Centrifugal fan and air conditioner using the same

Abstract

The present invention provides a centrifugal fan and an air conditioner using the same that can suppress the separation flow that occurs at the leading edge, thereby improving efficiency and reducing noise. [Solution] In a centrifugal fan in which a plurality of curved main blades are arranged at predetermined intervals in the circumferential direction and rotate around a rotation axis 210, the fan comprises a main blade 41 and a pair of micro-blades 42, the micro-blades are located on the rotation axis side of the leading edge P1 of the main blade, and the leading edge Ps1 of the micro-blades is located on the front side in the rotation direction of the radial line Lr passing through the leading edge P1 of the main blade, and the main blade and micro-blades are installed with a gap between them. When the inlet angle of the main blade is defined as β1, the inclination angle of the micro-blades as α, the tangent line at the leading edge P1 on the blade row line C of the main blade as Lp, the tangent line at the leading edge Ps1 on the blade row line C1 of the micro-blades as Lsp, and the angle between the tangent line Lsp and the tangent line Lp as γ, γ

Description

Technical Field

[0001] The present invention relates to a centrifugal fan and an air conditioner using the same.

Background Art

[0002] For example, in Patent Document 1, in a multi-blade fan of a centrifugal blower in which a plurality of blades (vanes) are arranged annularly, the inlet angle β1 of the blade defined by the angle formed by the tangent of the inscribed circle and the tangent of the blade center line at the intersection of the inscribed circle of each blade and the blade center line is defined within the range of 50° to 90°, thereby suppressing the separation phenomenon occurring at the leading edge portion to achieve low noise and high efficiency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, although the inlet angle β1 is set within the optimal range of 50° to 90°, since it is too large with respect to the non-collision inflow angle of the airflow flowing into the blade, there is a possibility that the separation flow at the leading edge portion cannot be sufficiently suppressed.

Means for Solving the Problems

[0005] To solve the above problems, the centrifugal fan according to claim 1 of the present invention is a centrifugal fan in which a plurality of curved main blades are arranged at predetermined intervals in the circumferential direction and rotate around a rotation axis, wherein the main blades and a pair of micro-blades are provided, the micro-blades are located on the rotation axis side of the leading edge P1 of the main blades, and the leading edge Ps1 of the micro-blades is located on the front side in the rotation direction of the radial line Lr passing through the leading edge P1 of the main blades, the main blades and the micro-blades are installed with an interval between them, and the leading edge P1 is on the blade row line C on the inner circumferential side of the main blades The wing is characterized in that, when Lp is defined as the tangent line to the main wing, Lm is the tangent line to the leading edge P1 on the centerline Rm of the main wing, the angle between tangent line Lm and tangent line Lp is defined as the inlet angle β1 of the main wing, the angle between tangent line Lp and the straight line Ls connecting the leading edge Ps1 and trailing edge Ps2 of the microwing is defined as the inclination angle α of the microwing, Lsp is the tangent line to the leading edge Ps1 on the blade row line C1 on the inner circumference side of the microwing, and γ is defined as the angle between tangent line Lsp and tangent line Lp, then the wing is formed such that γ < α < β1.

[0006] Furthermore, the centrifugal fan of claim 2 is characterized in that, when the length of the micro-blade projected in the direction of the tangent Lsp of the micro-blade is defined as d1, and the distance between the leading edge P1 of the main wing and the trailing edge Ps2 of the micro-blade is defined as the distance d2 between the main wing and the micro-blade, the fan is formed such that d2 ≤ d1.

[0007] Furthermore, the centrifugal fan of claim 3 is characterized in that, when the maximum blade thickness of the main blade is defined as d3, it is formed such that d3 ≤ d2.

[0008] Furthermore, in the centrifugal fan of claim 4, the main wing has a section Tr in which the wing thickness distance dr is constant, and Lm1 is defined as the tangent to the center line Rm at the end Tr1 on the leading edge P1 side of the section Tr, and a straight line L1 is defined at a distance of 1 / 2 × dr from Lm1 toward the front, and a straight line L2 is defined at a distance of 1 / 2 × dr from Lm1 toward the rear in the direction of rotation, wherein the leading edge Ps1 of the microwing is on the straight line L1 or toward the front from the straight line L1, and the trailing edge Ps2 of the microwing is on the straight line L2 or between the straight line L2 and the straight line L1.

