Centrifugal blower

Abstract

A side plate (20) of a turbo fan (18) has a side plate rib (22) that protrudes to one side in an axial direction (Da) of a fan axis and extends in a circumferential direction (Dc) of the fan axis. A cover part (13) is provided on the one side in the axial direction with a gap (Ca) between the cover part and the side plate. Moreover, the cover part has a cover recess (14) which is formed to be recessed to the one side from the other side in the axial direction, extends in the circumferential direction, and into which a tip part (22c) of the side plate rib enters from the other side in the axial direction. The cover recess has a recess outer wall surface (14a), which is formed on an outer side in a radial direction (Dr) relative to the side plate rib and faces the side plate rib in the radial direction with a space between the recess outer wall surface and the side plate rib, and a recess inner wall surface (14b), which is formed on an inner side in the radial direction relative to the side plate rib and faces the side plate rib in the radial direction with a space between the recess inner wall surface and the side plate rib. A minimum interval (C1n) in the radial direction formed between the recess outer wall surface and the side plate rib is smaller than a maximum interval (C2w) in the radial direction formed between the recess inner wall surface and the side plate rib.

Description

centrifugal blower CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2024-42673, filed on March 18, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a centrifugal blower that blows out air.

[0003] Patent Document 1 discloses a centrifugal blower. This centrifugal blower includes a turbofan that rotates together with a rotary shaft and a casing that houses the turbofan. The turbofan has a shroud that is provided on one axial side of the rotary shaft in relation to a plurality of blades and expands in the radial direction, and the casing has a cover portion that is provided on one axial side opposite the shroud with a gap therebetween.

[0004] The shroud has a ring-shaped projection that extends around the rotation axis and projects to one side in the axial direction, and the cover of the casing has a corresponding recess that extends around the rotation axis and fits into the projection of the shroud.

[0005] Japanese Patent Application Laid-Open No. 2018-168852

[0006] In centrifugal blowers, a gap between the shroud of the turbofan and the cover of the casing is necessary to prevent interference between the turbofan and the casing, but a backflow of air from the outlet side to the suction side occurs in this gap due to the static pressure difference between the intake and outlet of the turbofan. In other words, the gap between the shroud and the cover becomes a backflow path where the backflow of air occurs. This backflow of air is a cause of noise.

[0007] In order to suppress such backflow of air, the centrifugal blower of Patent Document 1 has a protrusion on the shroud to lengthen the backflow passage, thereby increasing the backflow pressure loss in the backflow passage and suppressing the backflow. However, since it is preferable to further suppress the noise caused by the backflow of air, a new technology for suppressing the backflow of air was needed. The inventors have found the above as a result of detailed studies. The shroud is also called a side plate, and the casing is also called a case.

[0008] In view of the above, the present disclosure aims to suppress backflow that occurs in the gap between the side plate of the turbofan and the cover portion of the case in a centrifugal blower by using a new technology not disclosed in Patent Document 1.

[0009] In order to achieve the above object, a centrifugal blower according to one aspect of the present disclosure is a centrifugal blower that blows out air, the centrifugal blower comprising: a turbofan that has a plurality of blades arranged side by side around a fan axis; and a side plate that has intake holes formed therein and is located on one axial side of the fan axis relative to the plurality of blades and is connected to each of the plurality of blades, the turbofan rotating around the fan axis to draw in air from one axial side through the intake holes and blow out the drawn-in air radially outward from the fan axis; and a case that has a cover portion that is located on one axial side with a gap from the side plate and that houses the turbofan, the side plate having a side plate rib that protrudes to one axial side and extends circumferentially about the fan axis, and the cover portion having a cover recess that is formed so as to be recessed from the other axial side to one side and extends circumferentially, and into which a tip of the side plate rib fits from the other axial side, The cover recess is formed with a recess outer wall surface that is located radially outward from the side plate rib and faces radially away from the side plate rib, and a recess inner wall surface that is located radially inward from the side plate rib and faces radially away from the side plate rib, and the minimum radial distance formed between the recess outer wall surface and the side plate rib is smaller than the maximum radial distance formed between the recess inner wall surface and the side plate rib.

[0010] In this way, the backflow air flowing from the outside to the inside in the radial direction in the gap between the side plate and the cover portion suddenly bends and rapidly expands radially as it enters the space between the outer wall surface of the recess and the side plate rib and enters the space between the inner wall surface of the recess and the side plate rib. This generates a vortex in the space between the inner wall surface of the recess and the side plate rib, creating a dead water area, which effectively reduces the cross-sectional area of ​​the flow path through which the backflow air can effectively pass and increases the pressure loss of the backflow air. As a result, it is possible to suppress the flow rate of the backflow air flowing in the gap between the side plate and the cover portion.

[0011] 1 is a longitudinal sectional view schematically showing the configuration of a blower according to a first embodiment; FIG. 2 is a view taken in the direction of an arrow II in FIG. 1 , showing a turbofan included in the blower according to the first embodiment alone; FIG. 3 is a longitudinal sectional view showing an enlarged view of part III of FIG. 1; FIG. 4 is a longitudinal sectional view showing an enlarged view of a part corresponding to part III of FIG. 1 in a blower according to a comparative example, the view corresponding to FIG. 3; FIG. 5 is a longitudinal sectional view showing an enlarged view of a part corresponding to part III of FIG. 1 in a side panel cover gap serving as a backflow flow path in the first embodiment, the view corresponding to FIG. 3; FIG. 6 is a longitudinal sectional view showing an enlarged view of part VII of FIG. 6; FIG. 7 is a longitudinal sectional view showing an enlarged view of part III of FIG. 1 in a first example of other embodiments, the view corresponding to FIG. 3; FIG. 8 is a longitudinal sectional view showing an enlarged view of part IX of FIG. 8 in a second example of other embodiments; FIG. 9 is a longitudinal sectional view showing an enlarged view of part IX of FIG. 8 in a third example of other embodiments, the view corresponding to FIG. 9. 9 is a longitudinal sectional view showing an enlarged view of a portion corresponding to portion IX of Fig. 8 in a fourth example of other embodiments, and corresponds to Fig. 9. 10 is a longitudinal sectional view showing an enlarged view of a portion corresponding to portion IX of Fig. 8 in a fifth example of other embodiments, and corresponds to Fig. 9. 11 is a longitudinal sectional view showing an enlarged view of a portion corresponding to portion IX of Fig. 8 in a sixth example of other embodiments, and corresponds to Fig. 9.

