Fan and air treatment device

Abstract

To improve quietness of a fan while ensuring strength of blades.SOLUTION: In an axial fan (31), a leading edge (43) of each of a plurality of blades extends forward in a rotation direction (Dr) toward a blade tip (41), to form an advance blade part (47) between itself and the blade tip (41). Each blade (35) is composed of a porous part (61) and a non-porous part (63). A tip portion (49) located on the blade tip (41) side of the advance blade part (47) includes a porous part (61).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to fans and air handling devices. [Background technology]

[0002] Patent Document 1 discloses a propeller-type fan (mixed flow fan). In this fan, the blades are configured to include a porous portion. Specifically, the outer peripheral edge portion of the blade is molded from a non-porous synthetic resin, and the central portion of the blade excluding the outer peripheral edge portion is configured from a porous material. In this fan, the porous material is used for the majority of the blades to reduce noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 04-272499 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to ensure quiet operation, propeller fans used in air conditioning and the like are known that have forward-swept blades. The forward-swept blades are the parts of the blade that protrude forward in the direction of rotation as they approach the blade tips, and have leading ends that taper forward in the direction of rotation.

[0005] When such a fan rotates, the peripheral speed of the blade increases toward the blade tip and is fastest at the tip of the forward-swept blade section. For this reason, the tip of the forward-swept blade section is likely to become the starting point for airflow separating from the blade surface. When airflow separates from the blade surface at the blade tip side, it forms a so-called tip vortex. A tip vortex is a vortex that is generated when air flows back from the pressure side of the blade to the suction side, around the blade tip.

[0006] The tip vortex develops rearward along the tip of the blade as the blade rotates. The longer the distance the tip vortex develops, the higher its energy becomes, and the louder the noise it produces. When the airflow separates at the tip of the forward-swept blade section to form a tip vortex, the distance over which the tip vortex develops includes almost the entire length of the blade tip. For this reason, even in the fan disclosed in Patent Document 1, noise reduction is compromised by the tip vortex.

[0007] An object of the present disclosure is to improve the quietness of a fan while ensuring the strength of the blades. [Means for solving the problem]

[0008] A first aspect of the present disclosure is directed to a fan (31). The fan (31) of the first aspect includes a plurality of blades (35) that rotate around a predetermined rotation axis (Ax). The blades (35) have a leading edge (43) that is the front edge in the direction of rotation (Dr) and a blade tip (41) that is the outer edge in the direction of rotation radius. The leading edge (43) extends toward the blade tip (41) so as to protrude forward in the direction of rotation (Dr), and forms a forward-moving blade portion (47) between the leading edge (43) and the blade tip (41). The blade (35) is composed of a porous portion (61) and a non-porous portion (63). A tip portion (49) located on the blade tip (41) side of the forward-moving blade portion (47) includes the porous portion (61).

[0009] In the first embodiment, a part of the blade (35) is made of a porous portion (61), while the other part is made of a non-porous portion (63). Thus, the strength of the blade (35) is ensured by the non-porous portion (63), and the separation of the airflow from the blade surface is suppressed by the porous portion (61). The tip portion (49) of the forward-moving blade portion (47) includes the porous portion (61). This suppresses the separation of the airflow at the tip portion (49) of the forward-moving blade portion (47), and even if a blade tip vortex occurs, the generation of the blade tip vortex is delayed to the rear side in the rotation direction (Dr) of the blade (35), and the development of the blade tip vortex can be inhibited. This reduces noise caused by the blade tip vortex. Thus, the strength of the blade (35) can be ensured, while improving the quietness of the fan (31).

[0010] A second aspect of the present disclosure is a fan (31) of the first aspect, wherein one or both of the leading edge (43) and the blade tip (41) of the tip portion (49) of the forward-swept blade section (47) are formed by the porous portion (61).

[0011] In the second embodiment, one or both of the leading edge (43) and the blade tip (41) of the tip portion (49) of the forward-swept blade portion (47) are formed of a porous portion (61). When the leading edge (43) of the tip portion (49) of the forward-swept blade portion (47) is a porous portion (61), separation of the airflow can be suppressed at the tip portion (49) including the leading edge (43) of the forward-swept blade portion (47). When the blade tip (41) of the tip portion (49) of the forward-swept blade portion (47) is a porous portion (61), separation of the airflow can be suppressed at the tip portion (49) including the blade tip (41) of the forward-swept blade portion (47), and the formation of a flow in which air flowing along the pressure side (51) of the blade (35) is drawn toward the suction side (53) can be suppressed. These are advantageous in inhibiting the development of a blade tip vortex and reducing noise caused by the blade tip vortex.

