Air blower

Abstract

To provide a blower capable of suppressing a flow velocity distribution near a front edge part of a blade.SOLUTION: A blower 1 comprises a shaft 2, and a centrifugal fan 10 coupled to the shaft 2. The centrifugal fan 10 includes: a plurality of blades 20; a shroud coupled to a first blade end portion of each of the plurality of blades 20; and a main plate 50 coupled to a second blade end portion of each of the plurality of blades 20. The plurality of blades 20 each have a front edge portion 23 constituting an inner peripheral part, and a rear end portion 24 constituting an outer peripheral part. Out of the plurality of blades 20, a projecting portion 30 projecting out so as to approach a positive pressure surface 20A of the adjacent blades is provided on a negative pressure surface 20B of an air inflow part 28 located closer to the front edge portion 23 than the rear edge portion 24 on a virtual flow line. The front pressure surface 20A of the air inflow part 28 is inclined so as to locate on the front side in a rotating direction Drt as at least a part thereof approaches the main plate 50.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a blower.

Background Art

[0002] Conventionally, as a blower, by inclining a portion near the shroud ring on the leading edge side of a plurality of blades forward in the rotational direction more than a portion near the main board, it is known to suppress the separation of the air flow near the shroud ring (see, 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] By the way, in the above-described conventional blower, near the leading edge of a plurality of blades, the flow velocity of the air flow on the negative pressure surface side of the blade tends to be faster than the flow velocity of the air flow on the positive pressure surface side. Such a flow velocity distribution is not preferable because it causes an increase in pressure loss and deterioration of noise. This was found as a result of intensive studies by the present inventors.

[0005] An object of the present disclosure is to provide a blower capable of suppressing the flow velocity distribution near the leading edge of a blade.

Means for Solving the Problems

[0006] The invention according to claim 1 is a blower, comprising a shaft (2), and a centrifugal fan (10) connected to the shaft, wherein the centrifugal fan includes a plurality of blades (20) arranged around the axis (CL) of the shaft, and A shroud (40) connected to a first blade end portion (21) located on one axial side of a shaft in each of a plurality of blades, and having an intake hole (41) through which air is sucked in, and a main board (50) connected to a second blade end portion (22) located on the other axial side of each of the plurality of blades, The plurality of blades have a leading edge portion (23) forming an inner peripheral portion and a trailing edge portion (24) forming an outer peripheral portion, The leading edge portion is divided into a predetermined number so that the lengths along the leading edge portion are equal, and the trailing edge portion is divided into a predetermined number so that the lengths along the trailing edge portion are equal. Further, one or more intermediate portions (25, 26, 27) located at equal division positions between the leading edge portion and the trailing edge portion are divided into a predetermined number so that the lengths along the intermediate portions are equal. Among the plurality of division points in each of the leading edge portion, the trailing edge portion, and the intermediate portion, when a line connecting those having the same number when counted from one side of the first blade end portion and the second blade end portion is defined as a virtual streamline (IL), On the negative pressure surface (20B) of an air inflow site (28) closer to the leading edge portion than the trailing edge portion on the virtual streamline among the plurality of blades, a convex portion (30) is provided so as to protrude toward the positive pressure surface (20A) of an adjacent blade, The positive pressure surface of the air inflow site is inclined so that at least a part thereof is located on the front side in the rotational direction as it approaches the main board. and the negative pressure surface has a curved surface at the connection portion between the portion provided with the convex portion and the portion on the upstream side of the air flow from the convex portion so that the portion provided with the convex portion and the portion on the upstream side of the air flow from the convex portion are continuously connected .

[0007] According to this, a force acts on a part of the airflow flowing along the negative pressure surface of the blade in a direction away from the negative pressure surface by the convex portion provided on the negative pressure surface of the blade, making it easier for the airflow to flow toward the positive pressure surface side. For this reason, the difference between the flow velocity of the airflow on the negative pressure surface side and the flow velocity of the airflow on the positive pressure surface side becomes smaller, and the flow velocity distribution near the leading edge portion of the blade can be suppressed.

[0008] Here, on the positive pressure surface of the blade, due to the influence of the centrifugal force caused by the curvature of the flow path formed between the blades, a vortex is generated in relation to the balance with the velocity boundary layer of the positive pressure surface. This vortex has a tendency to increase more easily when the flow velocity of the airflow is high on the positive pressure surface side, as in the present case.

[0009] In contrast, in the blower of the present disclosure, at least a part of the positive pressure surface of the air inlet portion is inclined so as to be located on the front side in the rotation direction as it approaches the main board. According to this, a force is likely to act in a direction to suppress the generation or development of vortices on the positive pressure surface side of the blade, and it is possible to suppress problems caused by the vortices on the positive pressure surface side.

[0010] Therefore, in the blower of the present disclosure, it is possible to suppress the flow velocity distribution near the leading edge portion of the blade, and suppress problems such as an increase in pressure loss and deterioration of noise caused by the flow velocity distribution.

[0011] The reference numerals with parentheses attached to each component etc. show an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Mode for Carrying Out the Invention

[0013] An embodiment of the present disclosure will be described with reference to FIGS. 1 to 19. The blower 1 shown in FIGS. 1 and 2 is applied to, for example, an indoor air conditioner. The blower 1 includes a casing (not shown), a shaft 2, an electric motor 3, and a centrifugal fan 10.

[0014] The casing is the housing of the blower 1. The casing protects the shaft 2, the electric motor 3, the centrifugal fan 10, etc. from dust and dirt outside the blower 1. Inside the casing, the shaft 2, the electric motor 3, and the centrifugal fan 10 are accommodated. The casing is provided with an air inlet and an air outlet.

