Blower

Abstract

To provide a blower that can suppress noise. [Solution] The blower of the present invention comprises a motor section having a rotor that rotates about a central axis, an impeller section that can rotate together with the rotor, a housing that houses the impeller section, and a reflector that is positioned radially between the impeller section and the inner surface of the housing and extends circumferentially. A portion of the inner surface faces the impeller section radially, and another portion of the inner surface faces the reflector radially.

Description

Technical Field

[0001] The present invention relates to a blower.

Background Art

[0002] A centrifugal fan including an impeller having a plurality of blade pieces arranged radially with respect to a rotation axis and a fan case having a peripheral wall plate surrounding the outer periphery of the impeller is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the centrifugal fan as described above, when the impeller rotates around the rotation axis, sound waves are generated when each blade piece sends air. If such sound waves resonate between the inner surfaces of the peripheral wall plate, there is a risk that the noise during the operation of the centrifugal fan increases.

[0005] In view of the above circumstances, one object of the present invention is to provide a blower capable of suppressing noise.

Means for Solving the Problems

[0006] One aspect of the blower of the present invention includes a motor unit having a rotor that rotates about a central axis, an impeller unit that can rotate together with the rotor, a housing that houses the impeller unit inside, and a reflecting plate that is disposed between the impeller unit and the inner surface of the housing in the radial direction and extends in the circumferential direction. A part of the inner surface faces the impeller unit in the radial direction, and another part of the inner surface faces the reflecting plate in the radial direction.

Effects of the Invention

[0007] According to one aspect of the present invention, noise can be suppressed in a blower. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view showing a blower according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view showing a blower according to the first embodiment. [Figure 3] Figure 3 is a cross-sectional view showing a blower according to the first embodiment, and is a cross-sectional view taken along line III-III in Figure 2. [Figure 4] Figure 4 is a cross-sectional view showing a blower according to the second embodiment. [Figure 5] Figure 5 is a cross-sectional view showing a blower according to the second embodiment, and is a cross-sectional view of VV in Figure 4. [Figure 6] Figure 6 is a cross-sectional view showing a blower according to the third embodiment. [Figure 7] Figure 7 is a cross-sectional view showing a blower according to the third embodiment, and is a cross-sectional view taken along line VII-VII in Figure 6. [Figure 8] Figure 8 is a side view of the reflector of the third embodiment, viewed from the radially inward direction. [Figure 9] Figure 9 is the first figure showing the noise reduction amount of the blower in the third embodiment. [Figure 10] Figure 10 is the first diagram showing the primary noise of the fan blades in the third embodiment. [Figure 11] Figure 11 is a second figure showing the noise reduction amount of the blower in the third embodiment. [Figure 12] Figure 12 is a second diagram showing the primary noise of the fan blades in the third embodiment. [Figure 13] Figure 13 is a third figure showing the noise reduction amount of the blower in the third embodiment. [Figure 14] Figure 14 is a third diagram showing the primary noise of the fan blades in the third embodiment. [Modes for carrying out the invention]

[0009] The following description of a blower according to an embodiment of the present invention will be made with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments, and modifications can be made as appropriate within the scope of the technical idea of ​​the present invention. Furthermore, in the following drawings, the scale and number of components may differ from the actual structure in order to make the components easier to understand.

[0010] In the following description, the Z-axis is shown in each figure. The Z-axis is the direction in which the central axis J, which is the rotation axis of the impeller section in the embodiment described below, extends. The central axis J shown in each figure is a virtual axis. In the following description, the direction in which the central axis J extends, that is, the direction parallel to the Z-axis, is referred to as the "axial direction". The radial direction centered on the central axis J is simply referred to as the "radial direction". The circumferential direction centered on the central axis J is simply referred to as the "circumferential direction". The side of the axial direction in which the Z-axis arrow points (+Z side) is referred to as the "one axial side" or "upper side". The side of the axial direction opposite to the side in which the Z-axis arrow points (-Z side) is referred to as the "other axial side" or "lower side". Note that the upper side and lower side are merely names used to describe the relative positional relationship of each part, and the actual arrangement may be different from the arrangement indicated by these names.

[0011] The circumferential direction is indicated by the arrow θ in each diagram. The side of the circumferential direction in which the arrow θ points (+θ side) is called the "one side of the circumferential direction." The side of the circumferential direction opposite to the side in which the arrow θ points (-θ side) is called the "other side of the circumferential direction." The one side of the circumferential direction is the side that proceeds counterclockwise around the central axis J when viewed from above. The other side of the circumferential direction is the side that proceeds clockwise around the central axis J when viewed from above.

[0012] <First Embodiment> The blower 10 of this embodiment, shown in Figures 1 and 2, comprises a motor unit 15, a housing 40, an impeller unit 60, and a reflector plate 70. In this embodiment, the blower 10 is a centrifugal fan that sends air out in one direction (+θ side) in the circumferential direction by the rotation of the impeller unit 60 around the central axis J.

[0013] As shown in FIG. 2, the housing 40 houses the motor unit 15 and the impeller unit 60 inside. As shown in FIG. 1, the housing 40 has a first housing part 41, a second housing part 45, an air duct 40a, and an exhaust port 40b. As shown in FIG. 3, the housing 40 has a side wall part 40d and an inner surface 50.

[0014] As shown in FIG. 1, the first housing part 41 is the upper part of the housing 40. The first housing part 41 has a first side wall part 42, a top plate part 43, and a first case opening 41a. That is, the housing 40 has a top plate part 43. As shown in FIG. 2, among the inner surfaces of the first housing part 41, the part located radially outside the impeller unit 60 surrounds the upper part of the air duct 40a.

[0015] As shown in FIG. 1, the top plate part 43 is in the shape of a substantially annular plate that extends in a direction perpendicular to the axial direction. When viewed from the axial direction, the top plate part 43 surrounds the central axis J. When viewed from the axial direction, the radially outer edge of the top plate part 43 is a curved shape in which the radial distance from the central axis J increases as it goes toward one side in the circumferential direction (+θ side). As shown in FIG. 2, the top plate part 43 is arranged above the motor unit 15 and the impeller unit 60, that is, on one side in the axial direction (+Z side). The top plate part 43 has an air intake port 43a. The air intake port 43a is a hole that penetrates the top plate part 43 in the axial direction. As shown in FIG. 1, when viewed from the axial direction, the air intake port 43a is substantially circular with the central axis J as the center.

[0016] As shown in FIG. 2, the first side wall part 42 is a cylindrical shape that extends downward from the radially outer edge of the top plate part 43. As shown in FIG. 1, the first side wall part 42 extends in the circumferential direction. As shown in FIG. 2, the first side wall part 42 is open at the lower side. The first side wall part 42 is located radially outside the impeller unit 60. The first side wall part 42 surrounds the upper part of the impeller unit 60 from the radially outside. As shown in FIG. 1, the first case opening 41a is open in the radial direction or on one side in the circumferential direction (+θ side).

[0017] As shown in Figure 2, the second housing portion 45 is the lower part of the housing 40. The second housing portion 45 has a second side wall portion 46 and a bottom plate portion 47. That is, the housing 40 has a bottom plate portion 47. As shown in Figure 1, the second housing portion 45 has a second case opening 45a. As shown in Figure 2, the portion of the inner surface of the second housing portion 45 that is located radially outward from the impeller portion 60 surrounds the lower part of the air passage 40a.

[0018] The bottom plate portion 47 is a roughly annular plate shape that extends in a direction perpendicular to the axial direction. Viewed from the axial direction, the bottom plate portion 47 surrounds the central axis J. Viewed from the axial direction, the radial outer edge of the bottom plate portion 47 is curved in shape, with the radial distance from the central axis J increasing as it moves toward one side in the circumferential direction (+θ side). The bottom plate portion 47 is located below the motor portion 15 and the impeller portion 60, i.e., on the other side in the axial direction (-Z side). The bottom plate portion 47 is provided with a bottom plate projection portion 47h. The bottom plate projection portion 47h is cylindrical and protrudes upward from the bottom plate portion 47. The bottom plate projection portion 47h is roughly cylindrical with the central axis J as its center. The bottom plate projection portion 47h is open on the upper side.

