JP7342782B2 - centrifugal blower - Google Patents

Description

The present disclosure relates to centrifugal blowers.

Conventionally, a centrifugal blower is known that includes a casing having an upper casing and a lower casing, and an impeller rotatably housed between the upper casing and the lower casing, and blows air from substantially the entire circumference of the side surface of the casing. (For example, see Patent Document 1). The upper casing and the lower casing are supported by a plurality of struts arranged radially outward of the impeller, and form a ventilation path between the upper casing and the lower casing. Note that in the following description, the impeller will be referred to as a centrifugal fan.

JP2017-96224A

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 the air flows through the ventilation path. Further, in the centrifugal blower described in Patent Document 1, when the air blown out from the centrifugal fan flows through the ventilation passage, it collides with the support column, causing pressure loss. These pressure losses are a factor in deteriorating the fan efficiency of the centrifugal blower.

In addition, the pressure loss caused by friction and the pressure loss caused by collision with the struts are the dynamic pressure, which is kinetic energy, out of the total pressure, which is the dynamic pressure, which is the pressure component of the air flowing through the ventilation passage, and the static pressure, which is the total pressure. The larger the value, the larger the value. The greater the pressure loss, the worse the fan efficiency becomes. Fan efficiency is the ratio of theoretical air power to the rotational driving force required to rotate a centrifugal fan. The driving force is shaft power that rotates the centrifugal fan. Theoretical air power is a value corresponding to the amount of work output by a centrifugal blower.

The present disclosure aims to provide a centrifugal blower that can suppress pressure loss and improve fan efficiency.

The invention according to claim 1 includes:
A centrifugal blower,
a centrifugal fan (20) that blows out air by rotating around a fan axis (CL);
A casing (10) that accommodates a centrifugal fan;
The casing is
an air intake port (111) through which air sucked by the centrifugal fan passes, and a first cover part (11) that covers one side of the centrifugal fan in the axial direction of the fan axis;
a second cover part (12) that covers the other side of the centrifugal fan in the axial direction;
It has at least one support column (13) that maintains a gap between the first cover part and the second cover part,
The first cover part and the second cover part include a part of the first cover surface (112) of the first cover part facing the second cover part that protrudes outward in the radial direction of the fan axis from the centrifugal fan, and A ventilation passage (15) through which air blown out by the centrifugal fan flows is formed in a gap between the second cover surface (123) of the second cover part facing the first cover part and a part of the second cover surface (123) that protrudes radially outward from the centrifugal fan. At the same time, the outer edge of the first cover surface and the outer edge of the second cover surface form an air outlet (16) that blows out air from the centrifugal fan over the entire circumference of the casing,
The support column is provided radially outward from the centrifugal fan in the ventilation passage,
At least one of the first cover surface and the second cover surface is arranged toward the air flow upstream side in the circumferential direction of the fan axis from the part where the support is provided, and from the air flow upstream side in the circumferential direction to the downstream side. has an inclined portion (115, 125) that gradually increases the size of the ventilation passage in the axial direction;
The inclined portion is inclined with respect to the circumferential direction.

According to this, the cross-sectional area of the surface perpendicular to the circumferential direction of the portion of the ventilation passage where air flows in the circumferential direction toward the support column can be increased toward the downstream side of the air flow by the inclined portion. When the air flows through the ventilation duct toward the pillars, the dynamic pressure of the air generated as the cross-sectional area of the ventilation duct expands is converted to static pressure, so the dynamic pressure of the total air pressure is 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 struts when flowing through the ventilation path, and improve the fan efficiency of the centrifugal blower.

Note that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence between the component etc. and specific components etc. described in the embodiments to be described later.

FIG. 1 is an exploded perspective view of a centrifugal blower according to an embodiment. FIG. 1 is a perspective view of a centrifugal blower according to an embodiment. FIG. 1 is a side view of a centrifugal blower according to an embodiment. 3 is a sectional view taken along line IV-IV in FIG. 2. FIG. 3 is a sectional view taken along the line VV in FIG. 2. FIG. FIG. 3 is a partially enlarged perspective view showing the vicinity of a second inclined portion and a second expanded portion formed on a second cover portion of the centrifugal blower. It is a figure showing the relationship between a flow coefficient and a pressure coefficient of a centrifugal blower of one embodiment and a centrifugal blower of a comparative example. It is a figure showing the relationship between a flow coefficient and fan efficiency of a centrifugal blower of one embodiment and a centrifugal blower of a comparative example. FIG. 3 is a schematic diagram showing the flow direction and reach distance of air blown out from a centrifugal blower of a comparative example with arrows. FIG. 2 is a schematic diagram showing, with arrows, the flow direction and distance of air blown out from a centrifugal blower according to an embodiment. FIG. 7 is an exploded perspective view of a centrifugal blower according to another embodiment. FIG. 7 is a perspective view of a centrifugal blower according to 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 that is a housing of the centrifugal blower 1, a centrifugal fan 20 that blows out air by rotating around a fan axis CL, and an electric motor that rotates the centrifugal fan 20. The motor 30 is also provided. In the present embodiment, the direction along the fan axis CL is referred to as the axial direction DRa, and the direction perpendicular to the axial direction DRa and extending radially from the fan axis CL is referred to as the radial direction DRr, and the rotation direction of the centrifugal fan 20. Various configurations of the centrifugal blower 1 will be described with reference to the circumferential direction DRc.

