Turbo fans and air conditioners

Abstract

Each backward curved blade of the turbofan of the present invention makes the leading edge located ahead of the trailing edge in the direction of rotation, when the junction point between the leading edge and the main board is set as the first point, and the intersection point between the leading edge and the imaginary plane passing through the outermost periphery of the shroud and perpendicular to the rotation axis is set as the second point, the first curve (L21) obtained by projecting the leading edge onto the plane perpendicular to the rotation axis has a first inflection point in a coordinate system with an imaginary straight line passing through the first point and the second point as the horizontal axis and the rotation direction side as the positive side when viewed from the axial direction of the rotation axis, the first curve has a portion protruding in the reverse rotation direction at a portion closer to the first point than the first inflection point and a portion protruding in the rotation direction at a portion closer to the second point than the first inflection point, when viewed from the direction of the rotation axis, the trailing edge is along an arc centered on the rotation axis, and a third curve drawn by projecting the trailing edge onto a cylindrical surface coaxial with the rotation axis protrudes in the rotation direction, and the junction point between the third curve and the shroud is located behind the junction point between the third curve and the main board in the direction of rotation. Thus, the reduction of suction efficiency and the unevenness of blade outlet velocity distribution are suppressed.

Description

Technical Field

[0001] The present invention relates to a turbofan having backward-curved blades and an air conditioner. Background Art

[0002] A turbofan has a structure in which an air flow sucked in axially is changed in the radial direction by centrifugal force and blown out. Therefore, the sucked air flow becomes an air flow biased toward the main board side by inertia, and the work done by the blades is insufficient with respect to the air flow on the shroud side facing the main board. In addition, when the air flow on the shroud side peels off, the pressure drag increases, resulting in a decrease in the efficiency of the fan. In addition, by blowing out a fast air flow, the air flow collides with the structures of the heat exchanger provided outside the turbofan, resulting in an increase in pressure loss or deterioration of noise. In particular, in an air conditioner, when the specific speed relatively increases, the above problems are significant. The specific speed is the rotational speed required to generate a unit flow rate of air flow.

[0003] In Patent Document 1, the leading edge and the trailing edge of the blade are formed concave in the air flow direction, or the blade is bent, thereby seeking to reduce the wing load and suppress peeling, and achieve low noise and high efficiency.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent No. 6642913 Gazette Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In Patent Document 1, the trailing edge of the blade has a concave shape in the direction along the air flow, that is, in the direction along the camber line which is the center line in the thickness direction of the blade. Therefore, the net diameter of the blade is reduced, and the air supply performance such as a pressure increase or a decrease in the air volume is deteriorated.

[0009] In addition, although there is also the following technique, that is, by bending in a concave and convex shape in the rotation axis direction, the surface area of the blade is increased, thereby improving the air supply characteristics and noise characteristics while maintaining the overall size of the fan, the air flow flowing into the blade tends to be biased in the rotation axis direction and has three-dimensionality. Therefore, the air flow does not follow the blade cross section, which may cause peeling of the negative pressure surface on the shroud side or unevenness of the velocity distribution at the blade outlet.

[0010] The present invention is made to solve the above problems, and an object thereof is to provide a turbofan and an air conditioner that suppress a decrease in air supply performance and unevenness of velocity distribution.

[0011] Means for Solving the Problems

[0012] The turbofan of the present invention comprises: a main board, the main board having a hub connected to a rotating shaft (or a rotating axis, called "huihuan shaft" in Japanese); a shroud, the shroud and the main board are arranged opposite to each other; and a plurality of blades, the plurality of blades are arranged between the main board and the shroud, the plurality of blades respectively having a leading edge and a trailing edge located at a position farther from the rotating shaft than the leading edge, the leading edge being located at a position forward of the trailing edge in the rotating direction than the trailing edge, when the junction point of the leading edge and the main board is set as a first point, and the intersection point of the leading edge and an imaginary plane passing through the outermost periphery of the shroud and perpendicular to the rotating shaft is set as a second point, a first curve drawn by projecting the leading edge onto a plane perpendicular to the rotating shaft, when viewed from above in the axial direction of the rotating shaft, is drawn with the first curve passing through the first point and the second point as the imaginary plane. In a coordinate system with a straight line as the horizontal axis and the rotation direction side as the positive side, there is a first inflection point, the first curve includes: a portion that protrudes in the reverse rotation direction in the portion that is closer to the first point than the first inflection point; and a portion that protrudes in the rotation direction in the portion that is closer to the second point than the first inflection point, the first point is located in front of the rotation direction compared to the second point, and when viewed from above from the axial direction of the rotation axis, the second curve drawn by projecting the trailing edge onto a plane perpendicular to the rotation axis is along an arc centered on the rotation axis, and the third curve drawn by projecting the trailing edge onto a cylindrical surface coaxial with the rotation axis is formed to protrude in the rotation direction, and the junction point of the third curve and the shield is located behind the rotation direction compared to the junction point of the third curve and the main board.

[0013] Effects of the Invention

[0014] According to the turbofan disclosed in the present invention, since the area where the distance between the leading edge of the blade and the rotation axis is reduced is enlarged, and the leading edge on the main board side is closer to the front of the leading edge on the shroud side in the rotation direction, it is possible to prevent the air flow from being sucked in and improve the air supply performance. In addition, since the trailing edge of the blade is protruding in the rotation direction, and the trailing edge on the shroud side is located behind the trailing edge on the main board side in the rotation direction, it is possible to suppress the unevenness of the velocity distribution at the blade outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic perspective view of the turbofan according to the first embodiment.

[0016] Figure 2 This is a perspective view of the main parts of the main board and blades of the turbofan according to the first embodiment.