[0019] The second side wall portion 46 is cylindrical, extending upward from the radial outer edge of the bottom plate portion 47. As shown in Figure 1, the second side wall portion 46 extends in the circumferential direction. As shown in Figure 2, the second side wall portion 46 opens upward. The second side wall portion 46 is located radially outward from the impeller portion 60. The upper end of the second side wall portion 46 is fixed to the lower end of the first side wall portion 42. As a result, the second housing portion 45 is fixed to the first housing portion 41. The second side wall portion 46 surrounds the lower part of the impeller portion 60 from the radial outside. As shown in Figure 1, the second case opening 45a opens radially or circumferentially on one side (+θ side). Viewed from the axial direction, the second case opening 45a overlaps with the first case opening 41a. In this embodiment, the exhaust port 40b is composed of the first case opening 41a and the second case opening 45a. The exhaust port 40b opens on one side, either radially or circumferentially.

[0020] In this embodiment, the side wall portion 40d is composed of a first side wall portion 42 and a second side wall portion 46. As shown in Figure 2, the side wall portion 40d is located radially outward from the impeller portion 60. The side wall portion 40d is radially opposite to the impeller portion 60. The side wall portion 40d connects the radial outer edge of the top plate portion 43 and the radial outer edge of the bottom plate portion 47 in the axial direction. As shown in Figure 1, the side wall portion 40d extends circumferentially along the radial outer edges of the top plate portion 43 and the bottom plate portion 47, respectively. As shown in Figure 2, the side wall portion 40d surrounds the air passage 40a from the radial outside. The inner surface 50 is the surface of the side wall portion 40d facing radially inward. The inner surface 50 will be described in detail later.

[0021] The air passage 40a is the space within the housing 40 through which air flows due to the rotation of the impeller section 60 around its central axis J. The air passage 40a is the space within the housing 40 that is radially outside the impeller section 60. The air passage 40a is the space enclosed by the top plate section 43, the bottom plate section 47, and the side wall section 40d. As shown in Figure 3, the air passage 40a extends in the circumferential direction. The airflow in the air passage 40a is indicated by the arrow AF. Due to the rotation of the impeller section 60 around its central axis J, the air flowing through the air passage 40a toward one side in the circumferential direction (+θ side) flows out to the outside of the blower 10 through the exhaust port 40b. In other words, the exhaust port 40b discharges air to the outside of the blower 10.

[0022] As shown in Figure 2, the impeller section 60 has a cup section 61 and a plurality of blades 64. The cup section 61 houses the motor section 15 inside. As shown in Figure 1, the blades 64 are arranged in a plurality at intervals along the circumferential direction.

[0023] As shown in Figure 2, the motor unit 15 is housed inside the cup unit 61. The motor unit 15 is fixed to the inner surface of the bottom plate projection 47h. In this way, the motor unit 15 is connected to the housing 40. The motor unit 15 has a rotor 20. The rotor 20 rotates about a central axis J. The impeller unit 60 is fixed to the rotor 20. Therefore, when the rotor 20 rotates about the central axis J, the impeller unit 60 can rotate together with the rotor 20 about the central axis J.

[0024] In this embodiment, the impeller section 60 rotates together with the rotor 20 around the central axis J toward one side in the circumferential direction (+θ side). When the impeller section 60 rotates around the central axis J, air is drawn into the housing 40 through the intake port 43a shown in Figure 1. As shown by the arrow AF in Figure 3, the air is blown out from the impeller section 60 radially outward and toward one side in the circumferential direction by the multiple blades 64 and flows through the air passage 40a. The air flowing through the air passage 40a is sent out to the outside of the blower 10 through the exhaust port 40b. Therefore, the airflow rate through the air passage 40a increases as it moves toward one side in the circumferential direction. Consequently, the airflow rate near the exhaust port 40b is high. Also, the airflow velocity of the air flowing through the air passage 40a increases as it moves toward one side in the circumferential direction. Consequently, the airflow velocity near the exhaust port 40b is high.

[0025] As shown in Figure 2, in this embodiment, the reflector 70 is plate-shaped and protrudes axially from the top plate portion 43. More specifically, the reflector 70 protrudes downward from the top plate portion 43, i.e., to the other axial side (-Z side). In other words, the reflector 70 protrudes axially from either the top plate portion 43 or the bottom plate portion 47. In this embodiment, the reflector 70 faces the bottom plate portion 47 with an axial gap between them. In other words, the reflector 70 faces the other side of the top plate portion 43 or the bottom plate portion 47 with an axial gap between them. In this embodiment, the reflector 70 and the first housing portion 41 are parts of the same member. The reflector 70 and the first housing portion 41 may be separate members. In this case, the reflector 70 may be fixed to the top plate portion 43 by adhesive or by welding or the like.

[0026] As shown in Figure 3, the reflector 70 is positioned radially between the impeller portion 60 and the inner surface 50 of the housing 40. The reflector 70 extends circumferentially. The reflector 70 has a first end 70a and a second end 70c. The first end 70a is the end on one side (+θ side) in the circumferential direction of the reflector 70. The second end 70c is the end on the other side (-θ side) in the circumferential direction of the reflector 70. The first virtual line V1 shown in Figure 3 is a virtual line that passes through the first end 70a and the central axis J when viewed from the axial direction. The second virtual line V2 shown in Figure 3 is a virtual line that passes through the second end 70c and the central axis J when viewed from the axial direction. In this embodiment, the central angle α, which is the angle formed by the first virtual line V1 and the second virtual line V2 when viewed from the axial direction, is 90° or more and 180° or less. The central angle α may be less than 90° or greater than 180°. The portion of the reflector 70 on the other side in the circumferential direction extends circumferentially with a constant radial distance G1 from the inner surface 50. That is, at least a part of the reflector 70 extends circumferentially with a constant radial distance G1 from the inner surface 50.

[0027] As described above, the inner surface 50 is the surface facing radially inward of the side wall portion 40d. Viewed from the axial direction, the inner surface 50 is curved in shape, with the radial distance from the central axis J increasing as it moves toward one side in the circumferential direction (+θ side). The inner surface 50 has a first inner surface 51, a second inner surface 53, and a straight portion 55.

[0028] The first inner surface 51 is the portion of the inner surface 50 located radially outward from the reflector 70. The reflector 70 is positioned between the first inner surface 51 and the impeller portion 60. The first inner surface 51 is the portion of the inner surface 50 that overlaps with the reflector 70 when viewed from the central axis J. The first inner surface 51 is located between the first virtual straight line V1 and the second virtual straight line V2. As shown in Figure 2, the first inner surface 51 has a first portion 51a and a second portion 51c.

[0029] The first portion 51a is the portion of the first inner surface 51 that is above the lower end of the reflector 70 in the axial direction. The first portion 51a is radially opposite to the reflector 70. The second portion 51c is the portion of the first inner surface 51 that is below the lower end of the reflector 70 in the axial direction. The second portion 51c is not radially opposite to the reflector 70, but is radially opposite to the impeller portion 60. As a result, a portion of the inner surface 50 is radially opposite to the impeller portion 60, and another portion of the inner surface 50 is radially opposite to the reflector 70.

[0030] As shown in Figure 3, the second inner surface 53 is the portion of the inner surface 50 that is radially opposite to the first inner surface 51 across the central axis J. No reflector 70 is positioned between the second inner surface 53 and the impeller portion 60. The second inner surface 53 does not overlap with the reflector 70 when viewed from the central axis J. As shown in Figure 2, the second inner surface 53 has a third portion 53a and a fourth portion 53c.

