JP2021175892A - Centrifugal blower - Google Patents

Abstract

To provide a centrifugal blower which suppresses a pressure loss, and can improve fan efficiency.SOLUTION: A centrifugal blower comprises: a centrifugal fan 20 for blowing out air; and a casing 10 having a first cover part 11 for covering one side of a fan axial core CL in an axial core direction, a second cover part 12 for covering the other side, and a columnar support 13 for maintaining a clearance between the first cover part 11 and the second cover part 12. The first cover part 11 and the second cover part 12 form a ventilation path 15 between a first cover face 112 and a second cover face 123, and also form a blowout port 16 over an entire periphery of the casing 10. The columnar support 13 is arranged outside the fan axial core CL in a radial direction rather than the centrifugal fan 20 in the ventilation path 15. At least either of the first cover face 112 and the second cover face 123 has an inclination part 125 which gradually enlarges a size of the ventilation path 15 in the axial core direction, and is inclined to a peripheral direction at an airflow upstream side in the peripheral direction of the fan axial core CL rather than a region in which the columnar support 13 is arranged.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a centrifugal blower.

Conventionally, a centrifugal blower having a casing having an upper casing and a lower casing and an impeller rotatably housed between the upper casing and the lower casing and blowing air from substantially the entire circumference of the side surface of the casing is known. (See, for example, Patent Document 1). The upper casing and the lower casing are supported by a plurality of columns arranged radially outside the impeller from the impeller, and form a ventilation path between the upper casing and the lower casing. In the following description, the impeller is referred to as a centrifugal fan.

JP-A-2017-96224

By the way, in the centrifugal blower described in Patent Document 1, pressure loss occurs due to friction generated between the lower surface of the upper casing and the upper surface of the lower casing and the air when flowing through the ventilation path. Further, in the centrifugal blower described in Patent Document 1, the air blown from the centrifugal fan collides with the support column when flowing through the ventilation path, and a pressure loss occurs. These pressure losses cause deterioration of fan efficiency of the centrifugal blower.

Further, the pressure loss generated by friction and the pressure loss generated by the collision with the support column are the dynamic pressure which is the kinetic energy of the total of the dynamic pressure and the static pressure which are the total pressure which is the pressure component of the air flowing through the ventilation path. The larger the value, the larger the value. The larger the pressure loss, the worse the fan efficiency. Fan efficiency is the ratio of theoretical air power to the rotational driving force required to rotate a centrifugal fan. The driving force is the axial power that rotates the centrifugal fan. The theoretical air power is a value corresponding to the amount of work output by the centrifugal blower.

It is an object of the present disclosure to provide a centrifugal blower capable of suppressing pressure loss and improving fan efficiency.

The invention according to claim 1
It ’s a centrifugal blower,
A centrifugal fan (20) that blows air by rotating around the fan axis (CL), and
A casing (10) for accommodating a centrifugal fan is provided.
The casing is
An air intake port (111) through which air sucked by the centrifugal fan passes is formed, and a first cover portion (11) that covers one side of the centrifugal fan in the axial direction of the fan axis and a first cover portion (11).
A second cover portion (12) that covers the other side of the centrifugal fan in the axial direction, and
It has at least one support column (13) that maintains a gap between the first cover portion and the second cover portion, and has.
The first cover portion and the second cover portion are a portion of the first cover surface (112) of the first cover portion facing the second cover portion, which projects outward from the centrifugal fan in the radial direction of the fan axis, and a second cover portion. A ventilation path (15) through which air blown out by the centrifugal fan flows is formed in a gap between the second cover surface (123) of the cover portion facing the first cover portion and a portion protruding outward in the radial direction from the centrifugal fan. At the same time, the outer edge portion of the first cover surface and the outer edge portion of the second cover surface form an outlet (16) for blowing out the air blown out by the centrifugal fan over the entire circumference of the casing.
The stanchions are provided on the outside of the centrifugal fan in the radial direction in the ventilation path.
At least one of the first cover surface and the second cover surface faces the upstream side of the air flow in the circumferential direction of the fan axis from the portion where the support column is provided, and from the upstream side to the downstream side of the air flow in the circumferential direction. It has inclined portions (115, 125) that gradually increase the size of the ventilation path in the axial direction.
The inclined portion is inclined with respect to the circumferential direction.

According to this, the inclined portion can increase the cross-sectional area of the surface orthogonal to the circumferential direction of the portion where the air flows in the circumferential direction toward the support column in the ventilation path toward the downstream side of the air flow. Then, when the air flows through the ventilation path toward the support column, the dynamic pressure of the air generated due to the expansion of the cross-sectional area of the ventilation path is converted into the static pressure. Can be made smaller. Therefore, it is possible to suppress the pressure loss caused by the friction between the first cover surface and the second cover surface and the collision with the support column when flowing through the ventilation path, and improve the fan efficiency of the centrifugal blower.

The reference reference numerals in parentheses attached to each component or the like indicate an example of the correspondence between the component or the like and the specific component or the like described in the embodiment described later.

It is an exploded perspective view of the centrifugal blower which concerns on one Embodiment. It is a perspective view of the centrifugal blower which concerns on one Embodiment. It is a side view of the centrifugal blower which concerns on one Embodiment. FIG. 2 is a sectional view taken along line IV-IV of FIG. FIG. 2 is a sectional view taken along line VV of FIG. It is a partially enlarged perspective view which showed the vicinity of the 2nd inclined part and the 2nd extended part formed in the 2nd cover part of a centrifugal blower. It is a figure which shows the relationship between the flow coefficient and the pressure coefficient of the centrifugal blower of one Embodiment and the centrifugal blower of a comparative example. It is a figure which shows the relationship between the flow coefficient and the fan efficiency of the centrifugal blower of one Embodiment and the centrifugal blower of a comparative example. It is a schematic diagram which showed the flow direction and reaching distance of the air blown out from the centrifugal blower of a comparative example by an arrow. It is a schematic diagram which showed the flow direction and reach distance of the air blown out from the centrifugal blower which concerns on one Embodiment by an arrow. It is an exploded perspective view of the centrifugal blower which concerns on another embodiment. It is a perspective view of the centrifugal blower which concerns on another embodiment.