[0009] Furthermore, the centrifugal fan of claim 5 is characterized in that the maximum blade thickness of the micro-blade is thin enough not to obstruct the airflow into the main blade, and the projected length d1 of the micro-blade is equal to the maximum blade thickness d3 of the main blade.

[0010] Furthermore, the air conditioner according to claim 6 is characterized by being equipped with a centrifugal fan as described in any one of claims 1 to 5. [Effects of the Invention]

[0011] According to the present invention, by providing a small wing on the rotation axis side of the main wing such that the inclination angle α is γ < α < β1, it is possible to minimize the flow separation at the leading edge while improving efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] External perspective view of an air conditioner in one embodiment of the present invention [Figure 2] Exploded perspective view of the air conditioner in the same embodiment. [Figure 3] Cross-sectional view of the air conditioner in the same embodiment. [Figure 4] Cross-sectional view of the blower in the same embodiment. [Figure 5] Detailed cross-sectional view of the main wing and microwing in the same embodiment. [Figure 6] This diagram shows the streamlines near the main wing in the same embodiment, with (a) the case without the microwing and (b) the case with the microwing. [Figure 7] Detailed cross-sectional view of the main wing and microwing in the same embodiment. [Figure 8] This is a streamline diagram of the blower in the same embodiment, showing the case without micro-blades. [Figure 9] This is a streamline diagram of the blower in the same embodiment, showing the case with micro-blades. [Figure 10] Detailed cross-sectional view of the main wing and microwing in the same embodiment. [Figure 11] Detailed cross-sectional view of the main wing and microwing in the same embodiment.

Best Mode for Carrying Out the Invention

[0013] Next, the centrifugal fan in the first embodiment of the present invention and the air conditioner using the same will be described based on the drawings. In this embodiment, a dehumidifier will be used as the air conditioner for description.

[0014] In the following description, "front (front side)", "rear (rear side)", "upper", "lower", "right", and "left" follow the definitions in each drawing. The vertical direction is the up-and-down direction, and the horizontal direction is the direction included in the plane direction including the front-rear, left-right directions.

[0015] 1 is a dehumidifier as an air conditioner having a housing 10 forming an appearance. The housing 10 has a front frame 111, a rear frame 112, a rear frame decorative panel 113, an upper panel 114, and a base 115.

[0016] The front frame 111 and the rear frame 112 are combined with each other to form the housing 10 facing the front-rear direction of the dehumidifier 1.

[0017] The rear frame 112 has a suction port 121 and a tank insertion port 122. The suction port 121 has a plurality of slits 126 and has a filter 127 and a filter case 128 on the outer surface. The filter 127 is made of a resin mesh, non-woven fabric, etc., and removes dust, odor components, etc. mixed in the inhaled air. The filter case 128 fixes the filter 127 to the suction port 121. The tank insertion port 122 is disposed below the suction port 121, and the drain tank 151 is inserted and removed therefrom.

[0018] [[ID=3l]] The upper panel 114 is disposed above the combined front frame 111 and rear frame 112 to form the housing 10 facing upward. The upper panel 114 has a blowout port 131, an operation unit 132, and an LED display unit 133. <\ The blowout port 131 is disposed on the upper panel 114. The air outlet 131 includes a first air outlet 31 positioned on an upward-facing surface, a second air outlet 32 ​​positioned on surfaces facing upward and horizontally, and a louver unit 135 capable of controlling the direction of dry air discharge from diagonally upward to horizontally. The louver unit 135 includes a first louver 21, a second louver 22, a first louver motor 137a for driving the first louver 21, and a second louver motor 137b for driving the second louver 22.

[0019] The control unit 132 and the LED display unit 133 are arranged on a surface that slopes diagonally downward from the top and forward. The control unit 132 is a touch panel that provides functions such as an operation switch, timer switch, and operation mode selection switch. The LED display unit 133 displays the operating status of the dehumidifier 1 by the illumination of LEDs.

