Impellers, blowers and air conditioners

Abstract

In the impeller, when a plurality of imaginary cylinders centered on the rotation axis are assumed, each imaginary cross section of a plurality of blades corresponding to the cylindrical portion is defined as a chord direction cross section, a straight line connecting the leading edge and the trailing edge in the chord direction cross section is defined as a chord, a center line of the blade cross section is defined as a camber line, a distance between the camber line and the chord is defined as a camber height, a position on the camber line where the distance from the leading edge and the trailing edge is equal is defined as a camber midpoint, and a point where the camber height is maximum is defined as a maximum extreme point, in the chord direction cross section close to the inner peripheral edge of the blade, the maximum extreme point is located closer to the trailing edge than the camber midpoint and on the air suction side than the chord, and the camber line has at least one inflection point between the leading edge and the maximum extreme point, and in the chord direction cross section close to the outer peripheral end of the blade, the maximum extreme point is located closer to the leading edge than the camber midpoint and on the air suction side than the chord.

Description

[Technical field]

[0001] The present disclosure relates to an impeller, a blower, and an air conditioner. [Background technology]

[0002] Conventionally, there is an impeller having a plurality of blades arranged radially (see, for example, Patent Document 1). In the impeller of Patent Document 1, the center in the circumferential direction of the root of the blade is R1, the center in the circumferential direction of the outer periphery of the blade is R2, and the center of rotation of the blade is O. In the impeller of Patent Document 1, the angle between the line connecting O and R1 and the line connecting O and R2 is 18 to 22°, and the line P connecting R1 and R2 is inclined at an angle of 22 to 27° toward the suction side with respect to a plane perpendicular to the rotation axis passing through R1. The impeller of Patent Document 1 has an inflection point within the blade cross section in the shape of the cross section in the circumferential direction of the blade. In the impeller of Patent Document 1, the discharge side between the leading edge of the blade in the rotation direction and the inflection point is a convex shape with a convex surface, and the discharge side between the inflection point and the trailing edge of the blade in the rotation direction is a concave shape with a concave surface. The impeller of Patent Document 1 has these convex and concave shapes formed over the entire length from the base of the blade to the outer periphery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 09-068200 Summary of the Invention [Problem to be solved by the invention]

[0004] The efficiency of an impeller is improved by suppressing separation that occurs on the blade surface. The impeller of Patent Document 1 has blades formed in the above-mentioned configuration, and is therefore said to be able to reduce noise caused by the rotation of the blades when the impeller rotates. However, the impeller of Patent Document 1 has a convex shape on the leading edge side and a concave shape on the trailing edge side over the entire length from the base of the blade to the outer periphery, so there is a risk that separation of the airflow will occur due to the convex shape on the outer periphery side, where the airflow is faster than on the inner periphery side of the impeller, and this will deteriorate the blowing performance.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide an impeller, a blower, and an air conditioner that suppress airflow separation and improve blowing performance. [Means for solving the problem]

[0006] The impeller according to the present disclosure includes a boss portion provided on a rotation shaft, and a plurality of blades provided on an outer periphery of the boss portion, and each of the plurality of blades has a leading edge portion which is an edge portion on the front side in the direction of rotation, a trailing edge portion which is an edge portion on the rear side in the direction of rotation, an outer peripheral end portion which is an edge portion on the outer peripheral side, and an inner peripheral edge portion which is an edge portion on the inner peripheral side. When a plurality of imaginary cylinders are assumed to be centered on the rotation shaft, each imaginary cross section of the plurality of blades corresponding to the cylindrical portion is defined as a chord direction cross section, a straight line connecting the leading edge portion and the trailing edge portion in the chord direction cross section is defined as a blade chord, a center line of the blade cross section is defined as a camber line, and a camber line in a direction perpendicular to the blade chord in the chord direction cross section is defined as a camber line. When the distance between the camber line and the chord is defined as the camber height, the position on the camber line where the distance from the leading edge and the trailing edge is equal is defined as the camber midpoint, and the point on the camber line where the camber height is maximum is defined as the maximum extreme point, in a cross section in the chord direction at a position closer to the inner peripheral edge than the outer peripheral edge of the blade, the maximum extreme point is located on the trailing edge side of the camber midpoint and on the air intake side of the chord, and the camber line has at least one inflection point between the leading edge and the maximum extreme point, and in a cross section in the chord direction at a position closer to the outer peripheral edge than the inner peripheral edge of the blade, the maximum extreme point is located on the leading edge side of the camber midpoint and on the air intake side of the chord. In the chord direction cross section at a position closer to the inner peripheral edge than the outer peripheral end of the blade, the inflection point is located on the air intake side of the blade chord. It is something.

[0007] The blower according to the present disclosure includes a casing having a bell mouth and an impeller having the above-described configuration housed inside the casing, and the length of the casing in the axial direction of the rotating shaft is defined as a length H b and the coefficient ε is defined as 0<ε≦0.5, the impeller has a length εH b The sensor is disposed in a region inside a virtual plane located at a distance of 10 mm from the casing.

[0008] An air conditioner according to the present disclosure includes an impeller having the above-described configuration, and a heat exchanger that exchanges heat between air supplied by the impeller and a refrigerant circulating inside the heat exchanger. Effect of the Invention