[0015] The shaft 2 is the rotating shaft in the blower 1. The shaft 2 is a cylindrical bar. The shaft 2 is made of a metal such as iron, stainless steel, or brass. In FIGS. 2 and the like, the direction along the axis CL of the shaft 2 is defined as the axial direction Dax, the direction away from the axis CL of the shaft 2 is defined as the radial direction Drd, and the direction in which the shaft 2 and the centrifugal fan 10 rotate is shown as the rotational direction Drt.

[0016] The electric motor 3 is a drive unit in the blower 1. When the electric motor 3 is energized, it rotates the shaft 2 and the centrifugal fan 10 about the axis CL of the shaft 2. The electric motor 3 is, for example, an outer-rotor type brushless DC motor.

[0017] The centrifugal fan 10 is an impeller applied to the blower 1. The centrifugal fan 10 is connected to the shaft 2. When the electric motor 3 is driven by energization, the centrifugal fan 10 rotates integrally with the shaft 2 about the axis CL of the shaft 2.

[0018] The centrifugal fan 10 includes a plurality of blades 20 arranged at intervals in the rotation direction Drt of the shaft 2, a shroud 40 connected to one side of the axial direction Dax in each of the plurality of blades 20, and a main plate 50 connected to the other side of the axial direction Dax in each of the plurality of blades 20.

[0019] The plurality of blades 20 are arranged at intervals in the rotation direction Drt of the shaft 2. Each of the plurality of blades 20 has the same shape. Each of the plurality of blades 20 has a first blade end portion 21 that is the end on one side of the axial direction Dax and a second blade end portion 22 that is the end on the other side of the axial direction Dax.

[0020] Each of the plurality of blades 20 has a leading edge portion 23 that constitutes the inner peripheral portion and a trailing edge portion 24 that constitutes the outer peripheral portion. The leading edge portion 23 has a distance from the axis CL that decreases from one side to the other side of the axial direction Dax. Specifically, the leading edge portion 23 is curved so that the angle formed with the axis CL decreases as it goes from one side to the other side of the axial direction Dax. The trailing edge portion 24 extends along the axis CL.

[0021] The plurality of blades 20 have a pressure surface 20A and a suction surface 20B that constitute the blade shape. The pressure surface 20A is the first blade surface located on the front side in the rotation direction Drt. The suction surface 20B is the second blade surface located on the rear side in the rotation direction Drt. And, an inter-blade flow path 29 through which air flows is formed between adjacent blades 20 among the plurality of blades 20.

[0022] The shroud 40 has an annular shape that expands in the radial direction Drd. The shroud 40 is connected to the first blade end portions 21 of the plurality of blades 20. The shroud 40 is formed with intake holes 41 through which air is sucked on its inner peripheral side.

[0023] The shroud 40 has an inner peripheral end portion 42 that constitutes the inner peripheral portion and an outer peripheral end portion 43 that constitutes the outer peripheral portion. The inner peripheral end portion 42 of the shroud 40 forms the intake holes 41. The shroud 40 protrudes upward along the axial direction Dax on the inner peripheral end portion 42 side so that air can easily flow into the intake holes 41. Also, the outer peripheral end portion 43 side of the shroud 40 extends in a direction intersecting the axial direction Dax.

[0024] The main board 50 has a disk shape that expands in the radial direction Drd. The inner peripheral side of the main board 50 is connected to the shaft 2 by a cap (not shown). The main board 50 is connected to the second blade end portions 22 of the plurality of blades 20. The main board 50 extends in a direction intersecting the axial direction Dax.

[0025] The centrifugal fan 10 of the present embodiment is configured as a closed fan whose both sides in the axial direction Dax are covered by the shroud 40 and the main board 50. The plurality of blades 20, the shroud 40, and the main board 50 of the centrifugal fan 10 may be formed as an integral structure by injection molding or the like, or may be formed by joining the plurality of blades 20, the shroud 40, and the main board 50, which are separately configured, by adhesion or the like.

[0026] The centrifugal fan 10 of this embodiment is a turbofan, and the part on the trailing edge 24 side of the blade 20 is inclined in the direction opposite to the rotation direction Drt of the shaft 2. When the centrifugal fan 10 rotates around the axis CL of the shaft 2, it sucks air from one side in the axial direction Dax. Then, the centrifugal fan 10 blows out the air sucked from one side in the axial direction Dax in the direction away from the axis CL of the shaft 2 (i.e., the radial direction Drd). The centrifugal fan 10 includes a mixed-flow fan that blows out the air sucked from one side in the axial direction Dax in a direction inclined with respect to the axis CL of the shaft 2. The centrifugal fan 10 flows, for example, along the virtual streamlines IL1 to IL4 shown in FIG. 3. Hereinafter, the virtual streamlines IL1 to IL4 will be described with reference to FIG. 3.

[0027] The virtual streamlines IL1 to IL4 are lines connecting a plurality of division points Xa set on the leading edge 23, a plurality of division points Xb set on the trailing edge 24, and a plurality of division points Xc, Xd, Xe set on a plurality of intermediate parts 25, 26, 27 between the leading edge 23 and the trailing edge 24 in a predetermined order.

[0028] The plurality of division points Xa provided on the leading edge 23 are those obtained by dividing the leading edge 23 into a predetermined number so that the lengths along the leading edge 23 are equal. In FIG. 3, the leading edge 23 is divided into three parts by four division points Xa1 to Xa4, but the number of divisions of the leading edge 23 may be different from that shown in FIG. 3.

