JP6332546B2 - Centrifugal blower - Google Patents

Description

Cross-reference to related applications

  This application is based on Japanese Patent Application No. 2015-30936 filed on Feb. 19, 2015, the description of which is incorporated herein by reference.

  The present disclosure relates to a centrifugal blower.

  Conventionally, a suction conduit having a trumpet shape on the downstream side is provided in the casing, and the leading edge of the impeller blade to the tip of the impeller blade and the intersection of the extension line of the rear end of the suction conduit and the leading edge of the impeller blade There is a centrifugal blower that generates a predetermined air flow in a region (Δb1) formed between the two. In such a centrifugal blower, air flow separation on the R surface at the rear end of the suction conduit is reduced to improve the blowing efficiency (see, for example, Patent Document 1).

JP 59-15696 A

  In such a centrifugal blower, the air sucked from the suction pipe and the suction conduit is discharged from the side plate of the impeller. Moreover, the air discharged | emitted from the side plate of the impeller is discharged | emitted from a blower outlet through the channel | path of a casing.

  Here, if the flow rate of the air passing through the region between the suction pipe and the front edge of the suction conduit is constant at each position in the circumferential direction of the casing, the suction conduit is like the centrifugal blower of Patent Document 1. Even if the rotational axis of the impeller is axisymmetric, separation of the air flow generated in the impeller can be prevented. In other words, air having a constant flow rate is formed in a region (Δb1) formed between the intersection of the extension line of the rear end portion of the suction conduit and the leading edge of the impeller blade and the leading edge of the impeller blade to the tip of the impeller blade. Therefore, separation of the air flow generated at the inlet portion on the side plate side of the impeller can be prevented.

  However, in such a centrifugal blower, the flow rate of the air passing through the region between the suction pipe and the front edge of the suction conduit varies depending on each position in the circumferential direction of the casing.

  For this reason, when the suction conduit is provided so as to be axially symmetric with respect to the rotating shaft of the impeller as in the centrifugal blower described in Patent Document 1, air having a sufficient flow rate in the above-described region (Δb1). May not flow. As described above, if air having a sufficient flow rate does not flow in the above-described region (Δb1), separation of the air flow generated at the inlet portion on the side plate side of the impeller cannot be prevented, and the efficiency is lowered. .

  The present disclosure has been made in view of the above problems, and an object of the present disclosure is to improve air blowing efficiency in a centrifugal fan having a trumpet-shaped suction conduit.

  In order to achieve the above object, according to one aspect of the present disclosure, a centrifugal blower includes a plurality of blades arranged in an annular shape around a rotation shaft, and air sucked into a radially inner peripheral side And an air passage for accommodating the impeller, and an air suction port for sucking air at one end side in the rotation axis direction and an air passage for collecting the air blown to the outer peripheral side of the impeller and leading to the air outlet The casing is formed into a trumpet shape that expands toward the downstream side of the air flow of the air sucked from the air suction port, and the air from the air suction port is branched into the trumpet inner peripheral side and outer peripheral side. A suction conduit that leads to the radially inner periphery of the impeller, wherein the suction conduit defines a region between the air inlet and the leading edge that is the upstream opening end of the suction conduit at each position in the circumferential direction of the casing. The flow rate of air passing through and the downstream opening of the suction conduit The flow rate of the air passing through the region between the extension line of the trailing edge, the intersection of the blade tip and the upper end of the blade on the air inlet side is matched with the rotation axis of the impeller. It is non-axisymmetric.

  According to such a configuration, the suction conduit is configured such that, at each position in the circumferential direction of the casing, the flow rate of air passing through the region between the air suction port and the leading edge that is the upstream opening end of the suction conduit, The impeller so that the flow rate of the air passing through the region between the extension line of the trailing edge which is the downstream open end of the conduit, the intersection of the blade tip and the upper end of the blade on the air inlet side coincides. Since it is non-axisymmetric with respect to the rotation axis, it is possible to more reliably prevent separation of the air flow generated at the inlet portion on the blade 22 side of the impeller 2 and improve the blowing efficiency.

