fan

Abstract

This enables the creation of fans with superior performance, such as noise reduction. [Solution] In a fan (31) equipped with a rotatable blade (35), the blade (35) has a leading edge (43) located forward in the direction of rotation, a trailing edge (45) located backward in the direction of rotation, and a communication portion (60) that connects the positive pressure surface (51) and the negative pressure surface (53) of the blade (35). The communication portion (60) is located in part between the leading edge (43) and the trailing edge (45) of the blade (35) and includes a positive pressure side portion (61) located on the positive pressure surface (51) side of the blade (35) and a negative pressure side portion (62) located on the negative pressure surface (53) side of the blade (35). The pressure loss characteristics at the positive pressure side portion (61) and the pressure loss characteristics at the negative pressure side portion (62) are different.

Description

Technical Field

[0001] The present disclosure relates to a fan.

Background Art

[0002] In a blower, a fan having blades is used. Patent Document 1 discloses an axial fan, and it is described that the blades include a leading edge, a trailing edge, and a porous portion. By providing the porous portion, pressure fluctuations can be suppressed by communicating the positive pressure side and the negative pressure side of the blade, and noise generation can be suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to achieve noise reduction or the like by providing a porous layer on the blade, it is necessary to set the characteristics of the porous layer. In this case, especially when the porous layer is provided integrally with the blade, optimization is not always easy depending on the shape, size, etc. of the blade.

[0005] An object of the present disclosure is to realize a fan excellent in performance such as noise reduction by controlling the characteristics of a communication portion in a fan including a blade having a communication portion that communicates the negative pressure side and the positive pressure side of the blade.

Means for Solving the Problems

[0006] A first aspect of this disclosure is a fan (31) having a rotatable blade (35). The blade (35) has a leading edge (43) located forward in the direction of rotation, a trailing edge (45) located backward in the direction of rotation, and a communication portion (60) connecting a positive pressure surface (51) and a negative pressure surface (53) of the blade (35). The communication portion (60) is located in part between the leading edge (43) and the trailing edge (45) of the blade (35) and includes a positive pressure side portion (61) located on the positive pressure surface (51) side of the blade (35) and a negative pressure side portion (62) located on the negative pressure surface (53) side of the blade (35). The pressure loss characteristics at the positive pressure side portion (61) and the pressure loss characteristics at the negative pressure side portion (62) are different.

[0007] In the first embodiment, since the communication portion (60) includes a positive pressure side portion (61) and a negative pressure side portion (62), the characteristics of the communication portion (60) can be controlled to achieve noise reduction and the like.

[0008] A second aspect of this disclosure is the first aspect, in which the pressure loss characteristics of the negative pressure side (62) are greater than those of the positive pressure side (61).

[0009] In the second embodiment, the effects of noise reduction and other benefits are achieved more reliably.

[0010] A third aspect of this disclosure is, in the first aspect, that the thickness of the negative pressure side (62) is smaller than the thickness of the positive pressure side (61).

[0011] In the third embodiment, noise reduction and other improvements are achieved, as well as cost reduction.

[0012] A fourth aspect of this disclosure is, in the first aspect, a pressure loss on the positive pressure side (61) that is smaller than the pressure loss on the negative pressure side (62).

[0013] A fifth aspect of this disclosure is, in the first aspect, a pressure loss on the positive pressure side (61) that is greater than the pressure loss on the negative pressure side (62).

[0014] In both the fourth and fifth embodiments, it may be desirable for noise reduction or other purposes.

[0015] A sixth aspect of the present disclosure is, in the first aspect, that the positive pressure side (61) is a through-hole structure having a plurality of through holes in the thickness direction of the blade (35), and the negative pressure side (62) is a porous structure.

[0016] In the sixth embodiment, the positive pressure side (61) can be made thicker and have a low resistance configuration, while the negative pressure side (62) can be made thinner and have a high resistance configuration.

[0017] A seventh aspect of this disclosure is the first aspect, in which the positive pressure side (61) is made of a member common to the other part of the wing (35).

[0018] In the seventh embodiment, the number of parts and manufacturing processes can be reduced and costs lowered by integrally molding the positive pressure side portion (61) with the wing (35).

[0019] An eighth aspect of the present disclosure is the first aspect wherein both the positive pressure side (61) and the negative pressure side (62) are porous structures and have different average pore diameters.

[0020] A ninth aspect of the present disclosure is, in the first aspect, that both the positive pressure side (61) and the negative pressure side (62) have a porous structure, and the number of pores per unit area on the outer surface is different from that of the other.