[0012] A third aspect of the present disclosure is the fan (31) of the first or second aspect, wherein the porous portion (61) is present only in the tip portion (49) of the forward-swept blade portion (47).

[0013] In the third aspect, the porous portion (61) is formed only at the tip portion (49) of the forward-moving blade portion (47), and the remaining portion of the blade (35) is formed of the non-porous portion (63). This is effective in improving the quietness of the fan (31) while ensuring the strength of the blade (35) with the non-porous portion (63).

[0014] A fourth aspect of the present disclosure is the fan (31) of any one of the first to third aspects, wherein the leading edge (43) is curved to form a concave shape toward the rear side in the direction of rotation (Dr). When a tangent line that contacts the leading edge (43) in the direction of the radius of rotation as viewed in the axial direction along the rotation axis (Ax) is defined as an area line (La), the forward-moving blade portion (47) is a portion of the blade (35) that is forward of the area line (La) in the direction of rotation (Dr), and the porous portion (61) constitutes a portion including the blade tip (41) side of the forward-moving blade portion (47).

[0015] In the fourth aspect, the forward-advancing blade portion (47) is a portion of the blade (35) forward of the area line (La) in the direction of rotation (Dr), and the porous portion (61) constitutes a portion including the blade tip (41) side of the forward-advancing blade portion (47). This makes it possible to effectively utilize the function of the porous portion (61) and preferably obtain the above-described effect of improving the noise reduction of the fan (31).

[0016] A fifth aspect of the present disclosure is directed to an air treatment device (1). The air treatment device (1) of the fifth aspect includes the fan (31) of any one of the first to fourth aspects.

[0017] In the fifth aspect, the fan (31) according to any one of the first to fourth aspects is provided, and therefore, the noise level of the fan (31) in the air treatment device (1) can be improved. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic configuration diagram of a refrigerant circuit provided in an air conditioner of an embodiment. [Diagram 2] FIG. 2 is a plan view illustrating the axial flow fan of the embodiment. [Diagram 3] FIG. 3 is a perspective view illustrating the axial flow fan of the embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the blade taken along line IV-IV in FIG. [Diagram 5]FIG. 5 is a graph illustrating the relationship between the air volume and the blowing noise in the axial flow fan of the embodiment. [Figure 6] FIG. 6 is a graph illustrating the relationship between the air volume and the static pressure in the axial flow fan of the embodiment. [Figure 7] FIG. 7 is a plan view illustrating an axial flow fan according to a modified example. [Figure 8] FIG. 8 is a plan view illustrating an axial flow fan according to a modified example. [Figure 9] FIG. 9 is a plan view illustrating an axial flow fan according to a modified example. [Figure 10] FIG. 10 is a plan view illustrating an axial flow fan according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Exemplary embodiments will be described in detail below with reference to the drawings. In the following embodiments, an axial fan as a fan according to the technology of the present disclosure is applied to an air conditioner. The drawings are intended to conceptually explain the technology of the present disclosure. Therefore, in the drawings, dimensions, ratios, and diagrams may be exaggerated or simplified to facilitate understanding of the technology of the present disclosure.

[0020] <<Embodiment>> The axial fan (31) of this embodiment is used in an air conditioner (1). In other words, the air conditioner (1) is equipped with the axial fan (31). The air conditioner (1) is an example of an air treatment device.

[0021] -Air conditioning equipment- The air conditioner (1) is a device that adjusts the air temperature in a target space. In this example, the target space is an indoor space. As shown in FIG. 1, the air conditioner (1) is a pair-type air conditioner and includes one indoor unit (3) and one outdoor unit (5). The indoor unit (3) is installed indoors. The outdoor unit (5) is installed outdoors. The indoor unit (3) and the outdoor unit (5) are connected to each other via a liquid connection pipe (7) and a gas connection pipe (9).

