Centrifugal fan and air conditioner

Abstract

The utility model discloses a centrifugal fan and an air conditioner, and belongs to the technical field of fans. The centrifugal fan comprises a wheel disc; the blades are connected to the wheel disc in a surrounding mode, and the length direction of the blades is parallel to the axis of the wheel disc; the blades comprise the first blades and the second blades, the first blades and the second blades are arranged in the radial direction of the wheel disc, the radial size of the first blades and the radial size of the second blades are overlapped, the first blades and the second blades are spaced in the circumferential direction, and the first blades are closer to the axis of the wheel disc than the second blades. And the second blade is positioned on the suction surface side of the first blade. The fan capacity can be improved, and noise can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of fans, and in particular to a centrifugal fan and an air conditioner. Background Art

[0002] At present, the blade structure of the fan is usually single-row. When the fluid flows through the blade, the deceleration process of the fluid on the suction side of the blade is more intense than that on the pressure side. The suction side is prone to a sharp increase in boundary layer thickness and boundary layer separation, which will increase the energy loss and noise of the fan. Utility Model Content

[0003] The present application provides a centrifugal fan and an air conditioner, which can improve the fan capacity and reduce noise by improving the blade structure.

[0004] In one aspect of the present application, a centrifugal fan comprises: a wheel; a plurality of blades circumferentially connected to the wheel, wherein the length direction of the blades is parallel to the axis of the wheel; the blades comprise a first blade and a second blade, the first blade and the second blade are arranged radially along the wheel, the radial dimensions of the first blade and the second blade overlap and are spaced apart in the circumferential direction, the first blade is closer to the axis of the wheel than the second blade, and the second blade is located on the suction surface side of the first blade.

[0005] In some embodiments, in the blade profile section of the blade, the angle between a tangent line at any point on the blade profile line and a tangent line of a circle passing through the point is defined as angle β; the ratio of the arc length between any point on the blade profile line and the inlet end of the blade to the total arc length of the blade is defined as Z;

[0006] Assuming that the horizontal axis of the β angle linear graph of the blade is the size of Z, and the vertical axis is the size of the β angle, the corresponding relationship between the β angle and Z is defined as the β angle linear line;

[0007] The β-angle linear line includes a first line segment corresponding to the first blade and a second line segment corresponding to the second blade, and both the first line segment and the second line segment gradually increase as Z increases.

[0008] In some embodiments, the second line segment can be divided into a first sub-segment and a second sub-segment, the β angle of the first sub-segment is smaller than the maximum β angle of the first line segment, and the β angle of the second sub-segment is larger than the maximum β angle of the first line segment.

[0009] In some embodiments, the length of the first sub-line segment is 1 / 9 to 1 / 7 of the length of the second sub-line segment.

[0010] In some embodiments, the β angle of the first blade ranges from 80° to 145°, and the β angle of the second blade ranges from 130° to 165°.

[0011] In some embodiments, the arc length of the first blade is L1, the total arc length of the blade is L, and L1=(0.35-0.65)L.

[0012] In some embodiments, the outlet end of the first blade and the inlet end of the second blade are both arc-shaped; in the radial direction, the center O of the inlet end of the second blade is 3 The center O of the outlet end of the first blade 2 far away from the center of the wheel disk; the end point C of the inlet end of the second blade is closer to the center of the wheel disk than the end point B of the outlet end of the first blade.

[0013] In some embodiments, in the blade profile section of the blade, the line connecting the outlet end of the first blade and the center of the disk is LP1, the line connecting the inlet end of the second blade and the center of the disk is LP2, and the angle θ between LP1 and LP2 is 1° to 3°.

[0014] In some embodiments, in the blade profile section of the blade, the angle between the tangent line at any point on the blade profile line and the circumferential tangent line passing through the point is defined as angle β; the size of angle β at the inlet end of the first blade is negatively correlated with θ.