[0017] Figure 3 It is from Figure 2 A perspective view of the main part of the main plate and blades of the turbofan according to Embodiment 1 as viewed from different directions.

[0018] Figure 4 This is a plan view of the blades of the turbofan according to Embodiment 1 as viewed from the axial direction of the rotation shaft.

[0019] Figure 5 It is magnified Figure 4 Figure 1 shows the main parts of the .

[0020] Figure 6 This is a schematic diagram showing the projection of the trailing edge line of the blade of the turbofan of Embodiment 1 onto a virtual cylindrical surface centered on the rotation axis.

[0021] Figure 7 This is a plan view of the blades of the turbofan according to Embodiment 2 as viewed from the axial direction of the rotation shaft.

[0022] Figure 8 This is a plan view of the blades of the turbofan according to Embodiment 3 as viewed from the axial direction of the rotation shaft.

[0023] Fig. 9 This is a meridian plane view showing the main parts of the blades of the turbofan according to the third embodiment.

[0024] Fig.10 This is a plan view of the blades of the turbofan according to the fourth embodiment as viewed from the axial direction of the rotation shaft.

[0025] Fig.11 It is a graph showing the relationship between the leading edge height and the inlet angle of the turbofan blades according to the fifth embodiment.

[0026] Fig.12 This is a schematic diagram showing the interior of the air conditioner according to Embodiment 6.

[0027] Fig.13 Graphs showing the relationship between the air volume and the rotation speed in the turbofans of the embodiment and the comparative example.

[0028] Fig.14 Graphs showing the relationship between the air volume and the input in the turbofans of the embodiment and the comparative example.

[0029] Fig.15 Graphs showing the relationship between the air volume and the noise level in the turbofans of the embodiment and the comparative example. DETAILED DESCRIPTION

[0030] Hereinafter, the turbofan of the embodiment will be described with reference to the accompanying drawings. It should be noted that in the following drawings, the relative size relationship and shape of each structural component are sometimes different from the actual situation. In addition, in the following drawings, the structural components marked with the same figure mark are the same or equivalent structural components, which is common throughout the entire text of the specification. In addition, in the following description, for easy understanding, terms indicating directions are appropriately used, for example, "up", "down", "left", "right", "front" or "back". However, the terms indicating directions are records for the convenience of explanation, and do not limit the configuration and orientation of the device or component.

[0031] Implementation method 1.

[0032] <Structure of turbo fan 100>

[0033] Figure 1 This is a schematic perspective view of a turbofan 100 according to Embodiment 1. The turbofan 100 includes: a main plate 2 having a hub 1; an annular shroud 3 disposed opposite to the main plate 2; and a plurality of blades 4 disposed between the main plate 2 and the shroud 3. The hub 1 is provided at the center of the main plate 2 and is connected to a rotation axis RS.

[0034] exist Figure 1 In FIG. 1 , the XY plane is a plane perpendicular to the rotation axis RS and a plane perpendicular to the Z direction. The shield 3 and the main plate 2 are arranged with a gap in the Z direction.

[0035] Turbofan 100 is driven by a motor (not shown) to rotate in a rotation direction RD about rotation axis RS. Turbofan 100 is rotationally driven to suck airflow A1 in the axial direction of rotation axis RS and blow airflow A1 radially outward by centrifugal force generated by the rotation.

[0036] The hub 1 is projected along the rotation axis RS to be circular. That is, the hub 1 is circular when viewed along the axial direction of the rotation axis RS. The hub 1 is formed into a truncated cone shape that bulges from the main plate 2 side toward the shroud 3 side. As described later, Fig.12 As shown, the shaft 201a of the motor 201 is connected to the hub 1. The shape of the hub 1 is not limited to the above shape, and can also be other shapes. In order to cool the motor 201, the hub 1 is provided with a hole for air to pass through.

[0037] The main board 2 has a hub 1. The main board 2 rotates together with the hub 1 by being driven by a motor. A plurality of blades 4 are connected to the main board 2. The main board 2 is formed in a disc shape. The shape of the main board 2 is not limited to a disc shape. For example, the main board 2 can be formed in a mountain shape with the hub 1 as the center. The outer edge shape of the main board 2 is not limited to a circle with a fixed outer diameter, but can also be a polygon with a variable outer diameter.

[0038] The shroud 3 is formed with an air guide wall for introducing air on the air intake side of the turbofan 100. The shroud 3 is maintained at a distance from the main board 2 by a plurality of blades 4. The shroud 3 is a trumpet-shaped shape with a varying diameter. The shroud 3 is formed in a manner that the opening diameter is enlarged from the air intake port to the air outlet of the turbofan 100. The shroud 3 is formed in a mountain shape from the radially outer side toward the central side.

[0039] The plurality of blades 4 are arranged between the main board 2 and the shroud 3, and are connected to the main board 2 and the shroud 3. The plurality of blades 4 send the air inside the turbofan 100 to the outer peripheral side by rotating together with the main board 2. The plurality of blades 4 have a leading edge 41 and a trailing edge 42 located at a position farther from the rotation axis RS than the leading edge 41. The leading edge 41 of the plurality of blades 4 is located at a position forward of the rotation direction RD than the trailing edge 42. That is, the plurality of blades 4 are backward curved blades. The plurality of blades 4 are arranged at predetermined intervals on a circumference centered on the rotation axis RS. The intervals between the plurality of blades 4 may be all equal or unequal.