[0009] According to the present disclosure, the impeller, and the impeller of the blower and air conditioner are configured as follows. In a chord direction cross section at a position closer to the inner circumferential edge than the outer circumferential edge of the blade, the maximum extreme point is located on the trailing edge side of the camber midpoint and on the air suction side of the blade chord. The camber line has at least one inflection point between the leading edge and the maximum extreme point. In a chord direction cross section at a position closer to the outer circumferential edge than the inner circumferential edge of the blade, the maximum extreme point is located on the leading edge side of the camber midpoint and on the air suction side of the blade chord. By having this configuration, the impeller can make the airflow follow the blade, so that separation of the airflow at the leading edge side on the outer circumferential side of the blade can be suppressed, and the blowing performance can be improved. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view showing the configuration of an impeller and a blower including the impeller according to a first embodiment; [Diagram 2] FIG. 1 is a conceptual diagram for explaining a basic configuration of an impeller according to a first embodiment, showing the impeller projected onto a plane perpendicular to the rotation axis. [Diagram 3]3 is a conceptual diagram showing a cross section taken along line III-III in FIG. 2 as viewed in the direction of the arrows. [Figure 4] 2 is a conceptual diagram showing an example of a cross section in a chord direction of a blade of an impeller according to the first embodiment. FIG. [Diagram 5] FIG. 4 is a conceptual diagram showing a chord and a camber line in a section in the chord direction taken along line IV-IV in FIG. 2. [Figure 6] 3 is a conceptual diagram showing the chord and camber lines in a cross section in the chord direction at the VV line position in FIG. 2. [Figure 7] 4 is a conceptual diagram illustrating the chord and camber lines in a cross section in the chord direction taken along line IV-IV in FIG. 2 for explaining the operation of the impeller and the flow of air currents according to the first embodiment. FIG. [Figure 8] 3 is a conceptual diagram showing the chord and camber lines in a cross section in the chord direction at line VV in FIG. 2 for explaining the operation of the impeller and the flow of air currents according to the first embodiment. FIG. [Figure 9] 4 is a conceptual diagram showing an impeller according to a second embodiment, illustrating a blade chord and a camber line in a cross section in the chord direction taken along line IV-IV in FIG. 2. [Figure 10] 3 is a conceptual diagram showing an impeller according to a second embodiment, illustrating a blade chord and a camber line in a cross section in the chord direction taken along line VV in FIG. 2. FIG. [Figure 11] 10 is a graph showing the relationship between the flow coefficient and the fan efficiency of the impeller according to the second embodiment and the impeller of the prior art. [Figure 12] 13 is a graph showing the relationship between the flow coefficient and the pressure coefficient of the impeller according to the second embodiment and the impeller of the prior art. [Figure 13] 4 is a conceptual diagram showing an impeller according to a third embodiment, illustrating a blade chord and a camber line in a cross section in the chord direction taken along line IV-IV in FIG. 2. FIG. [Figure 14] 3 is a conceptual diagram showing an impeller according to a third embodiment, illustrating a blade chord and a camber line in a cross section in the chord direction taken along line VV in FIG. 2. FIG. [Figure 15]1. FIG. 11 is a conceptual diagram showing a cross section of a blower according to a fourth embodiment of the present invention, taken along a plane parallel to and passing through the rotation axis of the blower shown in FIG. [Figure 16] FIG. 11 is a perspective view showing the configuration of an air conditioner according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an impeller, a blower, and an air conditioner according to an embodiment will be described with reference to the drawings. In the following drawings including FIG. 1, the relative dimensional relationship and shape of each component may differ from the actual one. In addition, in the following drawings, the same reference numerals are attached to the same or equivalent parts, and this is common throughout the entire specification. In addition, to facilitate understanding, terms expressing directions (e.g., "up", "down", "right", "left", "front" and "rear" are used as appropriate, but these notations are only described in this way for convenience of explanation and do not limit the arrangement and orientation of the device or parts. In addition, in the following drawings, the shape is not chamfered, but the same effect can be obtained even if chamfering is performed. That is, for example, the impeller, the blower, and the air conditioner can obtain the same effect whether C chamfering is performed or R chamfering is performed.

[0012] Embodiment 1 [Blower 100] Fig. 1 is a perspective view showing the configuration of an impeller 10 according to embodiment 1 and a blower 100 including the same. Fig. 1 shows a part of the configuration of the blower 100 as viewed from the suction side, i.e., the negative pressure surface 26 side of the blade 20. In Fig. 1 and the drawings described later, a thick black arrow R indicates the rotation direction of the impeller 10, i.e., the rotation direction of the boss portion 12 and the blade 20 which are part of the impeller 10. Also, a double-headed arrow CD in the drawing indicates the circumferential direction of the impeller 10.

[0013] 1 and the drawings described below, a hollow thick arrow F indicates the overall direction of air flow when the impeller 10 rotates. In the direction of air flow indicated by the hollow thick arrow F, the Y1 side with respect to the impeller 10 is the upstream side of the airflow with respect to the impeller 10, and the Y2 side with respect to the impeller 10 is the downstream side of the airflow with respect to the impeller 10. In other words, the Y1 side is the air intake side with respect to the impeller 10, and the Y2 side is the air blowing side with respect to the impeller 10.

[0014] 1 is a direction perpendicular to the rotation shaft 11 of the impeller 10 and represents the radial direction of the impeller 10. In the radial direction, the X2 side portion is located on the outer periphery side of the X1 side portion, and the X1 side portion is located on the inner periphery side of the X2 side portion. In other words, the X1 side of the impeller 10 is the inner periphery side of the impeller 10, and the X2 side of the impeller 10 is the outer periphery side of the impeller 10. The rotation shaft 11 is a virtual rotation shaft when the impeller 10 rotates.

[0015] An impeller 10 according to a first embodiment and a blower 100 including the same will be described with reference to Fig. 1. The blower 100 according to the first embodiment is a device that forms an air flow, and is used to blow air. The blower 100 according to the first embodiment is an axial flow blower that blows air in a direction along a rotating shaft 11. The blower 100 is used, as an example, in an air conditioner 200 (see Fig. 16) described below.

[0016] As shown in FIG. 1, blower 100 has a casing 80 and an impeller 10. Casing 80 forms the outer shell of blower 100. Casing 80 is formed, for example, in a box shape (not shown). Casing 80 has a substantially cylindrical bell mouth 81. Impeller 10 is disposed on the inner periphery side of bell mouth 81. Impeller 10 is provided so as to be rotatable about rotating shaft 11. Blower 10 also has a drive unit (not shown) such as a motor that rotates impeller 10.

[0017] [Impeller 10] Fig. 2 is a conceptual diagram for explaining the basic configuration of the impeller 10 according to the first embodiment, and is a diagram in which the impeller 10 is projected onto a plane perpendicular to the rotation shaft 11. Note that the impeller 10 depicted in Fig. 2 is a conceptual diagram used for explaining the basic configuration, and the relative dimensional relationships and shapes of each component may differ from the actual ones. Fig. 2 shows the configuration of the impeller 10 as viewed from the suction surface 26 side of the blade 20. The impeller 10 according to the first embodiment will be explained using Figs. 1 and 2.

[0018] The impeller 10 is an axial flow impeller, and is a device for forming a flow of a fluid such as air. The impeller 10 forms a flow of air by rotating in a rotation direction indicated by a thick black arrow R about a rotating shaft 11. As shown in FIG. 2, the impeller 10 includes a boss portion 12 provided on the rotating shaft 11 and a plurality of blades 20 provided on the outer periphery of the boss portion 12.

[0019] (Boss part 12) The boss portion 12 has a substantially cylindrical shape. A drive shaft (not shown) provided in the drive unit is connected to the center of the boss portion 12. The boss portion 12 rotates around the rotation axis 11 by a rotational driving force transmitted from the drive unit via the drive shaft. The boss portion 12 is rotationally driven by the drive unit to form the rotation axis 11.

[0020] (Multiple Wings 20) The multiple blades 20 transport air by pushing the air present between the blades 20 as the impeller 10 rotates. The multiple blades 20 are arranged at approximately equal angular intervals on the outer circumferential side of the boss portion 12. Each of the multiple blades 20 protrudes approximately radially from the outer circumferential wall of the boss portion 12. Each of the multiple blades 20 is formed around the boss portion 12 and extends radially outward from the boss portion 12.