The casing 10 is made of resin and houses a centrifugal fan 20 and an electric motor 30. The casing 10 includes a first cover part 11 that covers one side of the centrifugal fan 20 in the axial direction DRa, a second cover part 12 that covers the other side of the centrifugal fan 20 in the axial direction DRa, the first cover part 11, and It has four pillars 13 that maintain a gap between the second cover part 12. In the casing 10, a first cover part 11 and a second cover part 12 are coupled together by screws 14.

As shown in FIGS. 2 and 3, the first cover part 11 has a substantially disk shape, and the outer diameter of the first cover part 11 is larger than the outer diameter of the centrifugal fan 20. Further, in the first cover portion 11, respective portions where the struts 13 are provided protrude toward the outside in the radial direction DRr.

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

The first cover surface 112 has a substantially annular shape, and the outer diameter of the first cover surface 112 is larger than the outer diameter of the centrifugal fan 20 . The first cover surface 112 covers a part of the centrifugal fan 20 at a portion DRr inner than the centrifugal fan 20 in the radial direction. Further, a portion of the first cover surface 112 that protrudes outward from the centrifugal fan 20 in the radial direction DRr faces the second cover portion 12 . A portion of the first cover surface 112 that protrudes outward from the centrifugal fan 20 in the radial direction DRr is provided with ventilation, which will be described later, through which air blown out from the centrifugal fan 20 flows between the first cover part 11 and the second cover part 12. A path 15 is formed.

As shown in FIGS. 3 and 4, on the first cover surface 112, four strut forming portions 114 in which struts 13 are provided extend outward from the centrifugal fan 20 in the radial direction DRr, and extend along the circumferential direction DRc. They are arranged side by side at predetermined intervals. The first cover surface 112 has a first inclined part 115, which will be described later, and a first expanded part 116, which will be described later, between each of the four strut forming parts 114 arranged in the circumferential direction DRc. Further, the first cover surface 112 has an outer edge portion 117 on the outer edge in the radial direction DRr, which forms an air outlet 16 to be described later that blows air out of the casing 10 . Hereinafter, the outer edge 117 of the first cover surface 112 will be referred to as a first outer edge 117.

Each of the strut 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 DRr. The strut forming portion 114 is formed in a planar shape extending along the radial direction DRr. A pillar 13 is provided in each of the four pillar forming parts 114.

Each of the four pillars 13 protrudes 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 with a central axis parallel to the axial direction DRa. The four pillars 13 are arranged on the first cover surface 112 at equal pitches in the circumferential direction DRc with the fan axis CL as the center. Specifically, the four pillars 13 are provided on the first cover surface 112 at a pitch of 90 degrees around the fan axis CL. Moreover, screw holes (not shown) are formed inside each of the columns 13, into which screws 14 for connecting the first cover part 11 and the second cover part 12 are inserted.

As shown in FIG. 1, the second cover part 12 has a substantially disc shape that forms a pair with the first cover part 11, and the outer diameter of the second cover part 12 is substantially the same as the outer diameter of the first cover part 11. It is formed by size. That is, the outer diameter of the second cover part 12 is larger than the outer diameter of the centrifugal fan 20. The second cover part 12 has a motor housing part 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, a portion where the through hole 122 is formed protrudes toward the outside in the radial direction DRr.

The motor accommodating portion 121 is formed to be recessed toward the other side in the axial direction DRa, and accommodates the electric motor 30. The through holes 122 are formed in each of the portions facing the four pillars 13. A screw 14 that is inserted into a 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 is formed to have an outer diameter substantially the same as 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. A portion of the second cover surface 123 that protrudes outward from the centrifugal fan 20 in the radial direction DRr is opposed to a portion of the first cover surface 112 that protrudes outward from the centrifugal fan 20 in the radial direction DRr. A portion of the second cover surface 123 that faces the first cover surface 112 forms a pair with the first cover surface 112 to form a ventilation path 15 to be described later.

On the second cover surface 123, hole forming portions 124 in which through holes 122 are provided are provided in positions facing each of the four pillar forming portions 114 in line in the circumferential direction DRc. Each of the four hole forming portions 124 extends along the radial direction DRr, and is formed to be parallel to the supporting column forming portions 114 facing each other.

Further, the second cover surface 123 has a second inclined portion 125, which will be described later, and a second expanded portion 126, which will be 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 air outlet 16, which will be described later, on the outer edge in the radial direction DRr. Hereinafter, the outer edge 127 of the second cover surface 123 will be referred to as a second outer edge 127.