[0040] Since the plurality of blades 4 have the same features, one of the plurality of blades 4 will be described. The blade 4 has an outer surface 4a and an inner surface 4b which is the back of the outer surface 4a. The inner surface 4b is located closer to the rotation axis RS than the outer surface 4a. The outer surface 4a is a positive pressure surface that bears a pressure higher than the air pressure, and the inner surface 4b is a negative pressure surface that bears a pressure lower than the air pressure. The blade 4 is a shape in which the thickness gradually decreases from the position where the thickness is the maximum on the median camber line toward the leading edge or the trailing edge along the median camber line. The median camber line is the center line of the blade 4 in the thickness direction.

[0041] That is, the cross section of the blade 4 at a plane perpendicular to the rotation axis RS, that is, parallel to the XY plane, is a normal wing shape. It should be noted that the thickness change along the camber line of the blade 4 may not be monotonous, but may have a region where the thickness change varies midway.

[0042] <Structure of blade 4>

[0043] Figure 2 It is a perspective view of main parts of the main plate 2 and the blades 4 of the turbofan 100 according to the first embodiment. Figure 3 It is from Figure 2 A perspective view showing main parts of main plate 2 and blades 4 of turbofan 100 according to Embodiment 1 as viewed from different directions. Figure 2 as well as Figure 3 The state in which the protective cover 3 is removed is shown. Figure 4 This is a plan view of the blades 4 of the turbofan 100 according to the first embodiment as viewed from the axial direction of the rotation axis RS. Figure 4 In the figure, arrow A indicates Figure 2The main part of the main board 2 and the blade 4 of the turbo fan 100 is viewed from the direction of the arrow B. Figure 3 The viewing direction of the main part of the main board 2 and the blades 4 of the turbofan 100.

[0044] like Figure 2 to Figure 4 As shown, the blade 4 has a shape in which the center line in the thickness direction of the plane perpendicular to the rotation axis RS, i.e., the median arc line, is convex in the rotation direction RD. The cross-section of the blade 4 perpendicular to the rotation axis RS and parallel to the XY plane is a common wing shape.

[0045] Here, the center line of the blade 4 in the thickness direction in the cross section where the blade 4 is connected to the main board 2 is defined as the camber line LC1. The leading edge 41 of the camber line LC1 in the cross section where the blade 4 is connected to the main board 2 is defined as point P11. That is, point P11 is a point where the leading edge 41 is connected to the main board 2, and is an example of a first point. The trailing edge 42 of the camber line LC1 in the cross section where the blade 4 is connected to the main board 2 is defined as point P21.

[0046] In addition, when the shroud 3 is mounted on the blade 4, the center line in the thickness direction of the blade 4 in the cross section of the plane perpendicular to the rotation axis RS at the height position of the outermost periphery of the shroud 3 is defined as the center camber line LC2. The leading edge 41 of the center camber line LC2 at the height position of the outermost periphery of the shroud 3 is defined as point P12. That is, point P12 is an intersection of the leading edge 41 and the plane passing through the outermost periphery of the shroud 3 and perpendicular to the rotation axis RS, and is an example of a second point. In addition, the trailing edge 42 of the center camber line LC2 at the height position of the outermost periphery of the shroud 3 is defined as point P22.

[0047] The point farthest from the main plate 2 among the points where the blade 4 and the shroud 3 meet is defined as point P12a. The trajectory drawn by the leading edge 41 from point P11 to point P12a is defined as leading edge line L1. The trajectory drawn by the trailing edge 42 from point P21 to point P22 is defined as trailing edge line L2.

[0048] <Structure of the leading edge 41>

[0049] Figure 5 It is magnified Figure 4 The main parts of the diagram. Figure 5 In the figure, a coordinate system is considered in which the first straight line L11 passing through the points P11 and P12 is the horizontal axis and the first straight line L11 is perpendicular to the first straight line L11 and the rotation direction RD side of the blade 4, i.e., the pressure surface side, is positive. A line drawn by projecting the leading edge line L1 onto a plane perpendicular to the rotation axis RS is defined as a first curve L21.

[0050] At this time, the leading edge 41 of the blade 4 has the following shape: when viewed from above in the axial direction of the rotation axis RS, the first curve L21 has a first inflection point P13 in a coordinate system with the first straight line L11 as the horizontal axis. In addition, the first curve L21 of the leading edge 41 of the blade 4 when viewed from above describes an S-shaped curve, which is convex in the reverse rotation direction from the point P11 to the first inflection point P13, and is convex in the rotation direction RD from the point P12 to the first inflection point P13.

[0051] Here, consider using Figure 4 In the polar coordinate system of the distance R and the angle θ shown in FIG. 1 , the coordinate component of the point P11 is set to P11 (R11, θ11), and the coordinate component of the point P12 is set to P12 (R12, θ12). The distance R is the distance from the rotation axis RS to an arbitrary point. The angle θ is based on an arbitrary imaginary straight line passing through the rotation axis RS and is positive in the reverse rotation direction.

[0052] In the polar coordinate system, the first curve L21 satisfies R11<R12 and θ11<θ12. That is, in the leading edge line L1, the point P11 on the main board 2 side is located at a shorter radial inner side from the rotation axis RS than the point P12a on the shroud 3 side. In addition, in the leading edge line L1, the point P11 on the main board 2 side is located ahead of the point P12a on the shroud 3 side in the rotation direction RD.

[0053] The leading edge line L1 on the main board 2 side describes an S-shape protruding in the reverse rotation direction, whereby the area from the rotation axis RS to the leading edge 41, which is shorter than the distance between the rotation axis RS and the first straight line L11, increases on the main board 2 side. Therefore, the air flow concentrated on the main board 2 side due to inertia is effectively sucked into the turbofan 100.

