JP6113250B2 - Centrifugal fan - Google Patents

Description

  The present invention relates to a centrifugal fan, and more particularly to a centrifugal fan having a case and an impeller.

  A centrifugal fan (centrifugal blower) is a fan that blows air in a centrifugal direction by rotating an impeller having a plurality of blades (also referred to as blades or impellers). A centrifugal multiblade fan, which is a fan of this type, has a configuration in which an impeller having a large number of blades arranged around the rotation axis of a motor is stored in a casing having a suction port and a discharge port. The centrifugal multiblade fan causes air sucked from a suction port to flow between the blades from the center of the impeller, and is ejected toward the outside of the impeller by a centrifugal action accompanying the rotation of the impeller. The air ejected from the outer periphery of the impeller passes through the inside of the casing, becomes high-pressure air, and is ejected from the discharge port.

  Centrifugal multiblade fans are widely used in home appliances, OA equipment, industrial equipment cooling, ventilation, air conditioning, and vehicle blowers. The blowing performance and noise of the centrifugal multiblade fan are greatly affected by the blade shape and casing shape of the impeller.

  The following prior art exists as a device for the shape of the casing in the conventional fan.

  Patent Document 1 listed below discloses a technology for suppressing backflow of air from a gap formed by an upper case where a bell mouth is formed and a shroud in a centrifugal blower. In other words, the centrifugal blower has a bell mouth having a substantially semicircular cross section in the vicinity of the air intake of the upper case that houses the fan so that the gap with the upper end of the shroud is narrowed.

  Patent Document 2 listed below discloses a centrifugal blower that reduces noise as a whole blower while suppressing a separation phenomenon between the blade and the air flowing between the blades. That is, of the air blown outward from the centrifugal multiblade fan in the vicinity of the outer diameter of the shroud, the air flowing from the outer diameter toward the rotating shaft along the inner wall of the casing on the inlet side. Is formed with a bell mouth ring having a deflecting wall surface that deflects the motor toward the motor side. Thereby, it is suppressed that air flows backward from the gap between the shroud and the casing to the suction port. Therefore, it is possible to reduce the noise generated due to the interference between the air sucked from the suction port and the air flowing backward, and the turbulence of the flow generated when the gap flows backward.

  Patent Document 3 listed below discloses a centrifugal blower that can prevent flow disturbance in the vicinity of the suction port. That is, the multiblade blower is a blower that sucks gas from the rotation axis direction and blows out fluid in a direction intersecting the rotation axis, and includes an impeller and a bell mouth. The impeller rotates about the rotation axis. The bell mouth has a suction port disposed so as to face the impeller, and a concave portion that forms a negative pressure space around the suction port and that is recessed toward the impeller side. invite.

  Patent Document 4 listed below discloses a centrifugal blower that suppresses disturbance of the air flow at the bell mouth portion. That is, among the outer wall surfaces of the scroll casing, the suction side outer wall surface connected to the bell mouth portion is formed into a flat shape without a step. As a result, turbulence and the like can be prevented from occurring in the intake air flowing toward the inlet, so that the air flow can be prevented from being disturbed in the bell mouth portion, and new vortex loss and noise are induced. It is prevented.

JP 2006-207595 A Japanese Patent Laid-Open No. 9-242696 JP 2004-360670 A JP 2004-190535 A

  An object of the present invention is to provide a centrifugal fan having high rigidity.