In this embodiment, the column forming portion 114 and the hole forming portion 124 correspond to a seat surface that supports the column 13. Further, the first inclined portion 115 and the second inclined portion 125 correspond to inclined portions that gradually increase the size of the ventilation passage 15 in the axial direction DRa from the upstream side to the downstream side of the air flow in the circumferential direction DRc. . The first expanded portion 116 and the second expanded portion 126 correspond to expanded portions that gradually increase the size of the ventilation passage 15 in the axial direction DRa from the inside to the outside in the radial direction DRr. Details of the shapes of the first inclined portion 115, the second inclined portion 125, the first expanded portion 116, and the second expanded 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 protrudes outward from the centrifugal fan 20 in the radial direction DRr and a portion of the second cover surface 123 that protrudes outward from the centrifugal fan 20 in the radial direction DRr. It is formed. The ventilation passage 15 is provided with four pillars 13.

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

Here, each of the four pillars 13 is provided in the ventilation passage 15 on the radial direction DRr outer side than the centrifugal fan 20 and on the radial direction DRr inner side than the air outlet 16. Therefore, on the airflow downstream side of the portion of the air outlet 16 where the four struts 13 are provided, the four struts 13 prevent the air from being blown out of the casing 10 . Therefore, in this embodiment, the air outlet 16 is formed over the entire circumference of the side surface of the casing 10 includes that the air outlet 16 is formed over substantially the entire circumference of the side surface of the casing 10. It is the 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 receiving electricity from a power source (not shown).

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

The centrifugal fan 20 rotates around the fan axis CL, sucks in air from one side in the axial direction DRa, and transmits a speed component in the radial direction DRr and a speed component in the circumferential direction DRc to the outer circumferential side of the centrifugal fan 20. Blow out the air that has. The air blown out from the centrifugal fan 20 flows through the ventilation path 15 in the rotational direction of the centrifugal fan 20 in the circumferential direction DRc, and also in a direction away from the centrifugal fan 20. Hereinafter, in the circumferential direction DRc, the direction in which air flows, which is the direction in which the centrifugal fan 20 rotates, will be referred to as a normal rotation direction DRc1, and the direction opposite to the normal rotation direction DRc1 will be referred to as a reverse 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 in the axial direction DRa flows between the respective blades 21. An air circulation hole 221 is formed on the inner peripheral side of the side plate 22 to allow air to flow in from the air intake port 111. 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 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 .

Furthermore, the outer edges of each of the side plates 22 and the main plate 23 form a fan outlet 24 that blows out air that has flowed in between the plurality of blades 21 . Here, the innermost part in the radial direction DRr of the part forming the ventilation passage 15 on the first cover surface 112 is the first inner edge part 118 and the part forming the ventilation passage 15 on the second cover surface 123 in the radial direction DRr. The innermost portion is defined as a 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 approximately the same size as the distance d1 between the first inner edge 118 and the second inner edge 128.

Next, the first inclined part 115, the first extended part 116, the second inclined part 125, and the second extended part 126 will be explained with reference to FIGS. 3, 4, and 6. The first inclined portion 115 is provided between each of the four pillar forming portions 114 and faces the second inclined portion 125. The first expanded portion 116 is provided between each of the four pillar forming portions 114 and faces the second expanded portion 126 . Further, the second inclined portion 125 and the second expanded portion 126 are provided between each of the four hole forming portions 124 . In other words, the first inclined portion 115, the first expanded portion 116, the second inclined portion 125, and the second expanded portion 126 are provided between the respective portions where the four pillars 13 are provided. The first inclined portion 115 and the second inclined portion 125 are inclined with respect to the circumferential direction DRc. The first expanded portion 116 and the second expanded portion 126 are inclined with respect to the radial direction DRr, as shown in FIG. 4 .

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

Therefore, in this embodiment, among the four second inclined parts 125, the second inclined part 125a provided between the hole forming part 124a and the hole forming part 124b that are adjacent to each other, and the four first inclined parts 115, the details of the first inclined part 115a facing the second inclined part 125a will be explained. Further, a detailed description of the second slope portions 125 other than the second slope portion 125a and the first slope portions 115 other than the first slope portion 115a will be omitted.

Furthermore, in this embodiment, among the four second expansion parts 126, the second expansion part 126a provided between the hole forming part 124a and the hole formation part 124b that are adjacent to each other, and the four first expansion parts 116 Among them, details of the first extension part 116a facing the second extension part 126a will be explained. Further, a detailed description of the second expansion parts 126 other than the second expansion part 126a and the first expansion parts 116 other than the first expansion part 116a will be omitted.