  In order to achieve the above object, according to another aspect of the present disclosure, the centrifugal blower has a plurality of blades arranged in an annular shape around the rotation shaft, and has a diameter of the air sucked into the inner diameter side. An impeller that blows out to the outer peripheral side, and an air passage that houses the impeller and collects the air that is sucked into one end in the direction of the rotation axis and the air that the impeller blows out toward the outer peripheral side of the air to the air outlet And a trumpet shape that expands toward the downstream side of the air flow of the air sucked from the air suction port, and branches the air from the air suction port to the trumpet inner peripheral side and outer peripheral side And a suction conduit that leads to the radially inner periphery of the impeller, and the suction conduit is non-axisymmetric with respect to the rotational axis of the impeller.

  According to such a configuration, since the suction conduit is non-axisymmetric, depending on the eccentric angle of the suction conduit, the separation of the air flow generated at the inlet portion on the blade 22 side of the impeller 2 can be more reliably prevented. It is possible to improve the ventilation efficiency.

It is a schematic top view of the centrifugal blower according to the first embodiment of the present disclosure. It is sectional drawing along the II-II line | wire in FIG. It is a schematic top view of the centrifugal blower which concerns on 2nd Embodiment of this indication. It is sectional drawing along the IV-IV line in FIG. It is a schematic top view of the centrifugal fan which concerns on 3rd Embodiment of this indication. It is sectional drawing along the VI-VI line in FIG. It is a schematic top view of the centrifugal blower which concerns on 4th Embodiment of this indication. It is sectional drawing along the VIII-VIII line in FIG. It is a schematic top view of the centrifugal fan which concerns on 5th Embodiment of this indication. It is sectional drawing along the XX line in FIG. It is a schematic top view of the centrifugal fan which concerns on 6th Embodiment of this indication. It is sectional drawing along the XII-XII line | wire in FIG. It is a schematic top view of the centrifugal fan which concerns on 7th Embodiment of this indication. It is sectional drawing along the XIV-XIV line | wire in FIG. It is a figure which shows the ventilation efficiency of the centrifugal blower shown in FIG.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
With reference to FIGS. 1-4, the centrifugal blower which concerns on 1st Embodiment of this indication is demonstrated. The centrifugal blower 1 includes an impeller 2, a scroll casing (hereinafter referred to as a casing) 3, and a suction conduit 5.

  The impeller 2 is a centrifugal fan. The impeller 2 has a plurality of blades 22 arranged in an annular shape at regular intervals around the rotation axis J of the impeller 2. The impeller 2 is driven to rotate to blow out the air sucked to the inner diameter side toward the outer diameter side.

  The casing 3 is made of resin, for example, and houses the impeller 2 therein. An air inlet 30 that guides air to the inner diameter side of the impeller 2 is formed on one end side of the casing 3 in the rotation axis direction of the impeller 2. A rotating shaft 12 of an electric motor (not shown) is fixed to the other end side of the casing 3 in the rotating shaft direction of the impeller 2. The impeller 2 is rotationally driven by an electric motor.

  The casing 3 is formed in a spiral shape so that the impeller 2 is located substantially at the center. The casing 3 forms an air passage 31 that collects the air blown out by the impeller 2 toward the outer peripheral side and guides it to the air outlet 34. The air passage 31 has a passage cross-sectional area that increases from the winding start portion 32 of the casing 3 toward the winding end portion 33.

  The centrifugal blower 1 forms a curved wall having a small curvature radius R at the air suction port 30 in order to establish the continuity of the flow path surface between the air suction port 30 and the blade 22 of the impeller 2 in as small a space as possible. .

