded sectional view of an important section including a side plate of a centrifugal blower of a comparative example. It is an expanded sectional view showing the air flow near the side plate of the centrifugal blower of a 1st embodiment. It is the figure which compared the ventilation efficiency of the centrifugal blower of 1st Embodiment with the ventilation efficiency of the centrifugal blower of a comparative example. It is the figure which compared the noise of the centrifugal fan of 1st Embodiment, and the specific noise of the centrifugal fan of the comparative example. It is an expanded sectional view which shows the modification 1 of the principal part containing the side plate of the centrifugal blower of 1st Embodiment. It is an expanded sectional view showing an air flow near a side plate in modification 1 of a 1st embodiment. It is an expanded sectional view which shows the modification 2 of the principal part containing the side plate of the centrifugal blower of 1st Embodiment. It is an expanded sectional view showing an air flow near a side plate in modification 2 of a 1st embodiment. It is an expanded sectional view of the important section including the side plate of the centrifugal blower of a 2nd embodiment. It is an expanded sectional view showing the air flow near the side plate of the centrifugal blower of a 2nd embodiment. It is an expanded sectional view showing a modification of an important section including a side plate of a centrifugal blower of a 2nd embodiment. It is an expanded sectional view showing an air flow near a side plate in a modification of a 2nd embodiment. It is an expanded sectional view of an important section including a side plate of a centrifugal blower of a 3rd embodiment. It is an expanded sectional view showing the air flow near the side plate of the centrifugal blower of a 3rd embodiment. It is a typical axial sectional view of the centrifugal blower of a 4th embodiment. It is XIX-XIX sectional drawing of FIG. It is the arrow view of the centrifugal blower seen from the direction shown by arrow XX of FIG. It is the top view which looked at the centrifugal blower of a 1st embodiment from one end side of the direction of an axis. It is XXII-XXII sectional drawing of FIG. It is XXIII-XXIII sectional drawing of FIG. It is XXIV-XXIV sectional drawing of FIG. It is XXV-XXV sectional drawing of FIG. It is an axial sectional view showing the flow of air in the centrifugal blower of a 4th embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts as those described in the preceding embodiment are denoted by the same reference numerals, and description thereof may be omitted. Further, in the embodiment, when only a part of the component is described, the component described in the preceding embodiment can be applied to the other part of the component. The following embodiments can be partially combined with each other as long as the combination is not particularly hindered, even if not particularly specified.

(1st Embodiment)
The present embodiment will be described with reference to FIGS. The centrifugal blower 1 of the present embodiment illustrated in FIG. 1 is used, for example, in a blower unit that blows air to an indoor unit of a vehicle air conditioner.

  The centrifugal blower 1 includes an electric motor 2 having a rotating shaft 20, an impeller 3 that is driven to rotate by the electric motor 2 to blow out air, and a casing 4 that houses the impeller 3. The arrow AX shown in FIG. 1 indicates the axial direction along the axis CL of the rotating shaft 20. The arrow CD shown in FIG. 1 indicates the rotation direction of the rotation shaft 20. Further, an arrow RD shown in FIG. 2 indicates a radial direction orthogonal to the axial direction AX of the rotating shaft 20. This is the same in the drawings other than FIG. 1 and FIG.

  The impeller 3 is a cylindrical member that rotates about the axis CL of the rotating shaft 20. The impeller 3 includes a plurality of blades 31 radially arranged with respect to the rotation shaft 20, an annular side plate 32 connecting one end portion of each blade 31 in the axial direction AX, and an axial direction AX of each blade 31. And a disc-shaped main plate 33 connecting the other end of the main plate.

  The impeller 3 of the present embodiment is configured by a sirocco fan in which each blade 31 is a forward-facing blade. Each blade 31 is radially arranged about the axis CL of the rotating shaft 20. Each blade 31 has an air flow path through which air flows between adjacent blades 31.

  The side plate 32 is formed of an annular member whose center portion is open. In order to reduce the weight of the impeller 3, the side plate 32 of the present embodiment has a thickness Th of, for example, about 1 to 3 mm.

  The side plate 32 of the present embodiment has one end 321 that constitutes an end on the upstream side of the air flow, and the other end 322 that constitutes an end on the downstream side of the air flow. Further, the side plate 32 of the present embodiment includes an inner plate surface portion 323 that forms an inner plate surface of the rotating shaft 20 in the radial direction RD, and an outer plate surface portion 324 that forms an outer plate surface of the rotating shaft 20 in the radial direction RD. Have. In the present embodiment, one end 321 of the side plate 32 forms an upstream end. The side plate 32 is connected to one end of the blade 31 in the axial direction AX.

  The inner plate surface portion 323 forms an inlet for introducing the air sucked from the air suction portion 41 of the casing 4 described later into the impeller 3. The inner plate surface portion 323 of the present embodiment has a shape that bulges toward the inside of the impeller 3 so that the air that has flowed in the axial direction AX of the rotating shaft 20 is guided to the outside in the radial direction RD of the rotating shaft 20. are doing. Specifically, the diameter of the inner plate surface portion 323 gradually increases from the one end 321 side to the other end 322 side. In the present embodiment, one end portion 321 of the side plate 32 constitutes a portion having the minimum diameter in the inner plate surface portion 323.

  The central portion of the main plate 33 is connected to the rotating shaft 20. The other end of the main plate 33 in the axial direction AX of each blade 31 is connected to a portion facing the side plate 32. The main plate 33 of the present embodiment has a circular planar shape. Note that the main plate 33 may have a conical shape that is convex toward the side plate 32 in the axial direction AX of the rotation shaft 20.

  The casing 4 is a member that houses the impeller 3. The casing 4 of the present embodiment is configured by a scroll casing that forms a spiral air flow path 40 outside the impeller 3. The casing 4 is provided with a bell mouth-shaped air suction portion 41 for guiding air to the inside of the impeller 3.

  The air suction part 41 is formed at one end of the casing 4 in the axial direction AX of the rotating shaft 20 and at a position close to the side plate 32 of the impeller 3. The air suction section 41 has a downstream end 411 that forms an end on the downstream side of the air flow, and an inner wall 412 that forms the inner wall of the rotating shaft 20 in the radial direction RD.