[0054] Furthermore, by positioning the leading edge 41 on the main plate 2 forward in the rotation direction RD, the airflow on the main plate 2 is not disturbed by the blades 4 on the shroud 3 , and the airflow is efficiently sucked in from the blades 4 on the main plate 2 .

[0055] <Structure of the trailing edge>

[0056] The trailing edge 42 of the blade 4 is in a shape in which the trailing edge line L2 starts from the point P21 on the main board 2 side, passes through the point P23 which is ahead of the point P21 on the main board 2 side in the rotation direction RD, moves from the point P23 to the rear in the rotation direction RD, and reaches the point P22 on the shroud 3 side. The point P23 is the most forward point on the trailing edge line L2 in the rotation direction RD.

[0057] like Figure 4As shown, when the trailing edge line L2 is projected onto a plane perpendicular to the rotation axis RS, a second curve L22 is drawn. When viewed from above in the axial direction of the rotation axis RS, the second curve L22 follows a trajectory along an arc centered on the rotation axis RS.

[0058] Figure 6 Schematic diagram showing the projection of the trailing edge line L2 of the blade 4 of the turbofan 100 according to the first embodiment onto an imaginary cylindrical surface C centered on the rotation axis RS. Figure 6 As shown in FIG. 1 , when the trailing edge line L2 of the blade 4 is projected onto an imaginary cylindrical surface C centered on the rotation axis RS, a third curve L23 is drawn. On the imaginary cylindrical surface C centered on the rotation axis RS, the third curve L23 follows a trajectory that draws a convex U-shape from the junction point P21 with the main plate 2 to the front in the rotation direction RD, and reaches the junction point P22 with the shroud 3.

[0059] As described above, in a plane perpendicular to the rotation axis RS, the following polar coordinate system is considered, which uses: the distance R from the rotation axis RS; and the angle θ with the reverse rotation direction being positive based on an arbitrary imaginary curve passing through the rotation axis RS. At this time, the point P21 on the main board 2 side of the trailing edge line L2 is located ahead of the rotation direction RD relative to the point P22 on the shroud 3 side. That is, the junction point of the third curve L23 with the main board 2, i.e., point P21, is located ahead of the rotation direction RD compared to the junction point of the third curve L23 with the shroud 3, i.e., point P22. In addition, in the polar coordinate system, when the coordinate component of point P21 is set to P21 (R21, θ21) and the coordinate component of point P22 is set to (R22, θ22), the second curve L22 is a curve that satisfies θ21<θ22.

[0060] By making the trailing edge line L2 have the above-mentioned structure, the air flow concentrated on the main board 2 side is dispersed from the main board 2 side to the shroud 3 side in the process of moving along the rotating blades 4 toward the blowout side, so that the wind speed distribution of the air flow on the outer surface 4a of the blades 4 is uniform.

[0061] It should be noted that the second curve L22 only needs to be along the arc centered on the rotation axis RS. For example, fine sawtooth-like fine teeth can be provided on the trailing edge 42 of the blade 4. Even if the radial position of the trailing edge 42, i.e., the second curve L22, is not on the standard arc centered on the rotation axis RS, it will not affect the effect obtained by the second curve L22. As long as the second curve L22 does not deviate excessively from the arc centered on the rotation axis RS, the outer diameter of the blade 4 will not change, and therefore, the air supply performance can be maintained.

[0062] In addition, the change in the position of the trailing edge 42 in the rotation direction RD from point P21 to point P23 or from point P23 to point P22 does not necessarily need to be monotonous. As long as the positional relationship between point P21, point P22, and point P23 is within the range that satisfies the aforementioned positional relationship, a portion of the trailing edge 42 may have a portion where the direction of change is reversed.

[0063] Thus, in Embodiment 1, when viewed from above in the axial direction of the rotation axis RS, the leading edge 41 of the blade 4 is formed such that the leading edge line L1 describes an S-shaped shape protruding in the reverse rotation direction on the main plate 2 side, thereby improving the air supply characteristics of the turbofan 100.

[0064] The front edge 41 on the main plate 2 is shaped to be closer to the front side in the rotation direction RD than the front edge 41 on the shroud 3. Thus, the airflow is efficiently sucked by the blades 4 on the main plate 2 without being disturbed by the blades 4 on the shroud 3.

[0065] Furthermore, the efficiently inhaled air flow utilizes the shape of the trailing edge line L2, and is dispersed from the main board 2 side to the shroud 3 side as it moves toward the outlet side along the blade 4, making the wind speed distribution more uniform. As a result, it is possible to flow without causing the negative pressure surface on the shroud 3 side to peel off or the velocity distribution at the outlet of the blade 4 to be uneven, thereby preventing noise and adverse effects on fan efficiency.

[0066] For example, when the leading edge line L1 of the blade 4 is not an S-shaped protrusion in the reverse rotation direction on the main board 2 side, the area where the leading edge 41 is located on the inner diameter side relative to the rotation axis RS is limited compared to other areas on the main board 2 side where the air flow is concentrated. The case where the leading edge line L1 is not an S-shaped protrusion in the reverse rotation direction on the main board 2 side refers to, for example, a case where the trajectory of the leading edge 41 of the blade 4 is a straight line when viewed from above, or a case where the leading edge 41 protrudes in the rotation direction RD on the main board 2 side and in the reverse rotation direction on the shroud 3 side. On the main board 2 side, when the range of the area where the leading edge 41 is located on the inner diameter side relative to other areas is limited, the amount of air intake is also limited on the main board 2 side. In addition, when the position of the leading edge 41 in the rotation direction RD is the same on the main board 2 side and the shroud 3 side, the air flow is disturbed by the blade 4 on the shroud 3 side, and the air flow cannot be effectively sucked into the main board 2 side.