  The suction conduit 5 is provided in the air inlet 30 of the casing 3. The suction conduit 5 is connected to the casing 3 by a support member 50. The suction conduit 5 is formed with a leading edge 5a located at the upstream end of the air flow and a trailing edge 5b located at the downstream end of the air flow. The suction conduit 5 has a trumpet shape whose diameter increases toward the downstream side of the air flow. The suction conduit 5 divides the air sucked from the air suction port 30 into a trumpet-shaped inner peripheral side and an outer peripheral side, and guides it to the inner peripheral side of the impeller 2. The suction conduit 5 prevents separation of the air flow generated at the inlet portion C on the blade 22 side of the impeller 2.

  In such a centrifugal blower, the flow rate of air passing through the region between the air inlet 30 and the front edge 5a of the suction conduit 5 is in each position in the circumferential direction of the casing (the direction indicated by the arrow V in FIG. 1). Varies by And when there is little flow volume of the air which passes through the area | region between the air inlet 30 and the front edge 5a of the suction conduit 5, it cannot prevent separation of the air flow which arises in the inlet part C by the side of the braid | blade 22 of the impeller 2. There is a problem that efficiency is lowered.

  Therefore, in the centrifugal blower 1 of the present embodiment, the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2. Specifically, in each position of the casing 3 in the circumferential direction of the casing 3, the flow rate of the air passing through the region Ai and the flow rate of the air passing through the region Ao are matched. It is non-axisymmetric with respect to the rotation axis J. The region Ai means a region between the air suction port 30 and the front edge 5a of the suction conduit 5, and the region Ao is an intersection P between the extension line of the rear edge 5b of the suction conduit 5 and the tip of the blade 22. And the upper end of the blade on the air inlet side. Here, the front edge 5a of the suction conduit 5 means the upstream opening end, and the rear edge 5b of the suction conduit 5 means the downstream opening end.

  Specifically, the centrifugal blower 1 performs suction so that the flow rate of the air passing through the region Ai shown in FIG. 2 and the flow rate of the air passing through the region Ao coincide with each other in each circumferential position of the casing 3. The leading edge 5a of the conduit 5 and the trailing edge 5b of the suction conduit 5 are each elliptical. That is, in the centrifugal blower 1, the length between the rotating shaft J of the impeller 2 and the outer peripheral end of the front edge 5 a of the suction conduit 5 differs depending on the circumferential position of the casing 3. Further, the length between the rotating shaft J of the impeller 2 and the outer peripheral end of the rear edge 5 b of the suction conduit 5 differs depending on the circumferential position of the casing 3.

  In addition, the centrifugal blower 1 is So / S = h / H. So is the area of an opening located inside the air inlet 30 of the casing 3 and outside the front edge 5a of the suction conduit 5. Here, S is the area of the air inlet 30 of the casing 3. h is the length from the end of the trailing edge 5b of the suction conduit 5 to the air suction port side end of the blade 22 and the length from the end of the blade 22 on the air suction port 30 side to the intersection P. . H is the second length of the blade 22 in the axial direction.

  Next, the operation of the centrifugal blower 1 according to this embodiment will be described. When a control voltage is applied from the control device to the electric motor, the electric motor starts operating, and the impeller 2 is rotationally driven by the electric motor in the direction of arrow V in FIG.

  When the impeller 2 is rotationally driven by the electric motor, a part of the air sucked from the air suction port 30 passes through the outer peripheral side of the trumpet-shaped suction conduit 5 as shown by an arrow B1 in FIG. 2 to the inner diameter side. Further, the remaining part of the air sucked from the air suction port 30 is guided to the inner diameter side of the impeller 2 through the inner circumference side of the trumpet-shaped suction conduit 5 as indicated by an arrow B2.

  Further, the air guided to the radially inner peripheral side of the impeller 2 through the outer peripheral side of the trumpet-shaped suction conduit 5 and the inner diameter of the impeller 2 through the inner peripheral side of the trumpet-shaped suction conduit 5 The air guided to the side is blown out to the outer peripheral side of the diameter of the impeller 2. The air blown to the outer peripheral side of the impeller 2 flows through the air passage 31 toward the air outlet 34 and is blown out from the air outlet 34.