Note that, as shown in FIG. 3, the hole forming portion 124a is provided closer to the reversing direction DRc2 than the hole forming portion 124b. Further, the first inclined portion 115a and the first expanded portion 116a are provided between the column forming portion 114a facing the hole forming portion 124a and the column forming portion 114b opposing the hole forming portion 124b. Further, the support pillar 13a is provided in the support formation part 114a. The strut forming portion 114b is provided with a strut 13b that is provided closer to the normal rotation direction DRc1 than 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 in the axial direction DRa of the ventilation passage 15 gradually increases from the reverse direction DRc2 side toward the normal rotation direction DRc1 side. The second inclined portion 125a is inclined toward the other side in the axial direction DRa.

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

In other words, between the struts 13a and 13b in the ventilation passage 15, the second The inclined portion 125a is inclined with respect to the circumferential direction DRc.

An end portion of the second inclined portion 125a on the reverse direction DRc2 side is connected to the hole forming portion 124a. Further, the end portion of the second inclined portion 125a on the normal rotation direction DRc1 side is continuous with the hole forming portion 124b.

In this embodiment, the second inclined portion 125a is formed in the 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 downstream of the air flow side of the region where the strut 13a is provided to just before the air flow side of the region where the strut 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 side of the reversal direction DRc2, which is formed in the entire range from the second inner edge portion 128 to the second outer edge portion 127. In addition, the second inclined portion 125a is formed in approximately half of the region from the hole forming portion 124a to the hole forming portion 124b on the reverse direction DRc2 side, and 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 region from the hole forming portion 124a to the hole forming portion 124b on the normal rotation direction DRc1 side is smaller than the range from the second inner edge portion 128 to the second outer edge portion 127. Formed in a range.

Specifically, the inner end of approximately half of the second inclined portion 125a on the normal rotation direction DRc1 side in the radial direction DRr is separated from the second inner edge portion 128, and The size of the radial direction DRr continuously decreases toward the side. Approximately half of the second inclined portion 125a on the normal rotation direction DRc1 side includes an inner end and a second inner edge of the second inclined portion 125a in the radial direction DRr from the reverse direction DRc2 side toward the normal rotation direction DRc1 side. The distance from the portion 128 continues to increase. The second expanded portion 126a of the second inclined portion 125a is connected to a portion of the inner end in the radial direction DRr that is remote from the second inner edge portion 128.

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

In other words, the second expansion is performed such that the cross-sectional area of the plane perpendicular to the radial direction DRr of the ventilation passage 15 increases continuously from the innermost part of the ventilation passage 15 in the radial direction DRr as it approaches the air outlet 16. The portion 126a is inclined with respect to the radial direction DRr. The second expanded portion 126a has an inner end in the radial direction DRr connected to the second inner edge portion 128, and an outer end in the radial direction DRr connected to the second inclined portion 125a.

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

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

The end of the second extended portion 126a on the reverse direction DRc2 side is closer to the forward rotation direction DRc1 than the end of the second inclined portion 125a on the reverse direction DRc2 side, and It is provided on the reverse direction DRc2 side from the end portion. In the range from the hole forming part 124a to the hole forming part 124b, the range where the second inclined part 125a is provided is larger than the range where the second expanded part 126a is provided.

The second inclined portion 125a has a configuration symmetrical to the first inclined portion 115a with respect to the virtual center plane. The second expanded portion 126a has a symmetrical configuration with the first expanded portion 116a with respect to the virtual center plane.

That is, the first inclined portion 115a is formed in the range from the column forming portion 114a to the column forming portion 114b. Further, the first inclined portion 115a is inclined toward one side in the axial direction DRa such that the size of the ventilation passage 15 in the axial direction DRa gradually increases as it approaches the column forming portion 114 from the column forming portion 114a. are doing. In other words, between the support columns 13a and 13b in the ventilation passage 15, the first The inclined portion 115a is inclined with respect to the circumferential direction DRc.

The first expanded portion 116a is continuous with the first inclined portion 115a, and is formed in approximately half of the range from the column forming portion 114a to the column forming portion 114b on the normal rotation direction DRc1 side. The first expanded portion 116a is arranged at one end in the axial direction DRa such that the size of the ventilation passage 15 in the axial direction DRa gradually increases as it approaches the first outer edge 117 from the first inner edge 118. Sloped to the side. In other words, the first expansion is performed so that the cross-sectional area of the plane perpendicular to the radial direction DRr of the ventilation passage 15 increases continuously from the innermost part of the ventilation passage 15 in the radial direction DRr as it approaches the air outlet 16. The portion 116a is inclined with respect to the radial direction DRr.

As a result, the size of the flow path between the first inclined portion 115a and the second inclined portion 125a in the ventilation path 15 in the axial direction 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 of the air outlet 16 where the first inclined portion 115a and the second inclined portion 125a are formed is the largest in the radial direction DRr of the ventilation passage 15. It is larger than the size d1 in the axial direction DRa of the inner part.

The cross-sectional area of the flow path between the first inclined portion 115a and the second inclined portion 125a in the ventilation passage 15 on a plane perpendicular to the circumferential direction DRc becomes larger toward the downstream side of the air flow in the circumferential direction DRc. In other words, the cross-sectional area of the ventilation passage 15 between the struts 13a and 13b on a plane perpendicular to the circumferential direction DRc increases as it approaches the struts 13b from the struts 13a.