[0022] The indoor unit (3), the outdoor unit (5), the liquid connection pipe (7), and the gas connection pipe (9) constitute a refrigerant circuit (11). A refrigerant circulates through the refrigerant circuit (11). The refrigerant circuit (11) mainly includes a compressor (13), an outdoor heat exchanger (15), an expansion valve (17), a switching mechanism (19), and an indoor heat exchanger (21). The compressor (13), the outdoor heat exchanger (15), the expansion valve (17), the switching mechanism (19), and the indoor heat exchanger (21) are connected in series by piping.

[0023] The compressor (13), the outdoor heat exchanger (15), the expansion valve (17), and the switching mechanism (19) are included in the outdoor unit (5). That is, the outdoor unit (5) has the compressor (13), the outdoor heat exchanger (15), the expansion valve (17), and the switching mechanism (19). The outdoor unit (5) further has an outdoor fan (23). The axial fan (31) of this embodiment is used as the outdoor fan (23).

[0024] The compressor (13) draws in and compresses low-pressure gas refrigerant, and discharges the compressed refrigerant. The outdoor fan (23) is rotated by driving a first fan motor (27). The outdoor fan (23) takes in and transports outdoor air so that the air passes through the outdoor heat exchanger (15). The outdoor heat exchanger (15) exchanges heat between the outdoor air transported by the outdoor fan (23) and the refrigerant therein. The expansion valve (17) reduces the pressure of the refrigerant.

[0025] The switching mechanism (19) is, for example, a four-way switching valve. The switching mechanism (19) has a first port (P1), a second port (P2), a third port (P3), and a fourth port (P4). The first port (P1) is connected to the discharge port of the compressor (13). The second port (P2) is connected to the suction port of the compressor (13). The third port (P3) is connected to the gas end of the outdoor heat exchanger (15). The fourth port (P4) is connected to the gas connection pipe (9).

[0026] The switching mechanism (19) can be switched between a first state (a state shown by a solid line in FIG. 1) and a second state (a state shown by a dashed line in FIG. 1). In the first state, the switching mechanism (19) connects the first port (P1) to the third port (P3) and connects the second port (P2) to the fourth port (P4). In the second state, the switching mechanism (19) connects the first port (P1) to the fourth port (P4) and connects the second port (P2) to the third port (P3).

[0027] The indoor heat exchanger (21) is included in the indoor unit (3). That is, the indoor unit (3) has the indoor heat exchanger (21). The indoor unit (3) further has an indoor fan (25). As the indoor fan (25), for example, a sirocco fan is used.

[0028] The indoor fan (25) is rotated by being driven by the second fan motor (29). The indoor fan (25) takes in and transports indoor air so that the air passes through the indoor heat exchanger (21). The indoor heat exchanger (21) exchanges heat between the indoor air transported by the indoor fan (25) and the refrigerant therein. The air that has passed through the indoor heat exchanger (21) is supplied to the indoor space.

[0029] The refrigerant circuit (11) performs a first refrigeration cycle or a second refrigeration cycle in response to switching of the switching mechanism (19).

[0030] The first refrigeration cycle is a refrigeration cycle in which the indoor heat exchanger (21) functions as an evaporator and the outdoor heat exchanger (15) functions as a radiator. In the first refrigeration cycle, the switching mechanism (19) is set to the first state, and the refrigerant in the refrigerant circuit (11) flows in the direction of the solid arrow in FIG.

[0031] The second refrigeration cycle is a refrigeration cycle in which the indoor heat exchanger (21) functions as a radiator and the outdoor heat exchanger (15) functions as an evaporator. In the second refrigeration cycle, the switching mechanism (19) is set to the second state, and the refrigerant in the refrigerant circuit (11) flows in the direction of the dashed arrow in FIG.

[0032] The air conditioner (1) performs cooling operation and heating operation.

[0033] The cooling operation is an operation for cooling the air in the indoor space. In the cooling operation, the compressor (13), the outdoor fan (23), and the indoor fan (25) are operated to perform a first refrigeration cycle. During the cooling operation, the air transported by the indoor fan (25) is cooled by the refrigerant evaporating in the indoor heat exchanger (21). The air cooled in the indoor heat exchanger (21) is supplied to the indoor space.