[0012] Hereinafter, each embodiment will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

[0013] 1, a blower 10 is a centrifugal blower that draws air from one side of a fan axis center CL in an axial direction Da and blows the air outward in a radial direction Dr of the fan axis center CL. For example, the blower 10 is mounted on a vehicle, i.e., an automobile.

[0014] The blower 10 includes a case 12, a turbofan 18, and an electric motor (not shown) that rotates the turbofan 18. Fig. 1 shows a vertical cross section including a fan axis CL, specifically, a cross section taken along line I-I in Fig. 2.

[0015] In FIG. 1 , the fan axial direction Da, which is the axial direction Da of the fan axis center CL, and the fan radial direction Dr, which is the radial direction Dr of the fan axis center CL, are each indicated by a double-headed arrow. In FIG. 2 , the fan circumferential direction Dc, which is the circumferential direction Dc of the fan axis center CL, is indicated by a double-headed arrow. The fan axial direction Da is a direction parallel to the fan axis center CL. The fan radial direction Dr is a direction perpendicular to the fan axis center CL and away from the fan axis center CL. In other words, the fan radial direction Dr is the radial direction of a circle drawn on an imaginary plane perpendicular to the fan axis center CL, with the intersection of the imaginary plane and the fan axis center CL as its center. The fan circumferential direction Dc is the circumferential direction of the circle drawn on the imaginary plane.

[0016] 1, the case 12 is a housing that forms the outer shell of the blower 10 and is made up of a plurality of resin parts that are integrally connected by, for example, screws. The case 12 houses the turbofan 18 and the electric motor therein.

[0017] The case 12 is formed with a case inlet 12a, which is an inlet located on one side in the fan axis direction Da of the turbofan 18. This case inlet 12a is open on one side in the fan axis direction Da, and the turbofan 18 draws in air that has passed through this case inlet 12a.

[0018] The case 12 also has a case outlet 12b formed therein, which is an outlet arranged outside the turbofan 18 in the fan radial direction Dr. The case outlet 12b is open over substantially the entire circumference of the case 12, centered on the fan axis CL, except for, for example, a connecting portion that connects components of the case 12 on one side and the other side in the fan axis direction Da relative to the turbofan 18. Air blown out from the turbofan 18 passes through the case outlet 12b and is blown out of the case 12.

[0019] The turbofan 18 is a type of centrifugal fan and is also referred to as the impeller of the blower 10. The turbofan 18 includes a plurality of blades 19, a side plate 20 serving as one plate, and a main plate 24 serving as the other plate. The blades 19, the side plate 20, and the main plate 24 are joined together and fixed together as a single unit. Note that, for ease of viewing, in FIG. 1 , the blades 19 are not shown in cross section, but are shown as a shape projected onto a meridian plane including the fan axis CL. This method of showing the blades 19 will also be used appropriately in the cross-sectional views described below.

[0020] The blades 19 are arranged side by side at intervals around the fan axis CL, and each blade 19 has one end 19a on one side in the fan axis direction Da and another end 19b on the other side in the fan axis direction Da.

[0021] 1 and 2 , the side plate 20 has a disk shape that extends in the fan radial direction Dr around the fan axis CL, and an intake hole 20a is formed at the center of the disk shape, penetrating the side plate 20. The side plate 20 is provided on one side of the plurality of blades 19 in the fan axis direction Da, and the plurality of blades 19 are connected to the side plate 20 at one end 19a of each blade 19. The side plate 20 is also called a shroud.

[0022] The main plate 24 has a disk shape that expands in the fan radial direction Dr around the fan axis center CL. The main plate 24 is provided on the other side of the side plate 20 in the fan axis direction Da, with the plurality of blades 19 sandwiched between them. The plurality of blades 19 are connected to the main plate 24 at their other ends 19b. In other words, the main plate 24 is connected to the side plate 20 via each of the plurality of blades 19. In addition, a rotary shaft 181 of an electric motor that rotates the turbofan 18 is connected to the main plate 24.

[0023] The turbofan 18 is rotated around the fan axis CL by an electric motor. As the turbofan 18 rotates around the fan axis CL, it draws in air from one side in the fan axis direction Da through the case intake port 12a and the intake holes 20a in the side plate 20, and blows the drawn-in air outward in the fan radial direction Dr.

[0024] 1 and 3 , the case 12 houses the turbofan 18 as described above, and therefore has a cover portion 13 provided on one side of the side plate 20 in the fan axis direction Da. As described above, the case 12 is provided with the case inlet 12a, and more specifically, the case inlet 12a is provided in the cover portion 13 of the case 12. That is, the case inlet 12a is formed on the inner periphery of the cover portion 13, penetrating the cover portion 13 in the fan axis direction Da.

[0025] The cover portion 13 of the case 12 is formed to face the side plate 20 with a gap Ca therebetween and to cover the side plate 20 from one side in the fan axis direction Da. In the description of this embodiment, the gap Ca between the cover portion 13 and the side plate 20 may be referred to as a side plate cover gap Ca.

[0026] 2 and 3, the side plate 20 has a side plate main body 21 and multiple side plate ribs 221, 222, and 223. When the multiple side plate ribs 221, 222, and 223 are described collectively without distinguishing between them, the multiple side plate ribs 221, 222, and 223 may be referred to as a "side plate rib 22" or "multiple side plate ribs 22."