[0021] More specifically, each of the multiple blades 20 protrudes from the outer circumferential wall of the boss portion 12 toward the outer circumferential side so as to incline forward in the rotation direction of the impeller 10 with respect to the radial direction centered on the rotating shaft 11. In Fig. 2, the impeller 10 having four blades 20 is illustrated, but the number of blades 20 that the impeller 10 has is not limited to four, and may be less than four or more than four.

[0022] Each of the blades 20 has a leading edge 21, a trailing edge 22, an outer peripheral end 23, and an inner peripheral edge 24. The leading edge 21 is the edge of the peripheral edge of the blade 20 that is on the forward side in the direction of rotation. The trailing edge 22 is the edge of the peripheral edge of the blade 20 that is on the rearward side in the direction of rotation. The outer peripheral end 23 is the edge of the peripheral edge of the blade 20 on the outer peripheral side. The outer peripheral end 23 forms an outer edge between the leading edge 21 and the trailing edge 22. The inner peripheral edge 24 is the edge of the peripheral edge of the blade 20 on the inner peripheral side. The inner peripheral edge 24 has a shape that follows the outer peripheral wall of the boss portion 12 and is connected to the outer peripheral wall.

[0023] The outer peripheral end 23 and the leading edge 21 are adjacent to each other via an outer peripheral front end 23a. The outer peripheral front end 23a is the front end of the outer peripheral end 23 in the rotation direction, and is the outer peripheral end of the leading edge 21 in the radial direction of the rotating shaft 11. The outer peripheral end 23 and the trailing edge 22 are adjacent to each other via an outer peripheral rear end 23b. The outer peripheral rear end 23b is the rear end of the outer peripheral end 23 in the rotation direction, and is the outer peripheral end of the trailing edge 22 in the radial direction of the rotating shaft 11.

[0024] The inner peripheral edge 24 and the leading edge 21 are adjacent to each other via an inner peripheral front end portion 24a. The inner peripheral front end portion 24a is the front end portion of the inner peripheral edge 24 in the rotation direction, and is the inner peripheral end portion of the leading edge portion 21 in the radial direction of the rotating shaft 11. The inner peripheral edge 24 and the trailing edge portion 22 are adjacent to each other via an inner peripheral rear end portion 24b. The inner peripheral rear end portion 24b is the rear end portion of the inner peripheral edge 24 in the rotation direction, and is the inner end portion of the trailing edge portion 22 in the radial direction of the rotating shaft 11.

[0025] Each of the multiple blades 20 has a pressure surface 25 and a suction surface 26 as blade surfaces 35. The pressure surface 25 is the surface on the front side in the direction of rotation of the two blade surfaces 35 that the blade 20 has. When the blade 20 rotates, air is pushed by the pressure surface 25. The suction surface 26 is the surface on the rear side in the direction of rotation of the two blade surfaces 35 that the blade 20 has, and is the surface behind the pressure surface 25. Since Figures 1 and 2 respectively show the configurations of the blower 100 and the impeller 10 viewed from the suction surface 26 side, the pressure surface 25 is indicated by a dashed leading line.

[0026] In the air flow direction indicated by the white thick arrow F, the surface of the blade surface 35 facing the upstream side (Y1 side) of the blade 20 becomes the negative pressure surface 26, and the surface facing the downstream side (Y2 side) becomes the pressure surface 25. In addition, the pressure surface 25 is the surface facing the rotation direction of the blade 20, and the negative pressure surface 26 is the surface facing the opposite side to the rotation direction of the blade 20.

[0027] The multiple blades 20 rotate together with the boss portion 12 around the rotation shaft 11. When the multiple blades 20 rotate, as shown by the outlined thick arrow F in Fig. 1, air flows from the front side of the page along the rotation shaft 11 and is sucked into the fan 100. In Fig. 2, the air sucked into the fan 100 flows along the rotation shaft 11 and is blown out from the fan 100 to the back side of the page.

[0028] Fig. 3 is a conceptual diagram of a cross section taken along line III-III in Fig. 2, viewed in the direction of the arrows. Fig. 4 is a conceptual diagram showing an example of a chord direction cross section CS of a blade 20 of an impeller 10 according to embodiment 1. Fig. 5 is a conceptual diagram showing a chord 30 and a camber line 31 in a chord direction cross section CS1 taken along line IV-IV in Fig. 2. Fig. 6 is a conceptual diagram showing a chord 30 and a camber line 31 in a chord direction cross section CS2 taken along line VV in Fig. 2. In each of Figs. 3, 5, and 6, the vertical direction represents the direction along the rotation shaft 11, the upper side represents the suction side, and the lower side represents the blowing side.

[0029] 2, when multiple imaginary cylinders CL are assumed to be centered on the rotation axis 11, each imaginary cross section of the multiple blades 20 corresponding to a cylindrical portion is defined as a "chord direction cross section CS." In other words, when the blade 20 is cut by the imaginary cylinder CL centered on the rotation axis 11, the cross section of the imaginary blade 20 is defined as a "chord direction cross section CS."

[0030] The blade 20 has a plurality of chord direction cross sections CS in the radial direction centered on the rotation shaft 11. The chord direction cross section CS shown in Fig. 4 is an example. The blade surfaces 35 such as the pressure surface 25 and the suction surface 26 shown in Fig. 4 are an example, and the blade surfaces 35 are not limited to the illustrated embodiment. Here, as an example, among the plurality of chord direction cross sections CS, the cross section at the position of line IV-IV in Fig. 2 is the chord direction cross section CS1, and the cross section at the position of line VV in Fig. 2 is the chord direction cross section CS2.

[0031] As shown in Figures 5 and 6, a straight line connecting the leading edge 21 and the trailing edge 22 in the chord direction cross section CS is defined as a "chord 30", and a center line of the blade cross section connecting the leading edge 21 and the trailing edge 22 in the chord direction cross section CS is defined as a "camber line 31". The center line of the blade cross section is a line passing through the center between the pressure surface 25 and the suction surface 26 in the chord direction cross section CS. In Figures 5 and 6, in order to show the relationship between the chord 30 and the camber line 31, illustration of the blade surfaces 35 such as the pressure surface 25 and the suction surface 26 of the blade 20 is omitted, and only the chord 30 and the camber line 31 are shown.

[0032] Furthermore, in each of the multiple cord direction cross sections CS, a point where the ratio of the distance from the leading edge 21 to the distance from the trailing edge 22 is a constant value is defined as an "imaginary point P." A line connecting each of the imaginary points P in the multiple cord direction cross sections CS from the inner peripheral edge 24 to the outer peripheral end 23 is defined as a "span line 27" (see FIG. 2). The ratio of the distance from the leading edge 21 to the distance from the trailing edge 22 is determined based on the required design objective.