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

The cross-sectional area of a plane perpendicular to the radial direction DRr of the flow path between the first expanded portion 116a and the second expanded portion 126a in the ventilation path 15 increases as the air flow becomes more downstream in the radial direction DRr. In other words, the cross-sectional area of the ventilation passage 15 between the struts 13a and the struts 13b in the plane perpendicular to the radial direction DRr increases as it approaches the air outlet 16 from the innermost part of the ventilation passage 15 in the radial direction DRr. Become.

Next, the operation of the centrifugal blower 1 of this embodiment will be explained. In the centrifugal blower 1 of this embodiment, when the electric motor 30 is driven, the centrifugal fan 20 rotates. As a result, air that has flowed in from the air intake port 111 is sucked in from the air circulation hole 221, is given dynamic pressure as kinetic energy from the plurality of rotating blades 21, and is blown out from the fan outlet 24. The air blown out from the fan outlet 24 flows through the ventilation path 15 in the normal rotation direction DRc1 and in the direction away from the centrifugal fan 20. Further, the air flowing through the ventilation passage 15 collides with the support column 13, thereby suppressing the flow of air downstream of the support column 13. For this reason, the centrifugal blower 1 allows the air blown out from the fan outlet 24 to pass between each of the four support 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 dynamic pressure. However, when the air blown out from the fan outlet 24 flows through the ventilation path 15, a pressure loss occurs due to friction generated between the first cover surface 112 and the second cover surface 123. Further, the air blown out from the fan outlet 24 collides with the support column 13 when flowing through the ventilation path 15, causing a pressure loss. As a result, part of the dynamic pressure of the air flowing through the ventilation passage 15 is converted into static pressure.

The pressure loss that occurs when air flows through the ventilation path 15 becomes a factor in deteriorating the fan efficiency of the centrifugal blower 1. Moreover, the pressure loss increases as the dynamic pressure increases among the total pressure of the air flowing through the ventilation passage 15. The larger the pressure loss, the worse the fan efficiency becomes.

The centrifugal blower 1 is desired to improve fan efficiency in order to suppress the power required to rotate the electric motor 30. For this reason, it is desirable that the pressure loss that occurs when flowing through the ventilation path 15 is small. Below, the pressure loss during operation of the centrifugal blower 1 in this embodiment will be explained in comparison with the pressure loss during operation of a centrifugal blower according to a comparative example. Hereinafter, the centrifugal blower of the comparative example will be referred to as a comparative centrifugal blower. Moreover, the flow path corresponding to the ventilation path 15 in the comparison centrifugal blower is called the comparison ventilation path, and the air outlet corresponding to the air outlet 16 is called the comparison air outlet.

The comparative centrifugal blower is not provided with the first inclined portion 115, the second inclined portion 125, the first expanded portion 116, and the second expanded portion 126. That is, the comparison centrifugal blower has a configuration in which the cross-sectional area of the plane perpendicular to the circumferential direction DRc and the cross-sectional area of the plane perpendicular to the radial direction DRr of the comparative ventilation passage do not change toward the downstream side of the air flow. The other configuration of the comparative centrifugal blower is the same as the centrifugal blower 1 of this embodiment.

On the other hand, the ventilation passage 15 of the present embodiment has a first slope portion 115 and a second slope portion 125 between two adjacent pillars 13, from the pillar 13 on the upstream side to the pillar 13 on the downstream side. As the distance approaches , the cross-sectional area of the plane perpendicular to the circumferential direction DRc increases. As a result, when the air flowing through the ventilation passage 15 flows in the circumferential direction DRc, there is a conversion from dynamic pressure to static pressure due to the expansion of the cross-sectional area of the plane perpendicular to the circumferential direction DRc of the ventilation passage 15. occurs. Therefore, as the air flowing between two adjacent columns 13 approaches from the column 13 on the upstream side to the column 13 on the downstream side, the ratio of dynamic pressure to the total pressure gradually decreases. On the other hand, the proportion occupied by static pressure gradually increases.

In addition, the ventilation passage 15 has a cross section in a plane perpendicular to the radial direction DRr as it approaches the air outlet 16 from the innermost part of the ventilation passage 15 in the radial direction DRr. The area is larger. As a result, when the air flowing through the ventilation passage 15 flows in the radial direction DRr, there is a conversion from dynamic pressure to static pressure due to the expansion of the cross-sectional area of the plane perpendicular to the radial direction DRr of the ventilation passage 15. occurs. Therefore, as the air flowing through the ventilation passage 15 toward the air outlet 16 approaches the air outlet 16 from the innermost part of the air passage 15 in the radial direction DRr, the ratio of dynamic pressure to the total pressure gradually decreases. Conversely, the proportion occupied by static pressure gradually increases.