  Here, in the centrifugal blower 1, the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2.

  Thereby, in this centrifugal blower 1, depending on the eccentric angle of the suction conduit, it is possible to more reliably prevent the separation of the air flow generated at the inlet portion on the blade 22 side of the impeller 2 and improve the blowing efficiency. it can.

  Specifically, the centrifugal blower 1 includes the impeller 2 so that the flow rate of air passing through the region Ai matches the flow rate of air passing through the region Ao at each position in the circumferential direction of the casing 3. Is non-axisymmetric with respect to the rotation axis J. Specifically, the front edge 5a of the suction conduit 5 and the rear edge 5b of the suction conduit 5 are each elliptical.

  Thereby, in this centrifugal blower 1, since the same amount of air as the air passing through the region Ai is introduced into the region Ao even in the circumferential position where the flow rate of the casing 3 is small, the inlet on the blade 22 side of the impeller 2 The separation of the air flow generated in the part can be prevented, and the air blowing efficiency can be improved.

  The centrifugal blower 1 of the present embodiment can obtain the highest efficiency improvement effect of about 1% compared to the centrifugal blower in which the suction conduit 5 is axisymmetric with respect to the rotation axis J of the impeller 2. .

  In this embodiment, the front edge 5a of the suction conduit 5 and the rear edge 5b of the suction conduit 5 are each elliptical, but one of the front edge 5a of the suction conduit 5 and the rear edge 5b of the suction conduit 5 is elliptical. It is good also as a shape and making the other into a circular shape.

(Second Embodiment)
Next, a centrifugal blower according to a second embodiment of the present disclosure will be described with reference to FIGS. In the centrifugal blower 1 of the first embodiment, the front edge 5a of the suction conduit 5 and the rear edge 5b of the suction conduit 5 are each elliptical. However, in the centrifugal blower 1 of the present embodiment, the front edge 5a of the suction conduit 5 and the rear edge 5b of the suction conduit 5 are circular. Further, in the centrifugal blower 1 of the present embodiment, the axis of the suction conduit 5 is eccentric with respect to the rotation axis J of the impeller 2.

That is, the center O ₁ of the front edge 5 a and the center O ₂ of the rear edge 5 b of the suction conduit 5 are eccentric with respect to the rotation axis J of the impeller 2. The center _{O 2} of the center _{O 1} and the rear edge 5b of the front edge 5a of the suction conduit 5 is consistent.

  In the centrifugal blower 1, the axial center of the suction conduit 5 is a vane so that the flow rate of air passing through the region Ai matches the flow rate of air passing through the region Ao at each position in the circumferential direction of the casing 3. It is eccentric with respect to the rotation axis J of the car 2. Here, the region Ai means a region between the air inlet 30 and the front edge 5a of the suction conduit 5, and the region Ao is an intersection of the extension line of the rear edge 5b of the suction conduit 5 and the tip of the blade 22. It means the area between P and the upper end of the blade on the air inlet side. As described above, in the centrifugal blower 1, the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2.

  In the present embodiment, the effects produced from the configuration common to the first embodiment described above can be obtained as in the first embodiment.

  In addition, although this embodiment is embodiment based on 1st Embodiment, it is also possible to combine this embodiment with the above-mentioned 1st Embodiment.

(Third embodiment)
Next, a centrifugal fan according to a third embodiment of the present disclosure will be described with reference to FIGS. In the centrifugal blower 1 of the second embodiment, the axis of the suction conduit 5 is eccentric with respect to the rotation axis J of the impeller 2. However, the centrifugal blower 1 of this embodiment, the center O ₁ of the front edge 5a of the suction conduit 5 is eccentric relative to the rotational axis J of the impeller 2, the center O ₂ of the edge 5b after induction manifold 5 blades It coincides with the rotation axis J of the car 2.