[0031] The third portion 53a is the portion of the second inner surface 53 that is above the lower end of the reflector 70 in the axial direction. The third portion 53a is radially opposite to the reflector 70, with the impeller portion 60 in between. The second distance L2, which is the radial distance between the third portion 53a and the reflector 70, is shorter than the first distance L1, which is the radial distance between the second inner surface 53 and the first inner surface 51. In other words, the second distance L2 and the first distance L1 are different from each other.

[0032] The fourth portion 53c is the portion of the second inner surface 53 that is below the lower end of the reflector 70 in the axial direction. The fourth portion 53c is radially opposite to the second portion 51c with the impeller portion 60 in between. The radial distance between the fourth portion 53c and the second portion 51c is the first distance L1. The first distance L1, which is the radial distance between the fourth portion 53c and the second portion 51c, which are radially opposite to each other with the impeller portion 60 in between on the inner surface 50, and the second distance L2, which is the radial distance between the third portion 53a, which is the portion of the inner surface 50 that is radially opposite to the reflector 70 with the impeller portion 60 in between, and the reflector 70, are different from each other. In other words, the first distance L1, which is the radial distance between portions of the inner surface 50 that are radially opposite each other with the impeller portion 60 in between, and the second distance L2, which is the radial distance between the portion of the inner surface 50 that is radially opposite each other with the reflector 70 and the impeller portion 60 in between, and the reflector 70, are different from each other.

[0033] When the blower 10 is in operation, as the impeller section 60 rotates around the central axis J, sound waves are generated as each blade 64 sends air radially outward and circumferentially to one side (+θ side), as described above. When these sound waves propagate radially, they resonate between the fourth section 53c and the second section 51c, and between the reflector 70 and the third section 53a. In this embodiment, as described above, the first distance L1, which is the radial distance between the fourth section 53c and the second section 51c, and the second distance L2, which is the radial distance between the third section 53a and the reflector 70, are different from each other. Therefore, the frequency of the first sound wave S1 that resonates between the fourth section 53c and the second section 51c, and the frequency of the second sound wave S2 that resonates between the reflector 70 and the third section 53a are different from each other. Therefore, when the first sound wave S1 and the second sound wave S2 interfere with each other, they cancel each other out, thus reducing the intensity of both the first sound wave S1 and the second sound wave S2. Consequently, noise during the operation of the blower 10 can be effectively suppressed.

[0034] As shown in Figure 3, the straight section 55 is the portion of the inner surface 50 that includes the end on one side in the circumferential direction (+θ side). Viewed from the axial direction, the straight section 55 extends in a straight line. The straight section 55 is connected to the exhaust port 40b. Viewed from the radial direction, the portion of the reflector 70 on one side in the circumferential direction overlaps with the straight section 55. That is, viewed from the radial direction, a part of the reflector 70 overlaps with the straight section 55. As described above, in this embodiment, the airflow rate of the air passing through the air passage 40a increases as it approaches one side in the circumferential direction, and the airflow velocity of the air passing through the air passage 40a increases as it approaches one side in the circumferential direction. Therefore, the sound waves generated when each blade 64 sends air radially outward and towards one side in the circumferential direction become larger as they approach the exhaust port 40b. Consequently, the intensity of the sound waves generated near the straight section 55, which is the portion of the inner surface 50 that connects to the exhaust port 40b, is high.

[0035] According to this embodiment, the blower 10 includes a motor unit 15 having a rotor 20 that rotates about a central axis J, an impeller unit 60 that can rotate together with the rotor 20, a housing 40 that houses the impeller unit 60, and a reflector 70 that is positioned radially between the impeller unit 60 and the inner surface 50 of the housing 40 and extends circumferentially. A part of the inner surface 50 faces the impeller unit 60 radially, and another part of the inner surface 50 faces the reflector 70 radially. As described above, when the impeller unit 60 rotates about the central axis J, sound waves are generated when each blade 64 blows out air. In this embodiment, as described above, the first distance L1, which is the radial distance between the parts of the inner surface 50 that face each other radially with respect to the impeller unit 60 in between, and the second distance L2, which is the radial distance between the part of the inner surface 50 that faces the reflector 70 with respect to the impeller unit 60 in between, and the reflector 70, are different from each other. Therefore, as described above, the frequency of the first sound wave S1 that resonates between opposing portions of the inner surface 50 with the impeller portion 60 in between, and the frequency of the second sound wave S2 that resonates between the portion of the inner surface 50 with the reflector 70 and the impeller portion 60 in between, and the reflector 70, are different. As a result, as described above, the first sound wave S1 and the second sound wave S2 interfere with each other, thereby reducing the intensity of both the first sound wave S1 and the second sound wave S2. Consequently, the noise of the blower 10 can be effectively suppressed.

[0036] According to this embodiment, the housing 40 has a top plate portion 43 positioned above the impeller portion 60, i.e., on one axial side (+Z side), and a bottom plate portion 47 positioned below the impeller portion 60, i.e., on the other axial side (-Z side). The reflector 70 protrudes axially from either the top plate portion 43 or the bottom plate portion 47 and faces the other portion of the top plate portion 43 or the bottom plate portion 47 with an axial gap between them. Therefore, the first distance L1, which is the radial distance between the fourth portion 53c and the second portion 51c of the second inner surface 53, which are the parts of the second inner surface 53 that are radially opposite to the first inner surface 51 with the impeller portion 60 in between, and the second distance L2, which is the radial distance between the third portion 53a and the reflector 70 of the second inner surface 53, which are the parts of the second inner surface 53 that are radially opposite to the reflector 70 with the impeller portion 60 in between, can be set to different distances from each other. Therefore, the frequency of the first sound wave S1 that resonates between the fourth part 53c and the second part 51c, and the frequency of the second sound wave S2 that resonates between the third part 53a and the reflector 70 are different from each other. As a result, as described above, the first sound wave S1 and the second sound wave S2 interfere with each other, thereby reducing the intensity of both the first sound wave S1 and the second sound wave S2. Consequently, the noise of the blower 10 can be effectively suppressed.

[0037] According to this embodiment, the top plate portion 43 has an air intake port 43a that penetrates the top plate portion 43 in the axial direction, and the reflector plate 70 protrudes downward from the top plate portion 43, i.e., to the other axial side (-Z side), and faces the bottom plate portion 47 with an axial gap between them. Therefore, as described above, the first distance L1 and the second distance L2 can be set to different distances. As a result, as described above, the frequency of the first sound wave S1 that resonates between the fourth portion 53c and the second portion 51c and the frequency of the second sound wave S2 that resonates between the third portion 53a and the reflector plate 70 are different. This makes it possible to reduce the intensity of both the first sound wave S1 and the second sound wave S2, as described above. Therefore, the noise of the blower 10 can be suitably suppressed.

[0038] According to this embodiment, when viewed from the axial direction, the inner surface 50 is curved in shape, and the radial distance between it and the central axis J increases as it is directed toward one side in the circumferential direction (+θ side). At least a portion of the reflector 70 extends circumferentially with a constant radial distance G1 from the inner surface 50. Therefore, the radial distance between the second inner surface 53 and the reflector 70 can be continuously changed in the circumferential direction. As a result, the frequency of the sound waves resonating between the second inner surface 53 and the reflector 70 can be continuously changed in the circumferential direction. This makes it possible to suppress an increase in the intensity of sound waves of a specific frequency between the second inner surface 53 and the reflector 70. Therefore, the noise of the blower 10 can be suppressed more effectively.