[0067] In contrast, by forming the leading edge line L1 of the blade 4 into an S-shaped shape protruding in the reverse rotation direction when viewed from above as in Embodiment 1, the leading edge 41 of the blade 4 can be located in a wider range of the area on the main board 2 side than other areas, compared to the case where the leading edge 41 of the blade 4 is a straight line. As a result, the air flow is effectively sucked into the main board 2 side where the flow is concentrated by inertia, thereby improving the air supply performance of the turbofan.

[0068] In addition, for example, when a structure is provided that can efficiently suck in the air flow concentrated on the main board 2 side, there is a possibility that the negative pressure surface on the shroud 3 side may peel off or the velocity distribution at the outlet of the blade 4 may be uneven. In this case, in order to increase the surface area of ​​the blade 4 and improve the air supply characteristics and noise characteristics, it is considered that the blade 4 is curved in a concave-convex shape as a whole in the direction of the rotation axis. However, even if the blade 4 is formed in a concave-convex shape in the axial direction, in the case where the cross-sectional shape of the blade 4 from the leading edge side to the trailing edge side is substantially the same as the axial shape of the rotation axis RS, the air flow flowing into the blade 4 may be uneven in the axial direction of the rotation axis RS, or the three-dimensional air flow may not be along the cross section of the blade 4.

[0069] In contrast, in the blade 4 of the first embodiment, the air flow that flows into the blade 4 and concentrates on the main board 2 side is directed toward the outlet side along the blade 4 by the shape of the trailing edge line L2, and is dispersed from the main board 2 side to the shroud 3 side on the outlet side. Therefore, the wind speed distribution of the air flow that flows in toward the main board 2 side under the influence of inertia is made more uniform, and the separation of the air flow on the negative pressure surface on the shroud 3 side is suppressed, or the noise deterioration caused by the uneven speed distribution of the air flow at the outlet of the turbofan 100 is suppressed.

[0070] This can simultaneously achieve improvement in the air blowing performance of turbofan 100 , improvement in fan efficiency, and improvement in fan noise.

[0071] According to the turbofan 100 of the first embodiment described above, the first curve L21 of the leading edge 41 on the main board 2 side when the leading edge 41 is viewed from the axial direction of the rotation axis RS is an S-shaped shape that is convex in the reverse rotation direction. As a result, the area where the distance from the rotation axis RS to the leading edge 41 is smaller than the distance between the rotation axis RS and the first straight line L11 is larger on the main board 2 side. Therefore, the air flow on the main board 2 side that is concentrated on the leading edge 41 by inertia is effectively sucked in, and the air supply characteristics are improved. In addition, the part of the leading edge 41 on the main board 2 side is a shape that is located in front of the rotation direction RD compared to the leading edge 41 on the shroud 3 side. As a result, the air flow is not disturbed by the blades 4 on the shroud 3 side, and the air flow can be effectively sucked in by the blades 4 on the main board 2 side. In addition, the trailing edge 42 is a shape in which the second curve L22 in a plan view is located on an arc centered on the rotation axis RS, the third curve L23 viewed from the cylindrical surface C is convex in the rotation direction RD, and the main board 2 side is located in front of the shroud 3 side in the rotation direction RD. As a result, the air flow that is biased toward the main board 2 side at the leading edge 41 side is evenly dispersed from the main board 2 side to the shroud 3 side, preventing the air flow from being separated from the negative pressure surface of the shroud 3 side, or preventing the noise from being deteriorated due to the uneven velocity distribution at the air outlet. Therefore, the deterioration of the air supply characteristics in the turbofan 100 and the uneven velocity distribution at the outlet of the blade 4 are suppressed.

[0072] In particular, when there is only one first inflection point P13 in the first curve L21, the air flow is less likely to be disturbed at the leading edge due to the three-dimensionality of the intake flow, i.e., the axial component of the air flow. Therefore, the air flow can flow smoothly toward the trailing edge, and the decrease in the intake efficiency of the air flow in the turbofan 100 and the uneven velocity distribution at the outlet of the blade 4 can be further suppressed.

[0073] Implementation method 2.

[0074] Figure 7 This is a plan view of the blade 4 of the turbofan 100 according to Embodiment 2 as viewed from the axial direction of the rotation axis RS. The structure of the blade 4 according to Embodiment 2 is different from that of Embodiment 1, but the other structures are the same as those of Embodiment 1, so the description is omitted and the same reference numerals are given to the same or corresponding parts.

[0075] like Figure 7 As shown, the blade 4 of the second embodiment has the following structure when viewed from above in the axial direction of the rotation axis RS: the center arc line LC1 on the main board 2 side and the center arc line LC2 on the shroud 3 side intersect each other at point P14. The center arc line LC1 on the main board 2 side refers to the center line of the blade 4 in the thickness direction in the surface where the blade 4 and the main board 2 are connected. In addition, the center arc line LC2 on the shroud 3 side refers to the center line of the blade 4 in the thickness direction in an imaginary plane passing through the outermost periphery of the shroud 3 of the blade 4 and perpendicular to the rotation axis RS. In the structure in which the center arc line LC1 on the main board 2 side intersects with the center arc line LC2 on the shroud 3 side, the area of ​​the negative pressure surface of the blade 4 that can be seen when observing the blade 4 from the suction port side is increased compared to the case where there is no intersection. The negative pressure surface of the blade 4 is the inner surface 4b of the blade 4.