Centrifugal blower ₁ rotates center O ₁ of front edge 5a of suction conduit 5 so that the flow rate of air passing through region Ai matches the flow rate of air passing through region Ao at each position in the circumferential direction of casing 3. Eccentric with respect to the axis J, the center O ₂ of the rear edge 5b of the suction conduit 5 coincides with the rotation axis J. Here, the region Ai means a region between the air inlet 30 and the front edge 5a of the suction conduit 5, and the region Ao is an intersection of the extension line of the rear edge 5b of the suction conduit 5 and the tip of the blade 22. It means the area between P and the upper end of the blade on the air inlet side. As described above, in the centrifugal blower 1, the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2.

  In this embodiment, the effect produced from the configuration common to the second embodiment described above can be obtained in the same manner as the second embodiment.

  In addition, although this embodiment is embodiment based on 2nd Embodiment, it is also possible to combine this embodiment with the above-mentioned 1st Embodiment.

(Fourth embodiment)
Next, a centrifugal blower according to a fourth embodiment of the present disclosure will be described with reference to FIGS. In the centrifugal blower 1 of the second embodiment, the front edge 5 a of the suction conduit 5 and the axis of the suction conduit 5 are eccentric with respect to the rotation axis J of the impeller 2. However, the centrifugal blower 1 of this embodiment, the center O ₁ of the front edge 5a of the suction conduit 5 coincides with the rotational axis J of the impeller 2, the center O ₂ of the edge 5b after induction manifold 5 impellers It is eccentric with respect to the second rotation axis J.

Centrifugal blower ₁ rotates center O ₁ of front edge 5a of suction conduit 5 so that the flow rate of air passing through region Ai matches the flow rate of air passing through region Ao at each position in the circumferential direction of casing 3. Along with the axis J, the center O _{2 of the} trailing edge 5 b of the suction conduit 5 is eccentric with respect to the rotation axis J. Here, the region Ai means a region Ai between the air inlet 30 and the front edge 5a of the suction conduit 5, and the region Ao is an extension line of the rear edge 5b of the suction conduit 5 and the tip of the blade 22. It means the area between the intersection P and the upper end of the blade on the air inlet side. As described above, in the centrifugal blower 1, the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2.

  In this embodiment, the effect produced from the configuration common to the second embodiment described above can be obtained in the same manner as the second embodiment.

  In addition, although this embodiment is embodiment based on 2nd Embodiment, it is also possible to combine this embodiment with the above-mentioned 1st Embodiment.

(Fifth embodiment)
Next, a centrifugal blower according to a fifth embodiment of the present disclosure will be described with reference to FIGS. In the centrifugal blower 1 of the second embodiment, the axis of the suction conduit 5 is eccentric with respect to the rotation axis J of the impeller 2. However, in the centrifugal blower 1 of the present embodiment, the center O ₁ of the front edge 5a of the suction conduit 5, the center O ₂ of the rear edge 5b of the suction conduit 5, and the rotation axis J of the impeller 2 are eccentric from each other.

The centrifugal blower 1 has a center O ₁ of the front edge 5a of the suction conduit 5 so that the flow rate of air passing through the region Ai matches the flow rate of air passing through the region Ao at each position in the circumferential direction of the casing 3. The center O ₂ of the rear edge 5b of the suction conduit 5 and the rotation axis J of the impeller 2 are eccentric from each other. Here, the region Ai means a region Ai between the air inlet 30 and the front edge 5a of the suction conduit 5, and the region Ao is an extension line of the rear edge 5b of the suction conduit 5 and the tip of the blade 22. It means the area between the intersection P and the upper end of the blade on the air inlet side. As described above, in the centrifugal blower 1, the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2.

  In this embodiment, the effect produced from the configuration common to the second embodiment described above can be obtained in the same manner as the second embodiment.