[0039] According to this embodiment, the housing 40 has an exhaust port 40b for discharging air to the outside, and the inner surface 50 has a linear portion 55 that is connected to the exhaust port 40b and extends linearly when viewed in the axial direction, and when viewed in the radial direction, a part of the reflector 70 overlaps with the linear portion 55. This allows the reflector 70 to be positioned closer to the exhaust port 40b. As described above, the sound waves generated when each blade 64 blows out air become larger as they approach the exhaust port 40b. In this embodiment, since the reflector 70 can be positioned closer to the exhaust port 40b, the intensity of sound waves resonating in the vicinity of the exhaust port 40b of the housing 40 can be suitably reduced. Therefore, the noise of the blower 10 can be suppressed more suitably.

[0040] According to this embodiment, the central angle α, which is the angle formed by a first virtual straight line V1 passing through the first end 70a of the reflector 70, i.e., the end on one circumferential side (+θ side), and the central axis J, and a second virtual straight line V2 passing through the second end 70c of the reflector 70, i.e., the end on the other circumferential side (-θ side), and the central axis J, when viewed from the axial direction, is 90° or more. Therefore, it is possible to prevent the circumferential dimensions of the reflector 70 from becoming too small. As a result, it is possible to prevent the circumferential range in which the intensity of the first sound wave S1 and the intensity of the second sound wave S2 can be reduced, respectively, from becoming too narrow due to interference between the first sound wave S1 and the second sound wave S2. Therefore, the noise of the blower 10 can be suppressed more effectively.

[0041] According to this embodiment, the central angle α, which is the angle formed by a first virtual straight line V1 passing through the first end 70a of the reflector 70 and the central axis J, and a second virtual straight line V2 passing through the second end 70c of the reflector 70 and the central axis J, is 180° or less when viewed from the axial direction. Therefore, it is possible to suppress the radial opposition between the reflectors 70 with the impeller section 60 in between. This suppresses the resonance of sound waves between the reflectors 70. Consequently, the noise of the blower 10 can be suppressed more effectively.

[0042] <Second Embodiment> Figure 4 is a cross-sectional view showing the blower 210 of this embodiment. In the following description, components identical to those of the first embodiment described above are denoted by the same reference numerals, and their descriptions are omitted. The blower 210 of this embodiment shown in Figure 4 comprises a motor unit 15, a housing 240, an impeller unit 60, and a reflector plate 270. The blower 210 is a centrifugal fan in which the impeller unit 60 rotates about a central axis J, thereby sending air out in one direction (+θ side) in the circumferential direction.

[0043] The housing 240 houses the motor section 15 and the impeller section 60. The housing 240 has a first housing section 241, a second housing section 245, an air passage 40a, and an exhaust port 40b (see Figure 1). As shown in Figure 5, the housing 240 has a side wall section 40d and an inner surface 250.

[0044] The first housing portion 241 is the upper part of the housing 240. The first housing portion 241 has a first side wall portion 42, a top plate portion 43, and a first case opening 41a (see Figure 1). The top plate portion 43 has an air intake port 43a that penetrates the top plate portion 43 in the axial direction. The second housing portion 245 is the lower part of the housing 240. The second housing portion 245 has a second side wall portion 46, a bottom plate portion 47, and a second case opening 45a (see Figure 1). The side wall portion 40d is composed of the first side wall portion 42 and the second side wall portion 46. The inner surface 250 is the surface facing radially inward of the side wall portion 40d. The inner surface 250 will be described in detail later. Other configurations of the housing 240 in this embodiment are the same as other configurations of the housing 40 in the first embodiment described above.

[0045] In this embodiment, the reflector 270 is plate-shaped and protrudes axially from the bottom plate portion 47. More specifically, the reflector 270 protrudes upward from the bottom plate portion 47, i.e., to one side in the axial direction (+Z side). In other words, the reflector 270 protrudes axially from either the top plate portion 43 or the bottom plate portion 47. In this embodiment, the reflector 270 faces the top plate portion 43 with an axial gap between them. In other words, the reflector 270 faces the other side of the top plate portion 43 or the bottom plate portion 47 with an axial gap between them. In this embodiment, the reflector 270 and the second housing portion 45 are parts of the same member. The reflector 270 and the second housing portion 45 may be separate members. In this case, the reflector 270 may be fixed to the bottom plate portion 47 by adhesive or by welding or the like.

[0046] As shown in Figure 5, the reflector 270 is positioned radially between the impeller portion 60 and the inner surface 250 of the housing 240. The reflector 270 extends circumferentially. The reflector 270 has a first end 270a and a second end 270c. The first end 270a is the end on one side (+θ side) in the circumferential direction of the reflector 270. The second end 270c is the end on the other side (-θ side) in the circumferential direction of the reflector 270. The first virtual line V1 shown in Figure 5 is a virtual line that passes through the first end 270a and the central axis J when viewed from the axial direction. The second virtual line V2 shown in Figure 5 is a virtual line that passes through the second end 270c and the central axis J when viewed from the axial direction. In this embodiment, the central angle α, which is the angle formed by the first virtual line V1 and the second virtual line V2 when viewed from the axial direction, is 90° or more and 180° or less. The portion of the reflector 270 on the other side in the circumferential direction extends circumferentially with a constant radial distance G2 from the impeller portion 60. That is, at least a portion of the reflector 270 extends circumferentially with a constant radial distance G2 from the impeller portion 60.

[0047] As described above, the inner surface 250 is the surface facing radially inward of the side wall portion 40d. Viewed from the axial direction, the inner surface 250 is curved in shape, with the radial distance from the central axis J increasing as it moves toward one side in the circumferential direction (+θ side). The inner surface 250 has a first inner surface 251, a second inner surface 253, and a straight portion 55.

[0048] The first inner surface 251 is the portion of the inner surface 250 that is located radially outward from the reflector 270. The reflector 270 is positioned between the first inner surface 251 and the impeller portion 60. The first inner surface 251 is the portion of the inner surface 250 that overlaps with the reflector 270 when viewed from the central axis J. The first inner surface 251 is located between the first virtual straight line V1 and the second virtual straight line V2. As shown in Figure 4, the first inner surface 251 has a first portion 251a and a second portion 251c.

[0049] The first portion 251a is the portion of the first inner surface 251 that is below the upper end of the reflector 270 in the axial direction. The first portion 251a is radially opposite to the reflector 270. The second portion 251c is the portion of the first inner surface 251 that is above the upper end of the reflector 270 in the axial direction. The second portion 251c is not radially opposite to the reflector 270, but is radially opposite to the impeller portion 60. As a result, a portion of the inner surface 250 is radially opposite to the impeller portion 60, and another portion of the inner surface 250 is radially opposite to the reflector 270.

[0050] As shown in Figure 5, the second inner surface 253 is the portion of the inner surface 250 that is radially opposite to the first inner surface 251 across the central axis J. The reflector 270 is not positioned between the second inner surface 253 and the impeller portion 60. The second inner surface 253 does not overlap with the reflector 270 when viewed from the central axis J. As shown in Figure 4, the second inner surface 253 has a third portion 253a and a fourth portion 253c.

[0051] The third portion 253a is the portion of the second inner surface 253 that is below the upper end of the reflector 270 in the axial direction. The third portion 253a is radially opposite the reflector 270 with the impeller portion 60 in between. The second distance L2, which is the radial distance between the third portion 253a and the reflector 270, is shorter than the first distance L1, which is the radial distance between the second inner surface 253 and the first inner surface 251. In other words, the second distance L2 and the first distance L1 are different from each other.

[0052] The fourth portion 253c is the portion of the second inner surface 253 that is above the upper end of the reflector 270 in the axial direction. The fourth portion 253c is radially opposite to the second portion 251c with the impeller portion 60 in between. The radial distance between the fourth portion 253c and the second portion 251c is the first distance L1. The first distance L1 is the radial distance between the fourth portion 253c and the second portion 251c, which are radially opposite to each other with the impeller portion 60 in between on the inner surface 250, and the radial distance between the third portion 253a, which is the portion of the inner surface 250 that is radially opposite to the reflector 270 with the impeller portion 60 in between, and the reflector 270. The second distance L2 and the first distance L1 are different from each other. In other words, the first distance L1, which is the radial distance between portions of the inner surface 250 that are radially opposite each other with respect to the impeller portion 60, and the second distance L2, which is the radial distance between the portion of the inner surface 250 that is radially opposite each other with respect to the reflector 270 and the impeller portion 60, and the reflector 270, are different from each other. The other configurations of the blower 210 in this embodiment are the same as the other configurations of the blower 10 in the first embodiment described above.