[0033] The distance from each of the leading edge 21 and the trailing edge 22 to the imaginary point P is measured, for example, along the camber line of the blade 20 on the cylindrical cross section. That is, the distance from each of the leading edge 21 and the trailing edge 22 to the imaginary point P is measured, for example, along the camber line 31 of the blade 20 on the chord direction cross section CS. Note that the position of point P shown in Figures 5 and 6 is just an example, and is not limited to the position in Figures 5 and 6.

[0034] Additionally, the direction from the inner peripheral edge 24 toward the outer peripheral end 23 along the span line 27 is defined as the "span direction." Furthermore, a cross section of the blade 20 cut parallel to the rotation axis 11 along the span line 27 is defined as the "span direction cross section SS." The cross section shown in FIG. 3 is the span direction cross section SS cut through the blade 20 along one span line 27.

[0035] Span lines 27a, 27b, and 27c shown in Fig. 2 are examples of span lines 27 showing the span direction cross section SS of the blade 20. Span line 27b shown in Fig. 2 is a span line 27 passing through a virtual point P which is a midpoint between the leading edge 21 and the trailing edge 22 in the chord direction cross section CS which is a cylindrical cross section of the blade 20. That is, in the chord direction cross section CS of the blade 20 centered on the rotation axis 11, the distance between the leading edge 21 and the span line 27b is equal to the distance between the trailing edge 22 and the span line 27b. That is, in the chord direction cross section CS of the blade 20 centered on the rotation axis 11, the distance between the leading edge 21 and the virtual point P is equal to the distance between the trailing edge 22 and the virtual point P.

[0036] The span line 27a shown in FIG. 2 is one of the span lines 27 located closer to the leading edge 21 than the span line 27b. The span line 27a shown in FIG. 2 is a span line 27 passing through an imaginary point P located closer to the leading edge 21 than a midpoint between the leading edge 21 and the trailing edge 22 in the chord direction cross section CS, which is a cylindrical cross section of the blade 20. That is, in the chord direction cross section CS of the blade 20 centered on the rotation axis 11, the distance between the leading edge 21 and the span line 27a is smaller than the distance between the trailing edge 22 and the span line 27a. That is, in the chord direction cross section CS of the blade 20 centered on the rotation axis 11, the distance between the leading edge 21 and the imaginary point P is smaller than the distance between the trailing edge 22 and the imaginary point P.

[0037] The span line 27c shown in FIG. 2 is one of the span lines 27 located closer to the trailing edge 22 than the span line 27b. The span line 27c shown in FIG. 2 is the span line 27 passing through an imaginary point P located closer to the trailing edge 22 than the midpoint between the leading edge 21 and the trailing edge 22 in the chord direction cross section CS, which is a cylindrical cross section of the blade 20. That is, in the chord direction cross section CS of the blade 20 centered on the rotation axis 11, the distance between the leading edge 21 and the span line 27c is greater than the distance between the trailing edge 22 and the span line 27c. That is, in the chord direction cross section CS of the blade 20 centered on the rotation axis 11, the distance between the leading edge 21 and the imaginary point P is greater than the distance between the trailing edge 22 and the imaginary point P.

[0038] 3, in the spanwise cross section SS of the blade 20 on the trailing edge 22 side, for example in the entire region between the inner peripheral edge 24 and the outer peripheral end 23, the suction side is convex from the inner peripheral edge 24 to the outer peripheral end 23. That is, in the region between the radial intermediate portion 28 and the outer peripheral end 23, the blade 20 on the trailing edge 22 side is curved such that the suction side is convex from the radial intermediate portion 28 to the outer peripheral end 23 and the blowing side is concave.

[0039] The midpoint between the connection part of the boss 12 with the leading edge 21 and the connection part of the boss 12 with the trailing edge 22 is defined as the "boss midpoint 12a", and the cross section perpendicular to the axial direction of the rotation shaft 11 that passes through the boss midpoint 12a is defined as the "boss midsection 40". The distance between the boss midsection 40 and the spanwise cross section SS on the trailing edge 22 side in the axial direction of the rotation shaft 11 is defined as the "trailing-edge-side blade height Sh". If the extreme point on the spanwise cross section SS of the blade 20 on the trailing edge 22 side where the "trailing-edge-side blade height Sh" is minimum from the inner peripheral edge 24 to the outer peripheral end 23 is defined as the "trailing-edge-side recess 29", then the blade 20 has the "trailing-edge-side recess 29".

[0040] The distance from the rotation axis 11 to any point on the boss mid-section 40 is defined as "distance r." As shown in Fig. 2, the distance from the rotation axis 11 to the inner peripheral edge 24 is defined as distance r1, and the distance from the rotation axis 11 to the outer peripheral end 23 is defined as distance r2. In this case, if v is defined as v = (r - r1) / (r2 - r1), it is desirable that the trailing edge recess 29 be in the range of 0.4 < v < 0.8.

[0041] 5 and 6, the distance from the chord 30 on the camber line 31 is defined as the "camber height H". The camber height H is the distance between the camber line 31 and the chord 30 in a direction perpendicular to the chord 30 in the chord direction cross section CS. The point on the camber line 31 where the camber height H is maximum is defined as the "maximum extreme point 33", and the position on the camber line 31 where the distance from the leading edge 21 and the trailing edge 22 are equal is defined as the "camber midpoint 34".

[0042] As shown in Fig. 5, in a chord direction cross section CS1 located closer to the inner circumferential edge 24 than the outer circumferential edge 23 of the blade 20, a maximum extreme point 33 is located closer to the trailing edge 22 than the camber midpoint 34 and closer to the air suction side than the chord 30. As shown in Fig. 5, in a chord direction cross section CS1 located closer to the inner circumferential edge 24 than the outer circumferential edge 23 of the blade 20, a camber line 31 has at least one inflection point 32 between the leading edge 21 and the maximum extreme point 33. The inflection point 32 is a point where the camber line 31 changes from a convex toward the suction side to a convex toward the blowing side, or from a convex toward the blowing side to a convex toward the suction side, as it moves from the leading edge 21 to the trailing edge 22.

[0043] As shown in FIG. 6, in the chord direction cross section CS2 located closer to the outer circumferential end 23 than the inner circumferential edge 24 of the blade 20, the maximum extreme point 33 is located closer to the leading edge 21 than the camber midpoint 34 and closer to the air inlet than the chord 30.