[0027] The side plate main body 21 is a portion of the side plate 20 to which one ends 19a of the multiple blades 19 are respectively connected, and is disposed opposite the main plate 24 with the multiple blades 19 sandwiched between them. The side plate main body 21 is in the form of a circular plate that extends in the fan radial direction Dr and the fan circumferential direction Dc, and has air intake holes 20a formed on the inside of the side plate main body 21. Around the air intake holes 20a, the side plate main body 21 forms a cylindrical shape and extends in the fan axial direction Da, with the air intake holes 20a formed on the inside of the side plate main body 21.

[0028] Each of the side plate ribs 22 is formed to protrude from the side plate main body 21 to one side in the fan axial direction Da and extend in the fan circumferential direction Dc. Specifically, each of the side plate ribs 22 extends in an annular shape centered on the fan axis CL. That is, the side plate ribs 22 are formed as ribs extending in concentric annular shapes.

[0029] Each of the side plate ribs 22 has an outer peripheral side surface 22a facing outward in the fan radial direction Dr, an inner peripheral side surface 22b facing inward in the fan radial direction Dr, and a tip portion 22c provided on one side in the fan axial direction Da.

[0030] Specifically, the multiple side plate ribs 22 are a first side plate rib 221, a second side plate rib 222, and a third side plate rib 223. These first to third side plate ribs 221, 222, 223 are arranged in the order of the first side plate rib 221, the second side plate rib 222, and the third side plate rib 223, arranged at intervals from the outside in the fan radial direction Dr.

[0031] Therefore, for example, if the first side plate rib 221 corresponds to the outer side plate rib of the present disclosure, the second side plate rib 222 corresponds to the inner side plate rib of the present disclosure. Also, if the second side plate rib 222 corresponds to the outer side plate rib of the present disclosure, the third side plate rib 223 corresponds to the inner side plate rib of the present disclosure.

[0032] Furthermore, because each of the multiple side plate ribs 22 protrudes from the side plate main body 21, the spaces between the protruding side plate ribs 22 are concave. Therefore, side plate recesses 231, 232 are formed between the multiple side plate ribs 22 in the side plate 20. That is, the side plate 20 has multiple side plate recesses 231, 232. Each of the multiple side plate recesses 231, 232 is formed so as to be recessed from one side to the other in the fan axial direction Da, and extends in the fan circumferential direction Dc.

[0033] More specifically, each of the side plate recesses 231, 232 is formed so as to be sandwiched between adjacent side plate ribs 22 in the fan radial direction Dr, and therefore extends in an annular shape around the fan axis CL, similar to the side plate ribs 22. When the side plate recesses 231, 232 are described collectively without being distinguished from one another, the side plate recesses 231, 232 may be referred to as a "side plate recess 23" or a "plurality of side plate recesses 23."

[0034] Specifically, the multiple side plate recesses 23 are a first side plate recess 231 and a second side plate recess 232. The first side plate recess 231 is formed between the first side plate rib 221 and the second side plate rib 222 in the fan radial direction Dr, and the second side plate recess 232 is formed between the second side plate rib 222 and the third side plate rib 223 in the fan radial direction Dr. Therefore, the first and second side plate recesses 231, 232 are arranged in this order from the outside in the fan radial direction Dr, with the second side plate rib 222 interposed between the first side plate recess 231 and the second side plate recess 232.

[0035] 3, the cover portion 13 of the case 12 has a plurality of cover recesses 141, 142, and 143. These cover recesses 141, 142, and 143 are provided to correspond to the plurality of side plate ribs 22, respectively, and therefore the number of cover recesses provided is the same as the number of side plate ribs 22. When the plurality of cover recesses 141, 142, and 143 are described collectively without being distinguished from one another, the plurality of cover recesses 141, 142, and 143 may be referred to as a "cover recess 14" or a "plurality of cover recesses 14."

[0036] Each of the cover recesses 14 is recessed from one side to the other side in the fan axial direction Da and extends in the fan circumferential direction Dc. More specifically, each of the cover recesses 14 extends in an annular shape around the fan axis CL. That is, the cover recesses 14 are formed as grooves extending in concentric annular shapes.

[0037] Each of the cover recesses 14 has a rectangular cross section that includes the fan axis CL (e.g., the cross section in FIG. 3 ). Therefore, each of the cover recesses 14 has an outer wall surface 14 a, an inner wall surface 14 b, and a bottom surface 14 c.

[0038] The recess outer wall surface 14a of the cover recess 14 is a side wall surface that faces the inner space of the cover recess 14 from the outside in the fan radial direction Dr and faces inward in the fan radial direction Dr. The recess inner wall surface 14b is a side wall surface that faces the inner space of the cover recess 14 from the inside in the fan radial direction Dr and faces outward in the fan radial direction Dr. The recess bottom surface 14c is a wall surface that faces the inner space of the cover recess 14 from one side in the fan axial direction Da and forms the bottom of the inner space and faces the other side in the fan axial direction Da.

[0039] Specifically, the multiple cover recesses 14 are a first cover recess 141, a second cover recess 142, and a third cover recess 143. These first to third cover recesses 141, 142, and 143 are arranged in the order of first cover recess 141, second cover recess 142, and third cover recess 143 from the outside in the fan radial direction Dr.

[0040] Therefore, for example, if first cover recess 141 corresponds to the outer cover recess of the present disclosure, second cover recess 142 corresponds to the inner cover recess of the present disclosure, and if second cover recess 142 corresponds to the outer cover recess of the present disclosure, third cover recess 143 corresponds to the inner cover recess of the present disclosure.

[0041] The tip end 22 c of the first side plate rib 221 enters the inside of the first cover recess 141 from the other side in the fan axis direction Da. Therefore, the recess outer wall surface 14 a of the first cover recess 141 is provided outward from the first side plate rib 221 in the fan radial direction Dr and faces the outer peripheral side surface 22 a of the first side plate rib 221 in the fan radial direction Dr at a distance. The recess inner wall surface 14 b of the first cover recess 141 is provided inward from the first side plate rib 221 in the fan radial direction Dr and faces the inner peripheral side surface 22 b of the first side plate rib 221 in the fan radial direction Dr at a distance. Furthermore, the recess bottom surface 14 c of the first cover recess 141 is provided on one side in the fan axis direction Da at a distance from the first side plate rib 221 and faces the tip end 22 c of the first side plate rib 221 in the fan axis direction Da.