[0020] The base 115 is positioned below the combined front frame 111 and rear frame 112 and serves as the base for the dehumidifier 1.

[0021] The dehumidifier 1 includes, as its main internal components housed in the casing 10, a fan case 141, a blower 230 positioned in the airflow path 240 between the intake port 121 and the outlet port 131, a blower motor 143 which is the power source for the blower 230, a heating heater 144 which heats the air passing through the blower 230, a compressor 145, a heat exchanger 146, a drain pan 149, a drain tank 151, and a control unit 155 which serves as the control unit.

[0022] The fan case 141 is positioned on the base 115 and primarily supports and positions the blower 230, the blower motor 143, and the drain tank 151.

[0023] The blower device 230 consists of a blower fan 142 as a centrifugal fan and a scroll casing 200. In this embodiment, the blower fan 142 is a sirocco fan, which is a multi-blade blower with forward-facing blades. The detailed configuration of the blower fan 142 in this invention will be described later. The scroll casing 200 includes a circular fan intake port 204 opening at the rear, a bell mouth 209 formed in the fan intake port 204, a fan outlet port 206 opening tangentially to the blower fan 142, and a tongue portion 207. The fan intake port 204 is in communication with the intake port 121, and the fan outlet port 206 is in communication with the outlet port 131.

[0024] The blower fan 142 rotates due to the rotation of the blower motor 143, drawing in air from the intake port 121 and forming an airflow that is blown out from the outlet port 131. The blower fan 142 and blower motor 143 are mounted on the fan case 141 such that the rotating shaft 210 is aligned in the front-to-back direction.

[0025] The compressor 145 is fixed on the base 115 and connected to the heat exchanger 146 via piping 145a and a pressure reducing device 145b.

[0026] The heat exchanger 146 exchanges heat with the air drawn in from the intake port 121. The heat exchanger 146 includes an evaporator 146a positioned near the suction port 121, which is upstream of the air supply path 240, and a condenser 146b positioned downstream of the evaporator 146a in the air supply path 240. The evaporator 146a and condenser 146b are fin-tube type heat exchangers in which fins 148 are attached to U-shaped refrigerant pipes 147.

[0027] The compressor 145, piping 145a, pressure reducing device 145b, and heat exchanger 146 form a refrigeration cycle through which the refrigerant flows. The refrigeration cycle includes a compressor 145, a condenser 146b, a pressure reducing device 145b, and an evaporator 146a, in the order in which the refrigerant flows. As the refrigerant flows through the evaporator 146a, it absorbs heat from the air passing through the evaporator 146a and evaporates. Furthermore, as the refrigerant flows through the condenser 146b, it reheats and condenses the air passing through the condenser 146b. As a result, the air drawn in from the intake port 121 has dust and odor components removed by the filter 127, is then cooled and dehumidified in the evaporator 146a, and then heated in the condenser 146b before being discharged from the outlet port 131 as low-humidity air.

[0028] The drain pan 149 supports and fixes the heat exchanger 146 from below on the side opposite to the side of the fan case 141 where the blower fan 142 is located, in the front-rear direction. The drain pan 149 supports the heat exchanger 146 in the front-rear and left-right directions by engaging with the refrigerant pipes 147 and fins 148 located below the heat exchanger 146. The drain pan 149 has a drain port that receives the drain water generated and dripping from the evaporator 146a and discharges it through this drain port.

[0029] The drain tank 151 stores the drain water discharged from the drain port of the drain pan 149. The drain tank 151 is attached to and detached from the housing 10 by sliding it in the front-rear direction from the tank insertion port 122. When the drain tank 151 is inserted into the housing 10, it is placed in the tank chamber 141b formed by the fan case 141.

[0030] The drain tank 151 has a tank lid 154 and a float housing 152. The tank lid 154 allows drain water from the drain port of the drain pan 149 to fall into the drain tank 151. The float housing 152 houses a float 153, for example, one with a magnet (not shown), for detecting the water level in the drain tank 151. The magnetic field of the magnet, corresponding to the water level, is detected by an AMR sensor (anisotropic magnetoresistive sensor, not shown) mounted on a control unit 155 or the like, and the user is notified when the drain tank 151 is full.