  In addition, although this embodiment is embodiment based on 2nd Embodiment, it is also possible to combine this embodiment with the above-mentioned 1st Embodiment.

(Sixth embodiment)
Next, a centrifugal blower according to a sixth embodiment of the present disclosure will be described with reference to FIGS. In the centrifugal blower 1 of the second embodiment, the axis of the suction conduit 5 is eccentric with respect to the rotation axis J of the impeller 2, but the centrifugal blower 1 of the present embodiment has the suction conduit 5 of the impeller 2. Inclined with respect to the rotation axis J.

In the centrifugal blower 1, the suction conduit 5 is connected to the rotation axis J of the impeller 2 so that the flow rate of air passing through the region Ai matches the flow rate of air passing through the region Ao at each position in the circumferential direction of the casing 3. It is inclined and provided. That is, as shown in FIG. 12, the axis O ₁₂ of the suction conduit 5 is not parallel to the rotation axis J of the impeller 2. Here, the region Ai means a region between the air inlet 30 and the front edge 5a of the suction conduit 5, and the region Ao is an intersection of the extension line of the rear edge 5b of the suction conduit 5 and the tip of the blade 22. It means the area between P and the upper end of the blade on the air inlet side. As described above, in the centrifugal blower 1, the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2.

  In this embodiment, the effect produced from the configuration common to the second embodiment described above can be obtained in the same manner as the second embodiment.

  In addition, although this embodiment is embodiment based on 2nd Embodiment, it is also possible to combine this embodiment with the above-mentioned 1st-5th embodiment.

(Seventh embodiment)
Next, a centrifugal fan according to a seventh embodiment of the present disclosure will be described with reference to FIGS. Note that this embodiment is an embodiment based on the second embodiment, and is basically the same as the second embodiment. Therefore, only different portions from the second embodiment will be described.

In the centrifugal blower 1 of the present embodiment, the center O ₁ of the front edge 5 a of the suction conduit 5 and the center O ₂ of the rear edge 5 b of the suction conduit 5 end of winding of the casing 3 with respect to the rotation axis J of the impeller 2. It is eccentric to the region side between the part 33 and the winding start part 32. Further, the center O ₁ of the front edge 5 a of the suction conduit 5 and the center O ₂ of the rear edge 5 b of the suction conduit 5 are such that the axis O ₁₂ of the suction conduit 5 is substantially parallel to the rotation axis J of the impeller 2. Eccentric.

  Here, in the centrifugal blower in which the suction conduit 5 is axisymmetric with respect to the rotation axis J of the impeller 2, the direction from the impeller 2 to the region between the winding end portion 33 and the winding start portion 32 of the casing 3. The air blown out in this way becomes difficult to flow by colliding with the winding start portion 32. Thereby, in such a centrifugal blower, the problem that the air which goes to the area | region side between the winding end part 33 and the winding start part 32 among the casings 3 tends to peel from the braid | blade 22 of the impeller 2 tends to arise.

On the other hand, as described above, in the centrifugal blower 1 of the present embodiment, the center O ₁ of the front edge 5 a of the suction conduit 5 and the center O ₂ of the rear edge 5 b of the suction conduit 5 are the rotation shafts of the impeller 2. With respect to J, the casing 3 is eccentric to the region side between the winding end portion 33 and the winding start portion 32. Thus, in the centrifugal blower 1 of the present embodiment, the shape of the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2.

  For this reason, as shown in FIG. 13, in the centrifugal blower 1, the air in the region between the winding end portion 33 and the winding start portion 32 in the casing 3 is compared to the axially symmetrical centrifugal blower. The area of the region between the suction port 30 and the front edge 5a of the suction conduit 5 is narrowed. Moreover, in this centrifugal blower 1, the area of the area | region between the air inlet 30 and the rear edge 5b of the suction conduit 5 is narrow. Thereby, compared with the centrifugal blower which is axially symmetric, in the region between the winding end portion 33 and the winding start portion 32 in the casing 3, of the suction pipe 5 in the air sucked into the impeller 2. The air flowing on the outer periphery side of the trumpet shape is surely easily guided by the suction conduit 5. Therefore, in the centrifugal blower 1 of the present embodiment, the blowing efficiency can be improved as compared to the centrifugal blower that is axially symmetric. Here, the trumpet-shaped outer peripheral side of the suction conduit 5 means between the front edge 5 a and the rear edge 5 b of the suction conduit 5.