[0029] The plurality of division points Xb provided on the trailing edge 24 are those obtained by dividing the trailing edge 24 into a predetermined number so that the lengths along the trailing edge 24 are equal. In FIG. 3, the trailing edge 24 is divided into three parts by four division points Xb1 to Xb4, but the number of divisions of the trailing edge 24 may be different from that shown in FIG. 3. Note that the number of divisions of the trailing edge 24 needs to be the same as the number of divisions of the leading edge 23.

[0030] The plurality of intermediate portions 25, 26, 27 are portions located at positions equally dividing the space between the leading edge portion 23 and the trailing edge portion 24 in each of the plurality of blades 20. And the plurality of division points Xc, Xd, Xe provided at the plurality of intermediate portions 25, 26, 27 are those obtained by dividing the plurality of intermediate portions 25, 26, 27 into a predetermined number so that the lengths along the plurality of intermediate portions 25, 26, 27 are equal. In FIG. 3, although the illustration shows that the plurality of intermediate portions 25, 26, 27 are divided into three by four division points Xc1 to Xc4, Xd1 to Xd4, Xe1 to Xe4, the number of divisions of the plurality of intermediate portions 25, 26, 27 may be different from that shown in FIG. 3. Note that the number of divisions of the plurality of intermediate portions 25, 26, 27 needs to be the same as the number of divisions of the leading edge portion 23 and the trailing edge portion 24.

[0031] In the present embodiment, among the plurality of division points Xa, Xb, Xc, Xd, Xe set at the leading edge portion 23, the trailing edge portion 24, and the plurality of intermediate portions 25, 26, 27 respectively, lines connecting those having the same number when counted from the side of the first blade end portion 21 are defined as virtual streamlines IL1 to IL4. Note that, among the plurality of division points Xa, Xb, Xc, Xd, Xe set at the leading edge portion 23, the trailing edge portion 24, and the plurality of intermediate portions 25, 26, 27 respectively, lines connecting those having the same number when counted from the side of the second blade end portion 22 may be defined as virtual streamlines IL1 to IL4.

[0032] Here, FIG. 4 is an explanatory diagram for explaining the blade shape of the centrifugal fan CF of the blower CE which is a comparative example of the present embodiment. In FIG. 4, a plan view of the centrifugal fan CF with the shroud 40 removed is illustrated. Note that in FIG. 4, the same reference numerals are given to the portions corresponding to the centrifugal fan 10 of the present embodiment in the centrifugal fan CF of the comparative example.

[0033] As shown in Fig. 4, the plurality of blades 20 of the centrifugal fan CF have a curved pressure surface 20A and a curved suction surface 20B. When the centrifugal fan CF rotates about the axis CL of the shaft 2, air flows through the inter-blade flow path 29 formed between adjacent blades 20. At this time, near the leading edge 23 of the plurality of blades 20, as shown in Fig. 5, the flow velocity of the air flow on the suction surface 20B side of the blade 20 tends to be faster than the flow velocity of the air flow on the pressure surface 20A side of the blade 20. Such a flow velocity distribution is not preferable because it causes an increase in pressure loss and deterioration of noise.

[0034] In consideration of this, as shown in Fig. 6, the centrifugal fan 10 of the present embodiment is provided with a convex portion 30 that protrudes so as to approach the pressure surface 20A of the adjacent blade 20 with respect to the suction surface 20B of the air inflow portion 28 near the leading edge 23 among the plurality of blades 20.

[0035] The air inflow portion 28 is a portion on the virtual streamline IL that is closer to the leading edge 23 than the trailing edge 24. Specifically, the air inflow portion 28 is a portion of the blade 20 that is closer to the axis CL than the intermediate portion 26 at the center of the plurality of intermediate portions 25, 26, and 27.

[0036] The convex portion 30 redirects the direction of the air flow along the suction surface 20B of the blade 20 toward the pressure surface 20A of the adjacent blade 20. As shown in Figs. 7, 8, and 9, the convex portion 30 is provided on the downstream side of the air flow with respect to the leading edge 23 in the air inflow portion 28. The convex portion 30 is inclined with respect to the suction surface 20B such that the first portion 31 on the upstream side of the air flow close to the leading edge 23 approaches the pressure surface 20A, and the second portion 32 on the downstream side of the air flow away from the leading edge 23 moves away from the pressure surface 20A with respect to the suction surface 20B. The convex portion 30 has a curved surface at the connection portion with the suction surface 20B so that no step or corner is formed at the connection portion between the suction surface 20B and the first portion 31 and at the connection portion between the second portion 32 and the suction surface 20B.

[0037] The wing 20 configured in this way has a shape in which the portion where the first part 31 of the convex part 30 and the negative pressure surface 20B near the leading edge part 23 intersect is recessed, so that the direction of the airflow along the negative pressure surface 20B is turned toward the positive pressure surface 20A.

[0038] In order to appropriately turn the direction of the airflow along the negative pressure surface 20B toward the positive pressure surface 20A, it is desirable that the plate thickness at the portion including the convex part 30 is at most 1.5 times or more the plate thickness at the minimum inner diameter position of the positive pressure surface 20A. In the present embodiment, the length of the line segment connecting the intersection of the virtual circle having a predetermined radius centered on the axis CL and the positive pressure surface 20A and the intersections of the virtual circle and the negative pressure surface 20B is defined as the plate thickness of the wing 20.

[0039] The convex part 30 is provided in the section of the negative pressure surface 20B from the virtual streamline IL2 to the virtual streamline IL4. Specifically, as shown in FIGS. 7 and 8, the convex part 30 is not provided near the first wing end part 21 on one side in the axial direction Dax at the air inflow part 28. As shown in FIG. 9, the convex part 30 is provided near the second wing end part 22 on the other side in the axial direction Dax at the air inflow part 28.