An embodiment of the present disclosure will be described with reference to FIGS. 1 to 10. As shown in FIG. 1, the centrifugal blower 1 includes a casing 10 which is a housing of the centrifugal blower 1, a centrifugal fan 20 that blows air by rotating around a fan axis CL, and an electric motor that rotates the centrifugal fan 20. It includes a motor 30. In the present embodiment, the direction along the fan axis CL is orthogonal to the axis direction DRa and the axis direction DRa, and the direction extending radially from the fan axis CL is the radial direction DRr and the rotation direction of the centrifugal fan 20. The various configurations of the centrifugal blower 1 and the like will be described with reference to the circumferential DRc.

The casing 10 is made of resin and houses the centrifugal fan 20 and the electric motor 30. The casing 10 includes a first cover portion 11 that covers one side of the centrifugal fan 20 in the axial direction DRa, a second cover portion 12 that covers the other side of the centrifugal fan 20 in the axial DRa, a first cover portion 11, and the first cover portion 11. It has four columns 13 for maintaining a gap in the second cover portion 12. In the casing 10, the first cover portion 11 and the second cover portion 12 are connected by screws 14.

As shown in FIGS. 2 and 3, the first cover portion 11 has a substantially disk shape, and the outer diameter of the first cover portion 11 is formed to be larger than the outer diameter of the centrifugal fan 20. Further, in the first cover portion 11, each portion where the support column 13 is provided projects outward in the radial direction of the DRr.

An air intake port 111 that penetrates the first cover portion 11 in the axial direction DRa is formed at substantially the center of the first cover portion 11. The air intake port 111 is formed, for example, in a circular shape. The diameter of the air intake port 111 is set to be smaller than the outer diameter of the centrifugal fan 20. Further, on the other side of the axial direction DRa of the first cover portion 11, a first cover surface 112 covering one side of the centrifugal fan 20 in the axial direction DRa is provided.

The first cover surface 112 has a substantially annular shape, and the outer diameter of the first cover surface 112 is formed to be larger than the outer diameter of the centrifugal fan 20. On the first cover surface 112, a portion inside the DRr in the radial direction of the centrifugal fan 20 covers a part of the centrifugal fan 20. Further, on the first cover surface 112, a portion projecting outward from the centrifugal fan 20 in the radial direction DRr faces the second cover portion 12. Of the first cover surface 112, the portion protruding outward from the centrifugal fan 20 in the radial direction is the ventilation described later in which the air blown from the centrifugal fan 20 flows between the first cover portion 11 and the second cover portion 12. The road 15 is formed.

On the first cover surface 112, as shown in FIGS. 3 and 4, four support column forming portions 114 provided with support columns 13 are provided along the circumferential direction DRc at a portion protruding outward from the centrifugal fan 20 in the radial direction DRr. They are provided side by side at predetermined intervals. The first cover surface 112 has a first inclined portion 115 described later and a first expansion portion 116 described later between each of the four support column forming portions 114 arranged in the circumferential direction DRc. Further, the first cover surface 112 has an outer edge portion 117 forming an outlet 16 described later for blowing air to the outside of the casing 10 on the outer edge of the DRr in the radial direction. Hereinafter, the outer edge portion 117 of the first cover surface 112 will be referred to as the first outer edge portion 117.

Each of the support column forming portions 114 is formed in a portion of the first cover surface 112 that projects outward from the centrifugal fan 20 in the radial direction of the DRr. The strut forming portion 114 is formed in a planar shape extending along the radial DRr. A support column 13 is provided in each of the four support column forming portions 114.

Each of the four columns 13 projects from the first cover surface 112 toward the second cover portion 12 along the axial direction DRa. The support column 13 has a cylindrical shape having a central axis parallel to the axial direction DRa. The four columns 13 are arranged side by side on the first cover surface 112 with a uniform pitch in the circumferential direction DRc around the fan axis CL. Specifically, the four columns 13 are provided on the first cover surface 112 at a pitch of 90 ° with the fan axis CL as the center. Further, inside each of the columns 13, a screw hole (not shown) through which a screw 14 for connecting the first cover portion 11 and the second cover portion 12 is inserted is formed.

As shown in FIG. 1, the second cover portion 12 has a substantially disk shape paired with the first cover portion 11, and the outer diameter of the second cover portion 12 is substantially the same as the outer diameter of the first cover portion 11. It is formed in size. That is, the outer diameter of the second cover portion 12 is larger than the outer diameter of the centrifugal fan 20. The second cover portion 12 has a motor accommodating portion 121, a through hole 122 into which the screw 14 is inserted, and a second cover surface 123 facing the first cover surface 112. In the second cover portion 12, the portion where the through hole 122 is formed protrudes outward in the radial direction DRr.

The motor accommodating portion 121 is formed so as to be recessed toward the other side in the axial direction DRa, and accommodates the electric motor 30. Through holes 122 are formed in each of the portions facing the four columns 13. A screw 14 to be inserted into the screw hole of the support column 13 is inserted into the through hole 122.

As shown in FIGS. 2 and 3, the second cover surface 123 has an outer diameter substantially the same as that of the first cover surface 112, and the outer diameter of the second cover surface 123 is the outer diameter of the centrifugal fan 20. It is formed larger. The portion of the second cover surface 123 protruding outward from the centrifugal fan 20 in the radial direction faces the portion of the first cover surface 112 protruding outward from the centrifugal fan 20 in the radial direction. The portion of the second cover surface 123 facing the first cover surface 112 forms a ventilation passage 15 described later by pairing with the first cover surface 112.

On the second cover surface 123, hole forming portions 124 provided with through holes 122 are provided side by side in the circumferential direction DRc at portions facing each of the four strut forming portions 114. Each of the four hole forming portions 124 extends along the radial DRr and is formed so as to be parallel to the facing column forming portions 114.

Further, the second cover surface 123 has a second inclined portion 125 described later and a second expansion portion 126 described later between each of the four hole forming portions 124 arranged in the circumferential direction DRc. Further, the second cover surface 123 has an outer edge portion 127 forming an outlet 16 described later on the outer edge of the DRr in the radial direction. Hereinafter, the outer edge portion 127 of the second cover surface 123 will be referred to as a second outer edge portion 127.

In the present embodiment, the support column forming portion 114 and the hole forming portion 124 correspond to the seating surface that supports the support column 13. Further, the first inclined portion 115 and the second inclined portion 125 correspond to the inclined portions in which the size of the ventilation passage 15 in the axial direction DRa is gradually increased from the upstream side to the downstream side of the air flow in the circumferential direction DRc. .. The first expansion portion 116 and the second expansion portion 126 correspond to expansion portions that gradually increase the size of the ventilation passage 15 in the axial direction DRa from the inside to the outside of the radial DRr. Details of the shapes of the first inclined portion 115, the second inclined portion 125, the first extended portion 116, and the second extended portion 126 will be described later.