In order to achieve the above object, according to one aspect of the present invention, a centrifugal fan including an upper casing in which an air suction port is formed, a lower casing, and an impeller positioned between the upper casing and the lower casing is provided. The impeller includes a plurality of blades arranged on the circumference, and rotates around the rotation shaft to direct the air sucked through the suction port from the vicinity of the rotation shaft to the outside of the diameter of the impeller by centrifugal force. it is possible to blow Te, at a portion opposite to the side on which the impeller of the upper casing is disposed, and a rib for imparting rigidity to the upper casing is formed, radially outwardly of the impeller Are provided between the upper casing and the lower casing, maintaining the distance between the upper casing and the lower casing, and the air blown out from the impeller Is Balloon through the several struts, ribs are formed along the line connecting the rotation axis and one of a plurality of struts in a top view.
Preferably, the rib is disposed at a position closer to the rotation axis than the plurality of support columns.
Preferably, a portion of the upper casing opposite to the side where the impeller is disposed is provided with a plurality of recesses that are recessed in the direction in which the impeller is disposed, and the rib is formed between the plurality of recesses. It is provided between.
Preferably, the surface facing the upper casing of the impeller has a first portion that approaches the lower casing as it moves away from the rotation axis, and the surface facing the impeller of the upper casing is the second portion facing the first portion. In FIG. 2, the shape of the concave portion approaches the lower casing with increasing distance from the rotation axis, and the plurality of recesses are shallow at a portion near the rotation axis and deep at a portion far from the rotation axis.
According to another aspect of the present invention, a centrifugal fan including an upper casing in which an air suction port is formed, a lower casing, and an impeller positioned between the upper casing and the lower casing is an impeller. Equipped with a plurality of blades arranged on the circumference, the air sucked through the suction port can be blown from the vicinity of the rotation shaft toward the outside of the diameter of the impeller by centrifugal force by rotating around the rotation shaft The rib on the side of the upper casing opposite to the side on which the impeller is disposed is formed with a rib for imparting rigidity to the upper casing, and the side on which the impeller of the upper casing is disposed A plurality of recesses that are recessed in the direction in which the impeller is arranged are provided on the opposite side of the rib, and the ribs are provided between the plurality of recesses and face the upper casing of the impeller. The surface is The first portion that approaches the lower casing as it moves away from the rotation shaft has a shape that faces the impeller of the upper casing in a second portion that faces the first portion, and has a shape that approaches the lower casing as it moves away from the rotation shaft. The plurality of recesses are shallow at a portion near the rotation axis and deep at a portion far from the rotation axis.

  Preferably, the ribs are formed radially about the rotation axis.

  Preferably, the ribs are arranged at predetermined angles around the rotation axis.

  Preferably, the rib is formed so as to follow an annular shape surrounding the suction port and centering on the rotation axis in a top view.

  Preferably, the rib has a plurality of portions forming a first row arranged in a ring around the rotation axis and a plurality of portions forming a second row arranged around the rotation axis on the outer peripheral side of the first row in a top view. And have.

  Preferably, the rib is formed such that, when viewed from above, a plurality of portions arranged around the rotation axis so as to surround the suction port form a plurality of rows having different distances from the rotation axis.

  According to the present invention, it is possible to provide a centrifugal fan having high rigidity.

It is a perspective view of the centrifugal fan in one of the embodiments of the invention. It is a center longitudinal cross-sectional view of the centrifugal fan of FIG. It is the perspective view which looked at the impeller 3 from the upper shroud 23 side. It is a figure which shows the blade | wing shape of the centrifugal fan of FIG. 1 in the state which permeate | transmitted from the upper shroud 23 side. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is CC sectional drawing in FIG. It is a figure which shows the cross-sectional shape and noise characteristic of the conventional impeller. It is a figure which shows the cross-sectional shape and noise characteristic of an impeller in embodiment of this invention. It is sectional drawing of the impeller of the centrifugal fan in a modification. It is a perspective view of the centrifugal fan in other embodiments. It is a center longitudinal cross-sectional view of the centrifugal fan of FIG. It is a figure which shows the flow of the wind between the upper shroud of the centrifugal fan shown by the cross section of FIG. 2, and an upper casing. It is a figure which shows the flow of the wind between the upper shroud of the centrifugal fan shown by the cross section of FIG. 12, and an upper casing. It is a figure which shows the characteristic of the air volume and pressure of the centrifugal fan shown by the cross section of FIG. 2, and the centrifugal fan shown by the cross section of FIG. It is a figure which shows the cross-section of the centrifugal fan in a modification. It is sectional drawing of the centrifugal fan in a modification.