[0040] Here, among the virtual streamlines IL1 to IL4, assuming that a virtual line equidistant from those at both ends in the axial direction Dax is the intermediate virtual streamline IL5. At this time, the position in the axial direction Dax where the plate thickness of the wing 20 along the rotational direction Drt is maximum at the portion where the convex part 30 is provided on the negative pressure surface 20B is closer to the main plate 50 than the intermediate virtual streamline IL5. For example, the convex part 30 is set such that the top part 33 between the first part 31 and the second part 32 is closer to the main plate 50 than the intermediate virtual streamline IL5.

[0041] The protruding height of the convex part 30 is smaller than the interval between adjacent wings 20 at the portion where the convex part 30 is not provided. The protruding height of the convex part 30 is, for example, set to be at most half the interval between adjacent wings 20 at the portion where the convex part 30 is not provided.

[0042] Incidentally, on the pressure surface 20A of the blade 20, due to the influence of the centrifugal force caused by the bend of the inter-blade flow path 29, a vortex Vt is generated in a balanced relationship with the velocity boundary layer of the pressure surface 20A. This vortex Vt becomes prominent in a configuration where the flow velocity of the air flow on the pressure surface 20A side is increased by the convex portion 30 provided on the suction surface 20B side as in the present invention.

[0043] On the other hand, in the centrifugal fan 10 of the present embodiment, a part of the pressure surface 20A at the air inlet portion 28 is inclined so as to be located on the front side in the rotation direction Drt as it approaches the main board 50.

[0044] Specifically, as shown in FIG. 10, the pressure surface 20A of the air inlet portion 28 is inclined such that at least a part on the side closer to the main board 50 is located on the front side in the rotation direction Drt as it approaches the main board 50. That is, the pressure surface 20A of the air inlet portion 28 is inclined such that the lower blade portion 28B near the main board 50 is located at a position advanced in the rotation direction Drt as it approaches the main board 50.

[0045] Also, the pressure surface 20A of the air inlet portion 28 is inclined such that at least a part on the side closer to the shroud 40 is located on the front side in the rotation direction Drt as it approaches the shroud 40. That is, the pressure surface 20A of the air inlet portion 28 is inclined such that the upper blade portion 28A near the shroud 40 is located at a position advanced in the rotation direction Drt as it approaches the shroud 40.

[0046] Here, in the present embodiment, a line connecting a point P1 located on the most front side in the rotation direction Drt and a point P2 located on the most rear side in the rotation direction Drt among the upper blade portion 28A of the air inlet portion 28 is defined as the main board side reference line Lm. Also, in the present embodiment, a line connecting a point P3 located on the most front side in the rotation direction Drt and the point P2 located on the most rear side in the rotation direction Drt among the lower blade portion 28B of the air inlet portion 28 is defined as the shroud side reference line Ls.

[0047] The motherboard side reference line Lm and the shroud side reference line Ls are inclined with respect to the plane PL along the axis CL. The angle θm formed by the motherboard side reference line Lm and the plane PL along the axis CL is smaller than the angle θs formed by the shroud side reference line Ls and the plane PL along the axis CL. Among the sides closer to the motherboard 50, the point P1 located on the front side in the rotational direction Drt is located on the front side in the rotational direction Drt compared to the point P3 located on the front side in the rotational direction Drt among the sides closer to the shroud 40. Also, on the positive pressure surface 20A, the point P2 located on the rear side in the rotational direction Drt is closer to the motherboard 50 than the shroud 40.

[0048] The upper-wing portion 28A of the air inlet portion 28 is set such that the inlet angle of the blade 20 in the upper-wing portion 28A is smaller than the inlet angle of the blade 20 in the centrifugal fan CF of the comparative example shown in FIG. 4, and the position of the point P1 located on the front side in the rotational direction Drt is set. According to this, the incident angle of the inflowing air with respect to the blade 20 in the upper-wing portion 28A can be made smaller than the incident angle of the inflowing air with respect to the blade 20 of the centrifugal fan CF of the comparative example. As a result, the separation of the air flow from the blade 20 occurring near the shroud 40 can be reduced.

[0049] Here, the inlet angle is the angle formed by the tangent of the inscribed circle at the leading edge 23 of the blade 20 and the chord line of the blade. The inscribed circle is a virtual circle that touches the inside of each of the plurality of blades 20 in the radial direction Drd. The leading edge 23 is the portion of the blade 20 that touches the inscribed circle. The chord line is a straight line connecting the leading edge 23 and the trailing edge 24 of the blade 20. Also, the incident angle is the difference between the inflow angle of the inflowing air at the leading edge 23 of the blade 20 and the inlet angle. The inflow angle is the angle formed by the tangent of the inscribed circle at the position of the leading edge 23 of the blade 20 and the direction of the velocity vector of the inflowing air.

[0050] Also, the lower-wing portion 28B of the air inlet portion 28 changes such that the inclination toward the front side in the rotational direction Drt becomes smaller as it moves away from the motherboard 50. Specifically, as shown in FIGS. 12, 13, and 14, the inclination toward the front side in the rotational direction Drt gradually becomes smaller as it moves away from the leading edge 23 of the blade 20.

[0051] Here, FIG. 12 is a cross-sectional view of the blade 20 at the position where the inclination toward the front side in the rotation direction Drt is maximum. FIG. 13 is a cross-sectional view of the blade 20 at the position where the plate thickness of the blade 20 along the rotation direction Drt is maximum at the portion where the convex portion 30 is provided on the negative pressure surface 20B, as shown in FIG. 11. FIG. 14 is a cross-sectional view of the blade 20 at a position on the virtual streamline IL closer to the leading edge 23 than the trailing edge 24. FIG. 15 is a cross-sectional view of the blade 20 at the position where the chord length Lw at the second blade end portion 22 is intermediate.