The ventilation passage 15 is formed by a gap between the first cover surface 112 and the second cover surface 123. Specifically, the ventilation passage 15 is formed by a gap between a portion of the first cover surface 112 that projects outward from the centrifugal fan 20 in the radial direction and a portion of the second cover surface 123 that projects outward from the centrifugal fan 20 in the radial direction. It is formed. The ventilation passage 15 is provided with four columns 13.

The air outlet 16 is formed by the first outer edge portion 117 and the second outer edge portion 127 over the entire circumference of the side surface of the casing 10.

Here, each of the four columns 13 is provided in the ventilation passage 15 outside the radial DRr from the centrifugal fan 20 and inside the radial DRr from the outlet 16. Therefore, on the downstream side of the air flow at the portion of the outlet 16 where the four columns 13 are provided, the blowing of air from the casing 10 is hindered by the four columns 13. Therefore, the fact that the air outlet 16 is formed over the entire circumference of the side surface of the casing 10 in the present embodiment includes the fact that the air outlet 16 is formed over substantially the entire circumference of the side surface of the casing 10. Meaning.

The electric motor 30 is composed of an outer rotor type brushless DC motor. The electric motor 30 is connected to the centrifugal fan 20 and rotates the centrifugal fan 20 by being energized from a power source (not shown).

The centrifugal fan 20 is made of resin and is a centrifugal multi-blade fan, that is, an impeller of a centrifugal blower. As shown in FIGS. 1, 4, and 5, the centrifugal fan 20 includes a plurality of blades 21 arranged around the fan axis CL, an annular side plate 22, a substantially conical main plate 23, and air. It is equipped with a fan outlet 24 that blows out air. In the centrifugal fan 20 of the present embodiment, each of the blades 21 is curved so as to move from the inside to the outside of the radial DRr from a straight line along the radial DRr in the direction opposite to the rotation direction of the centrifugal fan 20. It is configured as a turbofan to be formed. The electric motor 30 is omitted in FIGS. 4 and 5.

The centrifugal fan 20 sucks air from one side of the axial DRa by rotating around the fan axis CL, and transfers the velocity component of the radial DRr and the velocity component of the circumferential DRc to the outer peripheral side of the centrifugal fan 20. Blow out the air you have. The air blown out from the centrifugal fan 20 flows through the ventilation passage 15 in the rotational direction of the centrifugal fan 20 in the circumferential DRc and in the direction away from the centrifugal fan 20. Hereinafter, among the circumferential DRc, the direction in which the air flows, which is the direction in which the centrifugal fan 20 rotates, is referred to as a forward rotation direction DRc1, and the direction opposite to the normal rotation direction DRc1 is referred to as a reverse rotation direction DRc2.

Each of the plurality of blades 21 is arranged radially around the fan axis CL, and is formed so that air flowing in from one side of the axial direction DRa flows between the respective blades 21. An air flow hole 221 is formed on the inner peripheral side of the side plate 22 to allow the air flowing in from the air suction port 111 to flow in. One end of each of the plurality of blades 21 in the axial direction DRa is joined to the side plate 22. The other end of each of the plurality of blades 21 in the axial direction DRa is joined to the main plate 23. That is, the side plate 22 and the main plate 23 are connected via each of the plurality of blades 21. An electric motor 30 is connected to the main plate 23.

Further, each outer edge portion of the side plate 22 and the main plate 23 forms a fan outlet 24 that blows out the air that has flowed in between the plurality of blades 21. Here, the innermost portion in the radial DRr of the portion forming the ventilation passage 15 on the first cover surface 112 is the first inner edge portion 118, and the portion in the radial DRr of the portion forming the ventilation passage 15 on the second cover surface 123. The innermost part is referred to as the second inner edge portion 128. As shown in FIG. 5, the size h of the fan outlet 24 in the axial direction DRa is set to be substantially the same as the distance d1 between the first inner edge portion 118 and the second inner edge portion 128.

Subsequently, the first inclined portion 115, the first extended portion 116, the second inclined portion 125, and the second extended portion 126 will be described with reference to FIGS. 3, 4, and 6. The first inclined portion 115 is provided between each of the four support column forming portions 114, and faces the second inclined portion 125. The first expansion portion 116 is provided between each of the four support column forming portions 114 and faces the second expansion portion 126. Further, the second inclined portion 125 and the second expansion portion 126 are provided between each of the four hole forming portions 124. In other words, the first inclined portion 115, the first extended portion 116, the second inclined portion 125, and the second extended portion 126 are provided between the portions where the four columns 13 are provided. The first inclined portion 115 and the second inclined portion 125 are inclined with respect to the circumferential DRc. As shown in FIG. 4, the first expansion portion 116 and the second expansion portion 126 are inclined with respect to the radial DRr.

Here, the four first inclined portions 115 and the four second inclined portions 125 have the same basic structure. Further, the four first expansion portions 116 and the four second expansion portions 126 have the same basic structure.

Therefore, in the present embodiment, of the four second inclined portions 125, the second inclined portion 125a provided between the hole forming portion 124a and the hole forming portion 124b adjacent to each other and the four first inclined portions 125a. Of the 115, the details of the first inclined portion 115a facing the second inclined portion 125a will be described. Then, detailed description of the second inclined portion 125 other than the second inclined portion 125a and the first inclined portion 115 other than the first inclined portion 115a will be omitted.

Further, in the present embodiment, of the four second expansion portions 126, the second expansion portion 126a provided between the hole forming portion 124a and the hole forming portion 124b adjacent to each other and the four first expansion portions 116 Of these, details of the first expansion unit 116a facing the second expansion unit 126a will be described. Then, detailed description of the second expansion unit 126 other than the second expansion unit 126a and the first expansion unit 116 other than the first expansion unit 116a will be omitted.

As shown in FIG. 3, the hole forming portion 124a is provided on the DRc2 side in the reverse direction with respect to the hole forming portion 124b. Further, the first inclined portion 115a and the first expansion portion 116a are provided between the strut forming portion 114a facing the hole forming portion 124a and the strut forming portion 114b facing the hole forming portion 124b. Further, the support column 13a is provided in the support column forming portion 114a. The strut forming portion 114b is provided with a strut 13b provided on the DRc1 side in the forward rotation direction with respect to the strut 13a.