[0076] The inner surface 4b of the blade 4 that can be seen from the suction port side is an area of ​​the blade 4 that is mainly located on the side of the shroud 3. By increasing the area of ​​the inner surface 4b that can be seen when observing the blade 4 from the suction port side, air tends to flow toward the negative pressure surface side of the blade 4 on the shroud 3 side, and the air flow is more effectively suppressed from peeling off the negative pressure surface of the blade 4 on the shroud 3 side.

[0077] According to the turbofan 100 of the second embodiment described above, since the area of ​​the negative pressure surface of the blade 4 visible from the suction port side is increased, the air flow tends to flow toward the negative pressure surface side of the blade 4 on the shroud 3 side. As a result, it is possible to more effectively suppress the air flow from being separated from the negative pressure surface of the blade 4 on the shroud 3 side, thereby improving the fan efficiency and fan noise.

[0078] Implementation method 3.

[0079] Figure 8This is a plan view of the blade 4 of the turbofan 100 according to Embodiment 3 as viewed from the axial direction of the rotation axis RS. The structure of the blade 4 according to Embodiment 3 is different from that of Embodiment 1, but the other structures are the same as those of Embodiment 1, so the description is omitted and the same reference numerals are given to the same or corresponding parts.

[0080] In the turbofan 100 of the third embodiment, the first inflection point P13 on the leading edge line L1 is closer to the point P11 than the point P12 in terms of the straight line distance when viewed from the axial direction of the rotation axis RS. That is, the distance between the first inflection point P13 and the point P11 is shorter than the distance between the first inflection point P13 and the point P12.

[0081] Fig. 9 This is a meridian plane view showing a main part of the blade 4 of the turbofan 100 according to Embodiment 3. The meridian plane view is a view showing a plane when a rotating solid formed by rotating the blade 4 is cut by a plane including the rotation axis RS.

[0082] like Fig. 9 As shown, in the meridian view of the blade 4, the angle θ3 formed by the normal line of the leading edge 41 on the shroud 3 side and the rotation axis RS is larger than the angle θ2 formed by the normal line of the leading edge 41 on the main board 2 side and the rotation axis RS. As described above, the blade 4 of the third embodiment is a structure in which the first inflection point P13 is arranged at a position closer to the point P11 than the point P12 when viewed from above in the axial direction of the rotation axis RS. Therefore, the angle θ3 formed by the normal line of the leading edge 41 on the shroud 3 side and the rotation axis RS is larger than the angle θ2 formed by the normal line of the leading edge 41 on the main board 2 side and the rotation axis RS.

[0083] In such a structure, the air flow A11 on the main board 2 side, the air flow A12 on the shroud 3 side, and the air flow A13 between the main board 2 and the shroud 3 flow in from the normal direction of the leading edge 41 of the blade 4. Therefore, on the shroud 3 side, the air flow A12 flowing in obliquely with respect to the cross section of the blade 4 can be adjusted so that the normal direction of the leading edge 41 of the blade 4 becomes the inflow direction of the air flow A12.

[0084] According to the turbofan 100 of the third embodiment described above, since the normal direction of the leading edge 41 of the blade 4 can be adjusted in accordance with the inflow direction of the air, flow loss can be suppressed, and the fan efficiency can be improved and the fan noise can be reduced.

[0085] Implementation method 4.

[0086] Fig.10 This is a plan view of the blade 4 of the turbofan 100 according to Embodiment 4 as viewed from the axial direction of the rotation axis RS. The structure of the blade 4 according to Embodiment 4 is different from that of Embodiment 1, but the other structures are the same as those of Embodiment 1, so the description is omitted and the same reference numerals are given to the same or corresponding parts.

[0087] like Fig.10 As shown, the blade 4 has a structure in which, in at least a portion from the main plate 2 side to the first inflection point P13, a second inflection point P15 where the curvature direction of the camber line in a cross section perpendicular to the rotation axis RS changes.

[0088] A straight line passing through the leading edge 41 and the trailing edge 42 in a certain cross section of the blade 4, i.e., the chord, is defined as a second straight line L12. Fig.10 In the figure, a straight line L12 relative to a section passing through a point P11 of the blade 4 is illustrated as an example. A straight line perpendicular to the second straight line L12 is defined as a third straight line L13. And, a coordinate system defined by the second straight line L12 and the third straight line L13 is considered. At this time, the bending direction of the center arc line LC1 in the section perpendicular to the rotation axis RS of the blade 4 changes at the second inflection point P15 in the coordinate system. The blade 4 has a structure in which the bending direction of the center arc line changes at the second inflection point P15 in at least a portion from the section on the main board 2 side to the section at the first inflection point P13. The blade 4 may also be a structure having a second inflection point P15 at all positions from the main board 2 side to the height of the first inflection point P13.

[0089] According to such a structure, the front edge of the cross section of the blade 4 on the main board 2 side protrudes in the reverse rotation direction, forming a reversely warped structure. The middle camber line of the blade 4 on the main board 2 side is reversely warped in a manner protruding in the reverse rotation direction, thereby, the inlet angle of the cross-sectional shape of the blade 4 becomes a shape that matches the inflow speed of the air flow. The inlet angle refers to the angle formed by the tangent line at the leading edge 41 of the imaginary circle with the rotation axis RS as the origin and passing through the leading edge 41 and the tangent line at the leading edge 41 of the middle camber line of the blade 4, which is the negative pressure surface of the blade 4 and the reverse rotation direction side.