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

  FIG. 1 is a perspective view of a centrifugal fan according to one embodiment of the present invention, and FIG. 2 is a central longitudinal sectional view of the centrifugal fan of FIG. 3 is a perspective view of the impeller 3 as seen from the upper shroud 23 side, and FIG. 4 is a view showing the blade shape of the centrifugal fan of FIG. 1 as seen through the upper shroud 23 side. It is. 5 to 7 are an AA sectional view, a BB sectional view, and a CC sectional view, respectively, in FIG.

  With reference to FIGS. 1-4, in the centrifugal fan 1, ventilation is performed when the center impeller 3 rotates. The impeller 3 has seven blades 2 arranged respectively, and is rotated around a rotation shaft 11 by a fan motor 13 built in the centrifugal fan 1. The direction of rotation is clockwise in FIG.

  The impeller 3 is accommodated in the casing 4. The casing 4 includes a plate-like upper casing 5 and a lower casing 6, and struts 7 are provided at four corners of the casing 4 in order to hold them at equal intervals. An air inlet 8 is provided at the top of the centrifugal fan 1. The air outlet 9 is provided between the column 7 and the column 7 of the casing 4. That is, the four sides 4 directions of the casing 4 are the air outlets 9 (open casing type). In addition, the casing 4 is good also as providing the blower outlet which collects the air blown from the impeller 3 to one direction (scroll casing type | mold).

  As shown in FIGS. 2 to 7, the impeller 3 includes an annular lower shroud 21, an annular upper shroud 23, and a plurality of circumferentially arranged between the lower shroud 21 and the upper shroud 23. It is possible to rotate around the rotating shaft 11.

  As shown in FIG. 4, the annular lower shroud 21 has an inner diameter 21 </ b> A and an outer diameter 21 </ b> B when viewed from the plane. The inner diameter 21A and the outer diameter 21B are circles in plan view. The annular upper shroud 23 has an inner diameter 23A and an outer diameter 23B when viewed from the plane. The inner diameter 23A and the outer diameter 23B are circles in plan view. The outer diameter 21 </ b> B of the lower shroud 21 overlaps with the inner diameter 23 </ b> A of the upper shroud 23. That is, the outer diameter 21B of the lower shroud 21 and the inner diameter 23A of the upper shroud 23 are equal. The outer diameter 21B of the lower shroud 21 may be slightly smaller than the inner diameter 23A of the upper shroud 23.

  In FIG. 4, the shape of each blade 2 visible from the space inside the inner diameter 23 </ b> A of the upper shroud 23 is indicated by a solid line. Between the inner diameter 23A and the outer diameter 23B of the upper shroud 23, the shape of each blade 2 hidden by the upper shroud 23 is indicated by a dotted line.

  As shown in FIG. 4, each blade has a shape that becomes thinner (thickness becomes thinner) from the inner side (rotation axis) toward the outer side in a plan view. Its entrance angle is 45 ° and its exit angle is 22 °. The diameter of the outer diameter 23B is 120 mm, and the diameter of the inner diameter 21A is 70 mm. The blade 2 is a swept wing.

  As shown in FIGS. 3 to 7, each blade 2 has an upper portion fixed to the lower surface of the upper shroud 23 and a lower portion fixed to the upper surface of the lower shroud 21. Here, the outer diameter 21B of the lower shroud 21 and the inner diameter 23A of the upper shroud 23 are designed to be equal (or the outer diameter 21B of the lower shroud 21 is smaller than the inner diameter 23A of the upper shroud 23). The impeller 3 can be integrally formed only by using a mold.

  4-7, the upper part of each blade | wing 2 is connected to the inner diameter side edge part of the upper shroud 23 by the inner diameter side (side near a rotating shaft). From that position, the upper part of each blade 2 is connected to the lower surface of the upper shroud 23 up to the outer diameter side end. That is, the upper shroud 23 and the blade 2 are in contact with each other in a place where the upper shroud 23 and the blade 2 are present in a plan view as shown in FIG.