In the comparative centrifugal blower, the cross-sectional area of the comparative ventilation passage does not change, so no conversion from dynamic pressure to static pressure occurs as the cross-sectional area of the comparative ventilation passage increases.

Therefore, the air flowing through the ventilation passage 15 of this embodiment has a lower dynamic pressure than the air flowing through the comparison ventilation passage. As a result, the pressure loss caused by the friction between the first cover surface 112 and the second cover surface 123 and the collision with the struts 13 when flowing through the ventilation path 15 of the present embodiment is eliminated from the pressure loss caused by the collision with the support column 13. This is smaller than the pressure loss that would otherwise occur.

Here, the difference between the pressure coefficient with respect to the flow coefficient of the centrifugal blower 1 of this embodiment and the pressure coefficient with respect to the flow coefficient of the centrifugal blower for comparison will be explained with reference to FIG. In each line in FIG. 7, a solid line indicates a pressure coefficient with respect to a flow coefficient of the centrifugal blower 1 of this embodiment, and a broken line indicates a pressure coefficient with respect to a flow coefficient of the centrifugal blower for comparison. Moreover, the dashed-dotted line shows the resistance curve of the centrifugal blower 1 of this embodiment, and the dashed-two dotted line shows the resistance curve of the centrifugal blower for comparison. Further, the intersection between the solid line and the dashed-dotted line indicates the operating point of the centrifugal blower 1 of this embodiment, and the intersection between the broken line and the dashed-two dotted line indicates the operating point of the centrifugal blower for comparison.

In this embodiment, by converting dynamic pressure into static pressure as the cross-sectional area of the ventilation passage 15 is expanded, as shown in FIG. The pressure coefficient can be greater than the flow coefficient of the comparative centrifugal blower. That is, the centrifugal blower 1 of the present embodiment can have a pressure coefficient greater than or equal to the pressure coefficient of the comparative centrifugal blower at the same flow rate coefficient as that of the comparative centrifugal blower. This means that the centrifugal blower 1 of the present embodiment can ensure the desired operating point, that is, the volume and pressure of air blown out from the outlet 16, at a lower rotational speed than the comparative centrifugal blower.

Further, the difference between the fan efficiency with respect to the flow coefficient of the centrifugal blower 1 of this embodiment and the fan efficiency with respect to the flow coefficient of the centrifugal blower for comparison will be explained with reference to FIG. In each line in FIG. 8, the solid line indicates the fan efficiency with respect to the flow coefficient of the centrifugal blower 1 of this embodiment, and the broken line indicates the fan efficiency with respect to the flow coefficient of the centrifugal blower for comparison. Further, the intersection between the solid line and the dashed-dotted line indicates the fan efficiency of the centrifugal blower 1 of this embodiment, and the intersection between the broken line and the dashed-two dotted 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 this embodiment can be improved over the fan efficiency with respect to the flow coefficient of the comparative centrifugal blower in the entire flow coefficient range shown in FIG. In other words, even if the flow coefficients of the centrifugal blower 1 of the present embodiment and the comparative centrifugal blower are changed by changing the air intake amount of the centrifugal blower 1 of the present embodiment and the comparative centrifugal blower, the centrifugal blower 1 of the present embodiment is different from the comparative centrifugal blower. It can operate at higher efficiency than the fan efficiency of the blower.

By the way, in the centrifugal blower 1 of the present embodiment and the comparative centrifugal blower, pressure loss occurs even when blowing out air due to the shear force of the air. The pressure loss when blowing out air becomes a factor in shortening the reach of the air blown out by the centrifugal blower 1 of this embodiment and the comparative centrifugal blower. Furthermore, the smaller the dynamic pressure of the total air pressure, the smaller the shearing force that the air has. Therefore, the more the dynamic pressure of the air blown out from the outlet 16 is suppressed, the further the centrifugal blower 1 can blow out the air.

Here, the difference in the reachable distance of the air blown out from the centrifugal blower 1 of this embodiment and the reachable distance of the air blown out from the comparative centrifugal blower will be explained with reference to FIGS. 9 and 10. Note that the arrows shown in FIGS. 9 and 10 indicate the flow of air blown out from the air outlet 16 and the comparative air outlet, respectively.

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

Therefore, the air blown out from the air outlet 16 of this embodiment has a smaller shear force than the air blown out from the comparison air outlet. Thereby, the centrifugal blower 1 of this embodiment can blow air farther than the comparative centrifugal blower. Specifically, as shown in the comparison between FIGS. 9 and 10, the distance of air blown out from between the four pillars 13 by the centrifugal blower 1 of this embodiment is the same as that of the air blown out by the comparative centrifugal blower. 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 air to flow from the upstream supporting post 13 to the downstream supporting post 13 in the ventilation passage 15 between two adjacent supporting posts 13. As it approaches , the cross-sectional area of the plane perpendicular to the circumferential direction DRc can be increased. In addition, the ventilation passage 15 is arranged to be perpendicular to the radial direction DRr of the ventilation passage 15 as it approaches the air outlet 16 from the innermost part of the ventilation passage 15 in the radial direction DRr. The cross-sectional area of the surface can be increased.