[0090] Compared with the leading edge 41 of the blade 4 on the shroud 3 side, the leading edge 41 of the blade 4 on the main board 2 side is smaller in distance from the rotation axis RS, i.e., in the inner diameter, and therefore, the leading edge 41 on the main board 2 side is closer to the hub 1 than the leading edge 41 on the shroud 3 side. In addition, at the leading edge 41 of the blade 4 on the main board 2 side, the air flow is affected by the viscosity of the main board 2, and the radial component of the air inflow velocity tends to decrease. By appropriately designing the inlet angle, the collision loss between the air flow at the leading edge 41 of the blade 4 and the blade 4 is effectively suppressed, or the separation of the air flow at the leading edge 41 is effectively suppressed, thereby achieving an improvement in fan efficiency and a reduction in fan noise.

[0091] The turbofan 100 of the fourth embodiment described above is a structure in which the curvature direction of the median arc line of the blade 4 changes. By designing the shape of the blade 4 in such a way that the inlet angle matches the inflow velocity of the air flow, the collision loss between the air flow at the leading edge 41 of the blade 4 and the separation of the air flow from the blade 4 can be effectively suppressed, thereby achieving an improvement in fan efficiency and a reduction in fan noise.

[0092] Implementation method 5.

[0093] Fig.11 1 is a graph showing the relationship between the height of the leading edge 41 of the blade 4 and the inlet angle of the turbofan 100 of Embodiment 5. The structure of the blade 4 of Embodiment 5 is different from that of Embodiment 1, and the other structures are the same as those of Embodiment 1, so the description is omitted and the same reference numerals are given to the same or corresponding parts.

[0094] like Fig.11 As shown, the blade 4 is structured as follows: when the height of the leading edge 41 of the blade 4 is greater than the first inflection point P13, the angle on the reverse rotation direction side in the inlet angle gradually decreases. The height of the leading edge 41 of the blade 4 refers to the distance in the vertical direction from the main board 2 to the leading edge 41 of the blade 4, and is the distance in the +Z direction when the intersection of the main board 2 and the rotation axis RS is taken as the origin. In addition, as described above, the inlet angle refers to the angle formed by the tangent at the leading edge 41 of the circle that takes the rotation axis RS as the origin and passes through the leading edge 41 of the blade 4 and the tangent at the leading edge 41 of the mid-arc line of the blade 4. That is, the blade 4 is a structure in which the inlet angle of the section perpendicular to the rotation axis RS is gradually reduced from the section of the blade 4 where the first inflection point P13 of the leading edge line L1 is set as the leading edge 41 to the section of the blade 4 on the shroud 3 side.

[0095] The air flow at the leading edge 41 is easily affected by the hub 1 and the main board 2 on the main board 2 side where the inner diameter of the blade 4 is reduced. In addition, as the air flow at the leading edge 41 moves toward the shroud 3 side, the situation where it is affected by the hub 1 and the main board 2 disappears, and the inflow angle of the air relative to the cross section of the blade 4 tends to decrease.

[0096] Therefore, since the inlet angle of the blade 4 is reduced on the shroud 3 side, the impact loss of the air flow on the blade 4 can be suppressed, or the separation of the air flow from the leading edge 41 of the blade 4 can be suppressed, thereby improving the fan efficiency and reducing the fan noise.

[0097] According to the turbofan 100 of the fifth embodiment described above, when the height of the leading edge 41 of the blade 4 is greater than the height of the leading edge 41 at the first inflection point P13, the inlet angle of the blade 4 gradually decreases. Therefore, it is possible to suppress the impact loss of the air flow on the blade 4 and the leading edge separation, thereby achieving an improvement in fan efficiency and a reduction in fan noise.

[0098] Implementation method 6.

[0099] Fig.12 1 is a schematic diagram showing the interior of an air conditioner 200 according to Embodiment 6. Embodiment 6 is an air conditioner 200 including the turbo fan 100 described in any one of Embodiments 1 to 5, and description of the same or corresponding parts as those in Embodiments 1 to 5 will be omitted and the same reference numerals will be used.

[0100] like Fig.12 As shown, air conditioner 200 is equipped with turbofan 100 having blades 4 and motor 201 connected to turbofan 100 via shaft 201a. Heat exchanger 202 is arranged on the outlet side of turbofan 100. Bell mouth 203 is provided on the inlet side of turbofan 100.

[0101] When turbofan 100 is driven to rotate, air is sucked into air conditioner 200 from suction port 205. After passing through bell mouth 203, turbofan 100, and heat exchanger 202, air is blown out of air conditioner 200 from blowout port 204.

[0102] Since the velocity distribution of the air flow blown out from the turbofan 100 is uniform at the outlet, the velocity distribution of the air flow flowing into the heat exchanger 202 is also uniform. As a result, the pressure loss of the air flow when passing through the heat exchanger 202 is reduced and the heat exchange performance is improved, which contributes to the performance improvement and energy saving of the air conditioner 200 as a whole.

[0103] Example

[0104] Next, the performance evaluation of the turbofan 100 of the embodiment will be described. The performance evaluation was performed based on a comparative experiment between the turbofan 100 of the embodiment and a turbofan of a conventional structure of a comparative example.

[0105] In the experiment, the turbofan 100 of the embodiment and the turbofan of the comparative example were each configured to have blades with a diameter of 480 [mm] as the blades 4 and were respectively mounted on an air conditioner for the experiment.

[0106] Then, the turbofan 100 of the embodiment and the turbofan of the comparative example mounted on the air conditioner are driven at a predetermined rotation speed. The air volume, motor input and noise level are measured under the condition that the pressure difference between the air inlet 205 and the air outlet 204 of the air conditioner is 0. In addition, the noise level is measured at a position 1 m away from the air inlet 205 in a direction perpendicular to the suction surface under the condition that the pressure difference between the air inlet 205 and the air outlet 204 of the air conditioner is 0.