[0042] The second and third cover recesses 142, 143 are similar to the first cover recess 141 described above. That is, the tip end 22c of the second side plate rib 222 enters the inside of the second cover recess 142 from the other side in the fan axis direction Da. Therefore, the recess outer wall surface 14a of the second cover recess 142 is provided outward from the second side plate rib 222 in the fan radial direction Dr and faces the fan radial direction Dr at a distance from the outer peripheral side surface 22a of the second side plate rib 222. The recess inner wall surface 14b of the second cover recess 142 is provided inward from the second side plate rib 222 in the fan radial direction Dr and faces the fan radial direction Dr at a distance from the inner peripheral side surface 22b of the second side plate rib 222. The recess bottom surface 14c of the second cover recess 142 is located on one side of the second side plate rib 222 in the fan axial direction Da, away from the second side plate rib 222, and faces the tip end 22c of the second side plate rib 222 in the fan axial direction Da.

[0043] The tip end 22 c of the third side plate rib 223 enters the inside of the third cover recess 143 from the other side in the fan axis direction Da. Therefore, the recess outer wall surface 14 a of the third cover recess 143 is provided outward from the third side plate rib 223 in the fan radial direction Dr and faces the outer peripheral side surface 22 a of the third side plate rib 223 in the fan radial direction Dr at a distance. The recess inner wall surface 14 b of the third cover recess 143 is provided inward from the third side plate rib 223 in the fan radial direction Dr and faces the inner peripheral side surface 22 b of the third side plate rib 223 in the fan radial direction Dr at a distance. Furthermore, the recess bottom surface 14 c of the third cover recess 143 is provided on one side in the fan axis direction Da at a distance from the third side plate rib 223 and faces the tip end 22 c of the third side plate rib 223 in the fan axis direction Da.

[0044] 3, the cover recesses 14 are formed in the shape of grooves arranged in parallel with one another, so that the spaces between the groove-shaped cover recesses 14 protrude from the recess bottom surfaces 14c of the cover recesses 14. Therefore, cover portion ribs 151, 152 are formed between the cover recesses 14 in the cover portion 13 of the case 12. That is, the cover portion 13 has the cover portion ribs 151, 152 formed to separate the cover recesses 14 adjacent to each other in the fan radial direction Dr.

[0045] Each of the multiple cover portion ribs 151, 152 is formed to protrude to the other side in the fan axial direction Da and extend in the fan circumferential direction Dc. More specifically, each of the multiple cover portion ribs 151, 152 is formed between adjacent cover recesses 14 in the fan radial direction Dr, and therefore extends in an annular shape around the fan axis center CL, similar to the cover recesses 14. When the multiple cover portion ribs 151, 152 are described collectively without being distinguished from one another, the multiple cover portion ribs 151, 152 may be referred to as a "cover portion rib 15" or "multiple cover portion ribs 15."

[0046] Specifically, the multiple cover portion ribs 15 are a first cover portion rib 151 and a second cover portion rib 152. The first cover portion rib 151 is interposed between the first cover recess 141 and the second cover recess 142 in the fan radial direction Dr. In other words, the second cover recess 142 is adjacent to the first cover recess 141 on the inside in the fan radial direction Dr, with the first cover portion rib 151 sandwiched between them. Therefore, the first cover portion rib 151 has a side surface facing inward in the fan radial direction Dr as the recess outer wall surface 14a of the second cover recess 142, and a side surface facing outward in the fan radial direction Dr as the recess inner wall surface 14b of the first cover recess 141. In other words, it can be said that the recess outer wall surface 14a of the second cover recess 142 and the recess inner wall surface 14b of the first cover recess 141 are formed on the first cover portion rib 151.

[0047] The second cover portion rib 152 is interposed between the second cover recess 142 and the third cover recess 143 in the fan radial direction Dr. In other words, the third cover recess 143 is adjacent to the second cover recess 142 on the inside in the fan radial direction Dr, with the second cover portion rib 152 sandwiched between them. Therefore, the second cover portion rib 152 has a side surface facing inward in the fan radial direction Dr as the recess outer wall surface 14a of the third cover recess 143, and a side surface facing outward in the fan radial direction Dr as the recess inner wall surface 14b of the second cover recess 142. In other words, it can be said that the recess outer wall surface 14a of the third cover recess 143 and the recess inner wall surface 14b of the second cover recess 142 are formed on the second cover portion rib 152.

[0048] Each of the cover ribs 15 has a tip 15c provided on the other side in the fan axial direction Da. The tip 15c of each of the cover ribs 15 extends from one side in the fan axial direction Da into the inside of a side panel recess 23 formed to face the tip 15c.

[0049] More specifically, the tip 15c of the first cover part rib 151 enters the inside of the first side plate recess 231 from one side in the fan axis direction Da. The tip 15c of the second cover part rib 152 enters the inside of the second side plate recess 232 from one side in the fan axis direction Da.

[0050] The relative arrangement of the first to third side plate ribs 221, 222, 223 and the first and second cover portion ribs 151, 152 can be described as follows: In other words, the side plate ribs 221, 222, 223 and the cover portion ribs 151, 152 are arranged in the following order from the outside in the fan radial direction Dr: first side plate rib 221, first cover portion rib 151, second side plate rib 222, second cover portion rib 152, third side plate rib 223, spaced apart from one another.

[0051] Figure 3 shows a first distance C1, which is the distance between the recess outer wall surface 14a and the side plate rib 22, and a second distance C2, which is the distance between the recess inner wall surface 14b and the side plate rib 22. These first and second distances C1 and C2 are distances in the fan radial direction Dr that appear in vertical cross sections such as Figure 3. Figure 3 also shows a rib tip distance Ct, which is the distance between the recess bottom surface 14c and the side plate rib 22, and a side plate rib thickness Tr, which is the thickness of the side plate rib 22 in the fan radial direction Dr.