  Further, the lower part of each blade 2 is connected to the lower shroud 21.

  As shown in FIG. 5, the upper part of each blade 2 is connected to the inner diameter side end of the upper shroud 23 on the inner diameter side. The upper part of each blade 2 has a taper portion (inclined portion) that extends further toward the inner diameter side. That is, the inner diameter portion of the blade 2 has an inclined portion that connects the inner diameter portion (inner diameter end portion) of the upper shroud 23 and the inner diameter portion of the lower shroud 21.

  The tapered portion of each blade 2 forms a slope that forms an angle of γ = 42 ° from the vertical direction. In FIG. 4, a portion indicated by a solid line of each blade 2 is a tapered portion, and a portion indicated by a dotted line indicates a portion where the upper portion of each blade 2 is connected to the upper shroud 23. Moreover, the part shown with the continuous line of each blade | wing 2 has shown the part by which the lower part is connected to the lower shroud 21. FIG. A portion indicated by a dotted line of each blade 2 indicates a portion where the lower portion is not connected to the lower shroud 21 (a portion where the lower shroud 21 is not therebelow).

  The angle γ = 42 ° in FIG. 5 is called a taper angle, but the numerical value is not limited to 42 °.

  In the impeller 3, the lower shroud 21 does not exist in a portion where the upper shroud 23 exists in a plan view. For this reason, as shown in FIG. 2, it is desirable to provide the lower casing 6 with a portion 6a that protrudes upward as a member that acts as a substitute for the lower shroud 21 that does not exist. The protruding portion 6a is formed in a portion where the upper shroud 23 exists (a portion where the lower shroud 21 does not exist) in a plan view so that the distance between the lower portion of the blade 2 and the lower casing 6 is shortened. It is. The protruding portion 6a protrudes to a height at which the lower shroud 21 exists. Thereby, it is possible to give the lower casing 6 a structure for functioning as a lower shroud.

  In the impeller 3 described above, the inner diameter portion of the blade 2 is tapered. The bottom portion of the taper is integrated with the lower shroud 21. All the upper portions of the blades 2 other than the tapered portion are integrated with the upper shroud 23. Also, as shown in FIG. 5, the inner diameter D1 of the upper shroud 23 and the outer diameter D2 of the lower shroud 21 are substantially equal (D1≈D2 or D1 ≧ D2). With such a shape, the impeller 3 can be integrally formed only with the upper and lower molds, and the impeller 3 and the centrifugal fan 1 with high mass productivity can be provided.

  Furthermore, since it is not necessary to widen or narrow the diameter of the air inlet, it is possible to suppress a decrease in static pressure and air volume.

  Furthermore, in the centrifugal fan 1 in the present embodiment, the flow of wind can be improved by the tapered shape of the blades 2. Moreover, an inflow port part can be covered with a shroud. For this reason, noise reduction can be realized. This will be described below.

  FIG. 8 is a diagram showing a cross-sectional shape and noise characteristics of a conventional impeller.

  As shown in the sectional view of FIG. 8A, the conventional impeller 3 ′ includes a plurality of lower shrouds 21 ′, an upper shroud 23 ′, and a plurality of lower shrouds 21 ′ and upper shrouds 23 ′. And a blade 2 '. The outer diameter of the lower shroud 21 'is equal to the outer diameter of the upper shroud 23'. For this reason, the impeller 3 'cannot be integrally formed only with the upper and lower molds.

  In FIG. 8B, the noise characteristics when the impeller 3 ′ of FIG. 8A is driven are shown, with the horizontal axis representing frequency and the vertical axis representing noise value (dB (A)). Yes.

  The noise is 58.0 dB (A) as a whole, and as shown in FIG. 8 (B), high values are shown for both discrete frequency noise and broadband noise (turbulent noise).

  FIG. 9 is a diagram showing a cross-sectional shape and noise characteristics of the impeller in the embodiment of the present invention.