[0015] In another aspect of the present application, an air conditioner includes a shell; a refrigerant circuit having a condenser and an evaporator; and a centrifugal fan as above, disposed in the shell and used to blow air to at least one of the condenser and the evaporator. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 shows an internal structural diagram of an air conditioner according to some embodiments;

[0017] Figure 2 shows a perspective view of a centrifugal fan of an air conditioner according to some embodiments;

[0018] Figure 3 shows a perspective view of a centrifugal fan according to some embodiments;

[0019] Figure 4 shows a side view of a centrifugal fan according to some embodiments;

[0020] Figure 5 Shows Figure 4 A-axis enlarged view;

[0021] Figure 6 A cross-sectional view of a blade profile of a centrifugal fan blade according to some embodiments is shown;

[0022] Figure 7 A blade profile diagram of a blade of a centrifugal fan according to some embodiments is shown;

[0023] Figure 8shows a linear graph of angle β of a blade of a centrifugal fan according to some embodiments;

[0024] Fig. 9 The static pressure cloud diagram of the centrifugal fan of the prior art is shown;

[0025] Fig.10 shows a static pressure contour diagram of a centrifugal fan according to some embodiments;

[0026] Fig.11 The static pressure cloud diagram of the outlet interface of the centrifugal fan in the prior art is shown;

[0027] Fig.12 shows a static pressure contour diagram of an outlet interface of a centrifugal fan according to some embodiments;

[0028] In the above figures, 10, shell; 11, air inlet; 12, air outlet; 20, heat exchanger; 30, centrifugal fan; 31, volute; 313, air suction part; 314, air exhaust part; 100, centrifugal fan; 110, wheel; 120, blade; 121, first blade; 122, second blade; 123, pressure surface; 124, suction surface; 130, fixing ring. DETAILED DESCRIPTION

[0029] In order to make the purpose and implementation method of the present application clearer, the exemplary implementation method of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0030] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0031] The terms "first", "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0032] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] [Air conditioner]

[0034] The air conditioner in this application performs a refrigeration cycle of the air conditioner by using a compressor, a condenser, an expansion valve and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion and evaporation, and supplies refrigerant to the air that has been conditioned and heat-exchanged.

[0035] The compressor compresses the refrigerant gas in a low temperature and low pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0036] The expansion valve expands the high-temperature and high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator can achieve a refrigeration effect by utilizing the latent heat of evaporation of the refrigerant to exchange heat with the material to be cooled. In the entire cycle, the air conditioner can adjust the temperature of the indoor space.

[0037] The outdoor unit of the air conditioner refers to a portion of a refrigeration cycle including a compressor and an outdoor heat exchanger, the indoor unit of the air conditioner includes an indoor heat exchanger, and an expansion valve may be provided in the indoor unit or the outdoor unit.

[0038] The indoor heat exchanger and the outdoor heat exchanger function as a condenser or an evaporator. When the indoor heat exchanger functions as a condenser, the air conditioner functions as a heater in a heating mode, and when the indoor heat exchanger functions as an evaporator, the air conditioner functions as a cooler in a cooling mode.

[0039] [Indoor unit]

[0040] Reference Figure 1 The air conditioner according to the embodiment of the present application includes a housing 10 in which a plurality of components constituting a refrigeration cycle are installed.

[0041] The housing 10 is in a rectangular box shape, and an air inlet 11 is provided on the side of the lower part of the housing 10, and the air inlet 11 is used to allow indoor air to enter the housing 10. An air outlet 12 is provided on the front side of the upper part of the housing 10, and the air outlet 12 is used to circulate the treated indoor air into the indoor space.

[0042] An air inlet grille may be provided at the air inlet 11 to filter the indoor air entering the housing 10 to prevent dust and impurities from entering the housing 10 .

[0043] The air conditioner may include a fan for driving the flow of air so that the air in the indoor space enters the housing 10 from the air inlet 11 and is blown out from the air outlet 12 .