[0052] 3 and other longitudinal cross sections, the first spacing C1, the second spacing C2, and the rib tip spacing Ct are all equal to or greater than the maximum side-plate rib thickness Trm, which is the maximum value of the side-plate rib thickness Tr. This is true for all of the first to third cover recesses 141, 142, and 143. In this embodiment, the side-plate rib thickness Tr is the same regardless of the position in the fan axial direction Da, so the maximum and minimum values ​​of the side-plate rib thickness Tr are also the same. Furthermore, the thickness of the cover portion rib 15 in the fan radial direction Dr is also the same regardless of the position in the fan axial direction Da.

[0053] 3, when the minimum first interval C1n, which is the minimum value of the first interval C1, is compared with the maximum second interval C2w, which is the maximum value of the second interval C2, the minimum first interval C1n is smaller than the maximum second interval C2w. This is true for any of the first to third cover recesses 141, 142, and 143.

[0054] The outer wall surface 14a and inner wall surface 14b of the cover recess 14, and the outer and inner side surfaces 22a and 22b of the side plate ribs 22 are all cylindrical surfaces extending along the fan axis direction Da. Therefore, in this embodiment, the maximum and minimum values ​​of the first distance C1 are the same, and the maximum and minimum values ​​of the second distance C2 are also the same. Therefore, in this embodiment, it can be said simply that the first distance C1 is smaller than the second distance C2.

[0055] Here, to explain the effects achieved by the blower 10 of this embodiment, a comparative blower 80 shown in Fig. 4 will be considered. As shown in Fig. 4, the comparative blower 80 is different from the blower 10 of this embodiment in that the first distance C1 and the second distance C2 are equal to each other in all of the first to third cover recesses 141, 142, and 143. Except for this point, the comparative blower 80 is similar to the blower 10 of this embodiment.

[0056] In contrast, as described above, according to this embodiment, as shown in FIG. 3, the minimum first distance C1n is smaller than the maximum second distance C2w for each of the first to third cover recesses 141, 142, and 143. Simply put, the first distance C1 is smaller than the second distance C2. Therefore, as shown in FIG. 5, a dead water area Ba is generated in the backflow air flow Rf that flows backward through the side panel cover gap Ca from the case air outlet 12b side to the case air inlet 12a side, i.e., the backflow air flow Rf. The dead water area Ba may also be referred to as a stagnation area because it is an area where the backflow air flow Rf stagnates.

[0057] Specifically, in the side panel cover gap Ca, which serves as a backflow flow path, the backflow air flow Rf abruptly bends and rapidly expands in the fan radial direction Dr as it enters the space between the recess inner wall surface 14b and the side panel rib 22 from the space between the recess outer wall surface 14a and the side panel rib 22. This causes a vortex Wh to be generated in the space between the recess inner wall surface 14b and the side panel rib 22, closer to the side panel rib 22, creating a dead water area Ba. For example, in this embodiment, the sudden expansion of the backflow flow path described above can create a larger dead water area Ba than in the comparative example.

[0058] Therefore, in this embodiment, the cross-sectional area of ​​the flow path through which the backflow airflow Rf effectively passes is substantially reduced, and the pressure loss of the backflow air can be increased significantly compared to, for example, the comparative example. As a result, the flow rate of the backflow air flowing through the side panel cover gap Ca can be suppressed, and the noise caused by the backflow airflow Rf can be reduced.

[0059] In the description of this embodiment, the space between the recess outer wall surface 14a and the side plate rib 22 may be referred to as a first space E1, and the space between the recess inner wall surface 14b and the side plate rib 22 may be referred to as a second space E2. Just to be clear, the first space E1 and the second space E2 are part of the side plate cover gap Ca.

[0060] Furthermore, in this embodiment, multiple combinations of the cover recess 14 and the side plate rib 22 are provided. That is, multiple structures are continuously provided in which the backflow flow path suddenly bends and expands as the backflow airflow Rf advances. This further promotes the expansion of each dead water area Ba, making it possible to further suppress the backflow air flow rate and reduce noise.

[0061] Furthermore, when the first and second spaces E1 and E2 are compared with each other across the side plate rib 22, the second space E2 is located more inward in the fan radial direction Dr than the first space E1, and therefore the length of the second space E2 in the fan circumferential direction Dc is shorter than that of the first space E1. That is, in a cross section perpendicular to the fan axis CL, the cross-sectional area of ​​the backflow passage in the second space E2 is smaller than that of the first space E1, resulting in a higher average flow velocity of the backflow air. In this embodiment, the generation of a dead water region Ba is promoted in the second space E2, which has a higher average flow velocity, and therefore the dead water region Ba can be generated efficiently.

[0062] Furthermore, according to this embodiment, as shown in FIG. 3 , predetermined flow path configurations in which the backflow flow path abruptly bends and rapidly expands downstream of the bend are provided across the side plate ribs 22 in the fan radial direction Dr. Three predetermined flow path configurations are formed. In contrast, a reversed assumed example is also conceivable in which the predetermined flow path configurations are provided across the cover portion ribs 15 in the fan radial direction Dr rather than across the side plate ribs 22. However, in this reversed assumed example, only two predetermined flow path configurations are formed. In other words, in this embodiment, it is possible to form more predetermined flow path configurations than in the reversed assumed example.

[0063] Second Embodiment Next, a second embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described. Furthermore, parts that are the same as or equivalent to the first embodiment will be omitted or simplified. This also applies to the following embodiments.

[0064] As shown in Figures 6 and 7, the inner peripheral side surface 22b of the side plate rib 22 includes a side plate rib inclined surface 22d and an other-side extended surface 22e provided on the other side of the side plate rib inclined surface 22d in the fan axial direction Da.

[0065] The side plate rib inclined surface 22d is formed to face the recess inner wall surface 14b of the cover recess 14 in the fan radial direction Dr. At the same time, the side plate rib inclined surface 22d extends from the tip end 22c of the side plate rib 22 to the other side in the fan axial direction Da and is inclined with respect to the fan axial direction Da. In detail, the side plate rib inclined surface 22d is positioned outward in the fan radial direction Dr toward one side in the fan axial direction Da and is inclined with respect to the fan axial direction Da so as to move away from the recess inner wall surface 14b in the fan radial direction Dr.