[0044] [Effects of impeller 10] The impeller 10 is configured as follows. In a chord direction cross section CS1 located closer to the inner circumferential edge 24 than the outer circumferential edge 23 of the blade 20, the maximum extreme value point 33 is located closer to the trailing edge 22 than the camber midpoint 34 and closer to the air intake side than the chord 30. The camber line 31 has at least one inflection point 32 between the leading edge 21 and the maximum extreme value point 33. In a chord direction cross section CS2 located closer to the outer circumferential edge 23 than the inner circumferential edge 24 of the blade 20, the maximum extreme value point 33 is located closer to the leading edge 21 than the camber midpoint 34 and closer to the air intake side than the chord 30. The impeller 10 has this configuration, so that the airflow can be made to follow the blade 20, and therefore separation of the airflow at the leading edge 21 side on the outer circumferential side of the blade 20 can be suppressed. Therefore, the impeller 10 can improve the air blowing performance and increase the air blowing efficiency, thereby achieving high efficiency in fan efficiency.

[0045] In a typical axial flow fan, the efficiency of the impeller is improved by suppressing separation on the blade surface. Also, the impeller can increase the air volume by increasing the impeller blade area or the rotation speed. However, the impeller cannot increase the blade area so that the height of the impeller blades is larger than the design constraint, or increase the rotation speed so that the impeller rotates above the maximum rotation speed determined by the strength of the impeller and the upper limit of the motor capacity.

[0046] In the impeller of Patent Document 1, the circumferential center of the root of the blade is designated as R1, the circumferential center of the outer periphery of the blade is designated as R2, and the center of rotation of the blade is designated as O. In the impeller of Patent Document 1, the angle between a line connecting O to R1 and a line connecting O to R2 is 18 to 22°, and a line P connecting R1 to R2 is inclined at an angle of 22 to 27° toward the suction side with respect to a plane perpendicular to the rotation axis that passes through R1.

[0047] The blades of the impeller described in Patent Document 1 have an inflection point in the cross section of the blade in the circumferential direction of the blade. The impeller of Patent Document 1 has a convex shape with a convex surface on the discharge side between the leading edge of the blade in the rotation direction and the inflection point, and a concave shape with a concave surface on the discharge side between the inflection point and the trailing edge of the blade in the rotation direction. The impeller of Patent Document 1 is formed so that the convex and concave shapes are formed over the entire length from the base of the blade to the outer periphery, so that it is said that the noise caused by the rotation of the blades during the rotation of the impeller can be reduced without increasing the height of the blade.

[0048] In an impeller, the magnitude of the rotational component of the airflow passing through the leading edge of the blade is proportional to the radius. Therefore, the magnitude of the rotational component of the airflow passing through the leading edge of the blade is smaller at a position closer to the inner peripheral edge than to the outer peripheral edge than to the inner peripheral edge, and is larger at a position closer to the outer peripheral edge than to the inner peripheral edge than to the outer peripheral edge. In other words, the magnitude of the rotational component of the airflow passing through the leading edge of the blade becomes smaller in the radial direction closer to the inner peripheral edge and becomes larger closer to the outer peripheral edge.

[0049] The blades of the impeller described in Patent Document 1 are formed with a convex shape on the leading edge side and a concave shape on the trailing edge side over the entire length from the root of the blade to the outer periphery, so the convex shape on the outer periphery side, where the airflow is fast, can cause airflow separation, which can deteriorate the blowing performance. Therefore, it is necessary for the impeller to suppress airflow separation on the leading edge side of the outer periphery of the blade.

[0050] Fig. 7 is a conceptual diagram showing the blade chord 30 and the camber line 31 in the chord direction cross section CS1 taken along the line IV-IV in Fig. 2 for explaining the operation of the impeller 10 according to the first embodiment and the flow of air. The vertical direction in Fig. 7 represents the direction along the rotation shaft 11, with the upper side representing the air intake side and the lower side representing the air blowing side. In Fig. 7, the dashed arrow FA indicates the air flow around the blade 20.

[0051] As shown in FIG. 7, in a chord direction cross section CS1 located closer to the inner circumferential edge 24 than the outer circumferential end 23 of the blade 20, the maximum extreme point 33 is located closer to the trailing edge 22 than the camber midpoint 34 and closer to the air intake side than the chord 30.

[0052] 7, the airflow is bent so that the radius of curvature becomes smaller on the trailing edge 22 side of the blade 20, i.e., on the portion closer to the trailing edge 22 than to the leading edge 21 of the blade 20, thereby increasing the rise in static pressure of the blade 20. Therefore, the impeller 10 can increase the amount of air flow at the same rotation speed of the blade 20 compared to a case not having this configuration.

[0053] In addition to the above-described shape, as shown in Figs. 5 and 7, in a chord direction cross section CS1 located closer to the inner circumferential edge 24 than the outer circumferential end 23 of the blade 20, the camber line 31 has at least one inflection point 32 between the leading edge 21 and the maximum extreme point 33.

[0054] As a result, the impeller 10 can reduce the radius of curvature on the trailing edge 22 side of the blade 20 compared to a case not having this configuration, and at the same time, suppress airflow separation on the leading edge 21 side of the blade 20, thereby improving the airflow blowing efficiency of the blade 20. That is, the impeller 10 can reduce the radius of curvature in a portion of the blade 20 closer to the trailing edge 22 than the leading edge 21, and at the same time, suppress airflow separation in a portion of the blade 20 closer to the leading edge 21 than the trailing edge 22, thereby improving the airflow blowing efficiency of the blade 20. Therefore, the impeller 10 can achieve higher fan efficiency compared to a case not having the above configuration.

[0055] In addition, the positions of the leading edge 21 and the trailing edge 22 of the blades 20 do not change in the impeller 10 compared to a case not having the above configuration. Therefore, the impeller 10 can obtain the above effects, such as high fan efficiency of the impeller 10 and increased air volume at the same rotation speed, without changing the size of the impeller 10.

[0056] Fig. 8 is a conceptual diagram showing the chord 30 and the camber line 31 in the chord direction cross section CS2 at the line VV position in Fig. 2 for explaining the operation of the impeller 10 according to the first embodiment and the flow of air. The vertical direction in Fig. 8 represents the direction along the rotation shaft 11, the upper side represents the air intake side, and the lower side represents the air blowing side. In Fig. 8, the dashed arrow FA indicates the air flow around the blade 20.

[0057] As shown in FIG. 8, in the chord direction cross section CS2 located closer to the outer circumferential end 23 than the inner circumferential edge 24 of the blade 20, the maximum extreme point 33 is located closer to the leading edge 21 than the camber midpoint 34 and closer to the air intake side than the chord 30.