  The air suction unit 41 of the present embodiment is configured such that the downstream end 411 and the one end 321 of the side plate 32 are opposed to each other in the axial direction AX of the rotary shaft 20 with a space in the axial direction AX of the rotary shaft 20. Formed in the casing 4. That is, the air suction portion 41 is formed at a portion of the casing 4 that does not overlap with the side plate 32 in the radial direction RD of the rotating shaft 20.

  The inner wall surface portion 412 has a shape bulging inward to guide air to the inside of the impeller 3. Specifically, the diameter of the inner wall surface portion 412 gradually decreases from the upstream side of the air flow toward the downstream end portion 411. In the present embodiment, the downstream end portion 411 of the air suction portion 41 forms a portion having the minimum diameter on the inner wall surface portion 412.

  The centrifugal blower 1 according to the present embodiment includes the air suction unit 41 and the side plate 32 in the entire rotation direction CD of the rotating shaft 20 in order to suppress the main flow from the air suction unit 41 to the side plate 32 from being separated. The shape has substantially no step between them.

  As shown in FIG. 2, the air suction portion 41 and the side plate 32 of the present embodiment have a diameter Db of a portion having a minimum diameter in the inner wall surface portion 412 of the air suction portion 41 and a minimum diameter in the inner plate surface portion 323 of the side plate 32. Is set to be equal to or less than the thickness Th of the side plate 32. The diameter of the inner wall surface 412 of the air suction unit 41 means a distance (for example, a radius) of the rotation shaft 20 from the inner wall surface 412 of the air suction unit 41 to the axis CL. In addition, the diameter of the inner plate surface portion 323 of the side plate 32 means a distance (for example, a radius) of the inner shaft surface portion 323 of the side plate 32 with respect to the axis CL of the rotating shaft 20.

  In the present embodiment, as described above, the downstream end 411 of the air suction portion 41 forms a portion having a minimum diameter on the inner wall surface portion 412, and the one end 321 of the side plate 32 has a minimum diameter on the inner plate surface portion 323. Constitute a part.

  For this reason, the air suction portion 41 and the side plate 32 of the present embodiment have a diameter Db of the downstream end 411 of the air suction portion 41 and a diameter of the one end 321 of the side plate 32 throughout the rotation direction CD of the rotating shaft 20. The difference from Ds is set to be equal to or less than the thickness Th of the side plate 32. The thickness Th of the side plate 32 is the thickness of a portion of the side plate 32 that is close to the air suction unit 41 side.

  In the present embodiment, the diameter Db of the downstream end 411 of the air suction unit 41 is set to be equal to or smaller than the diameter Ds of the one end 321 of the side plate 32 in the entire rotation direction CD of the rotary shaft 20. More specifically, in the present embodiment, the difference between the diameter Db of the downstream end portion 411 of the air suction portion 41 and the diameter Ds of the one end portion 321 of the side plate 32 over the entire region in the rotation direction CD of the rotary shaft 20. They are set to substantially match (Db ≒ Ds).

  Further, the air suction part 41 and the side plate 32 of the present embodiment are set such that the tangent to the downstream end 411 of the air suction part 41 and the tangent to the one end 321 of the side plate 32 are substantially parallel. I have. More specifically, in the present embodiment, both the tangent to the downstream end 411 of the air suction portion 41 and the tangent to the one end 321 of the side plate 32 extend in the direction along the axial direction AX of the rotating shaft 20. Is set to Thereby, even if the air is separated at the downstream end 411 of the air suction part 41, the separated air easily adheres to the one end 321 of the side plate 32.

  Here, the air suction side and the air discharge side of the impeller 3 communicate with each other via a gap between the air suction portion 41 and the side plate 32. For this reason, the air discharged from the air discharge side of the impeller 3 may flow back to the air suction side of the impeller 3 via the gap between the air suction part 41 and the side plate 32. In the present embodiment, the gap between the air suction portion 41 and the side plate 32 forms a reverse flow path from the air discharge side of the impeller 3 to the air suction side.

  The downstream end 411 of the air suction section 41 of the present embodiment has a shape in which a portion facing the one end 321 of the side plate 32 extends in the radial direction RD of the rotating shaft 20. In addition, one end 321 of the side plate 32 of the present embodiment has a shape in which a portion facing the downstream end 411 of the air suction portion 41 extends in the radial direction RD of the rotating shaft 20. Therefore, in the present embodiment, the gap between the air suction part 41 and the side plate 32 that constitute the reverse flow path has a flow path shape that extends in the radial direction RD of the rotating shaft 20.

  Next, the operation of the centrifugal blower 1 of the present embodiment will be described. In the centrifugal blower 1, the impeller 3 rotates with the rotation of the rotating shaft 20 of the electric motor 2. As a result, as shown in FIG. 3, the air sucked into the impeller 3 from the air suction portion 41 at one end in the axial direction AX of the rotating shaft 20 is directed outward in the radial direction RD of the rotating shaft 20 by centrifugal force. Is blown out.

  Here, FIG. 4 is a drawing showing an airflow near the side plate 32 of the centrifugal blower CE as a comparative example of the present embodiment. The centrifugal blower CE of the comparative example differs from the centrifugal blower 1 of the present embodiment only in that the side plate 32 is located on the outer peripheral side of the air suction section 41. For convenience of description, in FIG. 4, the same reference numerals are given to the same configurations as the centrifugal blower 1 of the present embodiment in the centrifugal blower CE of the comparative example.

  In the centrifugal blower CE of the comparative example, as shown in FIG. 4, air is sucked into the impeller 3 from the air suction portion 41 at one end in the axial direction AX of the rotating shaft 20 by the rotation of the impeller 3. In the centrifugal blower CE of the comparative example, since a large step is formed between the air suction part 41 and the side plate 32, the airflow along the surface of the air suction part 41 causes the air flow downstream end 411 of the air suction part 41. To peel off. As a result, the airflow flowing from the surface of the air suction portion 41 to the vicinity of the side plate 32 of the impeller 3 is disturbed with a lateral vortex. This turbulence grows as it proceeds to the downstream side of the air flow in the impeller 3. As a result, the noise increases and the air blowing efficiency decreases. Note that the lateral vortex is a vortex having a central axis of rotation that intersects the flow direction of the main flow of air.