[0031] The control unit 155 is supported by the case 156 and positioned to the left of the fan case 141. The control unit 155 comprehensively controls the operation of the dehumidifier 1 by electrically controlling each component, such as the first louver motor 137a, the second louver motor 137b, the blower motor 143, the compressor 145, and the LED display unit 133, based on instructions from the operation unit 132 and pre-stored programs.

[0032] Next, the configuration of adding micro-blades to the main blades of the blower fan 142 in the first embodiment of the present invention, and the effects of providing the micro-blades, will be explained based on Figures 4 to 10.

[0033] First, let's describe the problems with the conventional technology. The sirocco fan used in the blower fan 142 of this embodiment is a centrifugal fan that redirects the airflow flowing in parallel to the rotating shaft 210 from the fan intake port 204 by 90° using the impeller (corresponding to the main blade 41 described later) and the scroll casing 200. Regarding the blade shape, an inlet angle of 50° to 90° is considered optimal, and it is known that this is when the airflow efficiency and static pressure are maximized in many sirocco fans. This is because the static pressure increases as the inlet cross-sectional area increases as the inlet angle approaches 90°, and also because the deflection angle becomes smaller relative to the optimal outlet angle of 150° to 160° as the inlet angle increases, making it easier for the air to flow along the blade surface and reducing pressure loss.

[0034] However, when the inlet angle is between 50° and 90°, a large collision occurs with the leading edge of the blade, and a large flow separation occurs on the negative pressure surface of the blade. This is because the inlet angle of 50° to 90° is too large compared to the inlet angle of 10° to 30°, which is the angle at which airflow enters the blade without collision. The flow separation causes swirling airflow between the blades, resulting in a significant decrease in performance and an increase in noise.

[0035] Therefore, the present invention will describe in detail a method for suppressing flow separation while maintaining static pressure by providing a main blade and a micro-blade as the blower fan 142.

[0036] Figure 4 shows a cross-sectional view of the blower fan 142 and scroll casing 200 that constitute the blower device 230 of this embodiment.

[0037] The impeller constituting the blower fan 142 has main blades 41 arranged circumferentially at predetermined intervals, with the main blades 41 being forward-facing blades that are curved and oriented in the direction of rotation. The main blades 41 rotate in the rotational direction shown in the figure around the rotation axis 210. In addition, a pair of micro-blades 42 are installed at intervals from the main blades 41. The micro-blades 42 are installed on the rotation axis 210 side of the leading edge P1 of the main blade 41 (see Figure 5 for detailed position). Furthermore, the leading edge Ps1 of the micro-blades 42 (see Figure 5 for detailed position) is installed on the front side in the direction of rotation of the line Lr, where Lr is the line connecting the leading edge P1 of the main blade 41 and the rotation axis 210.

[0038] Figure 5 shows a magnified view of the detailed positional relationship between the microwing 42 and the main wing 41 in the cross-sectional view of Figure 4. On the inner circumference side (rotation axis 210 side) of the main wing 41, let Lp be the tangent line at the leading edge P1 on the blade row line C connecting the leading edges P1 of each main wing 41. Also, let Lm be the tangent line at the leading edge P1 on the center line Rm that bisects the distance of the wing thickness of the main wing 41. Here, the angle between tangent line Lp and tangent line Lm is defined as the inlet angle β1 of the main wing 41. Let Ls be the straight line connecting the leading edge Ps1 and the trailing edge Ps2 of the microwing 42, and let α be the inclination angle of the microwing 42, the angle between the line Ls and the tangent line Lp. On the inner circumference side (rotation axis 210 side) of the microwing 42, let Lsp be the tangent line at the leading edge Ps1 on the blade row line C1 connecting the leading edges Ps1 of each microwing 42. Here, let γ be the angle between the tangent line Lsp and the tangent line Lp.