  As shown in the sectional view of FIG. 9A, the impeller 3 in the present embodiment includes a lower shroud 21, an upper shroud 23, and a plurality of blades 2 provided between the lower shroud 21 and the upper shroud 23. And. The outer diameter of the lower shroud 21 is substantially equal to the inner diameter of the upper shroud 23. For this reason, it is possible to integrally mold the impeller only with the upper and lower molds.

  In FIG. 9B, the noise characteristics when the impeller of FIG. 9A is driven are shown with the frequency on the horizontal axis and the noise value (dB (A)) on the vertical axis.

  The noise as a whole is 57.3 dB (A), and as shown in the solid line circle in FIG. 9B, the discrete frequency noise (the primary and secondary noise of the blade blade) is shown in FIG. It is lower than B). Further, as shown in the circle of the alternate long and short dash line in FIG. 9B, the broadband noise (turbulent flow noise) is also lower than that in FIG. 8B.

  FIG. 10 is a cross-sectional view of an impeller of a centrifugal fan in a modified example.

  The impeller is different from the impeller shown in FIGS. 1 to 7 in that a bottom plate (plate) 21 a for extending the outer diameter of the lower shroud 21 outward is attached below the impeller 3. Is a point. The diameter (inner diameter) of the hollow portion of the bottom plate 21 a is equal to the outer diameter of the lower shroud 21. The outer diameter of the bottom plate 21 a is equal to the outer diameter of the upper shroud 23. Thereby, the outer diameter of the upper shroud 23 and the outer diameter of the bottom plate 21a can be matched, and the PQ characteristic similar to the configuration of the impeller as shown in FIG. 8 can be secured. In other words, the bottom plate 21a functions as a lower shroud attached later. By attaching the bottom plate 21a, it becomes possible to reduce noise while maintaining the PQ characteristic.

  Also in the present embodiment, the portion of the impeller 3 excluding the bottom plate 21a can be integrally formed only with the upper and lower molds, and the productivity of the impeller can be increased.

  The fan in this embodiment can be applied to all centrifugal fans such as a turbo type, a multi-blade type, and a radial type. As a device equipped with a fan, it can be applied mainly to products that require suction cooling (such as home appliances, PCs, OA devices, and in-vehicle devices).

  [Effects of the embodiment]

  As described above, the impeller in the present embodiment has no overlapping portion between the upper shroud and the lower shroud in plan view. For this reason, an impeller can be manufactured by integral molding by the upper and lower molds, and the productivity of the impeller is high.

  The upper part of the inner diameter portion of each blade contacts the apex of the upper shroud. The inner diameter portion of each blade descends downward from the position with a certain inclination (taper angle (γ)), and the lower portion of the inner diameter portion of each blade is in contact with the lower shroud. Thereby, since an inflow port diameter does not spread, a maximum static pressure does not fall.

  In addition, according to the present embodiment, it is possible to create an efficient blade shape along the air flow, which has the effect of leading to high flow rate, high static pressure, and low noise.

  [Other embodiments]

  11 is a perspective view of a centrifugal fan according to another embodiment, and FIG. 12 is a central longitudinal sectional view of the centrifugal fan of FIG.

  The centrifugal fan of FIG. 11 differs from the centrifugal fan of FIG. 1 in that the structure of the upper casing 5A is different. That is, a plurality of concave portions 54 are formed on the upper surface of the upper casing 5A, and ribs 52 are formed between the concave portions and the concave portions (portions where the concave portions 54 are not formed).

  A plurality of recesses 54 are formed so as to surround the periphery of the rotation shaft 11. The ribs 52 are formed radially about the rotation shaft 11. The number of the recesses 54 is 16, as shown in FIG. The number of ribs 52 is also sixteen. The number of the recesses 54 and the ribs 52 is not limited to this.

  As shown in FIG. 12, the upper surface of the upper shroud 23 (the surface facing the upper casing 5 </ b> A) has a portion (first portion) that approaches the lower casing 6 as it moves away from the rotating shaft 11. In this portion, the upper surface of the upper shroud 23 is a curved surface.