  On the other hand, the centrifugal blower 1 of the present embodiment has a diameter Db of a portion having a minimum diameter on the inner wall surface portion 412 of the air suction portion 41 and a diameter Ds of a portion having a minimum diameter on the inner plate surface portion 323 of the side plate 32. Is set to be equal to or less than the thickness Th of the side plate 32.

  For this reason, in the centrifugal blower 1 of the present embodiment, as shown in FIG. 5, the airflow along the surface of the air suction portion 41 is separated from the airflow downstream end portion 411 of the air suction portion 41 and then re-applied to the side plate 32. Adhere to. The airflow near the side plate 32 flows along the side plate 32 without separating from the side plate 32. As described above, in the centrifugal blower 1 according to the present embodiment, the airflow flowing along the air suction portion 41 easily flows smoothly to the side plate 32 side.

  Here, FIG. 6 is a diagram comparing the blowing efficiency when the discharge flow rate of air is changed in the centrifugal blower 1 of the present embodiment and the centrifugal blower CE of the comparative example. In FIG. 6, the blowing efficiency of the centrifugal blower CE of the comparative example is indicated by a solid line A, and the blowing efficiency of the centrifugal blower 1 of the present embodiment is indicated by a broken line B.

  FIG. 7 is a diagram comparing the specific noise when the discharge flow rate of air is changed in the centrifugal blower 1 of the present embodiment and the centrifugal blower CE of the comparative example. In FIG. 7, the specific noise of the centrifugal blower CE of the comparative example is shown by a solid line A, and the specific noise of the centrifugal blower 1 of the present embodiment is shown by a broken line B.

  According to FIG. 6, it can be confirmed that the centrifugal blower 1 of the present embodiment has improved ventilation efficiency in the entire flow rate range as compared with the centrifugal blower CE of the comparative example. According to FIG. 7, it can be confirmed that the centrifugal blower 1 of the present embodiment can reduce noise in the entire flow rate range as compared with the centrifugal blower CE of the comparative example. As described above, in the centrifugal blower 1 of the present embodiment, it is possible to reduce noise and improve blowing efficiency.

  In the centrifugal blower 1 of the present embodiment described above, the difference in diameter between the minimum diameter portions of the inner wall surface portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32 is set to be equal to or less than the thickness Th of the side plate 32. It has a configuration.

  According to this, it is possible to form a shape having substantially no step between the inner wall surface portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32. Thereby, the air flowing along the air suction part 41 easily flows to the side plate 32 side. Therefore, according to the centrifugal blower 1 of the present embodiment, it is possible to reduce noise and improve blowing efficiency.

  Further, the centrifugal blower 1 of the present embodiment is set so that the difference between the diameter Db of the downstream end 411 of the air suction part 41 and the diameter Ds of the one end 321 of the side plate 32 substantially coincides with each other. . According to this, it is possible to suppress the airflow along the air suction part 41 from colliding with the side plate 32, so that the airflow along the air suction part 41 can flow more smoothly to the side plate 32 side.

(Modification 1 of the first embodiment)
In this modified example, see FIGS. 8 and 9 for an example in which the diameters of the minimum diameter portions of the inner wall surface portion 412 and the inner plate surface portion 323 of the side plate 32 of the first embodiment are different from each other. Will be explained.

  As shown in FIG. 8, in the present modification, the diameter Db of the downstream end 411 of the air suction section 41 is set smaller than the diameter Ds of the one end 321 of the side plate 32 (Db <Ds). Also in this modification, the diameter difference ΔD between the minimum diameters of the inner wall surface portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32 is set to be equal to or less than the thickness Th of the side plate 32.

  Other configurations are the same as in the first embodiment. Also in the centrifugal blower 1 of the present modified example, as shown in FIG. 9, the airflow along the surface of the air suction part 41 adheres to the side plate 32 after leaving the air flow downstream end 411 of the air suction part 41. Thus, the water flows along the side plate 32 without being separated from the side plate 32. Therefore, according to the centrifugal blower 1 of the present modification, it is possible to reduce noise and improve the blowing efficiency as in the first embodiment.

(Modification 2 of the first embodiment)
In this modification, an example in which the shapes of the inner wall surface portion 412 and the inner plate surface portion 323 of the side plate 32 of the first embodiment are modified will be described with reference to FIGS.

  As shown in FIG. 10, the air suction portion 41 of the present modification is configured such that a portion of the inner wall surface portion 412 slightly upstream of the air flow from the downstream end portion 411 has a minimum diameter. That is, the diameter of the downstream end portion 411 of the inner wall surface portion 412 of this modified example is slightly larger than that of the downstream end portion 411 in a portion slightly upstream of the air flow.

  Further, the side plate 32 of the present modification is configured such that a portion between the one end 321 and the other end 322 of the inner plate surface portion 323 has a minimum diameter. That is, the diameter of the portion between the one end 321 and the other end 322 of the inner plate surface portion 323 of this modification is larger than the diameters of the one end 321 and the other end 322.

  The air suction portion 41 and the side plate 32 of the present modified example have a diameter Db of the minimum diameter on the inner wall surface portion 412 of the air suction portion 41 and a diameter of the minimum diameter on the inner plate surface portion 323 of the side plate 32. The difference from Ds is set to be equal to or less than the thickness Th of the side plate 32.

  Further, in the air suction portion 41 and the side plate 32 of the present modification, the tangent line of the portion having the minimum diameter on the inner wall surface portion 412 and the tangent line of the portion having the minimum diameter on the inner plate surface portion 323 are substantially parallel. Is set to More specifically, in the present modification, both the tangent to the portion having the minimum diameter in the inner wall surface portion 412 and the tangent to the portion having the minimum diameter in the inner plate surface portion 323 are along the axial direction AX of the rotating shaft 20. It is set to extend in the direction.

  Other configurations are the same as those of the first embodiment. Also in the centrifugal blower 1 of the present modified example, as shown in FIG. 11, the airflow along the surface of the air suction portion 41 reattaches to the side plate 32 after leaving the airflow downstream end 411 of the air suction portion 41. Thus, the water flows along the side plate 32 without being separated from the side plate 32. Therefore, according to the centrifugal blower 1 of the present modification, it is possible to reduce noise and improve the blowing efficiency as in the first embodiment.