[0021] A tenth aspect of the present disclosure is, in the first aspect, that both the positive pressure side (61) and the negative pressure side (62) are porous structures and have different air permeability resistances per unit thickness.

[0022] An eleventh aspect of the present disclosure is, in the first aspect, a through-hole structure in which both the positive pressure side (61) and the negative pressure side (62) have a plurality of through holes in the thickness direction of the blade (35), and the average hole diameters are different from each other.

[0023] In a twelfth aspect of the present disclosure, in the first aspect, both the positive pressure side portion (61) and the negative pressure side portion (62) have a through-hole structure with a plurality of through-holes in the thickness direction of the blade (35), and the number of holes per unit area on the outer surface is different from each other.

[0024] In the eighth to twelfth aspects, the pressure loss characteristics and the like of both the positive pressure side portion (61) and the negative pressure side portion (62) can be set individually, and it is possible to realize a desirable air flow velocity and flow rate and the state of the air layer.

[0025] A thirteenth aspect of the present disclosure is that in the first aspect, a hollow portion is formed between the positive pressure side portion (61) and the negative pressure side portion (62).

[0026] Even in the case of the thirteenth aspect, it is possible to realize a desirable air flow velocity and flow rate and the state of the air layer.

[0027] A fourteenth aspect of the present disclosure is that in the first aspect, it is an axial flow fan (31) configured by attaching a plurality of blades (35) to a hub.

[0028] In the fourteenth aspect, the technology of the present disclosure can be applied to an axial flow fan.

[0029] A fifteenth aspect of the present disclosure is that in the first aspect, it is a turbo fan (31) configured by arranging a plurality of the blades (35) between a plate-like member and a shroud.

[0030] In the fifteenth aspect, the technology of the present disclosure can be applied to a turbo fan.

[0031] A sixteenth aspect of the present disclosure is an air conditioner including the fan (31) of the first aspect.

[0032] In the sixteenth aspect, the noise of the air conditioner can be reduced.

Brief Description of the Drawings

[0033] [Figure 1] Figure 1 is a schematic diagram of the refrigerant circuit for an air conditioning system equipped with a fan according to an embodiment of the present disclosure. [Figure 2] Figure 2 is a perspective view showing an axial flow fan as an example of an embodiment of a fan. [Figure 3] Figure 3 is a schematic diagram showing the cross-section of the fan blades in the circumferential direction in the embodiment of the fan. [Figure 4] Figure 4 schematically shows the cross-section of the fan blade in the circumferential direction in the first modified example. [Figure 5] Figure 5 schematically shows the circumferential cross-section of the fan blades of the second modified fan. [Figure 6] Figure 6 shows a turbo fan as another example of a fan in this embodiment. [Modes for carrying out the invention]

[0034] The following exemplary embodiments will be described in detail with reference to the drawings. In the following embodiments, an axial flow fan applied to an air conditioning system will be described as an example of a fan relating to the technology of this disclosure. Note that the drawings are for conceptual explanation of the technology of this disclosure. Therefore, in order to facilitate understanding of the technology of this disclosure, dimensions, ratios, etc., may be exaggerated or simplified in the drawings.

[0035] 《Embodiment》 The axial fan (31) in this embodiment is used in an air conditioning system (1). In other words, the air conditioning system (1) includes an axial fan (31). The air conditioning system (1) is an example of an air treatment device.

[0036] -Air conditioning system- The air conditioning system (1) is a device that adjusts the temperature of the air in a target space. In this example, the target space is an indoor space. As shown in Figure 1, the air conditioning system (1) is a paired air conditioning system and consists of 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).

[0037] The indoor unit (3), outdoor unit (5), liquid connection pipe (7), and gas connection pipe (9) constitute a refrigerant circuit (11). 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), outdoor heat exchanger (15), expansion valve (17), switching mechanism (19), and indoor heat exchanger (21) are connected in series by piping.

[0038] The compressor (13), outdoor heat exchanger (15), expansion valve (17), and switching mechanism (19) are included in the outdoor unit (5). In other words, the outdoor unit (5) has a compressor (13), an outdoor heat exchanger (15), an expansion valve (17), and a switching mechanism (19). The outdoor unit (5) further has an outdoor fan (23). The axial flow fan (31) of this embodiment is used as the outdoor fan (23).

[0039] The compressor (13) draws in low-pressure gaseous refrigerant, compresses it, and discharges the compressed refrigerant. The outdoor fan (23) rotates driven by the first fan motor (27). The outdoor fan (23) takes in and transports outside air so that it passes through the outdoor heat exchanger (15). The outdoor heat exchanger (15) exchanges heat between the outside air transported by the outdoor fan (23) and the refrigerant inside. The expansion valve (17) reduces the pressure of the refrigerant.