[0034] The heating operation is an operation for heating the air in the indoor space. In the heating operation, with the switching mechanism (19) in the second state, the compressor (13), the outdoor fan (23), and the indoor fan (25) are operated to perform the second refrigeration cycle. In the heating operation, the air transported by the indoor fan (25) is heated by the refrigerant condensing in the indoor heat exchanger (21). The air heated in the indoor heat exchanger (21) is supplied to the indoor space.

[0035] -Axial flow fan- The axial fan (31) is a propeller type fan. As shown in Fig. 2 and Fig. 3, the axial fan (31) includes one hub (33) and a plurality of blades (35). The hub (33) and the plurality of blades (35) are integrally formed. The axial fan (31) of this example has three blades (35). The number of blades (35) may be two, or four or more.

[0036] The hub (33) is formed in a cylindrical shape. The hub (33) is a rotating shaft portion, and is located at the center of the axial flow fan (31). A shaft hole (37) is formed in the center of the hub (33). The drive shaft of the first fan motor (27) is attached to the hub (33) through the shaft hole (37). When the first fan motor (27) is driven, the hub (33) rotates about a predetermined rotation axis (Ax). The central axis of the hub (33) coincides with the rotation axis (Ax) of the axial flow fan (31).

[0037] The blades (35) are provided at regular angular intervals from one another in the circumferential direction of the hub (33). Each blade (35) extends outward in the direction of the rotation radius from the outer circumferential surface of the hub (33). The blades (35) spread radially outward from the hub (33) in the direction of the rotation radius of the axial flow fan (31). Adjacent blades (35) do not overlap with each other in a front or rear view.

[0038] The blades (35) have the same shape. Each blade (35) has a so-called forward-swept blade shape. Each blade (35) is formed in a smoothly curved plate shape along the rotation radius direction and the rotation direction (Dr) so as to have a slight convex shape on one blade surface side (the negative pressure surface (53) side) (see FIG. 4). Each blade (35) has a blade base (39), a blade tip (41), a leading edge (43), and a trailing edge (45).

[0039] The base (39) is the end of the blade (35) on the central side in the radial direction of the axial fan (31), i.e., the inner end in the direction of the rotation radius. The tip (41) is the end of the blade (35) on the outer periphery side in the radial direction of the axial fan (31), i.e., the outer end in the direction of the rotation radius. The base (39) and tip (41) of each blade (35) each extend along the rotation direction (Dr) of the axial fan (31).

[0040] A base (39) of each blade (35) is connected to the hub (33). In each blade (35), the distance from the rotation axis (Ax) of the axial fan (31) to the base (39) is substantially constant over the entire length of the base (39). In addition, a tip (41) of each blade (35) faces the outer periphery of the axial fan (31). In each blade (35), the distance from the rotation axis (Ax) of the axial fan (31) to the tip (41) is substantially constant over the entire length of the tip (41). In each blade (35), the length of the tip (41) is longer than the length of the base (39).

[0041] The leading edge (43) is the front edge of the blade (35) in the rotation direction (Dr). The trailing edge (45) is the rear edge of the blade (35) in the rotation direction (Dr). The leading edge (43) and the trailing edge (45) of each blade (35) extend from the hub (33) side toward the outer periphery of the axial fan (31). The leading edge (43) of each blade (35) extends toward the blade tip (41) side so as to jut out forward in the rotation direction (Dr).

[0042] In this example, the leading edge (43) is curved so as to be concave toward the rear side in the rotation direction (Dr) of the blades (35). The trailing edge (45) of each blade (35) is curved so as to protrude toward the rear side in the rotation direction (Dr) of the blades (35). The leading edge (43) and the trailing edge (45) of each blade (35) extend away from each other toward the blade tip (41). The leading edge (43) of each blade (35) forms a forward-swept blade portion (47) between itself and the blade tip (41).

[0043] The forward-advancing blade portion (47) is defined by the leading edge (43) and blade tip (41) of the blade (35). When viewed in the axial direction along the rotation axis (Ax), if a tangent line that touches the leading edge (43) in the direction of the rotation radius is defined as an area line (La), the forward-advancing blade portion (47) is the portion of the blade (35) that is forward of the area line (La) in the direction of rotation (Dr). The leading edge (43) and blade tip (41) that define the forward-advancing blade portion (47) approach each other toward the front in the direction of rotation (Dr) of the blade (35). The blade tip (41) side of the forward-advancing blade portion (47) has a tip portion (49) that tapers toward the front in the direction of rotation (Dr).