(2nd Embodiment)
Next, a second embodiment will be described with reference to FIGS. The present embodiment is different from the first embodiment in that the direction of the backflow between the air suction part 41 and the side plate 32 is deflected so as to approach the main flow.

  As shown in FIG. 12, the centrifugal blower 1 according to the present embodiment is configured such that a gap between the downstream end 411 of the air intake 41 and one end 321 of the side plate 32 is provided between the air intake 41 and the side plate 32. A deflection flow path 5 for deflecting the backflow so as to approach the main flow is set. The backflow is an airflow that flows from the gap between the downstream end 411 of the air suction portion 41 and the one end 321 of the side plate 32 toward the air suction side of the impeller 3. The mainstream is an airflow from the air suction part 41 toward the air suction side of the impeller 3.

  The deflection flow path 5 includes an upstream flow path 51 formed between the outer plate surface portion 324 of the side plate 32 and the inner wall surface of the casing 4, a downstream end 411 of the air suction section 41, and one end 321 of the side plate 32. And a downstream flow path 52 formed between them.

  The downstream end portion 411 of the air suction portion 41 of the present embodiment is inclined with respect to the inner wall surface portion 412 such that the diameter of the portion facing the one end portion 321 of the side plate 32 decreases as approaching the one end portion 321 side. ing. That is, the downstream end 411 of the present embodiment is inclined such that a portion facing the one end 321 of the side plate 32 intersects the inner wall surface 412 at an acute angle.

  In addition, in the upstream channel 51 of the present embodiment, the portion of the inner wall surface of the casing 4 that is continuous with the downstream end 411 is the same as the portion of the downstream end 411 that faces the one end 321 of the side plate 32. It is inclined with respect to the inner wall surface 412.

  On the other hand, the one end 321 of the side plate 32 of the present embodiment has a shape in which a portion facing the downstream end 411 of the air suction portion 41 extends in the radial direction RD of the rotating shaft 20. For this reason, the cross-sectional area of the downstream flow path 52 of the present embodiment decreases toward the air flow downstream.

  Other configurations are the same as in the first embodiment. In the centrifugal blower 1 of the present embodiment, as shown in FIG. 13, the airflow along the surface of the air suction portion 41 flows along the side plate 32 without separating from the side plate 32.

  Furthermore, in the centrifugal blower 1 of the present embodiment, the backflow from the gap between the downstream end 411 of the air intake 41 and the one end 321 of the side plate 32 approaches the main flow between the air intake 41 and the side plate 32. The deflection flow path 5 for deflecting is set as described above.

  For this reason, the direction of the backflow from the gap between the air suction part 41 and the side plate 32 is along the main flow, and it is possible to suppress interference between the main flow and the backflow. This facilitates the smooth flow of the airflow along the air suction section 41 toward the side plate 32, so that noise can be reduced and ventilation efficiency can be improved.

(Modification of the second embodiment)
In this modification, an example in which the downstream flow path 52 of the deflection flow path 5 of the second embodiment is changed will be described with reference to FIGS.

  When the cross-sectional area of the downstream flow path 52 is reduced toward the downstream side of the air flow as in the second embodiment, the reverse flow path is narrowed, so that the reverse flow is likely to be disturbed. This is not preferable because when the main flow and the backflow merge, the main flow is disturbed.

  Therefore, in the present modification, as shown in FIG. 14, a portion of the one end 321 of the side plate 32 facing the downstream end 411 is inclined with respect to the inner plate surface 323. Specifically, one end portion 321 of the side plate 32 of the present modified example has a diameter with respect to the inner plate surface portion 323 such that the diameter of a portion facing the downstream end portion 411 increases as approaching the downstream end portion 411 side. It is inclined. That is, one end 321 of the side plate 32 of the present modification is inclined such that a portion facing the downstream end 411 intersects the inner plate surface 323 at an obtuse angle. Thereby, the cross-sectional area of the downstream flow path 52 of the present modified example is equal between the upstream side and the downstream side of the air flow.

  Other configurations are the same as those of the second embodiment. In the centrifugal blower 1 of the present modification, as shown in FIG. 15, the airflow along the surface of the air suction portion 41 flows along the side plate 32 without separating from the side plate 32.

  Further, in the centrifugal blower 1 of the present modification, the cross-sectional area of the downstream flow path 52 of the deflection flow path 5 is equal between the upstream side and the downstream side of the air flow. Therefore, the turbulence of the backflow flowing from the gap between the air suction portion 41 and the side plate 32 is suppressed, and the turbulence of the main flow when the main flow and the backflow merge can be effectively suppressed.

(Third embodiment)
Next, a third embodiment will be described with reference to FIGS. In the present embodiment, the shape of the deflection channel 5 is different from that of the second embodiment.

  As shown in FIG. 16, in the centrifugal blower 1 of the present embodiment, the upstream channel 51 formed between the outer plate surface portion 324 of the side plate 32 and the inner wall surface of the casing 4 in the deflection channel 5 has a rounded shape. It has a shape.

  Specifically, the casing 4 of the present embodiment has a semicircular shape in which the inner wall surface forming the upstream flow path 51 is convex toward one end of the rotating shaft 20. In the side plate 32 of the present embodiment, one end 321 facing the downstream end 411 of the air suction portion 41 has an R shape.

  Other configurations are the same as those of the second embodiment. In the centrifugal blower 1 of the present embodiment, as shown in FIG. 17, the airflow along the surface of the air suction portion 41 flows along the side plate 32 without separating from the side plate 32.

  Further, in the centrifugal blower 1 of the present embodiment, the upstream flow path 51 in the deflection flow path 5 has a round shape. Therefore, the reverse flow easily flows through the upstream flow path 51 of the deflection flow path 5. Thereby, the turbulence of the backflow flowing from the gap between the air suction part 41 and the side plate 32 is suppressed, so that the turbulence of the main flow when the main flow and the backflow merge can be effectively suppressed.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIGS. The centrifugal blower 1 </ b> A of the present embodiment determines the difference between the diameters of the minimum diameters of the inner wall portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32 in a part of the rotation direction CD of the rotating shaft 20. The point that the thickness is set to be equal to or less than the thickness Th of the side plate 32 is different from the above-described embodiment.