[0058] As described above, the magnitude of the rotational component of the airflow passing through the leading edge of the blade is proportional to the radius, so the magnitude of the rotational component of the airflow passing through the leading edge of the blade on the outer peripheral end side is larger than the magnitude of the rotational component of the airflow passing through the leading edge of the blade on the inner peripheral edge side. As a result, in the portion of the impeller 10 closer to the outer peripheral end 23 than the inner peripheral edge 24 of the blade 20, the airflow that has passed the leading edge 21 side flows along the blade 20, so that separation of the airflow can be suppressed and the blowing efficiency of the blade 20 can be improved. Therefore, the impeller 10 can achieve higher fan efficiency than a case not having the above configuration.

[0059] In addition, the impeller 10 can reduce the radius of curvature on the leading edge 21 side of the blade 20 by having the maximum extreme point 33 located closer to the leading edge 21 than the camber midpoint 34 and closer to the air suction side than the chord 30. That is, the impeller 10 can reduce the radius of curvature in a portion of the blade 20 closer to the leading edge 21 than the trailing edge 22 by having the maximum extreme point 33 located closer to the leading edge 21 than the camber midpoint 34 and closer to the air suction side than the chord 30.

[0060] Therefore, compared to an impeller not having the above configuration, the impeller 10 can increase the static pressure rise on the leading edge 21 side of the blade 20, and can reduce the pressure gradient from the leading edge 21 side to the trailing edge 22 side of the blade 20. As a result, compared to an impeller not having the above configuration, the impeller 10 can increase the air volume at the same rotation speed of the blade 20. Therefore, the impeller 10 can achieve higher fan efficiency compared to an impeller not having the above configuration.

[0061] In addition, the positions of the leading edge 21 and the trailing edge 22 of the blades 20 do not change in the impeller 10 compared to a case not having the above configuration. Therefore, the impeller 10 can obtain the above effects, such as high fan efficiency of the impeller 10 and increased air volume at the same rotation speed, without changing the size of the impeller 10.

[0062] Embodiment 2 Fig. 9 is a conceptual diagram of the impeller 10 according to embodiment 2, showing the chord 30 and the camber line 31 at the chord direction cross section CS1 taken along line IV-IV in Fig. 2. Fig. 10 is a conceptual diagram of the impeller 10 according to embodiment 2, showing the chord 30 and the camber line 31 at the chord direction cross section CS2 taken along line VV in Fig. 2. Next, the impeller 10 according to embodiment 2 will be described.

[0063] The impeller 10 according to the second embodiment is characterized by a cross section CS in the chord direction of the blades 20 centered on the rotating shaft 11. The impeller 10 according to the second embodiment is similar to the impeller 10 according to the first embodiment in configuration other than that described below. The features of the impeller 10 according to the second embodiment will be described with reference to the already-shown Figures 2, 9 and 10. The same reference numerals are used for components having the same functions and actions as those in the first embodiment, and description thereof will be omitted.

[0064] 2, 9 and 10, the impeller 10 is formed such that the camber line 31 is located on the air suction side of the blade chord 30 over the entire area of ​​the blade 20 in the radial direction of the rotating shaft 11. That is, the impeller 10 is formed such that the camber line 31 is located on the air suction side of the blade chord 30 in any cross section CS in the chord direction from the inner peripheral edge 24 to the outer peripheral end 23 of the blade 20.

[0065] [Effects of impeller 10] The impeller 10 is formed such that the camber line 31 is located on the air suction side of the blade chord 30 over the entire area of ​​the blade 20 in the radial direction of the rotating shaft 11. Since the impeller 10 is formed such that the camber line 31 is located on the air suction side of the blade chord 30 over the entire area of ​​the blade 20, the amount of pressure rise of the impeller 10 can be increased and the fan efficiency can be improved compared to an impeller not having this configuration.

[0066] If the camber line is formed so that it is located on the air blowing side of the blade chord in a part of the blade, the airflow is bent significantly in the opposite direction to the direction in which the part can obtain the boost effect, and the impeller does not perform the work of the blade. Therefore, if the camber line is formed so that it is located on the air blowing side of the blade chord in a part of the blade, the impeller will have a small boost amount. Or, the airflow will not follow the blade in the part of the impeller, and separation of the airflow will occur, so the fan efficiency of the impeller will deteriorate. In contrast, the blade 20 of the impeller 10 according to the second embodiment is formed so that the camber line 31 is located on the air intake side of the blade chord 30 over the entire area of ​​the blade 20, so that the boost amount of the impeller 10 can be increased and the fan efficiency can be improved compared to an impeller not having the configuration.

[0067] Fig. 11 is a graph showing the relationship between the flow coefficient and the fan efficiency of the impeller 10 according to the second embodiment and the impeller of the prior art. In Fig. 11, circles indicate the impeller of the prior art, and crosses indicate the impeller 10 according to the second embodiment. The impeller of the prior art is a general impeller that does not have the characteristics of the impeller 10 according to the second embodiment. As shown in Fig. 11, the impeller 10 according to the second embodiment has a higher fan efficiency relative to the flow coefficient in all regions compared to the impeller of the prior art, and therefore has improved fan efficiency compared to the impeller of the prior art.

[0068] Fig. 12 is a graph showing the relationship between the flow coefficient and the pressure coefficient of the impeller 10 according to the second embodiment and an impeller of the prior art. In Fig. 12, circles indicate the impeller of the prior art, and crosses indicate the impeller 10 according to the second embodiment. The impeller of the prior art is a general impeller that does not have the characteristics of the impeller 10 according to the second embodiment. As shown in Fig. 12, the impeller 10 according to the second embodiment has a higher pressure coefficient relative to the flow coefficient in all ranges compared to the impeller of the prior art, and therefore can increase the air volume at the same rotation speed compared to the impeller of the prior art.

[0069] Embodiment 3 Fig. 13 is a conceptual diagram of the impeller 10 according to embodiment 3, showing the chord 30 and the camber line 31 at the chord direction cross section CS1 taken along line IV-IV in Fig. 2. Fig. 14 is a conceptual diagram of the impeller 10 according to embodiment 3, showing the chord 30 and the camber line 31 at the chord direction cross section CS2 taken along line VV in Fig. 2. Next, the impeller 10 according to embodiment 3 will be described.

[0070] The impeller 10 according to the third embodiment is characterized by a cross section CS in the chord direction of the blade 20, centered on the rotating shaft 11, in the portions close to the inner peripheral edge portion 24 and the outer peripheral end portion 23. The impeller 10 according to the third embodiment is similar to the impeller 10 according to the first or second embodiment in configuration other than the configuration described below. The characteristics of the impeller 10 according to the third embodiment will be described with reference to the already-shown Figures 2, 13, and 14. The same reference numerals are used for components having the same functions and actions as those in the first or second embodiment, and description thereof will be omitted.