[0044] As shown in Fig. 4, each blade (35) is inclined so as to intersect with a plane perpendicular to the rotation axis (Ax) of the axial fan (31). A leading edge (43) of each blade (35) is located on the rear side (negative pressure side) of the axial fan (31) and extends from a position near one end (the end where air flows in) of the hub (33) toward the upstream side of the transported air. A trailing edge (45) of each blade (35) is located on the front side (static pressure side) of the axial fan (31) and near the other end (the end where air flows out) of the hub (33).

[0045] Each blade (35) further has a positive pressure surface (51) and a negative pressure surface (53). The positive pressure surface (51) is a blade surface that becomes a positive pressure side due to the flow of air carried when the axial fan (31) rotates, and constitutes the surface facing the side from which the air flows out. The negative pressure surface (53) is a blade surface that becomes a negative pressure side due to the flow of air carried when the axial fan (31) rotates, and constitutes the surface on the side from which the air flows in.

[0046] The outer edge portion along the blade tip (41) of each blade (35) constitutes a winglet portion (55). The winglet portion (55) is slightly bent toward the suction surface (53) side with respect to the other portions of the blade (35). The winglet portion (55) is provided so as to gradually widen from the leading edge (43) side toward the trailing edge (45) side. The winglet portion (55) serves to straighten the airflow near the blade tip (41). The provision of the winglet portion (55) is advantageous in suppressing the generation of a blade tip vortex.

[0047] The blades (35) rotate around the rotation axis (Ax) together with the hub (33). When the axial fan (31) rotates around the rotation axis (Ax), the positive pressure surface (51) of each blade (35) pushes out air. As a result, as the blades (35) rotate, air flows from the inlet side at the rear of the axial fan (31) to the outlet side at the front. At that time, pressure increases on the positive pressure surface (51) of each blade (35) to push out the air. Meanwhile, pressure decreases on the negative pressure surface (53) of the blade (35).

[0048] During rotation of the axial flow fan (31), when the air flowing over the pressure surface (51) of the blade (35) reaches the blade tip (41) and leaves the pressure surface (51), it forms a flow that is drawn from the pressure surface (51) to the suction surface (53) and becomes a vortex. The vortex generated on the blade tip (41) side is called a blade tip vortex. The blade tip vortex develops rearward as the blade (35) rotates, and becomes a wake vortex that flows rearward in the direction of rotation (Dr) from the trailing edge (45) of the blade (35).

[0049] The peripheral speed of the blades (35) caused by the rotation of the axial fan (31) increases toward the blade tip (41) and is fastest at the tip portion (49) of the forward-advancing blade portion (47). For this reason, the tip portion (49) of the forward-advancing blade portion (47) is likely to be the starting point for airflow separation. When airflow separates at the tip portion (49) of the forward-advancing blade portion (47), a blade tip vortex is generated near the leading end of the outer edge of the blade (35), and the blade tip vortex develops over a relatively long distance. The longer the distance the blade tip vortex develops, the higher the energy of the wake vortex becomes, causing increased noise.

[0050] As a countermeasure against noise caused by such blade tip vortices, in the axial flow fan (31), at least a part of the tip portion (49) of the forward moving blade portion (47) of each blade (35) is made of a porous material. In the forward moving blade portion (47) of the axial flow fan (31) of this example, only a part of the tip portion (49) is made of a porous material. Each blade (35) is composed of a porous portion (61) and a non-porous portion (63).

[0051] The porous portion (61) constitutes the portion on the blade tip (41) side of the forward-advancing blade portion (47). The tip portion (49) of the forward-advancing blade portion (47) includes the porous portion (61). In this example, the porous portion (61) is only present in the tip portion (49) of the forward-advancing blade portion (47) of the blade (35). The porous portion (61) has the function of suppressing the separation of the airflow from the blade surface. By providing the porous portion (61) at the tip portion of the forward-advancing blade portion (47), it is possible to suppress the generation of a blade tip vortex originating from the tip portion (49).