[0044] The fan may be a centrifugal fan 30 , the air inlet end of the centrifugal fan 30 is arranged corresponding to the air inlet 11 , and the air outlet end of the centrifugal fan 30 faces upward.

[0045] The air conditioner may include a heat exchanger 20, which is disposed on the air outlet side of the centrifugal fan 30, that is, above the centrifugal fan 30, and the centrifugal fan 30 is located on the air movement path from the air inlet 11 to the air outlet 12. The heat exchanger 20 is used to absorb heat from the air blown out by the centrifugal fan 30 or transfer heat to the air.

[0046] The water receiving pan may be provided below the heat exchanger 20 to collect moisture condensed in the heat exchanger 20. The water receiving pan may be connected to a drain hose connected to the outside of the housing 10, and may discharge the condensed moisture to the outside of the housing 10.

[0047] Reference Figure 1 , the arrows in the figure indicate the direction of air flow. When the air conditioner is working, the centrifugal fan 30 runs, so that the air in the indoor space enters from the air inlet grille, then passes through the centrifugal fan 30, flows to the heat exchanger 20, exchanges heat with the heat exchanger 20, and is discharged to the indoor space through the air outlet 12.

[0048] Reference Figure 2 According to the embodiment of the present application, the centrifugal fan 30 includes a volute 31 .

[0049] The side of the volute 31 is provided with a through suction portion 313. The suction portion 313 may be circular. The top of the volute 31 is provided with an exhaust portion 314 for air to flow out. The air flow flows in from the suction portion 313 of the volute 31 and then flows out from the exhaust portion 314 at the top.

[0050] The centrifugal blower 30 includes a centrifugal fan 100 , which is connected to the volute 31 .

[0051] Reference Figures 3 to 5The centrifugal fan 100 includes a wheel disc 110. The wheel disc 110 may be in the shape of a circular disc, and a shaft sleeve is disposed at the center of the wheel disc 110 for connecting with a motor. The motor serves as a power source for the centrifugal fan 100 to rotate, and can drive the centrifugal fan 100 to rotate.

[0052] The centrifugal fan 100 includes a plurality of blades 120, which are circumferentially connected to the wheel disc 110. The length direction of the blades 120 is parallel to the axis of the wheel disc 110. The plurality of blades 120 are arranged at equal intervals along the circumferential direction.

[0053] The centrifugal fan 100 includes a fixing ring 130 , which is connected to one end of the blade 120 away from the wheel disc 110 , and is used to connect and support the blade 120 .

[0054] An air inlet passage is formed in the middle area surrounded by the plurality of blades 120 . Air flow can enter the air inlet passage along the axial direction of the centrifugal fan 100 .

[0055] The spaces between the blades 120 form blade air ducts for guiding the airflow out after it has done work.

[0056] In the centrifugal fan 100 according to the embodiment of the present application, each blade 120 includes a first blade 121 and a second blade 122 arranged in series along the radial direction. The first blade 121 is closer to the center of the axial flow fan 100 than the second blade 122.

[0057] The first blade 121 and the second blade 122 slightly overlap in radial dimension and have a certain spacing in the circumferential direction.

[0058] The end of the blade 120 close to the center of the centrifugal fan 100 is the inlet end, and the end of the blade 120 opposite to the inlet end and away from the center of the centrifugal fan 100 is the outlet end. The inlet end of the first blade 121 is the inlet end of the blade 120, and the outlet end of the second blade 122 is the outlet end of the blade 120.

[0059] The blade 120 has a pressure surface 123 and a suction surface 124. The pressure surface 123 is a convex side surface of the blade 120, and the suction surface 124 is a concave side surface of the blade 120. In the circumferential direction, the second blade 122 is located on the suction surface 124 side of the first blade 121, so that the pressure surface 123 at the air inlet end of the second blade 122 is close to the suction surface 124 at the outlet end of the first blade 121.