As shown in FIG. 6, the second inclined portion 125a is formed within a predetermined range between the hole forming portion 124a and the hole forming portion 124b. The second inclined portion 125a is inclined so that the size of the ventilation passage 15 in the axial direction DRa gradually increases from the reverse direction DRc2 side toward the forward rotation direction DRc1 side. The second inclined portion 125a is inclined to the other side in the axial direction DRa.

Here, a plane that passes through the center of the support column forming portion 114a and the hole forming portion 124a in the axial direction DRa and is parallel to the support column forming portion 114a and the hole forming portion 124a is defined as a virtual center surface. The distance of the second inclined portion 125a from the virtual center surface in the axial direction DRa increases continuously as the hole forming portion 124a approaches the hole forming portion 124b.

In other words, in the ventilation passage 15, between the columns 13a and 13b, the cross-sectional area of the surface orthogonal to the circumferential DRc becomes continuously larger toward the downstream side of the air flow in the circumferential direction DRc. The inclined portion 125a is inclined with respect to the circumferential DRc.

The end of the second inclined portion 125a on the DRc2 side in the reversing direction is connected to the hole forming portion 124a. Further, the end portion of the second inclined portion 125a on the DRc1 side in the normal rotation direction is connected to the hole forming portion 124b.

In the present embodiment, the second inclined portion 125a is formed in a range from the hole forming portion 124a to the hole forming portion 124b. In other words, the second inclined portion 125a is formed in a range from immediately after the air flow downstream side from the portion where the support column 13a is provided to immediately before the air flow upstream side from the portion where the support column 13b is provided.

The second inclined portion 125a has a portion connected to the hole forming portion 124a, that is, an end portion on the DRc2 side in the reversing direction is formed in the entire range from the second inner edge portion 128 to the second outer edge portion 127. Further, in the second inclined portion 125a, approximately half of the portion on the reverse direction DRc2 side in the range from the hole forming portion 124a to the hole forming portion 124b is formed in the entire range from the second inner edge portion 128 to the second outer edge portion 127. Has been done. In the second inclined portion 125a, approximately half of the portion on the normal rotation direction DRc1 side in the range from the hole forming portion 124a to the hole forming portion 124b is smaller than the range from the second inner edge portion 128 to the second outer edge portion 127. It is formed in the range.

Specifically, approximately half of the second inclined portion 125a on the normal rotation direction DRc1 side has an inner end portion in the radial direction DRr separated from the second inner edge portion 128, and the forward rotation direction DRc1 is separated from the reverse rotation direction DRc2 side. The magnitude of the radial DRr decreases continuously toward the side. Approximately half of the portion of the second inclined portion 125a on the normal rotation direction DRc1 side is the inner end portion and the second inner edge of the second inclined portion 125a in the radial direction DRr according to the direction from the reverse rotation direction DRc2 side to the forward rotation direction DRc1 side. The distance to the part 128 is continuously increasing. In the second inclined portion 125a, the second expanding portion 126a is connected to a portion of the inner end portion in the radial DRr that is separated from the second inner edge portion 128.

The second expansion portion 126a is inclined so that the size of the ventilation passage 15 in the axial direction DRa gradually increases as the second inner edge portion 128 approaches the second outer edge portion 127. The second expansion portion 126a is inclined to the other side in the axial direction DRa. That is, the second expansion portion 126a continuously increases as the distance from the virtual center plane in the axial direction DRa approaches the second inner edge portion 128 to the second outer edge portion 127.

In other words, the second expansion is such that the cross-sectional area of the surface of the ventilation path 15 orthogonal to the radial DRr increases continuously as it approaches the air outlet 16 from the innermost portion of the radial DRr of the ventilation path 15. The portion 126a is inclined with respect to the radial DRr. In the second expansion portion 126a, the inner end portion in the radial DRr is connected to the second inner edge portion 128, and the outer end portion in the radial DRr is connected to the second inclined portion 125a.

Further, the second expansion portion 126a is formed in a range substantially half of the range from the hole forming portion 124a to the hole forming portion 124b on the DRc1 side in the normal rotation direction. In the second expansion portion 126a, the distance between the outer end portion and the second inner edge portion 128 in the radial direction DRr is continuously increased from the inversion direction DRc2 side toward the forward rotation direction DRc1 side. That is, in the second expansion portion 126a, the size of the radial DRr is continuously increased from the inversion direction DRc2 side toward the forward rotation direction DRc1 side.

The end of the second expansion portion 126a on the DRc1 side in the normal rotation direction is connected to the hole forming portion 124b. In the second expansion portion 126a, a portion connected to the hole forming portion 124b, that is, an end portion on the DRc1 side in the normal rotation direction is formed in the entire range from the second inner edge portion 128 to the second outer edge portion 127.

The end portion of the second expansion portion 126a on the reverse rotation direction DRc2 side is on the normal rotation direction DRc1 side from the end portion of the second inclined portion 125a on the reverse rotation direction DRc2 side, and is on the forward rotation direction DRc1 side of the second inclined portion 125a. It is provided on the DRc2 side in the reverse direction from the end. In the range from the hole forming portion 124a to the hole forming portion 124b, the range in which the second inclined portion 125a is provided is larger than the range in which the second expanding portion 126a is provided.

The second inclined portion 125a has a configuration symmetrical with that of the first inclined portion 115a with reference to the virtual center surface. The second expansion portion 126a has a configuration symmetrical with that of the first expansion portion 116a with reference to the virtual center plane.

That is, the first inclined portion 115a is formed in a range from the strut forming portion 114a to the strut forming portion 114b. Further, the first inclined portion 115a is inclined to one side of the axial direction DRa so that the size of the ventilation passage 15 in the axial direction DRa gradually increases as the support column forming portion 114a approaches the support column forming portion 114. doing. In other words, in the ventilation passage 15, between the columns 13a and 13b, the cross-sectional area of the surface orthogonal to the circumferential DRc becomes continuously larger toward the downstream side of the air flow in the circumferential direction DRc. The inclined portion 115a is inclined with respect to the circumferential DRc.