[0071] As described above, the distance from the chord 30 to the camber line 31 is defined as the "camber height H." The camber height H is the distance between the camber line 31 and the chord 30 in a direction perpendicular to the chord 30 in the chord direction cross section CS.

[0072] Regarding the camber height H, in a chord direction cross section CS1 at a position closer to the inner peripheral edge 24 than the outer peripheral end 23 of the blade 20 as shown in FIG. 13, the distance between the maximum extreme point 33 in the direction perpendicular to the chord 30 and the chord 30 is defined as "distance H h " is defined as

[0073] Regarding the camber height H, in a chord direction cross section CS2 located closer to the outer peripheral end 23 than the inner peripheral edge 24 of the blade 20 as shown in FIG. 14, the distance between the maximum extreme point 33 in the direction perpendicular to the chord 30 and the chord 30 is defined as "distance H t " is defined as

[0074] The impeller 10 is at a distance H t is the distance Hh That is, the impeller 10 is formed so that the distance H h <distance H t The above relationship is satisfied.

[0075] [Effects of impeller 10] As described above, the magnitude of the rotational component of the airflow passing through the leading edge of the blade is proportional to the radius, so the magnitude of the rotational component of the airflow passing through the leading edge of the blade on the outer peripheral end side is larger than the magnitude of the rotational component of the airflow passing through the leading edge of the blade on the inner peripheral edge side. Also, when the chord direction cross section CS is defined, the area of ​​multiple cylindrical cross sections of the blade 20 centered on the rotation axis 11 is proportional to the radius when the axial height is constant, so the chord length can be increased from the inner peripheral edge 24 to the outer peripheral edge 23.

[0076] By increasing the chord length of the impeller 10, the amount of air flowing at the same rotation speed can be increased. h <distance H t By being formed so as to satisfy the relationship above, the static pressure can be further increased on the outer circumferential side of the blades 20 where the magnitude of the airflow is greater than that on the inner circumferential side, compared to a configuration not having this configuration. Therefore, the impeller 10 can increase the air volume at the same rotation speed of the blades 20, compared to a configuration not having this configuration. Therefore, the impeller 10 can achieve higher fan efficiency, compared to a configuration not having the above configuration.

[0077] Embodiment 4 Fig. 15 is a conceptual diagram showing a cross section of blower 100 according to embodiment 4, taken along an arbitrary plane parallel to and passing through rotation shaft 11 of blower 100 shown in Fig. 1. Blower 100 according to embodiment 4 will be described with reference to Fig. 15 and already shown Fig. 1. Note that components having the same functions and actions as those in embodiments 1 to 3 are given the same reference numerals, and description thereof will be omitted.

[0078] A blower 100 according to the fourth embodiment includes a casing 80 having a bell-mouth 81, and the impeller 10 according to any one of the first to third embodiments housed inside the casing 80. In other words, a blower 100 according to the fourth embodiment includes a casing 80 having a bell-mouth 81, and the impeller 10 according to any one of the first to third embodiments arranged on the inner circumferential side of the bell-mouth 81 when viewed in the axial direction of the rotating shaft 11.

[0079] The casing 80 is formed in a box shape that houses the impeller 10 inside. The casing 80 has a bell mouth 81 having a substantially cylindrical shape on each of the air blowing side and the air suction side. The bell mouth 81 is shaped such that, for example, in the axial direction of the rotating shaft 11, the distance from the rotating shaft 11 increases with increasing distance from the center of the casing 80. In other words, the casing 80 is shaped such that, for example, in the axial direction of the rotating shaft 11, the distance from the rotating shaft 11 increases with increasing distance from the center of the casing 80 due to the bell mouth 81.

[0080] Note that the bellmouth 81 and the casing 80 are not limited to the above shapes, and may have any shape as long as the distance from the rotating shaft 11 does not decrease with increasing distance from the center of the casing 80 in the axial direction of the rotating shaft 11. In other words, the casing 80 may have a cylindrical overall shape.

[0081] In Fig. 15, an example of a trajectory when the blades 20 are rotated is shown as the impeller 10. Also, the impeller 10S drawn by the dotted line in Fig. 15 indicates the limit position of the range where the effect of the impeller 10 can be obtained when the impeller 10 is moved in each direction of the air blowing side and the air suction side.

[0082] Here, the length of the casing 80 in the axial direction of the rotating shaft 11 is defined as a length H b In addition, when the casing 80 is installed so that the rotating shaft 11 is in the vertical direction, the length H of the casing 80 is b is the height of the casing 80.

[0083] As shown in FIG. 15, the impeller 10 has a length εH b The effect of the impeller 10 can be exhibited in an area inside the imaginary plane SF that is separated from the casing 80 by 10 mm. In this case, the coefficient ε may be greater than 0 and less than or equal to 0.5 (0<ε≦0.5). In other words, the impeller 10 has a length εH b The sensor 10 is disposed in an area inside an imaginary plane SF located at a distance of 1 mm from the casing 80.

[0084] [Effects of the blower 100] As shown in FIG. 15, the blower 100 has a length εH b The effects of impeller 10 can be achieved by disposing impeller 10 in a region on the inside of the surface that is distant from casing 80 by a distance of 10 mm from casing 80. With the above-described configuration, blower 100 according to embodiment 4 can obtain a blower that can improve the fan efficiency of impeller 10 and increase the amount of air flow at the same rotation speed without changing the size.

[0085] Embodiment 5. Fig. 16 is a perspective view showing the configuration of an air conditioner 200 pertaining to embodiment 5. The air conditioner 200 pertaining to embodiment 5 will be described with reference to Fig. 16. Note that components having the same functions and actions as those in embodiments 1 to 4 are given the same reference numerals and descriptions thereof will be omitted. In embodiment 5, an outdoor unit of a multi-air conditioner for a building is shown as an example of the air conditioner 200, but the air conditioner 200 is not limited to an outdoor unit of a multi-air conditioner for a building.

[0086] As shown in Fig. 16, air conditioner 200 has impeller 10 according to any one of embodiments 1 to 3 and blower 100 of embodiment 4 equipped with the impeller 10. Air conditioner 200 also has housing 203. Air conditioner 200 also has heat exchanger 204 that exchanges heat between air supplied by impeller 10 inside housing 203 and refrigerant circulating inside.

[0087] 16, the housing 203 is formed in a box shape, for example, in a rectangular parallelepiped shape. The shape of the housing 203 is not limited to a rectangular parallelepiped. An air outlet 202 is formed in the upper part of the housing 203 for discharging the outdoor air drawn into the inside of the housing 203 to the outside of the air conditioner 200 of the housing 203.

[0088] Intake port 201 is formed on each side surface of housing 203 for drawing outdoor air into housing 203. Intake port 201 may be formed on all four side surfaces of housing 203, or may be formed on one or more of the four surfaces instead of all four surfaces. Intake port 201 may be formed on a part of the side surface of housing 203, or may be formed on the entire side surface.