[0052] The porous portion (61) is provided in the blade (35) such that the radius ratio (r / R) is in the range of 0.8 to 0.98. The radius ratio (r / R) is the ratio (r / R) of the distance from the base (39) of the blade (35) to the tip (41) of the blade (35) to the distance from the base (39) of the blade (35) to an arbitrary position in a blade cross section (in the direction of the rotation radius of the blade (35)) passing through the rotation axis (Ax), where R(Ro-Ri) is the distance from the base (39) of the blade (35) to the tip (41). The radius ratio (r / R) indicates the position from the base (39) of the blade (35) in the direction of the rotation radius of the blade (35).

[0053] The porous portion (61) is provided in, for example, a quadrangle shape (more specifically, a quadrangle shape with curved corners). The porous portion (61) may be provided in other shapes, such as a triangle shape or an oval shape. The porous portion (61) constitutes the entire blade (35) in the thickness direction. In other words, the porous portion (61) is exposed on each of the pressure surface (51) and the suction surface (53) of the blade (35), and forms part of the pressure surface (51) and part of the suction surface (53) of the tip portion (49) of the forward-moving blade portion (47).

[0054] The porous portion (61) is made of a porous material having a plurality of continuous fine pores. The plurality of fine pores in the porous material communicate with the positive pressure side (51) and the negative pressure side (53) of the blade (35). The average diameter of the pores (voids) in the porous portion (61) is, for example, in the range of 15 μm to 300 μm. The porosity of the porous portion (61) (=pore volume / total volume of the porous portion) is, for example, in the range of 35% to 90%.

[0055] The porous material may be a synthetic resin, a ceramic, a metal, or the like. For example, a synthetic resin, a metal, or a ceramic may be used as a porous sintered body. A porous sintered body is formed by heating a powder material in an accumulated state to partially fuse the powder together. The synthetic resin may be a foamed resin containing open cells. The strength of the porous portion (61) is lower than the strength of the non-porous portion (63).

[0056] The other portion of the blade (35) (excluding the porous portion (61)) is a non-porous portion (63). The non-porous portion (63) is made of a non-porous material that is not a porous material. The non-porous material is a non-foamed synthetic resin or the like. The non-porous portion (63) in this example is made of the same synthetic resin that forms the hub (33), and is molded integrally with the hub (33). The majority of the blade (35) is made of the non-porous portion (63).

[0057] The area ratio of the non-porous portion (63) to the entire pressure surface (51) of the blade (35) in this example is 80% or more. This makes it possible to more appropriately ensure the strength of the blade (35) compared to the case where most of the blade (35) in this example is made of a porous material. From the viewpoint of ensuring the strength of the blade (35), the area ratio of the non-porous portion (63) is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more. The area ratio of the porous portion (61) to the pressure surface (51) of the blade (35) is set within a range that can provide a noise reduction effect (silencing effect) due to tip vortices.

[0058] In this example, the leading edge (43) and blade tip (41) of the forward-swept blade portion (47) of the blade (35) are formed of a non-porous portion (63). The porous portion (61) is provided integrally with the body (32) of the axial fan (31), which is composed of the hub (33) and the non-porous portion (63). The body (32) of the axial fan (31) and the porous portion (61) are molded integrally by, for example, insert molding. The porous portion (61) may be attached to the body (32) of the axial fan (31) by fitting, bonding, welding, or the like.

[0059] When the axial fan (31) rotates, air flows into the tip portion (49) of the forward-swept blade portion (47) of the blade (35) and forms air flows (F1, F2) flowing between the pressure surface (51) and the suction surface (53) of the blade (35) (see FIG. 4). As the axial fan (31) rotates, the air flows (F1, F2) along the blade surface (the pressure surface (51), the suction surface (53)) and flows out from the trailing edge (45). At this time, pressure fluctuations occur on the blade surface due to various factors, such as pressure fluctuations at the boundary surface of the air flows (F1, F2) and pressure fluctuations when transitioning from laminar flow to turbulent flow. Such pressure fluctuations on the blade surface cause the air flow to separate from the blade surface, resulting in the generation of wing tip vortices.