The first expansion portion 116a is connected to the first inclined portion 115a, and is formed in a range substantially half of the range from the strut forming portion 114a to the strut forming portion 114b on the DRc1 side in the normal rotation direction. Further, the first expansion portion 116a is arranged in the axial direction DRa so that the size of the ventilation path 15 in the axial direction DRa gradually increases as the first inner edge portion 118 approaches the first outer edge portion 117. It is tilted to the side. In other words, the first expansion is such that the cross-sectional area of the surface of the ventilation passage 15 orthogonal to the radial DRr increases continuously as it approaches the air outlet 16 from the innermost portion of the radial DRr of the ventilation passage 15. The portion 116a is inclined with respect to the radial DRr.

As a result, in the flow path between the first inclined portion 115a and the second inclined portion 125a of the ventilation passage 15, the size of the axial DRa becomes larger toward the downstream side of the air flow in the circumferential direction DRc. For example, as shown in FIG. 4, the size d2 in the axial direction DRa of the portion where the first inclined portion 115a and the second inclined portion 125a are formed in the air outlet 16 is the largest in the radial DRr of the ventilation path 15. It is larger than the size d1 of the axial direction DRa of the inner part.

The cross-sectional area of the surface of the ventilation passage 15 perpendicular to the circumferential direction DRc of the flow path between the first inclined portion 115a and the second inclined portion 125a becomes larger toward the downstream side of the air flow in the circumferential direction DRc. In other words, the ventilation passage 15 between the support columns 13a and the support column 13b has a larger cross-sectional area of the surface orthogonal to the circumferential DRc as the support column 13a approaches the support column 13b.

Further, in the flow path between the first expansion portion 116a and the second expansion portion 126a of the ventilation passage 15, the size of the axial DRa becomes larger toward the downstream side of the air flow in the radial DRr. For example, as shown in FIG. 4, the size d2 in the axial direction DRa of the portion where the first expansion portion 116a and the second expansion portion 126a are formed in the air outlet 16 is the largest in the radial DRr of the ventilation path 15. It is larger than the size d1 of the axial direction DRa of the inner part.

The cross-sectional area of the surface of the ventilation passage 15 perpendicular to the radial DRr of the flow path between the first expansion portion 116a and the second expansion portion 126a becomes larger toward the downstream side of the air flow in the radial DRr. In other words, the ventilation passage 15 between the support columns 13a and the support column 13b has a large cross-sectional area of the surface orthogonal to the radial DRr as it approaches the air outlet 16 from the innermost portion of the radial DRr of the ventilation path 15. Become.

Next, the operation of the centrifugal blower 1 of the present embodiment will be described. In the centrifugal blower 1 of the present embodiment, when the electric motor 30 is driven, the centrifugal fan 20 rotates. As a result, the air flowing in from the air intake port 111 is sucked in from the air flow hole 221 and dynamic pressure, which is kinetic energy, is applied from the plurality of rotating blades 21 and blown out from the fan outlet 24. The air blown out from the fan outlet 24 circulates in the ventilation path 15 in the direction away from the forward rotation direction DRc1 and the centrifugal fan 20. Further, the air flowing through the ventilation passage 15 collides with the support column 13, so that the flow of the support column 13 on the downstream side of the air flow is suppressed. Therefore, the centrifugal blower 1 passes the air blown from the fan outlet 24 between each of the four columns 13 and blows it out from the outlet 16.

By the way, in the air immediately after being blown out from the fan outlet 24, almost all of the total pressure, which is a pressure component, is occupied by the dynamic pressure. However, the air blown out from the fan outlet 24 causes a pressure loss due to the friction generated between the first cover surface 112 and the second cover surface 123 when flowing through the ventilation passage 15. Further, the air blown out from the fan outlet 24 causes a pressure loss by colliding with the support column 13 when flowing through the ventilation passage 15. As a result, a part of the dynamic pressure of the air flowing through the ventilation passage 15 is converted into a static pressure.

The pressure loss generated when flowing through the ventilation passage 15 causes deterioration of the fan efficiency of the centrifugal blower 1. Further, the pressure loss increases as the dynamic pressure of the total pressure of the air flowing through the ventilation passage 15 increases. The larger the pressure loss, the worse the fan efficiency.

Since the centrifugal blower 1 suppresses the power required to rotate the electric motor 30, it is desired to improve the fan efficiency. Therefore, it is desirable that the pressure loss generated when flowing through the ventilation passage 15 is small. Hereinafter, the pressure loss during operation of the centrifugal blower 1 in the present embodiment will be described in comparison with the pressure loss during operation of the centrifugal blower of the comparative example. Hereinafter, the centrifugal blower of the comparative example will be referred to as a comparative centrifugal blower. Further, the flow path corresponding to the ventilation passage 15 in the comparison centrifugal blower is referred to as a comparison ventilation passage, and the air outlet corresponding to the outlet 16 is referred to as a comparison outlet.

The comparative centrifugal blower is not provided with the first inclined portion 115, the second inclined portion 125, the first expansion portion 116, and the second expansion portion 126. That is, the comparative centrifugal blower has a configuration in which the cross-sectional area of the surface orthogonal to the circumferential DRc and the cross-sectional area of the surface orthogonal to the radial DRr of the comparative ventilation passage do not change toward the downstream side of the air flow. Other configurations of the centrifugal blower for comparison are the same as those of the centrifugal blower 1 of the present embodiment.

On the other hand, in the ventilation passage 15 of the present embodiment, the first inclined portion 115 and the second inclined portion 125 allow the air flow upstream side column 13 to the downstream side column 13 between two adjacent columns 13. The cross-sectional area of the plane orthogonal to the circumferential DRc increases as it approaches. As a result, the air flowing through the ventilation passage 15 is converted from dynamic pressure to static pressure due to the expansion of the cross-sectional area of the surface orthogonal to the circumferential DRc of the ventilation passage 15 when flowing through the ventilation passage 15 in the circumferential direction DRc. Occurs. Therefore, the ratio of the dynamic pressure to the total pressure gradually decreases as the air flowing between the two adjacent columns 13 approaches the column 13 on the downstream side from the column 13 on the upstream side of the air flow. On the contrary, the ratio of static pressure gradually increases.

Further, the ventilation passage 15 is cut off by the first expansion portion 116 and the second inclined portion 125 in a plane orthogonal to the radial DRr as it approaches the air outlet 16 from the innermost portion in the radial DRr of the ventilation passage 15. The area is getting bigger. As a result, the air flowing through the ventilation passage 15 is converted from dynamic pressure to static pressure due to the expansion of the cross-sectional area of the surface orthogonal to the radial DRr of the ventilation passage 15 when flowing through the ventilation passage 15 in the radial direction DRr. Occurs. Therefore, as the air flowing through the ventilation passage 15 toward the outlet 16 approaches the outlet 16 from the innermost portion of the radial DRr of the ventilation passage 15, the ratio of the dynamic pressure to the total pressure gradually increases. On the contrary, the ratio of static pressure gradually increases.