[0089] Inside the housing 203, a blower 100 and a heat exchanger 204 are provided in an air passage extending from the inlet 201 to the outlet 202. The blower 100 is disposed upstream of the outlet 202 and downstream of the heat exchanger 204 in the direction of air flow formed by the blower 100. The heat exchanger 204 exchanges heat between the outdoor air and the refrigerant flowing inside the heat exchanger 204 to produce conditioned air.

[0090] In the air conditioner 200, when the impeller 10 of the blower 100 rotates, outdoor air is drawn into the inside of the housing 203 from the air inlet 201. When this outdoor air passes through the heat exchanger 204, it is heated or cooled by heat exchange with the refrigerant to become conditioned air. The conditioned air that has undergone this heat exchange is blown out from the air outlet 202 to the area to be conditioned.

[0091] [Effects of the air conditioner 200] As described above, blower 100 is more efficient and produces a larger air volume than conventional impellers without changing the size of the impeller. Therefore, air conditioner 200 according to embodiment 5 can operate with improved power efficiency and a larger air volume than conventional air conditioners having a blower other than blower 100 without increasing the dimensions of air conditioner 200.

[0092] As described above, the air conditioner 200 according to the fifth embodiment includes the impeller 10 according to any one of the first to third embodiments, and a heat exchanger 204 that exchanges heat between the air supplied by the impeller 10 and the refrigerant circulating inside. According to this configuration, the air conditioner 200 includes the impeller 10, and therefore, compared to a conventional air conditioner that includes an impeller other than the impeller 10, the air conditioner 200 can operate at a large air volume with improved power efficiency without increasing the dimensions of the air conditioner 200.

[0093] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies. Parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0094] 10 impeller, 10S impeller, 11 rotating shaft, 12 boss portion, 12a boss midpoint, 20 blade, 21 leading edge portion, 22 trailing edge portion, 23 outer peripheral end portion, 23a outer peripheral front end portion, 23b outer peripheral rear end portion, 24 inner peripheral edge portion, 24a inner peripheral front end portion, 24b inner peripheral rear end portion, 25 pressure surface, 26 suction surface, 27 span line, 27a span line, 27b span line, 27c span line, 28 middle portion, 29 trailing edge side recess portion, 30 blade chord, 31 camber line, 32 inflection point, 33 maximum extreme point, 34 camber midpoint, 35 blade surface, 40 boss midsection, 80 casing, 81 bell mouth, 100 blower, 200 air conditioner, 201 suction port, 202 Air outlet, 203 housing, 204 heat exchanger, CD double arrow, CL cylinder, CS code direction cross section, CS1 code direction cross section, CS2 code direction cross section, F thick arrow, FA arrow, H height, H h distance, H t distance, P virtual point, R thick arrow, SF virtual plane, SS spanwise section, Sh trailing edge wing height, r distance, r1 distance, r2 distance.

Claims

1. a boss portion provided on a rotating shaft; a plurality of blades provided on the outer periphery of the boss portion; comprising; each of the plurality of blades has a leading edge which is an edge on the front side in the rotational direction, a trailing edge which is an edge on the rear side in the rotational direction, an outer peripheral end which is an edge on the outer peripheral side, an inner peripheral edge which is an edge on the inner peripheral side; and when assuming a plurality of virtual cylinders centered on the rotating shaft, a virtual cross-section of each of the plurality of blades corresponding to the cylindrical portion is defined as a cord direction cross-section, in the cord direction cross-section, a straight line connecting the leading edge and the trailing edge is defined as a blade chord, and a center line of the blade cross-section is defined as a camber line, in the cord direction cross-section, a distance between the camber line and the blade chord in a direction perpendicular to the blade chord is defined as a camber height, on the camber line, a position where distances from the leading edge and the trailing edge are equal is defined as a camber midpoint, when defining a point where the camber height is maximum on the camber line as a maximum extreme point, in the cord direction cross-section at a position closer to the inner peripheral edge than the outer peripheral end of the blade, the maximum extreme point exists on the trailing edge side of the camber midpoint and on the air suction side of the blade chord, and the camber line has at least one inflection point between the leading edge and the maximum extreme point, in the cord direction cross-section at a position closer to the outer peripheral end than the inner peripheral edge of the blade, the maximum extreme point exists on the leading edge side of the camber midpoint and on the air suction side of the blade chord, in the cord direction cross-section at a position closer to the inner peripheral edge than the outer peripheral end of the blade, the inflection point is located on the air suction side of the blade chord, a centrifugal fan.

2. The camber line is formed to be located on the air suction side of the blade chord in the entire area of the blade in the radial direction of the rotating shaft, the centrifugal fan according to claim 1.

3.

4. In the chord direction cross-section at a position closer to the inner peripheral edge than the outer peripheral end of the wing, the distance between the maximum extreme point in the direction perpendicular to the wing chord and the wing chord is defined as distance H ｈ and defined as In the cross-section in the cord direction at a position closer to the outer peripheral end portion than the inner peripheral edge portion of the wing, the distance between the maximum extreme point in the direction perpendicular to the chord of the wing and the chord is defined as distance H ｔ When defined as such, Distance H ｈ <Distance H ｔ The impeller according to claim 1 or 2, which is formed so as to satisfy the relationship of. a casing having a bellmouth; the centrifugal fan according to claim 1 or 2 housed inside the casing; comprising; wherein the centrifugal fan In the axial direction of the rotating shaft, the length of the casing extending is defined as length H ｂ When defined such that the coefficient ε satisfies 0 < ε ≤ 0.5

5. a casing having a bellmouth; In the axial direction of the rotating shaft, a blower is disposed in a region inside a virtual plane that is separated from the casing by only the length εH on the air suction side and the air blowing side. ｂ The blower is disposed in a region inside a virtual plane that is separated from the casing by only the length εH on the air suction side and the air blowing side. the centrifugal fan according to claim 3 housed inside the casing; comprising; when defining the length of the casing extending in the axial direction of the rotating shaft as length Hb and defining a coefficient ε such that 0 < ε ≤ 0.5, wherein the centrifugal fan ​ A blower disposed in a region inside a virtual plane that is separated from the casing by the length εHb on the air suction side and the air blowing side in the axial direction of the rotating shaft.

6. The impeller according to claim 1 or 2, A heat exchanger that exchanges heat between the air supplied by the impeller and the refrigerant flowing through the interior, An air conditioner comprising the same.

7. The impeller according to claim 3, A heat exchanger that exchanges heat between the air supplied by the impeller and the refrigerant flowing through the interior, An air conditioner comprising the same.

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