[0052] When the position in the axial direction Dax where the inclination toward the front side in the rotation direction Drt starts at the portion where the inclination toward the front side in the rotation direction Drt is maximum is defined as the inclination start position Px1, as shown in FIG. 12, the inclination start position Px1 is set approximately in the middle between the shroud 40 and the main plate 50.

[0053] As shown in FIG. 13, at the position where the plate thickness of the blade 20 along the rotation direction Drt is maximum at the portion where the convex portion 30 is provided on the negative pressure surface 20B, a part of the under-wing portion 28B on the positive pressure surface 20A of the blade 20 is inclined toward the front side in the rotation direction Drt. Therefore, the position where the inclination toward the front side in the rotation direction Drt in the under-wing portion 28B disappears is farther from the axis CL than the position where the plate thickness of the blade 20 along the rotation direction Drt is maximum at the portion where the convex portion 30 is provided on the negative pressure surface 20B.

[0054] Also, when the position in the axial direction Dax where the plate thickness of the blade 20 along the rotation direction Drt is maximum at the portion where the convex portion 30 is provided on the negative pressure surface 20B is defined as the plate thickness maximum position Px2, the plate thickness maximum position Px2 is set closer to the main plate 50 than the shroud 40. Specifically, the plate thickness maximum position Px2 is set closer to the main plate 50 with respect to the inclination start position Px1.

[0055] As shown in Fig. 14, at a position on the virtual streamline IL closer to the leading edge 23 than the trailing edge 24, a part of the under-wing portion 28B on the positive pressure surface 20A of the blade 20 is slightly inclined forward in the rotation direction Drt. Further, as shown in Fig. 15, at a position where the blade chord length Lw is approximately in the middle, the under-wing portion 28B on the positive pressure surface 20A of the blade 20 is not inclined forward in the rotation direction Drt.

[0056] Therefore, the position where the inclination of the under-wing portion 28B on the positive pressure surface 20A forward in the rotation direction Drt disappears is at the leading edge 23 on the virtual streamline IL. Specifically, the position where the inclination of the under-wing portion 28B on the positive pressure surface 20A forward in the rotation direction Drt disappears is closer to the leading edge 23 than the middle of the blade chord length Lw at the second blade end 22.

[0057] When the blower 1 of the present embodiment described above is energized to the electric motor 3, the centrifugal fan 10 rotates in the rotation direction Drt together with the shaft 2. At this time, the blades 20 of the centrifugal fan 10 impart momentum to the air. As a result, the centrifugal fan 10 sucks air from the intake hole 41 toward the inter-blade flow path 29 and blows out the air in the inter-blade flow path 29 toward the outside in the radial direction Drd of the centrifugal fan 10.

[0058] The blade 20 of the present embodiment is provided with a convex portion 30 protruding on the negative pressure surface 20B of the air inflow portion 28 so as to approach the positive pressure surface 20A of the adjacent blade 20. By applying a force to a part of the air flow flowing along the negative pressure surface 20B of the blade 20 by the convex portion 30 provided on the negative pressure surface 20B of the blade 20 in a direction away from the negative pressure surface 20B, as shown in Fig. 16, the air flow easily flows toward the positive pressure surface 20A side. As a result, as shown in Fig. 17, the flow velocity of the air flow on the negative pressure surface 20B side decreases, and the flow velocity of the air flow on the positive pressure surface 20A side increases, so that the difference between the flow velocity of the air flow on the negative pressure surface 20B side and the flow velocity of the air flow on the positive pressure surface 20A side becomes smaller.

[0059] Here, when the flow velocity of the air current on the positive pressure surface 20A side increases, vortices Vt are likely to occur on the positive pressure surface 20A side. However, the blade 20 of the present embodiment is inclined such that the positive pressure surface 20A is positioned on the front side in the rotation direction Drt as it approaches the main plate 50. Therefore, as shown in FIG. 18, a force Fc is likely to act in a direction to suppress the generation or development of the vortices Vt on the positive pressure surface 20A side of the blade 20, and problems caused by the vortices Vt on the positive pressure surface 20A side can be suppressed.

[0060] Therefore, in the blower 1 of the present embodiment, it is possible to suppress the flow velocity distribution near the leading edge portion 23 of the blade 20 and also suppress problems caused by the vortices Vt on the positive pressure surface 20A side resulting from the suppression of the flow velocity distribution. Examples of problems caused by the vortices Vt on the positive pressure surface 20A side include an increase in pressure loss and deterioration of noise. As shown in FIG. 19, the blower 1 of the present invention can suppress an increase in pressure loss compared to the blower CE of the comparative example shown in FIG. 4.

[0061] Also, according to the present embodiment, the following effects can be obtained.

[0062] (1) In the centrifugal fan 10, since the flow velocity on the main plate 50 side of the blade 20 is higher than that on the shroud 40 side, vortices Vt are more likely to occur on the positive pressure surface 20A side of the blade 20 than on the shroud 40 side. Also, near the shroud 40 at the leading edge portion 23 of the blade 20, air separation near the shroud 40 is likely to occur.

[0063] Taking these into consideration, in the present embodiment, the portion of the positive pressure surface 20A of the air inflow portion 28 closer to the main plate 50 is inclined so as to be positioned on the front side in the rotation direction Drt as it approaches the main plate 50. Thereby, a force is likely to act in a direction to suppress the generation or development of the vortices Vt on the positive pressure surface 20A side of the blade 20, and problems caused by the vortices Vt on the positive pressure surface 20A side can be suppressed.