[0060] In the porous portion (61), air flows in and out between the positive pressure surface (51) and the negative pressure surface (53) through a plurality of fine holes in response to pressure fluctuations on the blade surface. When the air pressure on the positive pressure surface (51) side increases, the air passes through the porous portion (61) and leaks slightly to the negative pressure surface (53). When the air pressure on the negative pressure surface (53) side increases, the air passes through the porous portion (61) and leaks slightly to the positive pressure surface (51). As a result, the porous portion (61) suppresses pressure fluctuations on the blade surface. This suppresses the airflows (F1, F2) from separating from the blade surface at the tip portion (49) of the forward-moving blade portion (47), making it difficult for a blade tip vortex to be generated from the tip portion (49). This is advantageous in reducing noise (blowing noise) generated during rotation of the axial flow fan (31).

[0061] In Fig. 5, the air volume-static pressure characteristic (PQ curve) of the axial fan (31) of this example is shown by a solid line, and the air volume-static pressure characteristic (PQ curve) of the axial fan of the comparative example is shown by a dashed line. The axial fan of the comparative example is a fan similar to the axial fan (31) of this example, except that it does not have the porous portion (61). In the axial fan of the comparative example, the blades (35) are entirely made of a non-porous material (non-foamed synthetic resin). As shown in Fig. 5, the axial fan (31) of this example has approximately the same air volume-static pressure characteristic as the axial fan of the comparative example.

[0062] In Fig. 6, the air volume-blow noise characteristics of the axial fan (31) of this example are shown by a solid line, and the air volume-blow noise characteristics of the axial fan of the comparative example are shown by a dashed line. The configuration of the comparative axial fan is the same as that described above. As shown in Fig. 6, in the axial fan (31) of this example, the blowing noise at the same air volume is reduced over the entire range of the graph (especially at and near the rated air volume) compared to the comparative axial fan.

[0063] -Features of the embodiment- In the axial flow fan (31) of this embodiment, a part of the blade (35) is made of a porous portion (61), while the other part is made of a non-porous portion (63). Thus, the strength of the blade (35) is ensured by the non-porous portion (63), and the separation of the airflow from the blade surface is suppressed by the porous portion (61). The tip portion (49) of the forward-moving blade portion (47) includes the porous portion (61). This suppresses the separation of the airflow at the tip portion (49) of the forward-moving blade portion (47), and even if a blade tip vortex occurs, the generation of the blade tip vortex is delayed to the rear side in the rotation direction (Dr) of the blade (35), and the development of the blade tip vortex can be inhibited. This reduces noise caused by the blade tip vortex. Therefore, the strength of the blade (35) can be ensured, and the quietness of the axial flow fan (31) can be improved.

[0064] In the axial flow fan (31) of this embodiment, the porous portion (61) is formed only at the tip of the forward-moving blade portion (47), and the remaining portion of the blade (35) is formed of a non-porous portion (63). This is effective in improving the quietness of the axial flow fan (31) while ensuring the strength of the blade (35) with the non-porous portion (63).

[0065] In the axial flow fan (31) of this embodiment, the forward-advancing blade portion (47) is a portion of the blade (35) that is forward of the area line (La) in the direction of rotation (Dr), and the porous portion (61) forms a portion that includes the blade tip (41) side of the forward-advancing blade portion (47). This makes it possible to effectively utilize the function of the porous portion (61) and preferably obtain the above-mentioned effect of improving the noise reduction of the axial flow fan (31).

[0066] In the air conditioner (1) of this embodiment, the outdoor unit (5) includes an axial flow fan (31), which can improve the quietness of the axial flow fan (31) in the outdoor unit (5).

[0067] -Variations- As shown in Fig. 7, in the axial flow fan (31), the blade tip (41) of the tip portion (49) of the forward-advancing blade portion (47) of each blade (35) may be formed of a porous portion (61). Also, as shown in Fig. 8, in the axial flow fan (31), the leading edge (43) of the tip portion (49) of the forward-advancing blade portion (47) of each blade (35) may be formed of a porous portion (61). Also, as shown in Fig. 9, in the axial flow fan (31), both the blade tip (41) and the leading edge (43) of the tip portion (49) of the forward-advancing blade portion (47) of each blade (35) may be formed of a porous portion (61). In these cases, the porous portion (61) is provided in the blade (35) in a range where the radius ratio (r / R) is 0.8 or more.