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

Therefore, pressure loss caused by friction between the first cover surface 112 and the second cover surface 123 and collision with the struts 13 when the air flows through the ventilation path 15 can be suppressed, thereby improving the fan efficiency of the centrifugal blower 1. can be done.

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

Moreover, the first expansion part 116 and the second expansion part 126 can continuously expand the cross-sectional area of the plane of the ventilation passage 15 perpendicular to the radial direction DRr from the inside to the outside in the radial direction DRr. Therefore, compared to the case where the cross-sectional area of the plane perpendicular to the radial direction DRr of the ventilation passage 15 is expanded in a stepwise manner, the contraction loss that occurs due to 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 of the two pillar forming portions 114 adjacent to each other to the other pillar forming portion 114. 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 part 115 with respect to the circumferential direction DRc is set to the angle with respect to the circumferential direction DRc of the first inclined part 115 when the first inclined part 115 is formed in a smaller range than the formation range of the present embodiment. It can be made smaller than the angle. Further, the angle of the second inclined portion 125 with respect to the circumferential direction DRc is set to be smaller 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 smaller range than the formation range of the present embodiment. Can be made smaller.

Therefore, the cross-sectional area of the plane perpendicular to the circumferential direction DRc in the ventilation passage 15 can be gradually increased, thereby suppressing the pressure loss that occurs when converting dynamic pressure to static pressure by expanding the cross-sectional area of the ventilation passage 15. It becomes easier to do.

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

In the embodiment described above, an example has been described in which the second inclined portion 125a is formed in the range from the hole forming portion 124a to the hole forming portion 124b, 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 smaller range than the range from the hole forming portion 124a to the hole forming portion 124b.

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

In the above-described embodiment, an example has been described in which the first expanded portion 116 is provided on the first cover surface 112 and the second expanded portion 126 is provided on the second cover surface 123, but the invention is not limited to this. For example, the centrifugal blower 1 may have a configuration in which only the first inclined part 115 is provided among the first inclined part 115 and the second inclined part 125 and the first extended part 116 is provided, or the first extended part 116 is provided. It is also possible to have a configuration that is not specified. Further, the centrifugal blower 1 may have a configuration in which only the second inclined part 125 is provided among the first inclined part 115 and the second inclined part 125 and the second extended part 126 is provided, or the second extended part 126 is provided. It is also possible to have a configuration that is not specified. Further, the centrifugal blower 1 is provided with both the first inclined part 115 and the second inclined part 125, and only one of the first extended part 116 and the second extended part 126 is provided. The configuration may include a configuration in which the extension is provided or a configuration in which no extension is provided.

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

For example, the first cover surface 112 is not provided with the strut forming part 114, and the plurality of first inclined parts 115 and the plurality of first extension parts 116 are arranged alternately in the circumferential direction DRc. But that's fine. 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 expanded portions 126 are arranged alternately in a row in the circumferential direction DRc. But it's okay. In this case, the plurality of struts 13 may be provided between each of the first inclined portion 115 and the first expanded portion 116 that are continuous in the circumferential direction DRc.

In the embodiment described above, the first slope portion 115 and the second slope portion 125 are formed between two adjacent support columns 13 in a range from the support column 13 on the upstream side of the air flow to the support column 13 on the downstream side. Although the example described above is not limited to this example. For example, the first slope portion 115 and the second slope portion 125 extend between two adjacent support columns 13 from a position overlapping the support column 13 on the upstream side of the air flow in the radial direction DRr to the support column 13 on the downstream side. may be formed. Moreover, the first slope part 115 and the second slope part 125 extend between two adjacent pillars 13 from the air flow upstream pillar 13 to the position where it overlaps the downstream pillar 13 in the radial direction DRr. may be formed. Furthermore, between two adjacent struts 13, the first sloped portion 115 and the second sloped portion 125 extend from a position overlapping with the strut 13 on the upstream side of the air flow in the radial direction DRr to with the strut 13 on the downstream side in the radial direction DRr. They may be formed in a range up to an overlapping position.

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

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

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

In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where it is specifically specified that they are essential, or where they are clearly considered essential in principle.

In the embodiments described above, when numerical values such as the number, numerical value, amount, range, etc. of the constituent elements of the embodiment are mentioned, it is especially specified that it is essential, or it is clearly limited to a specific number in principle. It is not limited to that specific number, except in certain cases.

In the above-described embodiments, when referring to the shape, positional relationship, etc. of components, etc., we refer to the shape, positional relationship, etc., unless explicitly stated or in principle limited to a specific shape, positional relationship, etc. etc., but not limited to.