Further, in the comparative centrifugal blower, since the cross-sectional area of the comparative ventilator does not change, the conversion from the dynamic pressure to the static pressure does not occur due to the expansion of the cross-sectional area of the comparative ventilator.

Therefore, the dynamic pressure of the air flowing through the ventilation passage 15 of the present embodiment is smaller than that of the air flowing through the comparison ventilation passage. As a result, the friction generated between the first cover surface 112 and the second cover surface 123 when flowing through the ventilation passage 15 of the present embodiment and the pressure loss generated by the collision with the support column 13 flow through the ventilation passage for comparison. It is smaller than the pressure loss that occurs at the time.

Here, the difference between the pressure coefficient with respect to the flow coefficient of the centrifugal blower 1 of the present embodiment and the pressure coefficient with respect to the flow coefficient of the comparative centrifugal blower will be described with reference to FIG. 7. In each line of FIG. 7, the solid line shows the pressure coefficient with respect to the flow coefficient of the centrifugal blower 1 of the present embodiment, and the broken line shows the pressure coefficient with respect to the flow coefficient of the comparative centrifugal blower. The alternate long and short dash line shows the resistance curve of the centrifugal blower 1 of the present embodiment, and the alternate long and short dash line shows the resistance curve of the comparative centrifugal blower. Further, the intersection of the solid line and the alternate long and short dash line indicates the operating point of the centrifugal blower 1 of the present embodiment, and the intersection of the broken line and the alternate long and short dash line indicates the operating point of the comparative centrifugal blower.

In the present embodiment, the dynamic pressure is converted to the static pressure as the cross-sectional area of the ventilation passage 15 is expanded, so that the pressure coefficient with respect to the flow coefficient of the centrifugal blower 1 of the present embodiment is calculated as shown in FIG. It can be greater than or equal to the pressure coefficient relative to the flow coefficient of the comparative centrifugal blower. That is, in the centrifugal blower 1 of the present embodiment, the pressure coefficient at the same flow coefficient as that of the comparative centrifugal blower can be made equal to or higher than the pressure coefficient of the comparative centrifugal blower. This means that the centrifugal blower 1 of the present embodiment can secure a desired operating point, that is, the air volume and pressure of the air blown out from the outlet 16, at a rotation speed lower than that of the comparative centrifugal blower.

Further, the difference between the fan efficiency with respect to the flow coefficient of the centrifugal blower 1 of the present embodiment and the fan efficiency with respect to the flow coefficient of the comparative centrifugal blower will be described with reference to FIG. In each line of FIG. 8, the solid line shows the fan efficiency with respect to the flow coefficient of the centrifugal blower 1 of the present embodiment, and the broken line shows the fan efficiency with respect to the flow coefficient of the centrifugal blower for comparison. Further, the intersection of the solid line and the alternate long and short dash line indicates the fan efficiency of the centrifugal blower 1 of the present embodiment, and the intersection of the broken line and the alternate long and short dash line indicates the fan efficiency of the comparative centrifugal blower.

As shown in FIG. 8, the fan efficiency with respect to the flow coefficient of the centrifugal blower 1 of the present embodiment can be improved more than the fan efficiency with respect to the flow coefficient of the comparative centrifugal blower in the total flow coefficient range shown in FIG. That is, even when the flow coefficients of the centrifugal blower 1 of the present embodiment and the comparative centrifugal blower are changed by changing the air suction amount, the centrifugal blower 1 of the present embodiment is a centrifugal blower for comparison. It can operate with higher efficiency than the fan efficiency of the blower.

By the way, in the centrifugal blower 1 and the comparative centrifugal blower of the present embodiment, a pressure loss occurs even when the air is blown out due to the shearing force of the air. The pressure loss when blowing out air causes a short reach of the air blown out by the centrifugal blower 1 and the comparative centrifugal blower of the present embodiment. Further, the smaller the dynamic pressure of the total pressure of air, the smaller the shearing force of air. Therefore, the centrifugal blower 1 can blow out air far enough to suppress the dynamic pressure of the air blown out from the air outlet 16.

Here, the difference between the reach of the air blown from the centrifugal blower 1 of the present embodiment and the reach of the air blown from the comparative centrifugal blower will be described with reference to FIGS. 9 and 10. The arrows shown in FIGS. 9 and 10 indicate the flow of air blown from each of the air outlet 16 and the comparative air outlet.

As described above, in the air flowing through the ventilation passage 15 of the present embodiment, conversion from dynamic pressure to static pressure occurs with the expansion of the cross-sectional area of the ventilation passage 15. Therefore, the dynamic pressure of the air at the outlet 16 of the present embodiment is smaller than the dynamic pressure of the air at the comparative outlet.

Therefore, the air blown out from the air outlet 16 of the present embodiment has a smaller shearing force than the air blown out from the comparative air outlet. As a result, the centrifugal blower 1 of the present embodiment can blow air farther than the comparative centrifugal blower. Specifically, as shown in the comparison of FIGS. 9 and 10, the reach of the air blown from each of the four columns 13 by the centrifugal blower 1 of the present embodiment is the reach of the air blown by the comparative centrifugal blower. It becomes large compared to the distance.

According to the centrifugal blower 1 described above, the first inclined portion 115 and the second inclined portion 125 allow the air flow upstream side column 13 to the downstream side column 13 in the ventilation passage 15 between the two adjacent columns 13. The cross-sectional area of the plane orthogonal to the circumferential DRc can be increased as it approaches. Further, the ventilation passage 15 is orthogonal to the radial DRr of the ventilation passage 15 as it approaches the air outlet 16 from the innermost portion in the radial DRr of the ventilation passage 15 by the first expansion portion 116 and the second inclined portion 125. The cross-sectional area of the surface to be used can be increased.

Therefore, the air flowing through the ventilation passage 15 undergoes conversion from dynamic pressure to static pressure as the cross-sectional area of the ventilation passage 15 expands. As a result, the dynamic pressure of the total air pressure can be reduced as the air flowing through the ventilation passage 15 flows toward the downstream side of the air flow in the circumferential DRc and the downstream side of the air flow in the radial DRr.