[0053] When the blower 210 is in operation, as the impeller section 60 rotates around the central axis J, sound waves are generated as each blade 64 sends air radially outward and circumferentially to one side (+θ side), as described above. When these sound waves propagate radially, they resonate between the fourth section 253c and the second section 251c, and between the reflector 270 and the third section 253a. In this embodiment, as described above, the first distance L1, which is the radial distance between the fourth section 253c and the second section 251c, and the second distance L2, which is the radial distance between the third section 253a and the reflector 270, are different distances. Therefore, the frequency of the first sound wave S1 that resonates between the fourth section 253c and the second section 251c, and the frequency of the second sound wave S2 that resonates between the reflector 270 and the third section 253a are different. Therefore, when the first sound wave S1 and the second sound wave S2 interfere with each other, they cancel each other out, thus reducing the intensity of both the first sound wave S1 and the second sound wave S2. Consequently, noise during the operation of the blower 210 can be effectively suppressed.

[0054] As described above, when the impeller section 60 rotates around the central axis J, as shown by the arrow AF in Figure 4, the air taken into the housing 240 through the intake port 43a is sent out radially outward and circumferentially to one side (+θ side) from the impeller section 60 by the multiple blades 64 and flows through the air passage 40a. The amount of air sent out from the impeller section 60 to the air passage 40a increases as it goes downwards. Therefore, the amount of air flowing between each blade 64 increases as it goes downwards. Consequently, the sound waves generated when each blade 64 sends air into the air passage 40a increase as it goes downwards.

[0055] In this embodiment, the top plate portion 43 has an air intake port 43a that penetrates the top plate portion 43 in the axial direction, and the reflector plate 270 protrudes upward from the bottom plate portion 47, i.e., to one side in the axial direction (+Z side), and faces the top plate portion 43 with an axial gap between them. As described above, the amount of air sent from the impeller portion 60 to the air passage 40a increases as it goes downward. Therefore, as described above, the sound waves generated when each blade 64 sends air to the air passage 40a increase as it goes downward. In contrast, in this embodiment, since the reflector plate 270 protrudes upward from the bottom plate portion 47, the intensity of sound waves resonating in the lower part of the housing 240 can be suitably reduced. Therefore, the noise of the blower 210 can be suitably reduced.

[0056] According to this embodiment, when viewed from the axial direction, the inner surface 250 is curved in shape, and the radial distance between it and the central axis J increases as it moves toward one side in the circumferential direction (+θ side). At least a portion of the reflector 270 extends circumferentially with a constant radial distance G2 from the impeller portion 60. Therefore, the radial distance between the second inner surface 253 and the reflector 270 can be continuously changed in the circumferential direction. As a result, the frequency of the sound waves resonating between the second inner surface 253 and the reflector 270 can be continuously changed in the circumferential direction. This effectively suppresses the increase in the intensity of sound waves of a specific frequency between the second inner surface 253 and the reflector 270. Therefore, the noise of the blower 210 can be more effectively suppressed.

[0057] <Third Embodiment> Figure 6 is a cross-sectional view showing the blower 310 of this embodiment. In the following description, components identical to those of the first embodiment described above are denoted by the same reference numerals, and their descriptions are omitted. The blower 310 of this embodiment shown in Figure 6 comprises a motor unit 15, a housing 340, an impeller unit 60, and a reflector plate 370. The blower 310 is a centrifugal fan that sends air out in one direction (+θ side) in the circumferential direction by the rotation of the impeller unit 60 around the central axis J.

[0058] The housing 340 houses the motor section 15 and the impeller section 60. The housing 340 has a first housing section 341, a second housing section 45, an air passage 40a, and an exhaust port 40b (see Figure 1). As shown in Figure 7, the housing 340 has a side wall section 40d and an inner surface 350.

[0059] As shown in Figure 6, the first housing portion 341 is the upper part of the housing 340. The first housing portion 341 has a first side wall portion 42, a top plate portion 43, and a first case opening 41a (see Figure 1). The top plate portion 43 has an air intake port 43a that penetrates the top plate portion 43 in the axial direction. The second housing portion 45 is the lower part of the housing 340. The second housing portion 45 has a second side wall portion 46, a bottom plate portion 47, and a second case opening 45a (see Figure 1). The side wall portion 40d is composed of the first side wall portion 42 and the second side wall portion 46. The inner surface 350 is the surface facing radially inward of the side wall portion 40d. The inner surface 350 will be described in detail later. Other configurations of the housing 340 in this embodiment are the same as other configurations of the housing 40 in the first embodiment described above.

[0060] In this embodiment, the reflector 370 is plate-shaped and protrudes axially from the top plate portion 43. More specifically, the reflector 370 protrudes downward from the top plate portion 43, i.e., to the other axial side (-Z side). In other words, the reflector 370 protrudes axially from either the top plate portion 43 or the bottom plate portion 47. In this embodiment, the reflector 370 faces the bottom plate portion 47 with an axial gap between them. In other words, the reflector 370 faces the other side of the top plate portion 43 or the bottom plate portion 47 with an axial gap between them. In this embodiment, the reflector 370 and the first housing portion 341 are parts of the same member. The reflector 370 and the first housing portion 341 may be separate members. In this case, the reflector 370 may be fixed to the top plate portion 43 by adhesive or by welding or the like. In this embodiment, the dimensional ratio Rs, which is the ratio of the maximum axial dimension Lr of the reflector 370 to the axial dimension Li of the inner surface 350, is 37.5% or more and 55.0% or less. The dimensional ratio Rs may be less than 37.5% or greater than 55.0%. A dimensional ratio Rs of about 50.0% is preferred.

[0061] As shown in Figure 7, the reflector 370 is positioned radially between the impeller portion 60 and the inner surface 350 of the housing 340. The reflector 370 extends circumferentially. The reflector 370 has a first end 370a and a second end 370c. The first end 370a is the circumferential end on one side (+θ side) of the reflector 370. The first end 370a is positioned on the other side (-θ side) of the straight portion 55 in the circumferential direction. The second end 370c is the circumferential end on the other side (-θ side) of the reflector 370. The first virtual straight line V1 shown in Figure 7 is a virtual straight line that passes through the first end 370a and the central axis J when viewed from the axial direction. The third virtual straight line V3 shown in Figure 7 is a virtual straight line that passes through the other circumferential end of the straight portion 55 and the central axis J. In this embodiment, the angle γ formed by the first virtual line V1 and the third virtual line V3, as viewed from the axial direction, is preferably 20° or more and 50° or less. The second virtual line V2 shown in Figure 7 is a virtual line that passes through the second end 370c and the central axis J, as viewed from the axial direction. In this embodiment, the central angle α, which is the angle formed by the first virtual line V1 and the second virtual line V2, as viewed from the axial direction, is 15° or more and 30° or less. The central angle α may be less than 15° or greater than 30°. In this embodiment, the central angle α is preferably about 25°. The reflector 370 extends circumferentially with a constant radial distance G1 from the inner surface 350. That is, at least a part of the reflector 370 extends circumferentially with a constant radial distance G1 from the inner surface 350. At least a part of the reflector 370 may extend circumferentially with a constant radial distance 60 from the impeller portion 60. As shown in Figure 8, the reflector 370 has a central portion 371, a protruding portion 372, and a rear end portion 373.