  As shown in FIGS. 18 to 20, the casing 4 of the centrifugal blower 1 </ b> A of the present embodiment has a spiral air outside the impeller 3 with the nose portion 42 as a starting point, similarly to the centrifugal blower 1 of the first embodiment. The scroll casing has a side wall 43 forming the flow path 40.

  The side wall portion 43 of the casing 4 extends from the winding start portion 431 located at the nose portion 42 of the side wall portion 43 to the winding end portion 432 such that the radius of the rotating shaft 20 with respect to the axis CL increases in a logarithmic spiral shape. Thereby, in the casing 4 of the present embodiment, the passage cross-sectional area of the air flow path 40 increases from the winding start portion 431 side of the side wall portion 43 toward the winding end portion 432 side.

  When the casing 4 is formed of a scroll casing as in the present embodiment, the interval between the trailing edge of the blade 31 of the impeller 3 and the side wall 43 increases from the winding start portion 431 toward the winding end portion 432. Specifically, the interval between the trailing edge side of the blade 31 and the side wall portion 43 is the narrowest at the winding start portion 431 and the widest at the winding end portion 432 of the side wall portion 43.

  For this reason, inside the casing 4 of the present embodiment, there are a portion where the airflow is likely to be turbulent on the air discharge side of the impeller 3 and a portion where the airflow is unlikely to be generated in the rotation direction CD of the rotating shaft 20.

  For example, in the section SE1 from the winding start portion 431 to the middle portion 433 in the side wall portion 43 shown in FIGS. 19 and 20, the airflow turbulence on the air discharge side of the impeller 3 is caused by the side wall portion 43 having ventilation resistance. Tends to occur.

  On the other hand, in the section SE2 from the intermediate portion 433 to the winding end portion 432 of the side wall portion 43 shown in FIGS. 19 and 20, the side wall portion 43 has almost no ventilation resistance, so that the turbulence of the air flow on the air discharge side of the impeller 3 is reduced. It is unlikely to occur.

  Here, as described in the first embodiment, it has been found that the centrifugal blower 1 of the first embodiment can reduce noise and improve the blowing efficiency as compared with the centrifugal blower CE of the comparative example. .

  In order to further reduce noise in the centrifugal blower 1 according to the first embodiment, the present inventors have conducted intensive studies on the magnitude of noise in the rotation direction CD of the rotating shaft 20 of the centrifugal blower 1. As a result, in the centrifugal blower 1 according to the first embodiment, the vicinity of the winding end portion 432 in the side wall portion 43 shown in FIG. 21 has lower noise than the section SE1 from the winding start portion 431 to the intermediate portion 433 in the side wall portion 43. It turned out to be bigger.

  Therefore, the present inventors first investigated differences in the flow of air in the section SE1 from the winding start portion 431 to the intermediate portion 433 in the side wall portion 43 and in the vicinity of the winding end portion 432 in the side wall portion 43.

  As a result, in the centrifugal blower 1 according to the first embodiment, in the section SE1 from the winding start portion 431 to the intermediate portion 433 in the side wall portion 43, as shown in FIG. It turned out that it flows along the side plate 32.

  In the section SE1 from the winding start portion 431 to the intermediate portion 433 in the side wall portion 43, a part of the air discharged from the air discharge side of the impeller 3 passes through the gap between the air suction portion 41 and the side plate 32. It was found that there was a tendency to flow backward to the air suction side of the impeller 3. The reason is that, in the section SE1 from the winding start portion 431 to the intermediate portion 433 in the side wall portion 43, as described above, the side plate 32 on the air discharge side of the impeller 3 has an air resistance.

  On the other hand, in the vicinity of the winding end portion 432 in the side wall portion 43, as shown in FIG. 23, it was found that the airflow flowing near the surface of the air suction portion 41 was flowing along the side plate 32.

  In the vicinity of the winding end portion 432 in the side wall portion 43, a part of the airflow flowing near the surface of the air suction portion 41 is transferred to the air discharge side of the impeller 3 via the gap between the air suction portion 41 and the side plate 32. It turns out that it has a tendency to flow. The reason for this is that there are fewer resistance elements on the air discharge side of the impeller 3 near the winding end 432 of the side wall 43 than in the section SE1 from the winding start 431 to the intermediate portion 433 of the side wall 43. Is mentioned.

  Further, in the vicinity of the winding end portion 432 in the side wall portion 43, the airflow flowing near the surface of the air suction portion 41 and the airflow flowing out of the gap between the air suction portion 41 and the side plate 32 are separated from the airflow near the side plate 32. It was found that there was a tendency to collide in the easily peeled area DA. Such airflow collisions are a cause of noise.

  As described above, according to the investigation by the present inventors, in the centrifugal blower 1 of the first embodiment, the direction of the airflow flowing through the gap between the air suction portion 41 and the side plate 32 changes in the rotation direction CD of the rotation shaft 20. Turned out to be prone.

  In view of the results of the investigation by the present inventors, it is inferred that near the winding end portion 432 in the side wall portion 43, a collision of an airflow flowing in the opposite direction in the separation region DA causes noise to increase. .

  Therefore, in the centrifugal blower 1A of the present embodiment, as shown in FIG. 18, in a part of the rotation shaft 20 in the rotation direction CD, there is substantially no step between the air suction part 41 and the side plate 32. .

  Specifically, the centrifugal blower 1A according to the present embodiment includes an air suction section 41 in a section SE1 from the winding start section 431 to the intermediate section 433 in the side wall section 43 shown in FIGS. 19 and 20, as shown in FIG. And the side plate 32 have substantially no step. That is, in the centrifugal blower 1A of the present embodiment, the diameter Db1 of the downstream end portion 411 of the air suction portion 41 and the one end portion 321 of the side plate 32 in the section SE1 from the winding start portion 431 to the intermediate portion 433 in the side wall portion 43. Is smaller than the thickness Th of the side plate 32.

  On the other hand, the centrifugal blower 1A of the present embodiment has a shape having a step between the air suction portion 41 and the side plate 32 in a part of the rotation direction CD of the rotation shaft 20, as shown in FIG.