Therefore, the friction generated between the first cover surface 112 and the second cover surface 123 when flowing through the ventilation passage 15 and the pressure loss caused by the collision with the support column 13 can be suppressed, so that the fan efficiency of the centrifugal blower 1 is improved. Can be made to.

Further, by reducing the dynamic pressure of the total pressure of the air flowing through the ventilation passage 15, the shearing force of the air flowing through the ventilation passage 15 can be suppressed. Therefore, when the air is blown out from the air outlet 16, the pressure loss due to the shearing force of the air can be suppressed, so that the reach of the air blown out from the air outlet 16 can be increased.

Further, the first expansion portion 116 and the second expansion portion 126 can continuously expand the cross-sectional area of the surface of the ventilation path 15 orthogonal to the radial DRr from the inside to the outside of the radial DRr. Therefore, as compared with the case where the cross-sectional area of the surface orthogonal to the radial DRr of the ventilation passage 15 is expanded in a stepped manner, the contraction loss caused by the expansion of the cross-sectional area of the ventilation passage 15 can be suppressed. Can be done.

Further, the first inclined portion 115 is formed in a range from one strut forming portion 114 to the other strut forming portion 114 among the two strut forming portions 114 adjacent to each other. The second inclined portion 125 is formed in a range from one hole forming portion 124 to the other hole forming portion 124 among the two hole forming portions 124 adjacent to each other. According to this, the angle of the first inclined portion 115 with respect to the circumferential direction DRc of the first inclined portion 115 with respect to the circumferential direction DRc of the first inclined portion 115 when the first inclined portion 115 is formed in a range smaller than the forming range of the present embodiment. Can be smaller than the angle. Further, the angle of the second inclined portion 125 with respect to the circumferential direction DRc is larger than the angle of the second inclined portion 125 with respect to the circumferential direction DRc when the second inclined portion 125 is formed in a range smaller than the forming range of the present embodiment. Can be made smaller.

Therefore, since the cross-sectional area of the surface of the ventilation passage 15 orthogonal to the circumferential DRc can be gradually increased, the pressure loss generated when the dynamic pressure is converted to the static pressure due to the expansion of the cross-sectional area of the ventilation passage 15 is suppressed. It becomes easier to do.

(Other embodiments)
Although the typical embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and can be variously modified as follows, for example.

In the above-described embodiment, an example in which the second inclined portion 125a is formed in the range from the hole forming portion 124a to the hole forming portion 124b has been described, but the present invention is not limited thereto. For example, as shown in FIGS. 11 and 12, the second inclined portion 125a may be formed in a range smaller than the range from the hole forming portion 124a to the hole forming portion 124b.

In the above-described embodiment, an example in which the first inclined portion 115 is provided on the first cover surface 112 and the second inclined portion 125 is provided on the second cover surface 123 has been described, but the present invention is not limited thereto. For example, the centrifugal blower 1 may have a configuration in which only one of the first inclined portion 115 and the second inclined portion 125 is provided.

In the above-described embodiment, an example in which the first expansion portion 116 is provided on the first cover surface 112 and the second expansion portion 126 is provided on the second cover surface 123 has been described, but the present invention is not limited thereto. For example, the centrifugal blower 1 is provided with a configuration in which only the first inclined portion 115 is provided and the first extended portion 116 is provided, or the first extended portion 116 is provided, out of the first inclined portion 115 and the second inclined portion 125. It may be a configuration that is not provided. Further, the centrifugal blower 1 is provided with a configuration in which only the second inclined portion 125 is provided and the second extended portion 126 is provided, or the second extended portion 126 is provided, out of the first inclined portion 115 and the second inclined portion 125. It may be a configuration that is not provided. Further, the centrifugal blower 1 is provided with both the inclined portions of the first inclined portion 115 and the second inclined portion 125, and only one of the first expansion portion 116 and the second expansion portion 126 is provided. It may be a configuration that is provided or a configuration that is not provided with any extension portion.

In the above-described embodiment, an example in which the support column forming portion 114 is provided on the first cover surface 112 and the hole forming portion 124 is provided on the second cover surface 123 has been described, but the present invention is not limited thereto.

For example, the first cover surface 112 is not provided with the support column forming portion 114, and the plurality of first inclined portions 115 and the plurality of first expansion portions 116 are alternately provided in the circumferential direction DRc. But it may be. Further, the second cover surface 123 is not provided with the hole forming portion 124, and the plurality of second inclined portions 125 and the plurality of second expansion portions 126 are alternately provided in the circumferential direction DRc. But it's okay. In this case, the plurality of columns 13 may be provided between the first inclined portion 115 and the first expansion portion 116 connected to the circumferential DRc.

In the above-described embodiment, the first inclined portion 115 and the second inclined portion 125 are formed in a range between the two adjacent columns 13 from the column 13 on the upstream side of the air flow to the column 13 on the downstream side. The example is described, but the present invention is not limited to this. For example, the first inclined portion 115 and the second inclined portion 125 are in a range between two adjacent columns 13 from a position overlapping the column 13 on the upstream side of the air flow and the radial DRr to the column 13 on the downstream side. It may be formed in. Further, the first inclined portion 115 and the second inclined portion 125 are in a range between two adjacent columns 13 from the column 13 on the upstream side of the air flow to a position overlapping the column 13 on the downstream side and the radial DRr. It may be formed in. Further, the first inclined portion 115 and the second inclined portion 125 are located between the two adjacent columns 13 from the position where they overlap the column 13 on the upstream side of the air flow and the radial DRr to the column 13 on the downstream side and the radial DRr. It may be formed in a range up to the overlapping position.

In the above-described embodiment, an example in which four columns 13 are provided on the first cover portion 11 has been described, but the present invention is not limited to this. For example, the support column 13 may be provided on the second cover portion 12. Further, the number of columns 13 is not limited to four, and the columns 13 may have a configuration of less than four or more than four as long as at least one is provided.

In the above-described embodiment, an example in which the centrifugal fan 20 is composed of a turbo fan has been described, but the present invention is not limited thereto. For example, the centrifugal fan 20 may be composed of a sirocco fan as long as it is an all-around blow-out type centrifugal blower that blows air from the entire circumference of the casing 10.

In the above-described embodiment, the example in which the first cover portion 11 and the second cover portion 12 are connected by the screw 14 has been described, but the present invention is not limited thereto. For example, the first cover portion 11 and the second cover portion 12 may be connected by a method other than the screw 14, such as adhesion.