  The recess 54 is shallow at a portion close to the rotation shaft 11 and deep at a portion far from the rotation shaft 11, and the bottom surface of the recess 54 connecting both portions is a curved surface. The thickness of the portion sandwiched between the bottom surface of the recess 54 and the lower surface of the upper casing 5A on the back side (the surface facing the upper shroud 23) is kept constant. The lower surface portion (second portion) of the upper casing 5A in the portion where the thickness is kept constant has a curved surface that is substantially equal to (or equal to) the bottom surface shape of the recess 54. The surface in the first portion and the surface in the second portion are substantially equal (or equal) curved surfaces.

  With such a configuration, the centrifugal fan in the present embodiment has the following characteristics.

  (1) The lower surface of the case (upper casing 5 </ b> A) on the side where the suction port (suction port) 8 exists has a shape that approximates (or is equal to) the upper surface of the upper shroud 23. Thereby, it is suppressed that the air which came out from the discharge side of the impeller 3 flows backward in the direction of the suction inlet 8 through the space between the upper casing 5A and the upper shroud 23. Thereby, deterioration of fan characteristics is prevented.

  (2) If the lower surface of the upper casing 5A has the shape described in (1) above, the upper casing 5A becomes thick. By providing the recess 54, the upper casing 5A can be prevented from becoming thick (the amount of material used can be reduced). The recess 54 may be one donut-shaped recess centered on the rotating shaft 11, but by providing the rib 52 at every predetermined angle, the upper casing 5 </ b> A can have a certain rigidity.

  (3) As the impeller 3, any one of FIGS. 1 to 10 may be used (conventional ones may be used). Further, the shape of the blade 2 is also arbitrary.

  13 is a view showing the flow of wind between the upper shroud and the upper casing of the centrifugal fan shown in the section of FIG. 2, and FIG. 14 is an upper shroud of the centrifugal fan shown in the section of FIG. It is a figure which shows the flow of the wind between an upper casing.

  As shown in FIG. 13, when the surface of the upper casing 5 facing the impeller 3 is flat, a small chamber is formed between the impeller 3 and the upper casing 5, and the air blown out from the impeller 3 A part flows backward in the small chamber toward the suction port 8. Moreover, a part of the backflowed air swirls in the small chamber.

  On the other hand, as shown in FIG. 14, the upper casing 5A is provided with a recess 54, and the surface of the upper casing 5A facing the impeller 3 is provided with the same curvature shape as the upper shroud of the impeller 3. Thus, the backflow of air is suppressed (improved).

  FIG. 15 is a diagram showing the air volume and pressure characteristics of the centrifugal fan shown in the cross section of FIG. 2 and the centrifugal fan shown in the cross section of FIG.

  In the figure, the characteristics of the centrifugal fan shown in the cross section of FIG. 12 are indicated by the mark “present invention (backflow prevention case)”, and the characteristics of the centrifugal fan shown in the cross section of FIG. “Flat case)”. That is, a structure in which the lower portion of the upper casing 5 shown in FIG. 2 is flat is called a flat case, and a structure of the upper casing 5A shown in FIG. 12 is called a backflow prevention case.

  As shown in FIG. 15, the fan characteristics can be improved by adopting a structure that prevents the backflow of air.

  FIG. 16 is a diagram illustrating a cross-sectional structure of a centrifugal fan in a modified example, and FIG. 17 is a cross-sectional view of the centrifugal fan in the modified example.

  The centrifugal fan in this modification is formed by integrally forming flanges 56A and 56B for attaching the centrifugal fan to the upper casing 5A of the fan shown in FIGS. The flanges 56A and 56B are provided with screw holes, and it is easy to attach the fan to other parts by passing the screws through the screw holes. There may be one or more flanges, and the fan can be easily attached.

  The above-described embodiment is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  [Others]

  As devices become smaller, thinner, denser and more energy efficient, the market strongly demands higher static pressure and higher efficiency for the fan motors mounted on them. It is also important to reduce noise in the fan. In particular, the conventional centrifugal fan has a problem that both the level of discrete frequency noise (narrow band noise) and broadband noise is high, and the noise level when mounted on a device is high.