(summary)
According to the first aspect shown in some or all of the above-described embodiments, the centrifugal blower includes a centrifugal fan that blows out air by rotating around the fan axis, and a casing that houses the centrifugal fan. Be prepared. The casing has an air intake port 111 through which air sucked by the centrifugal fan passes, and a first cover part 11 that covers one side of the centrifugal fan in the axial direction of the fan axis, and a first cover part 11 that covers one side of the centrifugal fan in the axial direction of the fan axis. It has a second cover part 12 that covers the side. The casing has at least one support that maintains a gap between the first cover part and the second cover part. The first cover part has a first cover surface that faces the second cover part of the first cover part. The second cover part has a second cover surface that faces the first cover part of the second cover part. The first cover part and the second cover part have a first cover surface that extends radially outward from the centrifugal fan, and a second cover surface that extends radially outward from the centrifugal fan. The first cover part and the second cover part form a ventilation path through which the air blown out by the centrifugal fan flows in the gap between the first cover part and the second cover part. A blowout port 16 is formed to blow out the water all around the casing. The support column is provided on the outside of the centrifugal fan in the radial direction in the ventilation passage. At least one of the first cover surface and the second cover surface is arranged toward the air flow upstream side in the circumferential direction of the fan axis from the part where the support is provided, and from the air flow upstream side in the circumferential direction to the downstream side. The ventilation passage has an inclined portion that gradually increases the size of the ventilation passage 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 passage from the inside in the radial direction to the outside. It has an extension that makes it larger. The expanded portion is connected to the inclined portion and is inclined with respect to the radial direction.

According to this, the cross-sectional area of the plane perpendicular to the radial direction of the ventilation passage can be gradually expanded from the inside to the outside in the radial direction. Therefore, compared to the case where the cross-sectional area of the plane perpendicular to the radial direction of the ventilation passage is expanded in a stepwise manner, contraction loss that occurs due to the expansion of the cross-sectional area of the ventilation passage can be suppressed.

According to the third aspect, a plurality of struts are provided side by side in the circumferential direction. Among the plurality of columns, a predetermined column is used as one column, and among the columns adjacent to the column, a column provided upstream of the predetermined column in the air flow is used 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 seat surface that supports one support and the other support. The inclined portion includes a range from the seat surface where one support column is provided to the seat surface where the other support column is provided.

According to this, the angle of the inclined part with respect to the circumferential direction is smaller than the range from the seat surface where one support is provided to the seat surface where the other support is provided. The angle can be made smaller than the angle with respect to the circumferential direction. Therefore, the cross-sectional area of the plane perpendicular to the circumferential direction in the ventilation passage can be gradually increased, making it easier to suppress the pressure loss that occurs when converting dynamic pressure to static pressure by expanding the cross-sectional area of the ventilation passage. .

10 Casing 11 First cover part 12 Second cover part 13 Support column 15 Ventilation passage 16 Air outlet 20 Centrifugal fan 112 First cover surface 123 Second cover surface 125 Inclined part

Claims (3)

A centrifugal blower,
a centrifugal fan (20) that blows out air by rotating around a fan axis (CL);
a casing (10) that accommodates the centrifugal fan;
The casing is
a first cover part (11) formed with an air intake port (111) through which air sucked by the centrifugal fan passes, and which covers one side of the centrifugal fan in the axial direction of the fan axis;
a second cover part (12) that covers the other side of the centrifugal fan in the axial direction;
at least one support post (13) that maintains a gap between the first cover part and the second cover part,
The first cover part and the second cover part are arranged on a first cover surface (112) of the first cover part that faces the second cover part and are located on the outside of the centrifugal fan in the radial direction of the fan axis. The centrifugal fan blows air into a gap between the projecting part and a part of the second cover surface (123) of the second cover part facing the first cover part that projects outward in the radial direction from the centrifugal fan. An air outlet that forms a ventilation passage (15) through which air flows, and that blows out air from the centrifugal fan over the entire circumference of the casing by an outer edge of the first cover surface and an outer edge of the second cover surface. (16),
The support column is provided outside the centrifugal fan in the radial direction in the ventilation passage,
At least one of the first cover surface and the second cover surface is arranged on an air flow upstream side in the circumferential direction of the fan axis from a portion where the support is provided, and on an air flow upstream side in the circumferential direction of the fan axis. an inclined portion (115, 125) that gradually increases the size of the ventilation passage in the axial direction toward the downstream side;
In the centrifugal blower, the inclined portion is 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 in the axial direction of the ventilation passage from the inside in the radial direction to the outside. an extension (116, 126);
The centrifugal blower according to claim 1, wherein the expanded portion is connected to the inclined portion and is inclined with respect to the radial direction. A plurality of the pillars are arranged in a row in the circumferential direction, and among the plurality of pillars, a predetermined pillar is used as one pillar, and among the pillars adjacent to the predetermined pillar, air flows from the predetermined pillar. 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 slope is formed has a seat surface (114, 124) that supports the one support and the other support,
The centrifugal blower according to claim 1 or 2, wherein the inclined portion includes a range from the seat surface where the one support column is provided to the seat surface where the other support column is provided.

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