  Specifically, the centrifugal blower 1A according to the present embodiment is arranged between the air suction portion 41 and the side plate 32 near the winding end portion 432 in the side wall portion 43 shown in FIGS. 19 and 20, as shown in FIG. The shape has a step. In the centrifugal blower 1A of the present embodiment, the difference between the diameter Db2 of the downstream end portion 411 of the air suction portion 41 and the diameter Ds of the one end portion 321 of the side plate 32 near the winding end portion 432 in the side wall portion 43 is shown in FIG. Is greater than the thickness Th. The diameter Db2 of the downstream end 411 of the air suction portion 41 is smaller than the diameter Ds of the one end 321 of the side plate 32 near the winding end 432 in the side wall 43.

  The centrifugal blower 1 </ b> A according to the present embodiment is configured such that the diameter Db of the downstream end 411 of the air suction part 41 and the one end 321 of the side plate 32 in the section SE <b> 2 from the middle part 433 to the vicinity of the winding end part 432 in the side wall 43. The difference from the diameter Ds continuously increases in the rotation direction CD of the rotating shaft 20.

  In the centrifugal blower 1A of the present embodiment, the diameter Db of the downstream end 411 of the air suction part 41 and the diameter Ds of the one end 321 of the side plate 32 in the section from the winding end 432 to the winding start 431 in the side wall 43. Is continuously reduced in the rotation direction CD of the rotating shaft 20. Note that the difference between the diameter Db of the downstream end 411 of the air suction part 41 and the diameter Ds of the one end 321 of the side plate 32 may be changed discontinuously without changing continuously. .

  Subsequently, the operation of the centrifugal blower 1A of the present embodiment will be described with reference to FIG. In FIG. 26, the right side of the drawing shows a cross-sectional shape near the winding start portion 431 in the side wall portion 43, and the left side of the drawing shows a cross-sectional shape near the winding end portion 432 in the side wall portion 43.

  As shown in FIG. 26, the centrifugal blower 1 </ b> A of the present embodiment has a diameter Db <b> 1 of the downstream end 411 of the air suction part 41 and a diameter of one end 321 of the side plate 32 on the winding start part 431 side of the side wall 43. The difference from Ds is equal to or less than the thickness Th of the side plate 32.

  For this reason, in the centrifugal blower 1 </ b> A of the present embodiment, the airflow that flows along the air suction part 41 on the side of the winding start part 431 on the side wall part 43 is easy to flow smoothly to the side plate 32 side. In the centrifugal blower 1 </ b> A of the present embodiment, the airflow on the air discharge side of the impeller 3 on the side of the winding start portion 431 in the side wall 43 passes through the gap between the air suction portion 41 and the side plate 32, and Backflow to the air intake side.

  Further, in the centrifugal blower 1A of the present embodiment, the difference between the diameter Db2 of the downstream end portion 411 of the air suction portion 41 and the diameter Ds of the one end portion 321 of the side plate 32 at the winding end portion 432 side of the side wall portion 43. It is larger than the thickness Th of the side plate 32.

  For this reason, in the centrifugal blower 1A of the present embodiment, the airflow along the air suction portion 41 is separated from the side plate 32 at the winding end portion 432 side of the side wall portion 43, but the airflow near the surface of the air suction portion 41 is The air does not flow to the air discharge side of the impeller 3 through the gap between the air suction part 41 and the side plate 32. That is, in the centrifugal blower 1A of the present embodiment, the airflow on the air discharge side of the impeller 3 also passes through the gap between the air suction portion 41 and the side plate 32 on the side of the winding end portion 432 of the side wall portion 43. Back to the air intake side of

  Other configurations are the same as in the first embodiment. For this reason, the centrifugal blower 1A of the present embodiment can obtain the same operational effects as those of the first embodiment, which are provided by the same configuration as the first embodiment. That is, in the centrifugal blower 1A of the present embodiment, in the section SE1 from the winding start portion 431 to the intermediate portion 433 in the side wall portion 43, the minimum diameter of the inner wall surface portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32. Is smaller than the thickness Th of the side plate 32.

  According to this, in the section SE1 from the winding start portion 431 to the middle portion 433 in the side wall portion 43 where the turbulence of the air flow is likely to occur in the inside of the casing 4, the inner wall portion 412 of the air suction portion 41 and the inner plate of the side plate 32 are formed. The shape becomes substantially free of a step with the surface portion 323. Accordingly, in a portion of the casing 4 where airflow is likely to be turbulent, the air flowing along the air suction portion 41 can easily flow to the side plate 32 side, so that the noise of the centrifugal blower 1A can be reduced and the airflow efficiency can be reduced. Improvement can be achieved.

  Further, in the centrifugal blower 1A of the present embodiment, the portion corresponding to the vicinity of the winding end portion 432 in the side wall portion 43 is located closer to the air suction portion 41 and the side plate 32 than the portion corresponding to the intermediate portion 433 from the winding start portion 431. The difference in diameter between the smaller diameter portions is large.

  According to this, a step is formed between the inner wall surface portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32 near the winding end portion 432 in the side wall portion 43. For this reason, it is possible to suppress the airflow near the surface of the air suction part 41 from flowing to the air discharge side of the impeller 3 via the gap between the air suction part 41 and the side plate 32. Thereby, in the centrifugal blower 1A of the present embodiment, it is possible to suppress the noise due to the collision of the airflow near the winding end portion 432 in the side wall portion 43. Therefore, the centrifugal blower 1A of the present embodiment can reduce noise compared to the centrifugal blower 1 of the first embodiment.

  In particular, the centrifugal blower 1 </ b> A of the present embodiment has a diameter of the minimum diameter of the inner wall portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32 near the winding end portion 432 in the side wall portion 43. The difference is larger than the thickness Th of the side plate 32.

  According to this, at a portion corresponding to the winding end portion 432 of the side wall portion 43, a step larger than the thickness Th of the side plate 32 is formed between the inner wall surface portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32. It is formed. Therefore, the flow of air near the surface of the air suction portion 41 to the air discharge side of the impeller 3 through the gap between the air suction portion 41 and the side plate 32 can be further suppressed.

  Here, in the present embodiment, in the vicinity of the winding end portion 432 of the side wall portion 43, the difference in diameter between the portions having the minimum diameters of the inner wall surface portion 412 of the air suction portion 41 and the inner plate surface portion 323 of the side plate 32 is determined. Although the example in which the thickness is greater than the thickness Th of 32 has been described, the present invention is not limited to this. In a configuration in which a step is formed between the air suction portion 41 and the side plate 32 in the vicinity of the winding end portion 432 in the side wall portion 43, for example, the diameter of the portion having the minimum diameter of the air suction portion 41 and the side plate 32 May be equal to or less than the thickness Th of the side plate 32.