  Here, “discrete frequency noise” is noise that depends on the blade passing frequency, and is also called NZ noise. Discrete frequency noise is noise having a characteristic peak at a specific frequency in a narrow frequency band. The frequency is represented by the equation fnz = [rotational frequency: n] × [number of blades: z]. Since the discrete frequency noise is generated in the second order, the third order,... In addition to the first order component, it becomes a serious problem in actual listening. That is, there is a risk that noise is generated as clear sound when a centrifugal fan is mounted on a device. The cause of broadband noise is dominated by turbulent flow, and it is also required to reduce broadband noise in order to determine the total noise level.

  Furthermore, it is necessary to increase the productivity of the fan while realizing the above-mentioned demand.

  Further, the techniques described in Patent Documents 1 to 4 are directed to a scroll casing type fan, and an improvement is also desired for a fan having an open type casing.

  On the other hand, the centrifugal fan which can make the flow of air more suitable of the following structures can be provided.

That is, the centrifugal fan is a centrifugal fan that includes an upper casing in which an air suction port is formed, a lower casing, and an impeller positioned between the upper casing and the lower casing. An upper shroud located on the upper casing side and a plurality of blades arranged on the circumference provided below the upper shroud, and capable of rotating around a rotation axis. Constitutes an open casing, and the surface facing the upper casing of the upper shroud has a first portion that approaches the lower casing as it moves away from the rotation axis, and the surface facing the upper shroud of the upper shroud The second portion facing the first portion has a shape that approaches the lower casing as it moves away from the rotation axis, and the second portion of the upper casing The opposite surface of the plurality of recesses, a rib provided between each other a plurality of recesses are formed.
Preferably, a plurality of recesses are formed so as to surround the rotation axis, and the ribs are formed radially about the rotation axis.
Preferably, the thickness of the portion sandwiched between the bottom surface of the recess and the second portion of the upper casing on the back side of the bottom surface of the recess is constant.
Preferably, the lower casing has a portion protruding in a direction of the impeller in a portion where the upper shroud exists in a plan view, and the air sucked from the suction port is impeller by centrifugal force accompanying the rotation of the impeller. Blow out toward the outside of the diameter.
The centrifugal fan is a centrifugal fan including an upper casing in which an air suction port is formed, a lower casing, and an impeller located between the upper casing and the lower casing. An upper shroud located on the upper casing side and a plurality of blades arranged on the circumference provided below the upper shroud, and capable of rotating around a rotation axis. Constitutes an open casing, and the surface facing the upper casing of the upper shroud has a first portion that approaches the lower casing as it moves away from the rotation axis, and the surface facing the upper shroud of the upper shroud The second part that faces the first part has a shape that approaches the lower casing as it moves away from the rotation axis. In a portion where loud there has a portion that protrudes in the direction of the impeller, the air sucked from the suction port, blow out toward the outside of the diameter of the impeller by centrifugal force caused by the rotation of the impeller.

  Preferably, the impeller has a lower shroud provided below the plurality of blades, and an outer diameter of the lower shroud is equal to or smaller than an inner diameter of the upper shroud. And an inclined portion that connects the inner diameter portion of each.

  Preferably, the shape of the first portion of the surface facing the upper casing of the upper shroud is substantially equal to the shape of the second portion of the surface facing the upper shroud of the upper casing.

  Preferably, the upper casing has a flange portion for attaching the centrifugal fan.

  Preferably, the upper shroud and the blade are in contact with each other at a place where the upper shroud and the blade are present in a plan view.

  Preferably, each of the plurality of blades has a shape that decreases in thickness as it moves away from the rotation axis.