[0060] In the implementation manner provided in the present application, a blade of a conventional centrifugal fan is split into two blades connected end to end, the two blades are arranged in series, and there is a certain gap in the circumferential direction and the radial direction. When the gas passes through the suction surface 124 of the first blade 121, a boundary layer of a certain thickness will be generated. When passing through the second blade 122, the boundary layer is redistributed, which is beneficial to reducing the aerodynamic loss and noise of the fan and improving the fan performance.

[0061] For the convenience of description, this application first explains several names:

[0062] Reference Figure 6 and Figure 7 The blade cross section refers to a cross section of the blade 120 taken by a plane perpendicular to the axis of the centrifugal fan 100 .

[0063] The blade profile line refers to the center line of the blade 120 in the blade cross section.

[0064] The β angle refers to the angle between the tangent line at any point on the blade profile and the tangent line in the circumferential direction of that point.

[0065] Z refers to the arc length between any point on the airfoil and the inlet end of the blade 120 divided by the total arc length of the blade 120 .

[0066] Specifically, refer to Figure 6 , Figure 7 , arc line AB is the blade profile line of the first blade 121 , and arc line CD is the blade profile line of the second blade 122 .

[0067] The intersection of a circle drawn with the axis of the wheel 110 as the center and the outlet end B of the first blade 121 as the point on the circle and the blade profile line of the second blade 122 is M. The intersection of a circle drawn with the inlet end C of the second blade 122 as the point on the circle and the blade profile line of the first blade 121 is N.

[0068] The total arc length L=L1+L2; L1 is the arc length of arc AB, and L2 is the arc length of arc CD.

[0069] The Z value of any point X on the first blade 121 = L(AX) / L; L(AX) is the arc length of the arc line AX.

[0070] The Z value of any point X on the second blade 122 = [L(AN)+L(CZ)] / L.

[0071] In some embodiments, the relationship between the arc length L1 of the first blade 121 and the total arc length L of the blade 120 satisfies: L1 = (0.35-0.65) L. This ensures that the lengths of the first blade 121 and the second blade 122 are not much different.

[0072] The arc length of the radially overlapping portion of the second blade 122 and the first blade 121 accounts for (0.15-0.3) times the total arc length of the second blade 122, i.e., L(CM)=(0.15-0.3)L2. Thus, the overlapping range of the first blade 121 and the second blade 122 can be limited. Within this range, the effect of the tandem blades on the redistribution of the boundary layer can be ensured.

[0073] According to an embodiment of the present application, the outlet end of the first blade 121 may be in an arc shape, and the inlet end of the second blade 122 may be in an arc shape.

[0074] Specific reference Figure 6 The center of the arc at the outlet of the first blade 121 is denoted as O 2 The center of the arc at the inlet end of the second blade 122 is marked as O 3 , O 2 The distance to the center of the roulette wheel 110 is less than O 3 The distance to the center of the roulette wheel 110.

[0075] The distance from the end point C of the inlet end of the second blade 122 to the center of the wheel disk 110 is smaller than the distance from the end point B of the outlet end of the first blade 121 to the center of the wheel disk 110 .

[0076] In some embodiments, reference Figure 8 Assuming that the horizontal axis of the β angle linear graph of the blade 120 is the size of the Z value, and the vertical axis is the size of the β angle, the corresponding relationship between the β angle and the Z value is defined as the β angle linear line.

[0077] The β-angle linear line includes a first line segment DL1 and a second line segment DL2 . The first line segment DL1 corresponds to the first blade 121 , and the second line segment DL2 corresponds to the second blade 122 . Both the first line segment DL1 and the second line segment DL2 gradually increase as the Z value increases.

[0078] A horizontal line passing through the highest point of the first line segment DL1 is defined as an imaginary line DL5, and DL5 divides the second line segment DL2 into a first sub-segment DL3 and a second sub-segment DL4. The first sub-segment DL3 is closer to the first line segment DL1 than the second sub-segment DL4. The β angle of the first sub-segment DL3 is smaller than the maximum value of the β angle of the first line segment DL1, and the β angle of the second sub-segment DL4 is larger than the maximum value of the β angle of the first line segment DL1.