[0064] In addition, in the present embodiment, a portion of the positive pressure surface 20A of the air inflow portion 28, which is closer to the shroud 40, is inclined so as to be located on the front side in the rotation direction Drt as it approaches the shroud 40. According to this, the inflow angle of the airflow with respect to the blade 20 in the vicinity of the shroud 40 can be reduced, and the separation of the air in the vicinity of the shroud 40 can be suppressed.

[0065] Therefore, in the blower 1 of the present embodiment, it is possible to suppress the separation of the air in the vicinity of the shroud 40 while suppressing the flow velocity distribution in the vicinity of the leading edge portion 23 of the blade 20.

[0066] (2) Also, since the flow velocity of the airflow is higher on the main board 50 side than on the shroud 40 side and noise is likely to increase, it is desirable that the configuration be such that the generation of the vortex Vt can be suppressed while gently inclining the air inflow portion 28. On the other hand, since the flow velocity is lower on the shroud 40 side than on the main board 50 side, even if the inclination of the air inflow portion 28 is increased to obtain the effect of suppressing the separation of the air in the vicinity of the shroud 40, noise is less likely to become a problem.

[0067] Taking these into consideration, for the blade 20, the angle θm formed by the main board side reference line Lm and the plane PL along the axis CL is smaller than the angle θs formed by the shroud side reference line Ls and the plane PL along the axis CL. According to this, it is possible to design the blower 1, which can suppress the separation of the air in the vicinity of the shroud 40 while suppressing the flow velocity distribution in the vicinity of the leading edge portion 23 of the blade 20, to be suitable for suppressing noise generation.

[0068] (3) The flow velocity of the airflow on the positive pressure surface 20A side of the blade 20 tends to be prominent in the vicinity of the portion corresponding to the convex portion 30 from the leading edge portion 23 on the positive pressure surface 20A of the blade 20. And in the vicinity of the portion where the convex portion 30 is provided on the leading edge portion 23 side and the negative pressure surface 20B of the blade 20, the vortex Vt is more likely to occur than on the trailing edge portion 24 side.

[0069] Taking these factors into account, it is desirable that the position where the inclination of the pressure surface 20A of the under-wing portion 28B toward the front side in the rotation direction Drt disappears is close to the leading edge 23 on the virtual streamline IL. Specifically, it is desirable that the position where the inclination of the pressure surface 20A of the under-wing portion 28B toward the front side in the rotation direction Drt disappears is farther from the axis center CL than the position where the plate thickness of the wing 20 along the rotation direction Drt is maximum at the portion where the convex portion 30 is provided on the negative pressure surface 20B. With such a configuration, it is possible to sufficiently suppress the problem caused by the vortex Vt on the pressure surface 20A side of the wing 20 while suppressing the flow velocity distribution in the vicinity of the leading edge 23 of the wing 20.

[0070] (4) The pressure surface 20A of the air inflow portion 28 changes such that the inclination toward the rotation direction Drt becomes smaller as a part of the under-wing portion 28B moves away from the leading edge 23. And the position where the inclination of the pressure surface 20A of the under-wing portion 28B toward the front side in the rotation direction Drt disappears is close to the leading edge 23 with respect to the position at the middle of the chord length Lw of the second wing end portion 22. According to this, it is possible to suppress the generation or development of the vortex Vt on the pressure surface 20A of the wing 20.

[0071] (5) Here, there is a tendency that the vortex Vt is likely to occur in the vicinity of the portion of the pressure surface 20A corresponding to the convex portion 30. For this reason, it is desirable that the maximum plate thickness position Px2 is set close to the main plate 50 with respect to the inclination start position Px1. In this way, it is possible to sufficiently suppress the problem caused by the vortex Vt on the pressure surface 20A side of the wing 20.

[0072] (6) Also, the flow velocity difference between the airflows on the negative pressure surface 20B side and the pressure surface 20A side of the wing 20 tends to be more easily enlarged on the main plate 50 side than on the shroud 40 side. For this reason, it is desirable that the maximum plate thickness position Px2 is set close to the main plate 50 with respect to the intermediate virtual streamline IL5. In this way, it is possible to sufficiently suppress the flow velocity difference between the airflows on the negative pressure surface 20B side and the pressure surface 20A side of the wing 20.

[0073] (Other embodiments) As described above, representative embodiments of the present disclosure have been explained. However, the present disclosure is not limited to the above-described embodiments and can be variously modified, for example, as follows.

[0074] In the centrifugal fan 10 of the above-described embodiment, although substantially the entire portion of the positive pressure surface 20A of the air inlet portion 28 closer to the main board 50 is inclined so as to be located on the front side in the rotation direction Drt as it approaches the main board 50, it is not limited thereto. For example, in the centrifugal fan 10, a part of the portion of the positive pressure surface 20A of the air inlet portion 28 closer to the main board 50 may not be inclined toward the front side in the rotation direction Drt.

[0075] Although it is desirable that the portion of the positive pressure surface 20A of the air inlet portion 28 closer to the shroud 40 in the centrifugal fan 10 is inclined so as to be located on the front side in the rotation direction Drt as it approaches the shroud 40, it is not limited thereto. For example, in the centrifugal fan 10, the portion of the positive pressure surface 20A of the air inlet portion 28 closer to the shroud 40 may not be inclined toward the front side in the rotation direction Drt.

[0076] Although it is desirable that the angle θm formed by the main board side reference line Lm and the plane PL along the axis CL of the plurality of blades 20 is smaller than the angle θs formed by the shroud side reference line Ls and the plane PL along the axis CL, it is not limited thereto. The angle θm formed by the main board side reference line Lm and the plane PL along the axis CL of the plurality of blades 20 may be equal to or larger than the angle θs formed by the shroud side reference line Ls and the plane PL along the axis CL.