[0107] Fig.13Graphs showing the relationship between the air volume and the rotation speed in turbofan 100 of the embodiment and the comparative example. Fig.14 Graphs showing the relationship between the air volume and the input in turbofan 100 of the embodiment and the comparative example. Fig.15 Graphs showing the relationship between the air volume and the noise level in the turbofan 100 of the embodiment and the comparative example. Figures 13 to 15 In FIG. 1 , fan A represents a turbofan of a comparative example, and fan B represents turbofan 100 of an embodiment.

[0108] Depend on Fig.13 As shown in the figure, at the rated speed of each turbofan, for the air volume at the same speed, the air volume of fan B increases by about 3 [m 3 / min]. That is, it was confirmed that the turbofan 100 of the embodiment has the effect of improving the air blowing performance of the air blowing fan.

[0109] Depend on Fig.14 As shown, at the rated air volume of each turbofan, the motor input at the same air volume is reduced by about 11 [W] in fan B compared to fan A. That is, it is confirmed that the energy-saving performance of the blower fan is improved by turbofan 100 of the embodiment.

[0110] Depend on Fig.15 As shown, at the rated air volume of each turbofan, the noise level at the same air volume is reduced by about 2 [dB] in fan B compared to fan A. That is, it is confirmed that turbofan 100 of the embodiment achieves the effect of reducing the noise of the blower fan.

[0111] As can be seen from the above experimental results, according to the turbo fan 100 of the embodiment, it is possible to simultaneously achieve improved air supply performance, lower input, and lower noise.

[0112] Description of Reference Numerals

[0113] 1 hub, 2 main board, 3 shield, 4 blades, 4A outer surface, 4B inner surface, 41 leading edge, 42 trailing edge, 100 turbo fan, 200 air conditioner, 201 motor, 201a shaft, 202 heat exchanger, 203 bell mouth, 204 blowing outlet, 205 suction inlet.

Claims

1. A turbo fan, wherein: include: A main board, the main board having a hub connected to the rotating shaft; A shield, wherein the shield is disposed opposite to the main board; and a plurality of blades, wherein the plurality of blades are arranged between the main board and the shield, Each of the plurality of blades has a leading edge and a trailing edge located farther from the rotation axis than the leading edge, and the leading edge is located forward of the trailing edge in the rotation direction. When the junction point between the front edge and the main plate is set as the first point, and the intersection point between the front edge and an imaginary plane passing through the outermost periphery of the shield and perpendicular to the rotation axis is set as the second point, A first curve drawn by projecting the leading edge onto a plane perpendicular to the rotation axis has a first inflection point in a coordinate system with an imaginary straight line passing through the first point and the second point as the horizontal axis and the rotation direction side as the positive side when viewed from above from the axial direction of the rotation axis. The first curve includes: a portion protruding in the reverse rotation direction at a portion closer to the first point than the first inflection point; and a portion protruding toward the rotation direction at a portion closer to the second point than the first inflection point, The first point is located ahead of the second point in the rotation direction, The second curve drawn by projecting the trailing edge onto a plane perpendicular to the rotation axis is along an arc centered on the rotation axis when viewed from above from the axial direction of the rotation axis. The third curve drawn by projecting the trailing edge onto a cylindrical surface coaxial with the rotation axis is formed to be convex in the rotation direction, Compared with a joining point of the third curve and the main plate, a joining point of the third curve and the shield is located rearward in the rotation direction.

2. The turbofan according to claim 1, wherein: There is a single first inflection point on the first curve.

3. The turbofan according to claim 1 or 2, wherein: When each of the multiple blades is viewed from above in the direction of the rotation axis, a center line of each of the multiple blades in the thickness direction in the surface connected to the main board intersects with a center line of each of the multiple blades in the thickness direction in an imaginary plane passing through the outermost periphery of the shroud and perpendicular to the rotation axis.

4. The turbo fan according to any one of claims 1 to 3, wherein: In a plan view as viewed from the axial direction of the rotation shaft, a distance between the first inflection point and the first point is shorter than a distance between the first inflection point and the second point.

5. The turbo fan according to any one of claims 1 to 4, wherein: at least a portion between a cross section of the blade in a plane passing through the first point and perpendicular to the rotation axis and a cross section of the blade in a plane passing through the first inflection point and perpendicular to the rotation axis, The bending direction of the center line of the blade in the thickness direction has a second inflection point in the coordinate system defined by the first straight line and the second straight line, The first straight line passes through the leading edge and the trailing edge in a cross section of the blade in a plane perpendicular to the rotation axis, and the second straight line is perpendicular to the first straight line.

6. The turbofan according to any one of claims 1 to 5, wherein: In the cross section of the blade in a plane perpendicular to the rotation axis, the angle of the blade in the reverse rotation direction in the inlet angle gradually decreases from the cross section of the blade in a plane passing through the first inflection point and perpendicular to the rotation axis to the surface where the blade and the shroud meet, The inlet angle is an angle formed by a tangent line at the leading edge of a circle that takes the rotation axis as an origin and passes through the leading edge and a tangent line at the leading edge of a center line in a thickness direction of the blade.

7. The turbo fan according to any one of claims 1 to 6, wherein: When the joining point of the leading edge and the shield is set as the third point, and the trajectory drawn by the leading edge from the first point to the third point is set as the leading edge line, the leading edge line protrudes in the rotation direction between the second point and the point on the leading edge line corresponding to the first inflection point.

8. The turbo fan according to any one of claims 1 to 7, wherein: The third curved line is convex in the rotation direction with respect to a straight line drawn by projecting the rotation axis onto the cylindrical surface.

9. An air conditioner, wherein: A turbo fan according to any one of claims 1 to 8 is mounted thereon, A heat exchanger is provided on the air outlet side of the turbo fan.

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