(Other embodiments)
As described above, the representative embodiments for carrying out the invention have been described. However, the present invention is not limited to the above embodiments, and various modifications can be made as follows, for example.

  In each of the embodiments described above, the example in which the centrifugal blowers 1 and 1A are applied to the blower unit of the vehicle air conditioner has been described, but the present invention is not limited to this. The centrifugal blowers 1 and 1A are applicable to, for example, a seat air conditioner of a vehicle. In addition, the centrifugal blowers 1 and 1A are not limited to vehicles, and can be applied to stationary air conditioners, ventilators, and the like. Furthermore, the centrifugal blowers 1 and 1A are not limited to an air conditioner, but can be applied to various devices.

  In each of the above-described embodiments, an example has been described in which the impeller 3 is configured by a sirocco fan in which each blade 31 is a forward-facing blade. However, the present invention is not limited thereto. The impeller 3 may be composed of, for example, a turbo fan in which each blade 31 is a backward-facing blade.

  In each of the above-described embodiments, the scroll casing has been exemplified as the casing 4. However, the present invention is not limited to this. For example, an all-outlet-type casing 4 may be employed. In this way, when the casing 4 is formed of a full-circumferential blow-out type casing, the direction of the airflow flowing through the gap between the air suction portion 41 and the side plate 32 is smaller than that in the case where the scroll casing is employed. It is considered that it is difficult to change in the direction CD. For this reason, when the casing 4 is formed of a full-circumferential blowout type casing, as in the first to third embodiments, the casing 4 is located between the air suction portion 41 and the side plate 32 in the entire rotation direction CD of the rotating shaft 20. It is desirable that the shape has substantially no steps.

  As in the above-described first to third embodiments, the diameter Db of the downstream end 411 of the air suction part 41 is desirably set to be equal to or smaller than the diameter Ds of the one end 321 of the side plate 32, but is not limited thereto. Not done. If the difference between the minimum diameter of the inner wall surface portion 412 of the air suction portion 41 and the minimum diameter of the inner plate surface portion 323 of the side plate 32 is equal to or less than the thickness Th of the side plate 32, the diameter Db of the downstream end portion 411 will be one end portion. 321 may be set to be larger than the diameter Ds.

  As in the above-described first to third embodiments, both the tangent to the downstream end 411 of the air suction part 41 and the tangent to the one end 321 of the side plate 32 extend in the direction along the axial direction AX of the rotating shaft 20. It is desirable that the setting be made as described above, but the present invention is not limited to this. Both the tangent to the downstream end 411 of the air suction portion 41 and the tangent to the one end 321 of the side plate 32 may be set so as to extend in a direction slightly inclined with respect to the axial direction AX of the rotating shaft 20.

  In the above-described second and third embodiments, the example in which the deflection flow path 5 is set between the air suction part 41 and the side plate 32 has been described, but the present invention is not limited to this. For example, a backflow prevention mechanism such as a labyrinth seal may be provided between the air suction section 41 and the side plate 32.

  In the above-described embodiment, it goes without saying that the elements constituting the embodiment are not necessarily essential, unless otherwise clearly indicated as essential or in principle considered to be clearly essential.

  In the above-described embodiment, when a numerical value such as the number, numerical value, amount, range, or the like of the constituent elements of the exemplary embodiment is mentioned, it is particularly limited to a specific number when it is clearly indicated as essential and in principle. It is not limited to that particular number, except in such cases.

  In the above-described embodiment, when referring to the shape, positional relationship, and the like of the components, the shape and positional relationship, unless otherwise specified, or limited in principle to a specific shape, positional relationship, etc. It is not limited to the above.

(Summary)
According to the first aspect shown in part or all of the above-described embodiments, the centrifugal blower has an air suction portion and a side plate in which the downstream end and the upstream end are spaced apart in the axial direction of the rotation shaft. Are arranged facing each other in the axial direction of the rotation shaft. In the air suction portion and the side plate, the difference between the diameter of the portion having the minimum diameter on the inner wall surface portion and the diameter of the portion having the minimum diameter on the inner plate surface portion is set to be equal to or less than the thickness of the side plate.

  According to the second aspect, in the centrifugal blower, the diameter of the minimum diameter portion on the inner wall surface portion is set to be equal to or less than the diameter of the minimum diameter portion on the inner plate surface portion. As described above, if the diameter of the portion having the minimum diameter on the inner wall surface portion is set to be equal to or smaller than the diameter of the portion having the minimum diameter on the inner plate surface portion, the airflow along the air suction portion collides with the side plate. Can be suppressed.

  According to the third aspect, the casing of the centrifugal blower is formed of a scroll casing having a side wall forming a spiral air flow path outside the impeller. The difference between the air suction portion and the side plate of the centrifugal blower in at least a part of the side wall portion between the winding start portion and the middle portion is smaller than the diameter of the portion having the minimum diameter in the inner wall surface portion and the inner plate surface portion. The thickness is set to be equal to or less than the thickness.

  According to this, at least a part of the section from the winding start part to the middle part in the side wall part where the turbulence of the air flow is likely to occur in the inside of the casing is formed between the inner wall part of the air suction part and the inner plate part of the side plate. Has substantially no step. Accordingly, in a portion of the casing where airflow is likely to be turbulent, the air flowing along the air suction portion easily flows smoothly to the side plate side, so that the noise of the centrifugal blower is reduced and the blowing efficiency is improved. Can be.

  According to the fourth aspect, the air suction portion and the side plate of the centrifugal blower are such that the portion near the winding end portion in the side wall portion has an inner wall surface portion and a portion near the winding end portion in the side wall portion in the middle section. The difference from the diameter of the portion having the minimum diameter of the inner plate surface is large.

  According to this, a step is formed between the inner wall surface portion of the air suction portion and the inner plate surface portion of the side plate at a portion corresponding to the winding end portion in the side wall portion. For this reason, it is possible to suppress the airflow near the surface of the air suction part from flowing to the air discharge side of the impeller through the gap between the air suction part and the side plate. Thus, noise due to the collision of the airflow in the vicinity of the winding end portion on the side wall portion can be suppressed, so that the noise of the centrifugal blower can be further reduced.