[0040] 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 section of the compressor (13). The second port (P2) is connected to the suction section 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 connecting pipe (9).

[0041] The switching mechanism (19) can be switched between a first state (shown by the solid line in Figure 1) and a second state (shown by the dashed line in Figure 1). In the first state, the switching mechanism (19) connects the first port (P1) and the third port (P3), and connects the second port (P2) and the fourth port (P4). In the second state, the switching mechanism (19) connects the first port (P1) and the fourth port (P4), and connects the second port (P2) and the third port (P3).

[0042] The indoor heat exchanger (21) is included in the indoor unit (3). In other words, the indoor unit (3) has the indoor heat exchanger (21). The indoor unit (3) further has an indoor fan (25). For example, a sirocco fan is used as the indoor fan (25).

[0043] The indoor fan (25) rotates under the drive of the second fan motor (29). The indoor fan (25) takes in and transports indoor air so that it 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 inside. The air that has passed through the indoor heat exchanger (21) is supplied to the indoor space.

[0044] The refrigerant circuit (11) performs a first refrigeration cycle and a second refrigeration cycle in response to the switching mechanism (19). As a result, the air conditioning unit (1) performs cooling and heating operations.

[0045] -Axial flow fan- An example of a fan in this disclosure, an axial fan (31), is a propeller-type fan. As shown in Figure 2, the axial fan (31) comprises one hub (33) and a plurality of blades (35). The hub (33) and the plurality of blades (35) are integrally formed. In this example of the axial fan (31), there are three blades (35). However, there may be two blades (35), or four or more blades (35).

[0046] The hub (33) is formed in a cylindrical shape. The hub (33) is the rotating shaft portion and is located at the center of the axial flow fan (31). An axle hole (37) is formed in the central part of the hub (33). The drive shaft of the first fan motor (27) is attached to the hub (33) through the axle hole (37). When the first fan motor (27) is driven, the hub (33) rotates around a predetermined axis of rotation (Ax). The central axis of the hub (33) coincides with the axis of rotation (Ax) of the axial flow fan (31).

[0047] The leading edge (43) is the front edge of the blade (35) in the direction of rotation (Dr). The trailing edge (45) is the rear edge of the blade (35) in the direction of rotation (Dr). The leading edge (43) and trailing edge (45) of each blade (35) extend from the hub (33) side to the outer circumference of the axial flow fan (31), respectively. The leading edge (43) of each blade (35) extends forward in the direction of rotation (Dr) toward the blade tip (41) side.

[0048] Each blade (35) is inclined to intersect a plane perpendicular to the rotation axis (Ax) of the axial fan (31). The leading edge (43) of each blade (35) is located on the rear side (negative pressure side) of the axial fan (31) and extends upstream of the air being transported from a position near one end of the hub (33) (the air inlet side). The trailing edge (45) of each blade (35) is located on the front side (static pressure side) of the axial fan (31) and is located near the other end of the hub (33) (the air outlet side).

[0049] Each blade (35) further has a positive pressure surface (51) and a negative pressure surface (53) on the opposite side. The positive pressure surface (51) is the blade surface that becomes the positive pressure side due to the airflow being transported when the axial flow fan (31) rotates, and constitutes the surface facing the side from which the air flows out. The negative pressure surface (53) is the blade surface that becomes the negative pressure side due to the airflow being transported when the axial flow fan (31) rotates, and constitutes the surface on which the air flows in.

[0050] -Connecting parts on the fan's wings- Figure 3 is a schematic cross-section of the blade (35) of the fan (31) of this disclosure, including the axial flow fan (31) described above, in the circumferential direction of the fan. In Figure 3, it is shown that a communication portion (60) is provided in a part between the leading edge (43) and the trailing edge (45) of the blade (35) that connects a positive pressure surface (51) and a negative pressure surface (53). The communication portion (60) includes a positive pressure side portion (61) located on the positive pressure surface (51) side and a negative pressure side portion (62) located on the negative pressure surface (53) side. Furthermore, the communication portion (60) is constructed using a material through which gas can pass, such as a porous material or a through-hole structure having multiple through holes, although this will be described in more detail later.

[0051] When the axial fan (31) rotates, a portion of the airflow (66) that flows from the leading edge (43) side of the blade (35) to the positive pressure surface (51) side flows through the communication section (60) to the negative pressure surface (53) side due to the pressure difference between the positive pressure surface (51) side and the negative pressure surface (53) side. This reduces the noise generated by the blade (35) when the axial fan (31) is operating.