DESCRIPTION OF SYMBOLS 1 Centrifugal fan 2 Blade | blade 3 Impeller 4 Casing 5 Upper casing 5A Upper casing 6 Lower casing 6a Lower casing protrusion 7 Strut 8 Suction port 9 Air outlet 11 Rotating shaft 13 Fan motor 21 Lower shroud 21A Lower shroud inner diameter 21B Lower shroud Outer diameter 23 Upper shroud 23A Upper shroud inner diameter 23B Upper shroud outer diameter 52 Rib 54 Recess 56A, 56B Flange D1 Upper shroud inner diameter D2 Lower shroud outer diameter

Claims (10)

An upper casing formed with an air inlet;
A lower casing,
A centrifugal fan provided with an impeller positioned between the upper casing and the lower casing,
The impeller includes a plurality of blades arranged on a circumference, and the air sucked through the suction port by rotating around the rotation shaft is separated from the vicinity of the rotation shaft by the centrifugal force from the vicinity of the rotation shaft. Can be blown out towards
A rib for giving rigidity to the upper casing is formed on a portion of the upper casing opposite to the side where the impeller is disposed ,
A plurality of struts are provided at positions outside the diameter of the impeller,
The plurality of support columns are located between the upper casing and the lower casing, and maintain a distance between the upper casing and the lower casing,
The air blown out from the impeller passes between the plurality of struts,
The centrifugal fan is a centrifugal fan formed so as to be along a line connecting one of the plurality of support columns and the rotation shaft in a top view . The centrifugal fan according to claim 1 , wherein the rib is disposed at a position closer to the rotation shaft than the plurality of support columns. A portion of the upper casing opposite to the side on which the impeller is disposed is provided with a plurality of recesses that are recessed in the direction in which the impeller is disposed,
The centrifugal fan according to claim 1 or 2 , wherein the rib is provided between the plurality of recesses. The surface of the impeller that faces the upper casing has a first portion that approaches the lower casing as it moves away from the rotating shaft,
The surface of the upper casing that faces the impeller has a shape that approaches the lower casing as it moves away from the rotation shaft in the second portion that faces the first portion,
4. The centrifugal fan according to claim 3 , wherein the plurality of recesses are shallow at a portion close to the rotation shaft and deep at a portion far from the rotation shaft. An upper casing formed with an air inlet;
A lower casing,
A centrifugal fan provided with an impeller positioned between the upper casing and the lower casing,
The impeller includes a plurality of blades arranged on a circumference, and the air sucked through the suction port by rotating around the rotation shaft is separated from the vicinity of the rotation shaft by the centrifugal force from the vicinity of the rotation shaft. Can be blown out towards
A rib for giving rigidity to the upper casing is formed on a portion of the upper casing opposite to the side where the impeller is disposed ,
A portion of the upper casing opposite to the side on which the impeller is disposed is provided with a plurality of recesses that are recessed in the direction in which the impeller is disposed,
The rib is provided between the plurality of recesses.
The surface of the impeller that faces the upper casing has a first portion that approaches the lower casing as it moves away from the rotating shaft,
The surface of the upper casing that faces the impeller has a shape that approaches the lower casing as it moves away from the rotation shaft in the second portion that faces the first portion,
The centrifugal fan is shallow in a portion close to the rotation shaft and deep in a portion far from the rotation shaft . The centrifugal fan according to any one of claims 1 to 5, wherein the ribs are formed radially about the rotation axis. The centrifugal fan according to any one of claims 1 to 6, wherein the ribs are arranged at predetermined angles around the rotation axis. The centrifugal fan according to any one of claims 1 to 7 , wherein the rib is formed so as to surround the suction port and along an annular shape centering on the rotation axis when viewed from above. The ribs, when viewed from above, have a plurality of portions arranged in a ring around the rotation axis and forming a first row, and a plurality of portions arranged around the rotation axis on the outer periphery side of the first row and forming a second row and a site, centrifugal fan according to any one of claims 1 to 8. The rib is formed such that, when viewed from above, a plurality of portions arranged around the rotation shaft so as to surround the suction port form a plurality of rows having different distances from the rotation shaft. The centrifugal fan according to any one of 1 to 8 .