  According to the fifth aspect, in the air suction portion and the side plate of the centrifugal blower, the portion corresponding to the winding end portion in the side wall portion has the minimum diameter in the inner wall surface portion and the minimum diameter in the inner plate surface portion. The difference from the diameter of the part is larger than the thickness of the side plate.

  According to this, a step larger than the thickness of the side plate is formed between the inner wall surface of the air suction portion and the inner plate surface of the side plate at a portion corresponding to the winding end portion in the side wall. According to this, it is possible to further suppress the flow of air near the surface of the air suction portion from flowing to the air discharge side of the impeller via the gap between the air suction portion and the side plate.

  According to the sixth aspect, the centrifugal blower changes the direction of the backflow from the gap between the downstream end and the upstream end toward the air suction side of the impeller between the air suction portion and the side plate. A deflection flow path is provided for deflecting so as to approach the main flow from the section toward the air suction side of the impeller. As described above, if the configuration is such that the direction of the backflow is deflected so as to approach the main flow, it is possible to suppress interference between the main flow and the backflow. This makes it easier for the airflow along the air suction portion to flow smoothly to the side plate side, so that it is possible to reduce noise and improve the blowing efficiency.

  In the seventh aspect, a specific configuration of the deflection flow path is specified. That is, the deflection flow path includes a gap between the downstream end and the upstream end. The downstream end is inclined with respect to the inner wall surface such that the diameter of the facing portion facing the upstream end decreases as approaching the upstream end.

  Here, for example, when the facing surface of the upstream end that faces the downstream end is configured to extend in the radial direction of the rotation shaft, the cross-sectional area of the gap between the upstream end and the downstream end Is reduced toward the downstream of the air flow. In this case, the backflow flowing in the gap between the upstream end and the downstream end is apt to be disturbed, which is not preferable.

  In view of this point, in the eighth aspect, the upstream end portion is inclined toward the inner plate surface portion such that the diameter of the facing portion facing the downstream end portion increases as approaching the downstream end portion. . According to this, since the turbulence of the backflow in the gap between the upstream end and the downstream end can be suppressed, the interference between the main flow and the backflow can be suppressed. This makes it easier for the air flowing along the air suction portion to flow smoothly to the side plate side, so that it is possible to reduce noise and improve blowing efficiency.

DESCRIPTION OF SYMBOLS 1 Centrifugal blower 3 Impeller 31 Blade 32 Side plate 321 One end (upstream end)
323 inner plate surface part 4 casing 41 air suction part 411 downstream end part 412 inner wall surface part

Claims (8)

A centrifugal blower for discharging air sucked from one end side in an axial direction (AX) of a rotating shaft (20) toward an outside in a radial direction (RD) of the rotating shaft,
It has a plurality of blades (31) radially arranged with respect to the axis (CL) of the rotating shaft, and an annular side plate (32) for connecting one end side portion of the plurality of blades in the axial direction. A cylindrical impeller (3) that rotates about the axis of the rotation shaft;
A casing (4) that accommodates the impeller and has a bell mouth-shaped air suction portion (41) formed at a portion adjacent to the side plate to guide air inside the impeller;
The air suction unit has a downstream end (411) forming an end on the air flow downstream side, and an inner wall surface (412) forming a radially inner wall surface of the rotating shaft,
The side plate has an upstream end portion (321) that constitutes an end portion on the air flow upstream side, and an inner plate surface portion (323) that constitutes a plate surface radially inside the rotation shaft.
The inside plate surface portion has a diameter of the inside plate surface portion increasing from one end side in the axial direction of the rotation shaft toward the other end side,
The air suction portion and the side plate are arranged such that the downstream end and the upstream end are spaced apart in the axial direction of the rotation shaft in at least a part of the rotation direction (CD) of the rotation shaft. A difference between a diameter (Db) of a portion having a minimum diameter on the inner wall surface portion and a diameter (Ds) of a portion having a minimum diameter on the inner plate surface portion is opposite to the axial direction of the rotation shaft. Centrifugal blower set to be less than the thickness of.   The centrifugal blower according to claim 1, wherein a diameter of a portion having a minimum diameter in the inner wall surface portion is set to be equal to or less than a diameter of a portion having a minimum diameter in the inner plate surface portion. The casing is a scroll casing having a side wall (43) forming a spiral air flow path (40) outside the impeller,
The air suction portion and the side plate are at least partially provided between the winding start portion (431) and the intermediate portion (433) located between the winding start portion and the winding end portion (432) on the side wall portion. 3. The centrifugal blower according to claim 2, wherein a difference between a diameter of a portion having a minimum diameter on the inner wall surface portion and a diameter of a portion having a minimum diameter on the inner plate surface portion is set to be equal to or less than the thickness of the side plate.   In the air suction unit and the side plate, a portion corresponding to the winding end portion in the side wall portion is more in the inner wall surface portion than a portion corresponding to the section from the winding start portion to the intermediate portion in the side wall portion. 4. The centrifugal blower according to claim 3, wherein a difference between a diameter of a portion having a minimum diameter and a diameter of a portion having a minimum diameter on the inner plate surface portion is large. 5.   The air suction portion and the side plate have a portion corresponding to the winding end portion in the side wall portion, a diameter of a portion having a minimum diameter in the inner wall surface portion and a diameter of a portion having a minimum diameter in the inner plate surface portion. The centrifugal blower according to claim 4, wherein the difference is larger than the thickness of the side plate.   Between the air suction portion and the side plate, the direction of reverse flow from the gap between the downstream end portion and the upstream end portion toward the air suction side of the impeller is changed from the air suction portion to the impeller. The centrifugal blower according to any one of claims 1 to 5, wherein a deflecting flow path (5) for deflecting so as to approach a main flow toward the air suction side is set. The deflection flow path includes a gap between the downstream end and the upstream end,
The centrifuge according to claim 6, wherein the downstream end is inclined with respect to the inner wall surface such that a diameter of a portion facing the upstream end decreases as approaching the upstream end. Blower.   The centrifuge according to claim 7, wherein the upstream end is inclined toward the inner plate surface so that a diameter of a portion facing the downstream end increases as approaching the downstream end. Blower.

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