[0077] Although it is desirable that the position where the inclination toward the front side in the rotation direction Drt on the positive pressure surface 20A of the under-wing portion 28B disappears is close to the leading edge 23 on the virtual streamline IL, it does not have to be so.

[0078] Also, although it is desirable that the position where the inclination toward the front side in the rotation direction Drt on the positive pressure surface 20A of the under-wing portion 28B disappears is set close to the leading edge 23 with respect to the position at the middle of the chord length Lw of the second blade end 22, it does not have to be so.

[0079] Furthermore, although it is desirable that the maximum plate thickness position Px2 is set near the main plate 50 with respect to the inclination start position Px1, it is not limited thereto. The maximum plate thickness position Px2 may be set near the shroud 40 with respect to the inclination start position Px1. Also, the maximum plate thickness position Px2 may not be set near the main plate 50 with respect to the intermediate virtual streamline IL5.

[0080] In the above-described embodiment, the centrifugal fan 10 is exemplified as being constituted by a turbo fan, but the centrifugal fan 10 is not limited thereto. The centrifugal fan 10 may be constituted by a sirocco fan or a radial fan. Also, the centrifugal fan 10 may be constituted by an axial - flow fan.

[0081] In the above-described embodiment, an indoor air conditioner is exemplified as the application target of the blower 1 of the present disclosure, but the application target of the blower 1 is applicable to devices other than indoor air conditioners.

[0082] In the above-described embodiment, it goes without saying that the elements constituting the embodiment are not necessarily essential except in cases where it is explicitly stated that they are particularly essential and cases where they are considered to be clearly essential in principle.

[0083] In the above-described embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the components of the embodiment are mentioned, they are not limited to that specific number except in cases where it is explicitly stated that they are particularly essential and cases where they are clearly limited to a specific number in principle.

[0084] In the above-described embodiment, when referring to the shape, positional relationship, etc. of components, etc., they are not limited to that shape, positional relationship, etc. except in cases where it is explicitly stated and cases where they are clearly limited to a specific shape, positional relationship, etc. in principle.

[0085] The present invention includes the following features.

[0086] [Claim 1] A blower, A shaft (2), and a centrifugal fan (10) connected to the shaft, comprising: the centrifugal fan includes a plurality of blades (20) arranged around the axis (CL) of the shaft, a shroud (40) connected to a first blade end portion (21) located on one side in the axial direction of the shaft in each of the plurality of blades, and having an intake hole (41) through which air is sucked, and a main plate (50) connected to a second blade end portion (22) located on the other side in the axial direction in each of the plurality of blades; the plurality of blades have a leading edge portion (23) constituting an inner peripheral portion and a trailing edge portion (24) constituting an outer peripheral portion, the leading edge portion is divided into a predetermined number so that the lengths along the leading edge portion are equal, the trailing edge portion is divided into the predetermined number so that the lengths along the trailing edge portion are equal, and one or more intermediate portions (25, 26, 27) located at equal division positions between the leading edge portion and the trailing edge portion are divided into the predetermined number so that the lengths along the intermediate portions are equal. When a line connecting those having the same number when counted from one side of the first blade end portion and the second blade end portion among the plurality of division points in each of the leading edge portion, the trailing edge portion, and the intermediate portions is defined as a virtual streamline (IL), among the plurality of blades, a convex portion (30) protruding so as to approach the positive pressure surface (20A) of the adjacent blade is provided on a negative pressure surface (20B) of an air inflow site (28) closer to the leading edge portion than the trailing edge portion on the virtual streamline, a blower in which at least a part of the positive pressure surface of the air inflow site is inclined so as to be located on the front side in the rotation direction of the centrifugal fan as it approaches the main plate.

[0087] [Claim 2] The positive pressure surface of the air inlet portion is inclined such that at least a part of the side closer to the main board is located on the front side in the rotation direction as it approaches the main board, and at least a part of the side closer to the shroud is inclined such that it is located on the front side in the rotation direction as it approaches the shroud. The blower according to claim 1.

[0088] [Claim 3] When a line connecting the point located most on the front side in the rotation direction and the point located most on the rear side in the rotation direction among the sides closer to the main board on the positive pressure surface of the air inlet portion is defined as the main board side reference line (Lm), and a line connecting the point located most on the front side in the rotation direction and the point located most on the rear side in the rotation direction among the sides closer to the shroud on the positive pressure surface of the air inlet portion is defined as the shroud side reference line (Ls), The angle (θm) formed by the main board side reference line and the plane along the axis is smaller than the angle (θs) formed by the shroud side reference line and the plane along the axis. The blower according to claim 2.

[0089] [Claim 4] The positive pressure surface of the air inlet portion changes such that at least a part of the side closer to the main board has a decreasing inclination toward the front side in the rotation direction as it moves away from the main board. The position where the inclination toward the front side in the rotation direction on the positive pressure surface of the blade on the side closer to the main board disappears is closer to the leading edge on the virtual streamline, and is farther from the axis than the position where the plate thickness of the blade along the rotation direction is maximum at the portion where the convex portion is provided on the negative pressure surface. The blower according to any one of claims 1 to 3.

[0090] [Claim 5] The positive pressure surface of the air inlet portion changes such that at least a part of the side closer to the main board has a decreasing inclination toward the front side in the rotation direction as it moves away from the leading edge. The position where the inclination of the positive pressure surface of the blade on the side closer to the main board towards the front side in the rotation direction disappears is closer to the leading edge than the position at the middle of the chord length of the blade at the second blade end portion, the blower according to claim 4.