Needless to say, in the above-described embodiment, the elements constituting the embodiment are not necessarily essential except when it is clearly stated that they are essential and when they are clearly considered to be essential in principle.

In the above-described embodiment, when numerical values such as the number, numerical values, quantities, ranges, etc. of the components of the embodiment are mentioned, when it is clearly stated that they are particularly essential, and in principle, they are clearly limited to a specific number. Except as the case, it is not limited to the specific number.

In the above-described embodiment, when referring to the shape, positional relationship, etc. of a component or the like, the shape, positional relationship, etc., unless otherwise specified or limited in principle to a specific shape, positional relationship, etc. Etc. are not limited.

(summary)
According to the first aspect shown in part or all of the above embodiments, the centrifugal blower comprises a centrifugal fan that blows air by rotating about a fan axis and a casing that houses the centrifugal fan. Be prepared. The casing is formed with an air intake port 111 through which air sucked by the centrifugal fan passes, and a first cover portion 11 that covers one side of the centrifugal fan in the axial direction of the fan axis and the other of the centrifugal fan in the axial direction. It has a second cover portion 12 that covers the side. The casing has at least one strut that maintains a gap between the first cover and the second cover. The first cover portion has a first cover surface facing the second cover portion in the first cover portion. The second cover portion has a second cover surface facing the first cover portion in the second cover portion. The first cover portion and the second cover portion protruded outward from the centrifugal fan in the radial direction of the fan axis on the first cover surface and outward from the centrifugal fan on the second cover surface. The first cover portion and the second cover portion, which form a ventilation path through which the air blown out by the centrifugal fan flows in the gap between the portions, are the air blown out by the centrifugal fan by the outer edge portion of the first cover surface and the outer edge portion of the second cover surface. Is formed over the entire circumference of the casing. The columns are provided on the outside of the centrifugal fan in the radial direction in the ventilation path. At least one of the first cover surface and the second cover surface faces the upstream side of the air flow in the circumferential direction of the fan axis from the portion where the support column is provided, and from the upstream side to the downstream side of the air flow in the circumferential direction. It has an inclined portion that gradually increases the size of the ventilation path in the axial direction. The inclined portion is inclined with respect to the circumferential direction.

According to the second aspect, of the first cover surface and the second cover surface, the cover surface on which the inclined portion is formed gradually increases in size in the axial direction of the ventilation path from the inside to the outside in the radial direction. Has an extension to make it larger. The extension portion is connected to the inclined portion and is inclined in the radial direction.

According to this, the cross-sectional area of the surface orthogonal to the radial direction of the ventilation path can be gradually expanded from the inner side to the outer side in the radial direction. Therefore, as compared with the case where the cross-sectional area of the surface orthogonal to the radial direction of the ventilation passage is expanded in a stepped manner, the contraction loss generated by the expansion of the cross-sectional area of the ventilation passage can be suppressed.

According to the third viewpoint, a plurality of columns are provided side by side in the circumferential direction. Of the plurality of columns, a predetermined column is defined as one column, and among columns adjacent to the predetermined column, a column provided on the upstream side of the air flow from the predetermined column is defined as the other column. Of the first cover surface and the second cover surface, the cover surface on which the inclined portion is formed has a support surface for supporting one support column and the other support column. The inclined portion includes a range from the seat surface on which one support column is provided to the seat surface on which the other support column is provided.

According to this, when the angle of the inclined portion with respect to the circumferential direction is smaller than the range from the seat surface on which one support is provided to the seat surface on which the other support is provided, the inclined portion is formed. It can be smaller than the angle with respect to the circumferential direction. Therefore, since the cross-sectional area of the plane orthogonal to the circumferential direction in the ventilation path can be gradually increased, it becomes easy to suppress the pressure loss generated when the dynamic pressure is converted to the static pressure due to the expansion of the cross-sectional area of the ventilation path. ..

10 Casing 11 1st cover part 12 2nd cover part 13 Strut 15 Ventilation passage 16 Air outlet 20 Centrifugal fan 112 1st cover surface 123 2nd cover surface 125 Inclined part

Claims (3)

It ’s a centrifugal blower,
A centrifugal fan (20) that blows air by rotating around the fan axis (CL), and
A casing (10) for accommodating the centrifugal fan is provided.
The casing is
An air suction port (111) through which air sucked by the centrifugal fan passes is formed, and a first cover portion (11) that covers one side of the centrifugal fan in the axial direction of the fan axis is formed.
A second cover portion (12) that covers the other side of the centrifugal fan in the axial direction, and
It has at least one support column (13) that maintains a gap between the first cover portion and the second cover portion.
The first cover portion and the second cover portion are located outside the first cover surface (112) of the first cover portion facing the second cover portion in the radial direction of the fan axis from the centrifugal fan. The centrifugal fan blows out into a gap between the overhanging portion and the portion of the second cover portion of the second cover surface (123) facing the first cover portion that protrudes outward in the radial direction from the centrifugal fan. An outlet for blowing air blown out by the centrifugal fan over the entire circumference of the casing by forming a ventilation path (15) through which air flows and the outer edge portion of the first cover surface and the outer edge portion of the second cover surface. Form (16)
The support column is provided outside the centrifugal fan in the radial direction in the ventilation path.
At least one of the first cover surface and the second cover surface is on the upstream side of the air flow in the circumferential direction of the fan axis from the portion where the support column is provided, and on the upstream side of the air flow in the circumferential direction. It has inclined portions (115, 125) that gradually increase the size of the ventilation passage in the axial direction toward the downstream side.
The inclined portion is a centrifugal blower inclined with respect to the circumferential direction. Of the first cover surface and the second cover surface, the cover surface on which the inclined portion is formed gradually increases in size of the ventilation path in the axial direction from the inside to the outside in the radial direction. Has an extension (116, 126) to
The centrifugal blower according to claim 1, wherein the expansion portion is connected to the inclined portion and is inclined with respect to the radial direction. A plurality of the columns are provided side by side in the circumferential direction, and among the plurality of columns, a predetermined column is one of the columns, and air flows from the predetermined columns among the columns adjacent to the predetermined columns. When the support provided on the downstream side is used as the other support,
Of the first cover surface and the second cover surface, the cover surface on which the inclined portion is formed has a seating surface (114, 124) for supporting the one support column and the other support column.
The centrifugal blower according to claim 1 or 2, wherein the inclined portion includes a range from the seat surface on which one of the columns is provided to the seat surface on which the other column is provided.

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