[0066] The side plate rib 22 is formed so that the radial width Trs of the side plate rib inclined surface 22d in the fan radial direction Dr is as large as possible within the maximum side plate rib thickness Trm. For example, in this embodiment, the radial width Trs of the side plate rib inclined surface 22d is equal to or greater than 50% of the maximum side plate rib thickness Trm.

[0067] The other-side extending surface 22e extends from the other end of the side plate rib inclined surface 22d on the other side in the fan axial direction Da along the fan axial direction Da to the other side in the fan axial direction Da.

[0068] The recess outer wall surface 14a formed as the side surface of the cover portion rib 15 includes a recess outer inclined surface 14d and a one-side extension surface 14e provided on one side of the recess outer inclined surface 14d in the fan axis direction Da.

[0069] Note that the recess outer wall surfaces 14a of the second and third cover recesses 142, 143 are also side surfaces of the cover portion rib 15, but the recess outer wall surface 14a of the first cover recess 141 is not a side surface of the cover portion rib 15. Therefore, among the multiple recess outer wall surfaces 14a, the recess outer wall surfaces 14a of the second and third cover recesses 142, 143 include recess outer inclined surfaces 14d, but the recess outer wall surface 14a of the first cover recess 141, which is not a side surface of the cover portion rib 15, does not include recess outer inclined surfaces 14d. This recess outer inclined surface 14d corresponds to the cover portion rib inclined surface of the present disclosure.

[0070] The recess outer inclined surface 14d is formed to face the outer peripheral side surface 22a of the side plate rib 22 in the fan radial direction Dr. At the same time, the recess outer inclined surface 14d extends from the tip end 15c of the cover portion rib 15 to one side in the fan axial direction Da and is inclined with respect to the fan axial direction Da. More specifically, the recess outer inclined surface 14d is positioned more outward in the fan radial direction Dr as it approaches the other side in the fan axial direction Da, and is inclined with respect to the fan axial direction Da so as to move away from the outer peripheral side surface 22a of the side plate rib 22 in the fan radial direction Dr.

[0071] The one-side extending surface 14e of the cover recess 14 extends from one end of the recess outer inclined surface 14d on one side in the fan axial direction Da along the fan axial direction Da to one side in the fan axial direction Da.

[0072] In this embodiment, because the inner peripheral side surface 22b of the side plate rib 22 includes the side plate rib inclined surface 22d as described above, the second distance C2 in the fan radial direction Dr between the recess inner wall surface 14b and the side plate rib 22 is not constant. Specifically, the second distance C2 is a maximum second distance C2w at one end of the side plate rib inclined surface 22d on one side of the fan axis direction Da. The second distance C2 then narrows toward the other side of the fan axis direction Da. For example, in this embodiment, the second distance C2 is a minimum second distance C2n, which is the minimum value of the second distance C2, at the other end of the recess inner wall surface 14b on the other side of the fan axis direction Da.

[0073] The position of one end of the side plate rib inclined surface 22d is, in other words, the position where the surface formed by the corner R of the tip 22c of the side plate rib 22 and the side plate rib inclined surface 22d connect. The position of the other end of the recess inner wall surface 14b is, in other words, the position where the surface formed by the corner R of the tip 15c of the cover portion rib 15 connects with the recess inner wall surface 14b.

[0074] Furthermore, as described above, because the recess outer wall surface 14a formed on the cover portion rib 15 includes the recess outer inclined surface 14d, the first distance C1 in the fan radial direction Dr between the recess outer wall surface 14a and the side plate rib 22 is also not constant. Specifically, the first distance C1 reaches a maximum first distance C1w, which is the maximum value of the first distance C1, at the other end of the recess outer inclined surface 14d on the other side of the fan axis direction Da. The first distance C1 then narrows toward one side in the fan axis direction Da. For example, in this embodiment, the first distance C1 reaches a minimum first distance C1n at one end of the outer peripheral side surface 22a of the side plate rib 22 on one side in the fan axis direction Da.

[0075] The position of the other end of the recess outer inclined surface 14d is, in other words, the connection position between the surface formed by the corner R of the tip 15c of the cover portion rib 15 and the recess outer inclined surface 14d. Moreover, the position of one end of the outer peripheral side surface 22a is, in other words, the connection position between the surface formed by the corner R of the tip 22c of the side plate rib 22 and the outer peripheral side surface 22a.

[0076] In this embodiment, as described above, a corner R is formed at the tip end 22 c of the side plate rib 22. The corner R of the tip end 22 c extends from one end of the side plate rib inclined surface 22 d to the outer peripheral side surface 22 a of the side plate rib 22, and is smoothly connected to both the side plate rib inclined surface 22 d and the outer peripheral side surface 22 a.

[0077] As described above, a corner R is also formed at the tip 15c of the cover rib 15. The corner R of the tip 15c extends from the other end of the recess outer inclined surface 14d to the recess inner wall surface 14b, and is smoothly connected to both the recess outer inclined surface 14d and the recess inner wall surface 14b.

[0078] Furthermore, in any of the first to third cover recesses 141, 142, and 143, the minimum first distance C1n between the recess outer wall surface 14a and the side plate rib 22 is smaller than the maximum second distance C2w between the recess inner wall surface 14b and the side plate rib 22. The magnitude relationship between the minimum first distance C1n and the maximum second distance C2w is the same as in the first embodiment.

[0079] Furthermore, unlike the first embodiment, the present embodiment includes the recess outer inclined surface 14d and the side plate rib inclined surface 22d as described above. Therefore, the minimum second distance C2n between the first cover portion rib 151 and the first side plate rib 221 is smaller than the maximum first distance C1w between the first cover portion rib 151 and the second side plate rib 222. Similarly, the minimum second distance C2n between the second cover portion rib 152 and the second side plate rib 222 is smaller than the maximum first distance C1w between the second cover portion rib 152 and the third side plate rib 223.