[0079] According to the changing trend of the first line segment DL1, an extension line DL6 of DL1 is made, and the intersection point of the extension line DL6 and the second line segment DL2 is Y. The first line segment DL1, the extension line DL6 and the YD part of the second line segment are the β angle linear line of the existing integral blade.

[0080] After the present application sets a conventional blade as two tandem blades, for the β angle linear line, except that the inlet end of the second blade 122 is changed from the extended line DL6 to CY, the angle parameters of other parts remain unchanged, thus reducing the changes to the blade structure.

[0081] According to an embodiment of the present application, the length of the first line segment DL3 is 1 / 9 to 1 / 7 of the length of the second line segment DL4. Thus, it is possible to ensure that the radial overlap area of ​​the second blade 122 and the first blade 121 is relatively small, thereby avoiding a weakening of the adjustment effect on the outlet flow field of the first blade 121 when there is a large overlap area.

[0082] According to an embodiment of the present application, the β angle of the first blade 121 is in the range of 80° to 145°, and the β angle of the second blade 122 is in the range of 130° to 165°.

[0083] From the inlet end to the outlet end, the β angle of the first blade 121 can gradually increase from 80° to 145°, and the β angle of the second blade 122 can gradually increase from 130° to 165°. In this way, the first blade 121 and the second blade 122 can be arc-shaped as a whole, similar to the shape of the integral blade, thereby ensuring that the serial blades will not weaken the performance of the blade 120.

[0084] In some embodiments, reference Figure 5 The line from the axis of the wheel disc 110 to the outlet end of the first blade 121 is LP1, and the line from the axis of the wheel disc 110 to the inlet end of the second blade 122 is LP2. The angle θ between LP1 and LP2 is 1° to 3°.

[0085] The setting of the angle θ can basically determine the approximate positional relationship between the outlet end of the first blade 121 and the inlet end of the second blade 122. That is, after the outlet end of the first blade 121 is determined, the inlet end of the second blade 122 is on the angle line of the distance θ; and then the inlet end of the second blade 122 can be determined by the radial overlap size of the second blade 122 and the first blade 121.

[0086] If the value of θ is less than 1°, the distance between the first blade 121 and the second blade 122 is too close, which will weaken the effect on the boundary layer. If the value of θ is greater than 3°, the distance between the first blade 121 and the second blade 122 is too far, which will make the blade series meaningless and fail to redistribute the boundary layer.

[0087] The size of the angle β at the inlet end of the first blade 121 is negatively correlated with θ, that is, the larger the angle β at the inlet end of the first blade 121 is, the smaller θ is.

[0088] Reference Fig. 9 and Fig.10 , by comparing the centrifugal fan of the prior art ( Fig. 9 ) and the centrifugal fan of the present application ( Fig.10 ) is simulated to obtain a static pressure cloud diagram of the fan, in which the red area represents a high wind speed area. By comparing the wind speed areas of the prior art and the centrifugal fan 30, it can be seen that after the centrifugal fan 30 of the present application adopts tandem blades, the air outlet of the centrifugal fan is farther.

[0089] Reference Fig.11 and Fig.12 , by comparing the centrifugal fan of the prior art ( Fig.11 ) and the centrifugal fan of the present application ( Fig.12 ) is simulated to obtain a static pressure cloud diagram of the fan outlet interface. By comparing the wind speed area of ​​the prior art and the centrifugal fan 30, it can be seen that after the centrifugal fan 30 of the present application adopts tandem blades, the wind speed at the volute outlet interface is greater.

[0090] The following table is a comparison of the centrifugal fan of the prior art and the centrifugal fan 30 of the present application:

[0091] Comparison Items Air volume Speed efficiency Prior art (integral blade) 365.2 1000 34％ This application (tandem blades) 380.6 1000 41％

[0092] After the centrifugal fan of the present application adopts tandem blades, the fan efficiency is significantly improved by 7%, the air volume is increased by 15CMH, and the improvement effect is obvious.