[0039] In this embodiment, the relationship between the inlet angle β1, the inclination angle α, and the angle γ formed by the tangent line Lsp is such that γ < α < β1. In other words, the position of the microwing 42 is on the rotation axis 210 side of the leading edge P1 and on the front side in the rotation direction of the straight line Lr relative to the position of the main wing 41, and the inclination angle α of the microwing 42 is smaller than the inlet angle β1 of the main wing 41 and larger than the angle γ formed by the tangent line Lsp at the leading edge Ps1. Here, the angle γ should ideally be between 10° and 30°, which is the angle at which the airflow enters the blade without collision.

[0040] Here, we will describe in detail the effects of installing the microwing 42 on the main wing 41 at the aforementioned position and angle. Figure 6 is a streamline diagram showing the airflow around the main wing 41, where (a) is the streamline in a conventional impeller without microwings, and (b) is the streamline in the impeller of this embodiment with microwings. In Figure 6(a), when the airflow flowing into the leading edge P1 of the main wing 41 collides with the leading edge P1 and flows towards the negative pressure side (part a2 in the figure), the flow separates, generating a swirling flow (vortex). This is the separated flow mentioned above, a phenomenon that occurs because the airflow flowing into the negative pressure side cannot flow along the blade surface.

[0041] On the other hand, in Figure 6(b), the airflow flowing into the leading edge P1 of the main wing 41 is straightened by the inclination of the microwing 42 (set by the inclination angle α), and flows in at an angle close to the inlet angle β1 of the main wing 41 (part b2 in the same figure). As a result, the collision at the leading edge P1 is mitigated, and the airflow that flows into the negative pressure side flows along the blade surface, suppressing airflow separation and thus reducing the occurrence of separated flow.

[0042] Furthermore, in Figures 6(a) and (b), the airflow flowing into the positive pressure side of the main wing 41 (parts a1 and b1 in the figure) remains unchanged regardless of the presence or absence of the micro-wing 42, and therefore the generated static pressure and airflow rate do not change.

[0043] Therefore, by setting the position and inclination angle α of the micro-wing 42 as in this embodiment, it is possible to suppress the flow separation that occurs at the leading edge P1 of the main wing 41 while maintaining the static pressure and airflow rate from the blower fan 142, thereby improving efficiency and reducing noise.

[0044] Figure 7 shows how the direction of the incoming airflow is straightened by the micro-wings 42. In the diagram, direction S represents the initial inflow airflow direction, indicating the direction of airflow flowing into the impeller as the blower fan 142 rotates. Since the micro-blade 42 is installed on the front side in the direction of rotation, the airflow S flows into the leading edge Ps1 of the micro-blade 42. However, if the impeller consists only of the main blade 41, the airflow S flows into the leading edge P1 of the main blade 41.

[0045] The airflow S that flows into the leading edge Ps1 of the microwing 42 is rectified by the inclination of the microwing 42 (set by the inclination angle α), flows out from the trailing edge Ps2 of the microwing 42 as airflow S1, and flows into the leading edge P1 of the main wing 41. Here, if we define the initial inflow airflow angle θ as the angle between the initial inflow airflow direction S and the tangent Lp, and the angle θ1 as the angle between the airflow direction S1 flowing out from the microwing 42 and the tangent Lp, then the airflow that flows into the leading edge P1 of the main wing 41 by the microwing 42 can flow in at an angle θ1 that is close to the inlet angle β1 from the initial inflow airflow angle θ.

[0046] Figures 8 and 9 are streamlines of the blower fan 142 and scroll casing 200 that constitute the blower device 230, showing the airflow simulation with and without the micro-blades 42. Figure 8 is the streamline when there are no micro-blades, and Figure 9 is the streamline when there are micro-blades. The direction of the streamlines is such that the airflow that flows from rear to front into the fan intake 204 makes a 90° turn and flows into the micro-blades 42 and main blade 41 that constitute the blower fan 142, and then flows along the scroll casing 200 toward the fan outlet 206. In Figure 8, many swirling vortices are observed on the negative pressure side of the main wing 41, but in Figure 9, they are hardly observed. According to simulations performed with the configuration of the blower 230 of this embodiment, the blower efficiency improved by approximately 5% when the micro-wings 42 shown in Figure 9 were installed compared to when the micro-wings were not present in Figure 8.