[0062] The central portion 371 is the circumferentially central part of the reflector 370. The central portion 371 is plate-shaped and extends in the circumferential direction. The plate surface of the central portion 371 faces radially. Viewed radially, the central portion 371 is roughly rectangular in shape, with its longer side extending in the circumferential direction. The upper end of the central portion 371 is connected to the top plate portion 43. The axial dimension of the central portion 371 is the maximum axial dimension Lr of the reflector 370.

[0063] The projection 372 is the part of the reflector 370 on the other side in the circumferential direction (-θ side). The projection 372 is plate-shaped and protrudes from the other end of the central part 371 in the circumferential direction to the other side. The plate surface of the projection 372 is oriented radially. Viewed radially, the projection 372 is approximately a right triangle. Viewed radially, the hypotenuse of the projection 372 is located on the upper side as it moves from the other end of the central part 371 in the circumferential direction, and from the lower end, toward the other side in the circumferential direction. The upper end of the projection 372 is connected to the top plate part 43. The axial dimension of the projection 372 increases as it moves from the second end 370c, i.e., the other end of the reflector 370, toward one side in the circumferential direction (+θ side). The axial dimension of the end of the projection 372 on one side in the circumferential direction is the maximum axial dimension Lr of the reflector 370. The protruding portion 372 has a tip surface 372a and a corner portion 372c.

[0064] The tip surface 372a is a plane facing between the other circumferential side (-θ side) and the lower side of the outer surface of the protruding portion 372. The other circumferential end of the tip surface 372a is connected to the lower side of the top plate portion 43. The one circumferential end (+θ side) of the tip surface 372a is connected to the other circumferential end of the central portion 371, and also to the lower end portion.

[0065] The corner portion 372c is a corner portion that includes the end of the projection portion 372 on the other side in the circumferential direction (-θ side). In this embodiment, when viewed from the radial direction, the angle β of the corner portion 372c is 40° or more and 60° or less. The angle β of the corner portion 372c may be less than 40° or greater than 60°. In this embodiment, it is preferable that the angle β of the corner portion 372c is about 45°.

[0066] The rear end portion 373 is the portion of the reflector 370 on one side in the circumferential direction (+θ side). The rear end portion 373 is plate-shaped and protrudes from one end of the central portion 371 in the circumferential direction to the other side in the circumferential direction. The plate surface of the rear end portion 373 is oriented radially. Viewed radially, the rear end portion 373 is approximately triangular in shape. Viewed radially, the hypotenuse of the rear end portion 373 is located on the upper side as you move from the end of the central portion 371 in the circumferential direction, and from the lower end portion toward the other side in the circumferential direction. The upper end of the rear end portion 373 is connected to the top plate portion 43. The axial dimension of the rear end portion 373 increases as you move from the first end portion 370a, i.e., one end of the reflector 370 in the circumferential direction toward the other side in the circumferential direction (-θ side). Note that the shape of the rear end portion 373 is not limited to this embodiment and may be rectangular when viewed radially. The other configurations of the reflector 370 in this embodiment are the same as those of the reflector 70 in the first embodiment described above.

[0067] As described above, the inner surface 350 is the surface facing radially inward of the side wall portion 40d. As shown in Figure 7, when viewed from the axial direction, the inner surface 350 is curved in shape, with the radial distance from the central axis J increasing as it moves toward one side in the circumferential direction (+θ side). The inner surface 350 has a first inner surface 351, a second inner surface 353, and a straight portion 55.

[0068] The first inner surface 351 is the portion of the inner surface 350 located radially outward from the reflector 370. The reflector 370 is positioned between the first inner surface 351 and the impeller portion 60. Viewed from the axial direction, the first inner surface 351 is located between the first virtual line V1 and the second virtual line V2. As shown in Figure 6, the first inner surface 351 has a first portion 351a and a second portion 351c.

[0069] The first portion 351a is the portion of the first inner surface 351 that is above the lower end of the reflector 370 in the axial direction. The first portion 351a is radially opposite to the reflector 370. The second portion 351c is the portion of the first inner surface 351 that is below the lower end of the reflector 370 in the axial direction. The second portion 351c is not radially opposite to the reflector 370, but is radially opposite to the impeller portion 60. As a result, a portion of the inner surface 350 is radially opposite to the impeller portion 60, and another portion of the inner surface 350 is radially opposite to the reflector 370.

[0070] As shown in Figure 7, the second inner surface 353 is the portion of the inner surface 350 that is radially opposite to the first inner surface 351 across the central axis J. The reflector 370 is not positioned between the second inner surface 353 and the impeller portion 60. The second inner surface 353 does not overlap with the reflector 370 when viewed from the central axis J. As shown in Figure 6, the second inner surface 353 has a third portion 353a and a fourth portion 353c.

[0071] The third portion 353a is the portion of the second inner surface 353 that is above the lower end of the reflector 370 in the axial direction. The third portion 353a is radially opposite the reflector 370 with the impeller portion 60 in between. The second distance L2, which is the radial distance between the third portion 353a and the reflector 370, is shorter than the first distance L1, which is the radial distance between the second inner surface 353 and the first inner surface 351. In other words, the second distance L2 and the first distance L1 are different from each other.

[0072] The fourth portion 353c is the portion of the second inner surface 353 that is below the lower end of the reflector 370 in the axial direction. The fourth portion 353c is radially opposite the second portion 351c with the impeller portion 60 in between. The radial distance between the fourth portion 353c and the second portion 351c is the first distance L1. As described above, the first distance L1 and the second distance L2 are different from each other. The other configurations of the blower 310 in this embodiment are the same as the other configurations of the blower 10 in the first embodiment described above.

[0073] When the blower 210 is in operation, as the impeller section 60 rotates around the central axis J, sound waves are generated as each blade 64 sends air radially outward and circumferentially to one side (+θ side), as described above. When these sound waves propagate radially, they resonate between the fourth section 353c and the second section 351c, and between the reflector 370 and the third section 353a. In this embodiment, as described above, the first distance L1, which is the radial distance between the fourth section 353c and the second section 351c, and the second distance L2, which is the radial distance between the third section 353a and the reflector 370, are different distances. Therefore, the frequency of the first sound wave S1 that resonates between the fourth section 353c and the second section 351c, and the frequency of the second sound wave S2 that resonates between the reflector 370 and the third section 353a are different. Therefore, when the first sound wave S1 and the second sound wave S2 interfere with each other, they cancel each other out, thus reducing the intensity of both the first sound wave S1 and the second sound wave S2. Consequently, noise during the operation of the blower 210 can be effectively suppressed.

[0074] The noise reduction effect of the blower 310 in this embodiment will be described below. Figure 9 is the first figure showing the noise reduction amount Nd of the blower 310 in this embodiment. The horizontal axis of Figure 9 is the central angle α. The vertical axis of Figure 9 is the noise reduction amount Nd. In this embodiment, the noise reduction amount Nd is calculated by subtracting the noise with a frequency of 4000 Hz generated by the blower 310 from the noise with a frequency of 4000 Hz generated by the blower without the reflector 370. That is, the noise reduction amount Nd is the magnitude of the noise with a frequency of 4000 Hz that can be reduced by the blower 310 being equipped with the reflector 370. The larger the noise reduction amount Nd, the greater the noise reduction effect of the reflector 370, and the smaller the noise reduction amount Nd, the smaller the noise reduction effect of the reflector 370.

[0075] As shown in Figure 9, the noise reduction amount Nd increases as the central angle α increases when the central angle α is 25° or less, and remains almost the same when the central angle α is between 25° and 90°. The noise reduction amount Nd is a positive value in the range where the central angle α is 90° or less. Therefore, in this embodiment, when the central angle α of the reflector 370 is 90° or less, the reflector 370 can reduce noise at a frequency of 4000Hz. As described above, in this embodiment, the central angle α is between 15° and 30°, so the blower 310 can reduce noise at a frequency of 4000Hz by being equipped with the reflector 370.