[0080] In this embodiment, as in the first embodiment, the first distance C1, the second distance C2, and the rib tip distance Ct are all equal to or greater than the maximum side plate rib thickness Trm in the vertical cross section shown in Fig. 7. This is true for any of the first to third cover recesses 141, 142, and 143.

[0081] (1) As described above, according to this embodiment, the side plate rib 22 has the side plate rib inclined surface 22 d. The side plate rib inclined surface 22 d is positioned outward in the fan radial direction Dr toward one side in the fan axial direction Da and is inclined with respect to the fan axial direction Da so as to be spaced apart in the fan radial direction Dr from the recess inner wall surface 14 b.

[0082] This allows the tip 22 c of the side plate rib 22 to have a sharper shape, so that the counterflow airflow Rf rapidly expands in the fan radial direction Dr as it enters the second space E2 between the recess inner wall surface 14 b and the side plate rib 22 from the first space E1 between the recess outer wall surface 14 a and the side plate rib 22, and bends more sharply than if the side plate rib inclined surface 22 d were not present.

[0083] As a result, the dead water area Ba in the second space E2 is larger than when the side plate rib inclined surface 22d is not provided, and the cross-sectional area of ​​the flow path through which the backflow airflow Rf effectively passes can be substantially reduced. Arrow A2 in Figure 7 indicates the backflow airflow Rf passing through the second space E2.

[0084] (2) Furthermore, according to this embodiment, the minimum second distance C2n between the first cover portion rib 151 and the first side plate rib 221 is smaller than the maximum first distance C1w between the first cover portion rib 151 and the second side plate rib 222. Moreover, the minimum second distance C2n between the second cover portion rib 152 and the second side plate rib 222 is smaller than the maximum first distance C1w between the second cover portion rib 152 and the third side plate rib 223.

[0085] Therefore, the backflow airflow Rf in the side panel cover gap Ca sharply bends and expands in the fan radial direction Dr when it enters the first space E1 from the second space E2 across the first cover portion rib 151. This also increases the dead water area Ba in the first space E1, thereby increasing the pressure loss of the backflow air. As a result, the flow rate of backflow air flowing through the side panel cover gap Ca can be further suppressed than in the first embodiment, for example, and noise caused by the backflow airflow Rf can be reduced. For example, in this embodiment, the flow rate of backflow air is reduced by approximately 30% compared to the comparative example shown in FIG. 4. Arrow A1 in FIG. 7 indicates the backflow airflow Rf passing through the first space E1.

[0086] (3) In this embodiment, the first distance C1, the second distance C2, and the rib tip distance Ct are all equal to or greater than the maximum side rib thickness Trm in the longitudinal cross section, as in the first embodiment. Furthermore, in this embodiment, the radial width Trs of the side rib inclined surface 22d is equal to or greater than 50% of the maximum side rib thickness Trm.

[0087] Therefore, in the longitudinal cross section, the radius of curvature formed along the surface of the side plate rib 22 near the tip end 22c of the side plate rib 22 can be made significantly smaller than the radius of curvature of the main flow of the countercurrent airflow Rf that bends around the side plate rib 22. This can promote the expansion of the dead water area Ba that occurs in the second space E2.

[0088] Furthermore, according to this embodiment, the inner peripheral side surface 22b of the side plate rib 22 is not entirely formed as the side plate rib inclined surface 22d, but includes an other-side extending surface 22e provided on the other side in the fan axial direction Da of the side plate rib inclined surface 22d. The other-side extending surface 22e is connected to the side plate rib inclined surface 22d and extends along the fan axial direction Da.

[0089] 7 and other longitudinal cross sections, the inner peripheral side surface 22b of the side plate rib 22 bulges toward the second space E2. Therefore, compared to when the entire inner peripheral side surface 22b is the side plate rib inclined surface 22d without changing the maximum side plate rib thickness Trm, the width of the backflow passage facing the inner peripheral side surface 22b is narrower. Therefore, the flow velocity of the backflow air flowing through the backflow passage increases, making the backflow air flow Rf more turbulent, and thus enlarging the dead water area Ba generated in the second space E2.

[0090] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0091] (Other embodiments) (1) In the second embodiment described above, as shown in Figures 6 and 7, the cover portion rib 15 has a recess outer inclined surface 14d, and the side plate rib 22 has a side plate rib inclined surface 22d, but it is not necessary for all ribs 15, 22 to have an inclined surface.

[0092] 8, the side plate rib 22 may have a side plate rib inclined surface 22d, but the cover portion rib 15 may not have a recess outer inclined surface 14d, and the cover portion rib 15 may have the same shape as in the first embodiment. Although not shown, this may be reversed between the cover portion rib 15 and the side plate rib 22. That is, the cover portion rib 15 may have a recess outer inclined surface 14d, but the side plate rib 22 may not have a side plate rib inclined surface 22d, and the side plate rib 22 may have the same shape as in the first embodiment.

[0093] Alternatively, the recess outer inclined surface 14d may not be formed on all cover portion ribs 15, and with regard to the side plate ribs 22, the side plate rib inclined surface 22d may be formed only on the third side plate rib 223, which is the innermost of the multiple side plate ribs 22 in the fan radial direction Dr.

[0094] 8, the other-side extending surface 22e may be omitted, and the entire inner peripheral side surface 22b of the side plate rib 22 may be the side plate rib inclined surface 22d. Also, the tip end 22c of the side plate rib 22 may not be rounded, or as shown in FIG. 9, the tip end 22c may be rounded.

[0095] Similarly, although not shown, the cover portion rib 15 may not have the one-side extending surface 14e, and the entire recess outer wall surface 14a may be the recess outer inclined surface 14d. Also, the tip end 15c of the cover portion rib 15 may not be rounded, or may have a rounded corner at the tip end 15c.