[0047] Figure 10 shows the optimal arrangement of the main wing 41 and the microwing 42. In the figure, distance d1 represents the length when the microwing 42 is projected in the direction of the tangent line Lsp of the microwing 42. Distance d2 represents the distance between the leading edge P1 of the main wing 41 and the trailing edge Ps2 of the microwing 42. Note that distance d2 is the distance between the main wing 41 and the microwing 42.

[0048] In this embodiment, the relationship between distance d1 and distance d2 is set such that d2 ≤ d1. As a result, the airflow flowing into the microwing 42 flows in from the direction of the tangential Lsp from the region of distance d1, but when distance d2 is equal to or smaller than distance d1, the rectified airflow flowing into the microwing 42 pushes the airflow between the main wing 41 and the microwing 42, allowing it to flow into the leading edge P1 of the main wing 41 at an angle closer to the inlet angle β1.

[0049] Furthermore, the distance d2 between the main wing 41 and the microwing 42 is formed such that d3 ≤ d2, where d3 is the maximum thickness of the main wing 41. In other words, in order to ensure that the amount of airflow S1 passing between the main wing 41 and the microwing 42 is sufficient to suppress the flow separation on the negative pressure side of the main wing 41, it is desirable that the distance d2 be at least equal to or greater than the maximum thickness d3 of the main wing.

[0050] Figure 11 shows an even more optimal arrangement of the main wing 41 and the microwing 42. In the diagram, section Tr represents the section of the main wing 41 where the wing thickness distance dr is constant. Let Tr1 be the leading edge P1 side of section Tr, and let Lm1 be the tangent line at Tr1 on the centerline Rm of the main wing 41. Let L1 be a straight line parallel to the tangent line Lm1 and located a distance of 1 / 2 × dr from the tangent line Lm1 in the direction of the front of the main wing 41 in the direction of rotation. Similarly, let L2 be a straight line located a distance of 1 / 2 × dr from the tangent line Lm1 in the direction of the rear of the main wing 41 in the direction of rotation.

[0051] In Figure 11, the leading edge Ps1 of the microwing 42 is on the straight line L1 or ahead of the straight line L1, and the trailing edge Ps2 of the microwing 42 is formed to be on the straight line L2 or between the straight line L2 and the straight line L1. This allows the leading edge Ps1 of the microwing 42 to be positioned on the windward side in the direction of rotation relative to the positive pressure surface of the main wing 41, and the trailing edge Ps2 to be positioned on the windward side in the direction of rotation relative to the negative pressure surface of the main wing, so that the airflow rectified by the microwing 42 can reliably flow into the leading edge P1 of the main wing 41.

[0052] Furthermore, it is desirable that the micro-wings 42 have as little influence as possible, except to suppress the flow separation that occurs on the main wing 41, in order to ensure the static pressure and airflow that are the blowing performance of the blower fan 142. For this reason, it is desirable that the maximum thickness of the micro-wings 42 be thin enough not to obstruct the airflow flowing into the main wing 41, such as the airflow in section b1 of Figure 6(b). Here, a thickness thin enough not to obstruct the airflow flowing into the main wing 41 means a thickness that is thinner than about half the thickness of the main wing 41 (1 / 2 × dr), while still ensuring sufficient rigidity so that the micro-wings 42 do not flex due to the airflow. For example, if we consider a pair of main wings 41 and microwings 42, and designate the main wing on the rear side in the direction of rotation as 41a (not shown), then the microwing 42 will be located upstream of the main wing 41a in the airflow. Therefore, making the thickness of the microwing 42 as thin as possible will minimize the influence of the airflow flowing into the main wing 41a.

[0053] Furthermore, it is desirable that the projected length d1 of the microwing 42, when projected in the direction of the tangent Lsp, be equal to the maximum thickness d3 of the main wing. In other words, to minimize the influence on the main wing 41a, the length of the microwing 42 should be minimized, and the maximum thickness d3 of the main wing = the distance d2 between the main wing 41 and the microwing 42 = the projected length d1.