[0068] In this manner, in the axial flow fan (31), one or both of the leading edge (43) and the blade tip (41) of the tip portion (49) of the forward-advancing blade portion (47) of each blade (35) may be formed of a porous portion (61). When the leading edge (43) of the tip portion (49) of the forward-advancing blade portion (47) is a porous portion (61), separation of the airflow can be suppressed at the tip portion (49) including the leading edge (43) of the forward-advancing blade portion (47). When the blade tip (41) of the tip portion (49) of the forward-advancing blade portion (47) is a porous portion (61), separation of the airflow can be suppressed at the tip portion (49) including the blade tip (41) of the forward-advancing blade portion (47), and the formation of a flow in which air flowing along the positive pressure side (51) of the blade (35) is drawn toward the negative pressure side (53) can be suppressed. These are advantageous in preventing the development of a blade tip vortex and reducing noise caused by the blade tip vortex.

[0069] Other Embodiments The above embodiment may be configured as follows.

[0070] The porous portion (61) of the blade (35) may be provided so as to extend beyond the tip portion (49) of the forward-advancing blade portion (47). For example, as shown in FIG. 10, the porous portion (61) may be provided so as to extend from the tip portion (49) of the forward-advancing blade portion (47) along the blade tip (41) to the rear side of the forward-advancing blade portion (47). The porous portion (61) may be provided in a range of the blade (35) where the radius ratio (r / R) is less than 0.8. Furthermore, the porous portion (61) may be provided in a portion other than the forward-advancing blade portion (47) in addition to the tip portion (49) of the forward-advancing blade portion (47) of the blade (35).

[0071] The fan according to the technology of the present disclosure may be any fan including a plurality of blades (35) that rotate around a rotation axis (Ax), and may be, for example, a mixed flow fan. The fan according to the technology of the present disclosure may be used as an indoor fan (25).

[0072] The air treatment device according to the technology of the present disclosure may be a device other than an air conditioner as long as it is a device that blows air using a fan. The air treatment device may be a humidity control device that adjusts the humidity of the air in the target space. The air treatment device may be a ventilation device that ventilates the target space. Furthermore, the air treatment device may be an air purifier that purifies the air in the target space.

[0073] Although the embodiments and modifications have been described above, it will be understood that various modifications of form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be appropriately combined or substituted as long as the functions of the subject of the present disclosure are not impaired.

[0074] The descriptions "first," "second," etc. mentioned above are used merely to distinguish the words to which these descriptions are attached, and do not limit the number or order of those words. [Industrial Applicability]

[0075] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for fans and air treatment devices. [Explanation of symbols]

[0076] Ax Rotation axis Dr Rotation direction La area line 1. Air conditioning equipment (air treatment equipment) 31 Axial flow fan (fan) 35 wings 41 Wingtip 43 Leading Edge 47 Forward wing section 49 Tip part 61 Porous part 63 Non-porous part

Claims

1. A plurality of blades (35) that rotate around a predetermined rotation axis (Ax), The blade (35) has a leading edge (43) which is a front edge in a rotation direction (Dr) and a blade tip (41) which is an outer edge in a rotation radial direction, the leading edge (43) extends toward the blade tip (41) in a forward direction of rotation (Dr) and forms a forward-moving blade portion (47) between the leading edge (43) and the blade tip (41), The blade (35) is composed of a porous portion (61) and a non-porous portion (63), A fan, wherein a tip portion (49) located on the blade tip (41) side of the forward moving blade portion (47) includes the porous portion (61).

2. The fan according to claim 1 , a forward-moving blade portion (47) having a leading edge (43) and / or a blade tip (41) formed by the porous portion (61).

3. The fan according to claim 1, The porous portion (61) is only a tip portion (49) of the forward-moving blade portion (47).

4. The fan according to claim 1 , The front edge (43) is curved to form a concave shape toward the rear side in the direction of rotation (Dr), when viewed in the axial direction along the rotation axis (Ax), a tangent line that contacts the leading edge (43) in the direction of the rotation radius is defined as an area line (La), the forward-moving blade portion (47) is a portion of the blade (35) that is forward of the area line (La) in the direction of rotation (Dr), The porous portion (61) constitutes a portion including the blade tip (41) side of the forward moving blade portion (47).

5. 1. An air treatment device comprising: An air treatment device comprising a fan (31) according to any one of claims 1 to 4.

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