[0096] Furthermore, the corner R of each of the tip portions 15 c, 22 c may be formed only on the inside of the fan radial direction Dr as shown in FIG. 10 , or may be formed only on the outside of the fan radial direction Dr as shown in FIG. 11 .

[0097] Furthermore, as shown in FIG. 12, for example, the tip portions 15c and 22c may not be formed with rounded corners, and the tip portions 15c and 22c may have flat surfaces perpendicular to the fan axis direction Da.

[0098] (2) The first intervals C1 do not need to be uniform among the multiple cover recesses 14, and the second intervals C2 do not need to be uniform among the multiple cover recesses 14. For example, the first and second intervals C1 and C2 may each be smaller toward the inside of the cover recesses 14 in the fan radial direction Dr.

[0099] Furthermore, it is not necessary for the rib tip side spacing Ct to be uniform among the plurality of cover recesses 14. For example, the rib tip side spacing Ct may be smaller as the rib is formed closer to the inside in the fan radial direction Dr.

[0100] (3) For example, as shown in Fig. 13, the side plate rib inclined surface 22d may be configured as a curved surface that is curved in vertical cross section. Similarly, although not shown, the recess outer inclined surface 14d formed on the cover portion rib 15 may also be configured as a curved surface that is curved in vertical cross section.

[0101] (4) Note that the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms. Furthermore, it goes without saying that, in each of the above-described embodiments, elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle.

[0102] Furthermore, in each of the above embodiments, when numerical values ​​such as the number, values, amounts, and ranges of components of the embodiments are mentioned, they are not limited to the specific numbers, except when it is particularly clearly stated that they are essential or when they are clearly limited to a specific number in principle, etc. Furthermore, in each of the above embodiments, when the material, shape, positional relationship, etc. of components are mentioned, they are not limited to the material, shape, positional relationship, etc., except when it is particularly clearly stated or when they are clearly limited to a specific material, shape, positional relationship, etc. in principle, etc.

Claims

1. A centrifugal blower for blowing out air, comprising: a turbofan (18) having a plurality of blades (19) arranged side by side around a fan axis (CL); and a side plate (20) having intake holes (20a) formed therein and connected to each of the plurality of blades, the turbofan (18) rotating around the fan axis to draw in air from the one side in the axial direction through the intake holes and blow out the drawn air radially (Dr) of the fan axis; and a case (12) for accommodating the turbofan, the case having a cover (13) provided on the one side in the axial direction with a gap (Ca) from the side plate, the case having side plate ribs (22, 221, 222, 223) protruding to the one side in the axial direction and extending in the circumferential direction (Dc) of the fan axis. the cover portion has a cover recess (14, 141, 142, 143) formed to be recessed from the other side in the axial direction toward the one side, extending in the circumferential direction, and into which a tip end portion (22c) of the side plate rib fits from the other side in the axial direction, and the cover recess is formed with a recess outer wall surface (14a) provided radially outward from the side plate rib and facing the radial direction at a distance from the side plate rib, and a recess inner wall surface (14b) provided radially inward from the side plate rib and facing the radial direction at a distance from the side plate rib, and the radial minimum distance (C1n) formed between the recess outer wall surface and the side plate rib is smaller than the radial maximum distance (C2w) formed between the recess inner wall surface and the side plate rib.

2. A centrifugal blower as described in claim 1, wherein the side plate rib has a side plate rib inclined surface (22d) formed so as to face the inner wall surface of the recess in the radial direction, and the side plate rib inclined surface is inclined with respect to the axial direction so as to be positioned radially outward toward one side in the axial direction and move away from the inner wall surface of the recess in the radial direction.

3. A centrifugal blower as described in claim 1 or 2, wherein the cover portion has a cover portion rib (15, 151, 152) that is provided radially inward of the side plate rib, extends in the circumferential direction, and protrudes to the other side in the axial direction, and the inner wall surface of the recess is formed on the cover portion rib.

4. A plurality of the side plate ribs are provided, and the plurality of side plate ribs include outer side plate ribs (221, 222) and inner side plate ribs (222, 223) arranged radially inward relative to the outer side plate ribs, and the cover portion has cover portion ribs (15, 151, 152) protruding to the other side in the axial direction and extending in the circumferential direction, and the outer side plate ribs, the cover portion ribs, and the inner side plate ribs are arranged in the order of outer side plate rib, cover portion rib, and inner side plate rib from the outside in the radial direction, and are spaced apart from one another, and between the outer side plate rib and the inner side plate rib, side plate recesses (23, 231, 232) are formed in the side plates so as to be recessed from one side in the axial direction to the other side, extend in the circumferential direction, and receive the tip ends (15c) of the cover portion ribs from one side in the axial direction, and a plurality of the cover recesses are provided, the cover recesses include outer cover recesses (141, 142) into which the tip ends of the outer side plate ribs are fitted, and inner cover recesses (142, 143) adjacent to the outer cover recesses on the radially inner side with the cover portion ribs in between, and into which the tip ends of the inner side plate ribs are fitted; the cover portion ribs have a side surface facing inward in the radial direction as the recess outer wall surface of the inner cover recess, and a side surface facing outward in the radial direction as the recess inner wall surface of the outer cover recess; the recess outer wall surface includes a cover portion rib inclined surface (14d) that is positioned radially outward as it approaches the other side in the axial direction and is separated radially from the inner side plate rib; and the radial minimum distance (C2n) formed between the cover portion rib and the outer side plate rib is smaller than the radial maximum distance (C1w) formed between the cover portion rib and the inner side plate rib.

5. A centrifugal blower as set forth in claim 2, wherein the cover recess has a recess bottom surface (14c) that is located on one side of the axial direction away from the side plate rib and faces the other side in the axial direction, and in a longitudinal cross section including the fan axis, the distances (C1, Ct, C2) between the recess outer wall surface, the recess bottom surface, and the recess inner wall surface and the side plate rib are all equal to or greater than the maximum thickness (Trm) of the side plate rib in the radial direction, and the radial width (Trs) occupied by the side plate rib inclined surface in the radial direction is equal to or greater than 50% of the maximum thickness of the side plate rib.

Images