[0054] In this embodiment, the configuration of the main blade 41 and micro-blade 42 of the blower fan 142 was described using a dehumidifier as an example of an air conditioner, but of course, other air conditioners may also be used. In other words, any air conditioner that uses a centrifugal fan falls within the technical field of the present invention. As for other embodiments, for example, the effects and advantages of the present invention extend similarly to air conditioners such as evaporative humidifiers, air purifiers, dryers, and ventilation fans. By installing the centrifugal fan of the present invention in these air conditioners, it is possible to improve the overall efficiency of the air conditioner and reduce noise.

[0055] Furthermore, in this embodiment, the blower fan 142, which is a centrifugal fan, was described as a sirocco fan, which is a multi-blade blower with forward-facing blades, but other types of centrifugal fans may also be used. For example, it may be a centrifugal fan such as a turbo fan.

[0056] Furthermore, the other configurations used in this embodiment are presented as examples only and are not intended to limit the scope of the invention. It can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0057] 41... Main wing 42...Minute wing 142... Blower fan 210... Rotation axis P1…(The leading edge of the main wing) Ps1…(Leading edge of a microwing) Lr… (A straight line connecting the leading edge P1 of the main wing 41 and the rotation axis 210) C... (wing) wing line C1…(small wing) wing line Lp…Tangency (at the leading edge P1 on the wing line C) Rm… (Wing) centerline Lm…Tangent line (at the leading edge P1 on the center line Rm) Ls… (a straight line connecting the leading edge Ps1 and the trailing edge Ps2) Lsp…Tangency (at the leading edge Ps1 on the wing line C1) β1…Inlet angle of main wing 41 α... Inclination angle of the microwing 42 γ...Angle between tangent line Lsp and tangent line Lp

Claims

1. In a centrifugal fan in which multiple curved main blades are arranged at predetermined intervals in the circumferential direction and rotate around a rotation axis, The system comprises a main wing and a pair of microwings, the microwings being located on the rotation axis side of the leading edge P1 of the main wing, and the leading edge Ps1 of the microwings being located on the front side in the rotation direction of the radial line Lr passing through the leading edge P1 of the main wing. The main wing and the mini-wing are installed with a gap between them. Let Lp be the tangent line at the leading edge P1 on the blade row line C on the inner circumference side of the main wing. Let Lm be the tangent line at the leading edge P1 on the centerline Rm of the main wing, and let the angle between the tangent line Lm and the tangent line Lp be the inlet angle β1 of the main wing. The angle between the tangent line Lp and the straight line Ls connecting the leading edge Ps1 and trailing edge Ps2 of the microwing is defined as the inclination angle α of the microwing. When Lsp is defined as the tangent line at the leading edge Ps1 on the blade row line C1 on the inner circumference side of the aforementioned microwing, and the angle between the tangent line Lsp and the tangent line Lp is defined as γ, A centrifugal fan characterized by being formed such that γ < α < β1.

2. Let d1 be the length when the microwing is projected in the direction of the tangent Lsp of the microwing. When the distance between the leading edge P1 of the main wing and the trailing edge Ps2 of the microwing is defined as the distance d2 between the main wing and the microwing, A centrifugal fan according to claim 1, which is formed such that d2 ≤ d1.

3. When the maximum wing thickness of the main wing is defined as d3, The centrifugal fan according to claim 2, which is formed such that d3 ≤ d2.

4. The main wing has a section Tr in which the wing thickness distance dr is constant. Let Lm1 be the tangent to the center line Rm at the end Tr1 on the front edge P1 side of the section Tr. A straight line L1 is located at a distance of 1 / 2 × dr from Lm1 toward the front side, When a straight line L2 is defined as being located at a distance of 1 / 2 × dr from Lm1 on the rear side in the direction of rotation, The leading edge Ps1 of the microwing is on the straight line L1, or on the front side of the straight line L1. The centrifugal fan according to claim 3, characterized in that the trailing edge Ps2 of the microwing is on the straight line L2, or between the straight line L2 and the straight line L1.

5. The maximum thickness of the aforementioned microwing is thin enough not to obstruct the airflow into the main wing. The projected length d1 of the aforementioned microwing is equal to the maximum thickness d3 of the main wing. The centrifugal fan according to feature 4.

6. An air conditioner characterized by being equipped with a centrifugal fan as described in any one of claims 1 to 5.

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