[0093] In the present application, after the centrifugal fan 100 adopts tandem blades, the fan can blow air farther, the wind speed at the volute outlet is greater, and the fan efficiency and air volume are improved.

[0094] In the present application, after the centrifugal fan 100 adopts tandem blades, the air volume is improved at the same speed compared to the prior art, the fan speed is reduced at the same air volume, and the fan noise can be reduced.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0096] For the convenience of explanation, the above description has been made in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or limit the embodiments to the specific forms disclosed above. Based on the above teachings, various modifications and variations can be obtained. The selection and description of the above embodiments are to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various different variations of the embodiments suitable for specific use considerations.

Claims

1. A centrifugal fan, characterized in that: include: Roulette; A plurality of blades are circumferentially connected to the wheel disc, and the length direction of the blades is parallel to the axis of the wheel disc; the blades include a first blade and a second blade, the first blade and the second blade are arranged along the radial direction of the wheel disc, the radial dimensions of the first blade and the second blade overlap and are spaced in the circumferential direction, the first blade is closer to the axis of the wheel disc than the second blade, and the second blade is located on the suction surface side of the first blade.

2. The centrifugal fan according to claim 1, characterized in that: In the blade profile section of the blade, the angle between the tangent line at any point on the blade profile line and the tangent line of the circle passing through the point is defined as angle β; the ratio of the arc length between any point on the blade profile line and the inlet end of the blade to the total arc length of the blade is defined as Z; Assuming that the horizontal axis of the β angle linear graph of the blade is the magnitude of Z, and the vertical axis is the magnitude of the β angle, the corresponding relationship between the β angle and Z is defined as the β angle linear line; The β-angle linear line includes a first line segment corresponding to the first blade and a second line segment corresponding to the second blade, and both the first line segment and the second line segment gradually increase as Z increases.

3. The centrifugal fan according to claim 2, characterized in that: The second line segment may be divided into a first sub-segment and a second sub-segment, wherein the β angle of the first sub-segment is smaller than the maximum value of the β angle of the first line segment, and the β angle of the second sub-segment is larger than the maximum value of the β angle of the first line segment.

4. The centrifugal fan according to claim 3, characterized in that: The length of the first sub-line segment is 1 / 9 to 1 / 7 of the length of the second sub-line segment.

5. The centrifugal fan according to claim 2, characterized in that: The β angle of the first blade is in the range of 80° to 145°, and the β angle of the second blade is in the range of 130° to 165°.

6. The centrifugal fan according to claim 1, characterized in that: The arc length of the first blade is L1, the total arc length of the blade is L, and L1=(0.35-0.65)L.

7. The centrifugal fan according to claim 1, characterized in that: The outlet end of the first blade and the inlet end of the second blade are both arc-shaped; in the radial direction, the center O3 of the inlet end of the second blade is farther away from the center of the wheel disc than the center O2 of the outlet end of the first blade; the end point C of the inlet end of the second blade is closer to the center of the wheel disc than the end point B of the outlet end of the first blade.

8. The centrifugal fan according to claim 1, characterized in that: In the blade profile section of the blade, the line connecting the outlet end of the first blade and the center of the wheel disk is LP1, the line connecting the inlet end of the second blade and the center of the wheel disk is LP2, and the angle θ between LP1 and LP2 is 1° to 3°.

9. The centrifugal fan according to claim 8, characterized in that: In the blade profile section of the blade, the angle between the tangent line at any point on the blade profile line and the circumferential tangent line passing through the point is defined as angle β; the size of angle β at the inlet end of the first blade is negatively correlated with θ.

10. An air conditioner, characterized in that: include: case; a refrigerant circuit having a condenser and an evaporator; The centrifugal fan according to any one of claims 1 to 9 is arranged in the housing and is used to blow air to at least one of the condenser and the evaporator.

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