[0076] Figure 10 is the first diagram showing the primary blade noise Nw of the blower 310 in this embodiment. The horizontal axis of Figure 10 is the central angle α. The vertical axis of Figure 10 is the primary blade noise Nw. In this embodiment, the primary blade noise Nw is the noise with a frequency of 3000 Hz generated in the blower 310. In this embodiment, the value obtained by multiplying the number of blades 64 in the impeller section 60 by the rotational speed (rps) of the impeller section 60 is approximately 3000. Air taken into the housing 340 through the intake port 43a is sent out from the impeller section 60 radially outward and circumferentially to one side (+θ side) by each blade 64. Therefore, when the impeller section 60 rotates around the central axis J, the intensity of the air sent towards the reflector 370 fluctuates approximately 3000 times per second, generating primary blade noise Nw, which is noise at 3000 Hz.

[0077] As shown in Figure 10, the primary blade noise Nw is approximately the same when the central angle α is 35° or less, increases as the central angle α increases when the central angle α is between 35° and 60°, and is approximately the same when the central angle α is between 60° and 90°. As described above, in this embodiment, the central angle α is between 15° and 30°. Therefore, in this embodiment, the increase in primary blade noise Nw can be suppressed compared to the case where the central angle α is 35° or more. As described above, in this embodiment, since the central angle α is between 15° and 30°, noise at a frequency of 4000Hz can be reduced. Therefore, in this embodiment, since the central angle α is between 15° and 30°, noise at a frequency of 4000Hz can be reduced while suppressing the increase in primary blade noise Nw.

[0078] In this embodiment, in order to increase the noise reduction amount Nd and reduce the primary blade noise Nw, the central angle α is preferably 10° or more and 60° or less, more preferably 15° or more and 45° or less, and even more preferably 25° or more and 35° or less.

[0079] Figure 11 is a second figure showing the noise reduction amount Nd of the blower 310 of this embodiment. The horizontal axis of Figure 11 is the angle β of the corner 372c. The vertical axis of Figure 11 is the noise reduction amount Nd. As shown in Figure 11, the noise reduction amount Nd increases as the angle β of the corner 372c increases in the range of 30° to 60°. The noise reduction amount Nd is a positive value in the range of 30° to 60° for the angle β of the corner 372c. Therefore, in this embodiment, noise with a frequency of 4000Hz can be reduced in the range of 30° to 60° for the angle β of the corner 372c. As described above, in this embodiment, the angle β of the corner 372c is 40° to 60°, so the blower 310 can reduce noise with a frequency of 4000Hz by providing the reflector 370.

[0080] Figure 12 is a second diagram showing the primary blade noise Nw of the blower 310 in this embodiment. The horizontal axis of Figure 12 is the angle β of the corner 372c. The vertical axis of Figure 12 is the primary blade noise Nw. As shown in Figure 12, the primary blade noise Nw decreases as the angle β of the corner 372c increases in the range of 30° to 45°, and increases as the angle β of the corner 372c increases in the range of 45° to 60°. The primary blade noise Nw in the range of 40° to 60° is smaller than the primary blade noise Nw at an angle β of 30°. As described above, in this embodiment, the angle β of the corner 372c is between 40° and 60°. Therefore, in this embodiment, the increase in primary blade noise Nw can be suppressed compared to the case where the angle β of the corner 372c is 30°. As described above, in this embodiment, since the angle β of the corner 372c is 40° or more and 60° or less, noise at a frequency of 4000Hz can be reduced. Therefore, in this embodiment, since the angle β of the corner 372c is 40° or more and 60° or less, noise at a frequency of 4000Hz can be reduced while suppressing the increase in primary blade noise Nw.

[0081] In this embodiment, in order to increase the noise reduction amount Nd and reduce the primary blade noise Nw, the angle β of the corner portion 372c is preferably 40° or less and 60° or less, more preferably 45° or more and 50° or less, and even more preferably 45°.

[0082] Figure 13 is a third figure showing the noise reduction amount Nd of the blower 310 of this embodiment. The horizontal axis of Figure 13 is the dimensional ratio Rs. The vertical axis of Figure 13 is the noise reduction amount Nd. As shown in Figure 13, the noise reduction amount Nd increases as the dimensional ratio Rs increases in the range of 37.5% to 50.0% and decreases as the dimensional ratio Rs increases in the range of 50.0% to 62.5%. The noise reduction amount Nd is a positive value in the range of 37.5% to 62.5%. Therefore, in this embodiment, noise with a frequency of 4000 Hz can be reduced in the range of 37.5% to 62.5%. As described above, in this embodiment, the dimensional ratio Rs is between 37.5% and 55.0%, so the blower 310 can reduce noise at a frequency of 4000 Hz by providing the reflector 370.

[0083] Figure 14 is a third diagram showing the primary blade noise Nw of the blower 310 in this embodiment. The horizontal axis of Figure 14 represents the dimensional ratio Rs. The vertical axis of Figure 14 represents the primary blade noise Nw. As shown in Figure 14, the primary blade noise Nw is approximately the same in the range where the dimensional ratio Rs is between 37.5% and 50.0%, and increases as the dimensional ratio Rs increases in the range where the dimensional ratio Rs is between 50.0% and 62.5%. The primary blade noise Nw in the range where the dimensional ratio Rs is between 37.5% and 55.0% is smaller than the primary blade noise Nw at a dimensional ratio Rs of 62.5%. As described above, in this embodiment, the dimensional ratio Rs is between 37.5% and 55.0%. Therefore, in this embodiment, it is possible to suppress the increase in primary blade noise Nw compared to the case where the dimensional ratio Rs is 62.5%. As described above, in this embodiment, since the dimensional ratio Rs is between 37.5% and 55.0%, noise at a frequency of 4000 Hz can be reduced. Therefore, in this embodiment, since the dimensional ratio Rs is between 37.5% and 55.0%, noise at a frequency of 4000 Hz can be reduced while suppressing an increase in the primary blade noise Nw.

[0084] In this embodiment, in order to increase the noise reduction amount Nd and reduce the primary blade noise Nw, the dimensional ratio Rs is preferably 32.5% or more and 40.0% or less, more preferably 35.0% or more and 38.0% or less, and even more preferably 37.5%.

[0085] According to this embodiment, the central angle α, which is the angle formed by a first virtual straight line V1 passing through the first end 370a of the reflector 370, i.e., the end on one circumferential side (+θ side), and the central axis J, and a second virtual straight line V2 passing through the second end 370c of the reflector 370, i.e., the end on the other circumferential side (-θ side), and the central axis J, is 15° or more and 30° or less. Therefore, as described above, in this embodiment, noise at a frequency of 4000 Hz can be reduced while suppressing an increase in the primary blade noise Nw. Thus, the noise of the blower 310 can be suitably suppressed.

[0086] Furthermore, in this embodiment, since the central angle α is 30° or less, it is possible to prevent the circumferential length of the reflector 370 from becoming too long. This prevents the length over which the air flowing through the air passage 40a and the reflector 370 interfere from becoming too long. Therefore, it is possible to effectively suppress a decrease in the amount of air sent out from the exhaust port 40b to the outside of the blower 310.

[0087] According to this embodiment, the reflector 370 has a projection 372 whose axial dimension increases as it moves from the other end (-θ side) in the circumferential direction toward the one end (+θ side) in the circumferential direction. When viewed from the radial direction, the angle β of the corner 372c including the other end of the projection 372 in the circumferential direction is 40° or more and 60° or less. Therefore, as described above, in this embodiment, it is possible to reduce noise at a frequency of 4000 Hz while suppressing an increase in the primary noise Nw of the blades.