FIG. 15 shows a comparison of the blowing efficiency of the centrifugal blower 1 in which the centers O ₁ and O ₂ of the suction conduit 5 are eccentric and the centrifugal blower that is axially symmetric without being eccentric. . The horizontal axis of FIG. 15 indicates the center O ₁ of the suction conduit 5 when the direction of the imaginary line connecting the rotation axis J of the impeller 2 and the winding start portion 32 of the casing 3 is 0 [°] and 360 [°]. , The eccentric angle of the center O ₂ , and the vertical axis is the blowing efficiency of the centrifugal blower. The eccentric angles of the center O ₁ and the center O ₂ of the suction conduit 5 mean the eccentric angle when the angle is measured in the direction from the downstream side to the upstream side of the air passage 31 of the casing 3. Further, the blowing efficiency of the centrifugal blower is a general value calculated by P × Q / T × ω (where P is the flow rate of the blower 1 and the blow pressure of the centrifugal blower 1). Yes, T is the torque of the electric motor that rotationally drives the impeller 2, and ω is the angular velocity of the electric motor that rotationally drives the impeller 2.

As shown in FIG. 15, the center O ₁ and the center O ₂ of the suction conduit 5 are located on the region side between the winding end portion 33 and the winding start portion 32 of the casing 3 with respect to the rotation axis J of the impeller 2. When it was made eccentric, the result that ventilation efficiency became better than the centrifugal fan which is axisymmetric was obtained. That is, when the centers O ₁ and O ₂ of the suction conduit 5 are eccentric in the direction of, for example, 0 to 20 [°], the blowing efficiency is improved as compared with the axially symmetric centrifugal fan.

In addition, as shown in FIG. 15, even when the center O ₁ and the center O ₂ of the suction conduit 5 are eccentric in the direction of 270 to 360 [°] with respect to the centrifugal blower 1, the centrifugal blower is axially symmetric. As a result, the air blowing efficiency was improved.

  As described above, in the centrifugal blower 1, the suction conduit 5 is non-axisymmetric with respect to the rotation axis J of the impeller 2.

  Thereby, in this centrifugal blower 1, depending on the eccentric angle of the suction conduit, it is possible to more reliably prevent the separation of the air flow generated at the inlet portion on the blade 22 side of the impeller 2 and improve the blowing efficiency. it can.

(Other embodiments)
(1) In the first to seventh embodiments, the cross-sectional area of the air passage 31 increases from the winding start portion 32 toward the winding end portion 33 of the casing 3. It may be constant.

  (2) In the said 1st-6th embodiment, although the shape of the casing 3 is spiral shape, it is good also as other than such a shape.

(3) In the seventh embodiment, the center O ₁ and the center O ₂ of the suction conduit 5 are arranged between the winding end portion 33 and the winding start portion 32 of the casing 3 with respect to the rotation axis J of the impeller 2. It was eccentric to the area side. However, in the seventh embodiment, only _one of the center O ₁ and the center O ₂ of the suction conduit 5 is connected to the rotation end J of the impeller 2 with respect to the winding end portion 33 and the winding start portion 32 of the casing 3. You may make it eccentric to the area | region side in between. Even in this case, it is possible to obtain a higher air blowing efficiency than the axially symmetric centrifugal fan.