[0091] [Claim 6] The positive pressure surface of the air inflow portion changes such that the inclination towards the front side in the rotation direction decreases as it moves away from the leading edge. The axial position where the plate thickness of the blade along the rotation direction is maximum at the portion where the convex portion is provided on the negative pressure surface is closer to the main board than the axial position where the inclination of the positive pressure surface of the blade on the side closer to the main board towards the front side in the rotation direction starts to incline at the portion where the inclination is maximum, the blower according to any one of claims 1 to 5.

[0092] [Claim 7] When a virtual line equidistant from the virtual streamlines at both axial ends of the virtual streamlines is defined as the intermediate virtual streamline. The axial position where the plate thickness of the blade along the rotation direction is maximum at the portion where the convex portion is provided on the negative pressure surface is closer to the main board than the intermediate virtual streamline, the blower according to claim 6.

Explanation of reference numerals

[0093] 2 Shaft 10 Centrifugal fan 20 Blade 20A, 20B Positive pressure surface, negative pressure surface 21 First blade end portion 22 Second blade end portion 23 Leading edge 24 Trailing edge 40 Shroud 50 Main board

Claims

1. A blower, comprising: a shaft (2); a centrifugal fan (10) connected to the shaft, wherein the centrifugal fan includes: a plurality of blades (20) arranged around the axis (CL) of the shaft; a shroud (40) connected to a first blade end portion (21) located on one side in the axial direction of the shaft in each of the plurality of blades, and having an intake hole (41) through which air is sucked; a main plate (50) connected to a second blade end portion (22) located on the other side in the axial direction in each of the plurality of blades; the plurality of blades have a leading edge portion (23) forming an inner peripheral portion and a trailing edge portion (24) forming an outer peripheral portion; the leading edge portion is divided into a predetermined number of parts so that the lengths along the leading edge portion are equal, the trailing edge portion is divided into the predetermined number of parts so that the lengths along the trailing edge portion are equal, and one or more intermediate portions (25, 26, 27) located at equally divided positions between the leading edge portion and the trailing edge portion are divided into the predetermined number of parts so that the lengths along the intermediate portions are equal. When a line connecting those having the same number when counted from one side of the first blade end portion and the second blade end portion among the plurality of division points in each of the leading edge portion, the trailing edge portion, and the intermediate portions is defined as a virtual streamline (IL), in the plurality of blades, a convex portion (30) protruding so as to approach the positive pressure surface (20A) of the adjacent blade is provided on the negative pressure surface (20B) of an air inflow site (28) closer to the leading edge portion than the trailing edge portion on the virtual streamline; the positive pressure surface of the air inflow site is inclined such that at least a part closer to the main plate is located on the front side in the rotation direction of the centrifugal fan as it approaches the main plate; the negative pressure surface is such that the connection portion between the portion where the convex portion is provided and the portion upstream of the convex portion in the air flow direction is curved so that the portion where the convex portion is provided and the portion upstream of the convex portion in the air flow direction are continuously connected. The blower.

2. The blower according to claim 1, wherein the positive pressure surface of the air inflow site is inclined such that at least a part closer to the main plate is located on the front side in the rotation direction as it approaches the main plate, and at least a part closer to the shroud is inclined such that it is located on the front side in the rotation direction as it approaches the shroud.

3. When a line connecting a point located on the frontmost side in the rotational direction and a point located on the rearmost side in the rotational direction among the sides closer to the main board on the positive pressure surface of the air inflow portion is defined as the main board side reference line (Lm), and a line connecting a point located on the frontmost side in the rotational direction and a point located on the rearmost side in the rotational direction among the sides closer to the shroud on the positive pressure surface of the air inflow portion is defined as the shroud side reference line (Ls), The blower according to claim 2, wherein an angle (θm) formed by the main board side reference line and a plane along the axis is smaller than an angle (θs) formed by the shroud side reference line and a plane along the axis.

4. At least a part of the side closer to the main board of the positive pressure surface of the air inflow portion changes such that the inclination toward the front side in the rotational direction decreases as it moves away from the main board. The position where the inclination toward the front side in the rotational direction on the positive pressure surface of the blade on the side closer to the main board disappears is closer to the leading edge on the virtual streamline and is farther from the axis than the position where the plate thickness of the blade along the rotational direction is maximum at the portion where the convex portion is provided on the negative pressure surface. The blower according to any one of claims 1 to 3.

5. At least a part of the side closer to the main board of the positive pressure surface of the air inflow portion changes such that the inclination toward the front side in the rotational direction decreases as it moves away from the leading edge. The position where the inclination toward the front side in the rotational direction on the positive pressure surface of the blade on the side closer to the main board disappears is closer to the leading edge than the middle of the chord length of the blade at the second blade end portion. The blower according to claim 4.

6. The positive pressure surface of the air inflow portion changes such that the inclination toward the front side in the rotational direction decreases as it moves away from the leading edge. The axial position where the plate thickness of the blade along the rotational direction is maximum at the portion where the convex portion is provided on the negative pressure surface is closer to the main board than the axial position where the inclination toward the front side in the rotational direction starts on the positive pressure surface of the blade on the side closer to the main board at the portion where the inclination toward the front side in the rotational direction is maximum. The blower according to any one of claims 1 to 3.

7. When a virtual line equidistant from the virtual streamlines at both axial ends of the virtual streamline is defined as the middle virtual streamline, The axial position where the plate thickness of the blade along the rotational direction is maximum at the portion provided with the convex portion on the negative pressure surface is closer to the main plate with respect to the intermediate virtual streamline, the blower according to claim 6.

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