[0088] Furthermore, in this embodiment, it is possible to suppress the angle β of the corner portion 372c from becoming too large, making it easier to orient the tip surface 372a closer to a direction perpendicular to the circumferential direction. As a result, the air flowing through the air passage 40a tends to flow circumferentially along the tip surface 372a, making it easier to suppress interference between the air flowing through the air passage 40a and the tip surface 372a. Therefore, it is possible to more effectively suppress a decrease in the amount of air sent out from the exhaust port 40b to the outside of the blower 310.

[0089] According to this embodiment, the dimensional ratio Rs, that is, the ratio of the maximum axial dimension Lr of the reflector 370 to the axial dimension Li of the inner surface 350, is 37.5% or more and 55.0% or less. Therefore, as described above, in this embodiment, it is possible to reduce noise at a frequency of 4000 Hz while suppressing an increase in the primary blade noise Nw.

[0090] Furthermore, in this embodiment, since the dimensional ratio Rs is 55.0% or less, it is possible to suppress the maximum axial dimension Lr of the reflector 370 from becoming too large. This makes it possible to more effectively suppress interference between the air flowing through the air passage 40a and the reflector 370. Therefore, it is possible to more effectively suppress a decrease in the amount of air sent out from the exhaust port 40b to the outside of the blower 310.

[0091] Although one embodiment of the present invention has been described above, the configurations and combinations thereof in the embodiment are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the embodiments. For example, the applications of the blower shown in the above-described embodiment are not particularly limited.

[0092] The configuration of the inner surface is not limited to this embodiment. For example, when viewed from the axial direction, the inner surface may be curved in such a way that the radial distance from the central axis increases as it extends toward the other side in the circumferential direction. Furthermore, the inner surface does not have to have straight sections.

[0093] Furthermore, the radial distance between the reflector and the inner surface may increase towards one side in the circumferential direction, or towards the other side in the circumferential direction. In addition, the radial distance between the reflector and the impeller may increase towards one side in the circumferential direction, or towards the other side in the circumferential direction.

[0094] Furthermore, this technology can be configured as follows: (1) A blower comprising: a motor section having a rotor that rotates about a central axis; an impeller section rotatable together with the rotor; a housing that houses the impeller section; and a reflector that is positioned radially between the impeller section and the inner surface of the housing and extends circumferentially, wherein a portion of the inner surface faces the impeller section radially, and another portion of the inner surface faces the reflector radially. (2) The blower according to (1), wherein the housing has a top plate portion located axially to one side of the impeller portion and a bottom plate portion located axially to the other side of the impeller portion, and the reflector protrudes axially from one of the top plate portion or the bottom plate portion and faces the other of the top plate portion or the bottom plate portion with an axial gap between them. (3) The blower according to (2), wherein the top plate portion has an air intake port that penetrates the top plate portion in the axial direction, and the reflector plate protrudes from the top plate portion to the other side in the axial direction and faces the bottom plate portion with an axial gap between them. (4) The blower according to (2), wherein the top plate portion has an air intake port that penetrates the top plate portion in the axial direction, and the reflector plate protrudes from the bottom plate portion to one side in the axial direction and faces the top plate portion with an axial gap between them. (5) The blower according to any one of (1) to (4), wherein, when viewed from the axial direction, the inner surface is curved in shape, the radial distance between it and the central axis increases as it is directed toward one side in the circumferential direction, and at least a portion of the reflector extends in the circumferential direction at a constant radial distance from the inner surface. (6) The blower according to any one of (1) to (4), wherein, when viewed from the axial direction, the inner surface is curved in shape, the radial distance from the central axis increases as it is directed toward one side in the circumferential direction, and at least a part of the reflector extends in the circumferential direction at a constant radial distance from the impeller portion. (7) The blower according to any one of (1) to (6), wherein the housing has an exhaust port for discharging air to the outside, the inner surface has a straight portion connected to the exhaust port and extending linearly when viewed in the axial direction, and a part of the reflector overlaps with the straight portion when viewed in the radial direction. (8) The blower according to any one of (1) to (7), wherein, when viewed from the axial direction, the angle formed by a first imaginary straight line passing through one circumferential end of the reflector and the central axis, and a second imaginary straight line passing through the other circumferential end of the reflector and the central axis, is 15° or more and 30° or less. (9) The blower according to any one of (1) to (8), wherein the reflector has a projection whose axial dimension increases from the other end of the reflector toward the one end in the circumferential direction, and the angle of the corner of the projection including the other end in the circumferential direction, when viewed from the radial direction, is 40° or more and 60° or less. (10) The blower according to any one of items (1) to (9), wherein the ratio of the maximum axial dimension of the reflector to the axial dimension of the inner surface is 37.5% or more and 55.0% or less. [Explanation of Symbols]

[0095] 10, 210, 310… Blower, 15… Motor section, 20… Rotor, 40, 240, 340… Housing, 40b… Exhaust port, 43… Top plate section, 43a… Intake port, 47… Bottom plate section, 50, 250, 350… Inner surface, 55… Straight section, 60… Impeller section, 70, 270, 370… Reflector, 372… Protrusion, 372c… Corner section, J… Center axis, Li… Axial dimension of the inner surface, Lr… Maximum axial dimension of the reflector, V1… First virtual straight line, V2… Second virtual straight line, α… Center angle (angle), β… Corner angle

Claims

1. A motor section having a rotor that rotates around a central axis, An impeller section that can rotate together with the rotor, A housing that houses the impeller section inside, A reflector is positioned radially between the impeller portion and the inner surface of the housing, and extends circumferentially. Equipped with, A blower in which a portion of the inner surface faces radially opposite the impeller portion, and another portion of the inner surface faces radially opposite the reflector.

2. The housing has a top plate portion located axially to one side of the impeller portion and a bottom plate portion located axially to the other side of the impeller portion. The blower according to claim 1, wherein the reflector protrudes axially from either the top plate or the bottom plate and faces the other of the top plate or the bottom plate with an axial gap between them.

3. The top plate portion has an air intake port that penetrates the top plate portion in the axial direction. The blower according to claim 2, wherein the reflector protrudes from the top plate portion to the other side in the axial direction and faces the bottom plate portion with an axial gap between them.

4. The top plate portion has an air intake port that penetrates the top plate portion in the axial direction. The blower according to claim 2, wherein the reflector protrudes from the bottom plate portion to one side in the axial direction and faces the top plate portion with an axial gap between them.

5. Viewed from the axial direction, the inner surface is curved in such a way that the radial distance between it and the central axis increases as it moves toward one side in the circumferential direction. The blower according to any one of claims 1 to 4, wherein at least a portion of the reflector extends circumferentially at a constant radial distance from the inner surface.

6. Viewed from the axial direction, the inner surface is curved in such a way that the radial distance between it and the central axis increases as it moves toward one side in the circumferential direction. The blower according to any one of claims 1 to 4, wherein at least a portion of the reflector extends circumferentially at a constant radial distance from the impeller portion.

7. The housing has an exhaust port for discharging air to the outside, The inner surface is connected to the exhaust port and has a straight portion that extends linearly when viewed in the axial direction. A blower according to any one of claims 1 to 4, wherein, when viewed from the radial direction, a part of the reflector overlaps with the straight portion.

8. The blower according to any one of claims 1 to 4, wherein, when viewed from the axial direction, the angle formed by a first imaginary straight line passing through one circumferential end of the reflector and the central axis, and a second imaginary straight line passing through the other circumferential end of the reflector and the central axis, is 15° or more and 30° or less.

9. The reflector has a projection whose axial dimension increases from the other end of the reflector in the circumferential direction toward the one end in the circumferential direction, The blower according to any one of claims 1 to 4, wherein, when viewed from the radial direction, the angle of the corner including the other end of the protruding portion in the circumferential direction is 40° or more and 60° or less.

10. The blower according to any one of claims 1 to 4, wherein the ratio of the maximum axial dimension of the reflector to the axial dimension of the inner surface is 37.5% or more and 55.0% or less.

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