  Note that the present disclosure is not limited to the above-described embodiment, and can be modified as appropriate. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, it is needless to say that elements constituting the embodiment are not necessarily indispensable except for the case where it is clearly indicated that the element is essential and the case where the element is clearly considered essential in principle. Yes. In each of the above embodiments, when referring to the material, shape, positional relationship, etc. of the constituent elements, etc., unless otherwise specified, or in principle limited to a specific material, shape, positional relationship, etc. The material, shape, positional relationship, etc. are not limited.

Claims (8)

A centrifugal blower,
An impeller (2) having a plurality of blades arranged in a ring around the rotation axis, and blowing out the air sucked into the inner diameter side toward the outer diameter side;
Air that houses the impeller and collects air that is sucked into one end in the direction of the rotation axis and air that the impeller blows to the outer peripheral side of the air and guides it to the air outlet (34). A casing (3) in which a passage (31) is formed;
The impeller is formed in a trumpet shape whose diameter increases toward the downstream side of the air flow of air sucked from the air suction port, and the air from the air suction port is branched into a trumpet inner peripheral side and an outer peripheral side. A suction conduit (5) leading to the radially inner periphery of
The suction conduit has a flow rate of air passing through a region (Ai) between the air suction port and a front edge (5a) which is an upstream opening end of the suction conduit at each position in the circumferential direction of the casing. A region (Ao) between the extension line of the rear edge (5b), which is the downstream opening end of the suction conduit, the intersection (P) of the blade tip and the upper end of the blade on the air inlet side A centrifugal blower that is non-axisymmetric with respect to the rotational axis of the impeller so that the flow rate of air passing therethrough coincides. A centrifugal blower,
An impeller (2) having a plurality of blades arranged in a ring around the rotation axis, and blowing out the air sucked into the inner diameter side toward the outer diameter side;
Air that houses the impeller and collects air that is sucked into one end in the direction of the rotation axis and air that the impeller blows to the outer peripheral side of the air and guides it to the air outlet (34). A casing (3) in which a passage (31) is formed;
The impeller is formed in a trumpet shape whose diameter increases toward the downstream side of the air flow of air sucked from the air suction port, and the air from the air suction port is branched into a trumpet inner peripheral side and an outer peripheral side. A suction conduit (5) leading to the radially inner periphery of
The casing is formed in a spiral shape, collects the air blown out by the impeller and guides it to the air outlet (34),
One or both of the center (O ₁ ) of the leading edge (5a) which is the upstream opening end of the suction conduit and the center (O ₂ ) of the trailing edge (5b) which is the downstream opening end of the suction conduit are With respect to the rotating shaft of the impeller, the suction conduit is connected to the rotating shaft of the impeller by being eccentric to the region side between the winding end portion (33) and the winding start portion (22) of the casing. Centrifugal blower that is non-axisymmetric with respect to it. 2. The length between the outer peripheral end of the leading edge and the outer peripheral end of the rear edge of the suction conduit and the rotational axis of the impeller differs depending on the circumferential position of the casing. 2. The centrifugal blower according to 2.   The centrifugal blower according to any one of claims 1 to 3, wherein a center of the leading edge of the suction conduit and a center of the trailing edge of the suction conduit are each eccentric with respect to a rotation shaft of the impeller.   The center of the front edge of the suction conduit is eccentric with respect to the rotation axis of the impeller, and the center of the rear edge of the suction conduit is aligned with the rotation axis of the impeller. The centrifugal blower as described in any one of these.   The center of the leading edge of the suction conduit coincides with the rotational axis of the impeller, and the center of the trailing edge of the suction conduit is eccentric with respect to the rotational axis of the impeller. The centrifugal blower as described in any one.   The centrifugal blower according to any one of claims 1 to 3, wherein a center of the front edge of the suction conduit, a center of the rear edge of the suction conduit, and a rotation shaft of the impeller are eccentric to each other.   The centrifugal blower according to any one of claims 1 to 7, wherein an axis of the suction conduit is non-parallel to a rotation axis of the impeller.

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