[0052] In the case of a wing without a connecting section (60), Karman vortices are generated near the trailing edge (45) on the negative pressure surface (53) side, which are the cause of noise. In contrast, when a connecting section (60) is provided, turbulence is generated downstream of the connecting section (60) (on the trailing edge (45) side) by the airflow passing through the connecting section (60), and this turbulence suppresses the generation of Karman vortices. As a result, noise is suppressed. Although the turbulence caused by the airflow passing through the connecting section (60) itself is a cause of noise, it is less than the noise caused by Karman vortices, and as a result, the generated noise is suppressed. In this way, the connecting section (60) has the effect of stabilizing the entire airflow by generating relatively small turbulence in the airflow on the negative pressure surface (53) side.

[0053] However, in order to achieve such effects, it is desirable that the airflow flowing out from the negative pressure surface (53) side of the connecting section (60) has a desirable flow velocity and flow rate, and that the outflowing airflow forms a uniform air layer. When the connecting section (60) is made of a single material, controlling these is not always easy. For example, when the connecting section (60) is made of a porous material, the pore diameter and amount of pores in the porous material affect both the flow velocity and flow rate of the airflow passing through the connecting section (60) and the state of the airflow generated on the negative pressure surface (53) side.

[0054] Therefore, in the fan (31) of this disclosure, the communication portion (60) is configured to include a positive pressure side portion (61) located on the positive pressure surface (51) side and a negative pressure side portion (62) located on the negative pressure surface (53) side.

[0055] The negative pressure side (62) has multiple holes on the surface facing the negative pressure surface (53), and airflow flows out through these holes. By designing the average hole diameter, number, and arrangement density (number per unit area) of the surface holes, a uniform air layer is formed in the outflowing airflow.

[0056] The positive pressure side (61) uniformly distributes the airflow from the positive pressure surface (51) to the negative pressure side (62) and adjusts it to a desired flow velocity and flow rate.

[0057] The positive pressure side (61) and the negative pressure side (62) have different pressure loss characteristics. Here, the pressure loss characteristics can be evaluated, for example, by the pressure loss per unit thickness measured over the same area. Alternatively, they can be evaluated by the pressure loss when airflow passes through each.

[0058] The relative magnitudes of the pressure loss characteristics of the positive pressure side (61) and the negative pressure side (62) vary depending on the shape and size of the individual fan (31), the rotational speed, etc., and it is possible for one to be larger than the other. In other words, it may be desirable for the pressure loss characteristics of the negative pressure side (62) to be larger than those of the positive pressure side (61), or it may be desirable for them to be smaller.

[0059] Similarly, the pressure loss at the positive pressure side (61) (the pressure loss when the airflow passes from the positive pressure surface (51) side to the positive pressure side (61)) may be desirable to be larger or smaller than the pressure loss at the negative pressure side (62) (the pressure loss when the airflow passes from the negative pressure side (62) to the negative pressure surface (53) side).

[0060] The positive pressure side (61) and the negative pressure side (62) may be made of, for example, a porous structure having continuous pores, or a through-hole structure in which multiple through-holes extend in the thickness direction of the blade (35). This creates a structure through which airflow can pass.

[0061] Furthermore, in order to achieve desirable pressure loss characteristics or pressure loss, if a porous structure is used for both the positive pressure side (61) and the negative pressure side (62), the average pore diameter and the number of pores per unit volume are designed. In the case of a through-hole structure, the average diameter, number, and arrangement density (number per unit area in a cross section perpendicular to the direction in which the through-holes extend) of the through-holes are designed.

[0062] For example, the positive pressure side (61) may have a through-hole structure, while the negative pressure side (62) may have a porous structure. For the negative pressure side (62), it is preferable to use a porous structure in order to form a uniform air layer on the negative pressure surface (53) side as described above. On the other hand, for the positive pressure side (61), airflow distribution and adjustment of flow velocity and flow rate can also be achieved by a through-hole structure. Since porous structures tend to be more expensive than through-hole structures, such a configuration is also useful for cost reduction.

[0063] Furthermore, it is preferable that the thickness of the negative pressure side (62) is smaller than the thickness of the positive pressure side (61). For example, if a high-cost porous structure is used for the negative pressure side (62), making the negative pressure side (62) thinner is useful for cost reduction. In order to achieve this thickness relationship, the average diameter, number, and arrangement density of pores and through-holes are set for the porous structure and the through-hole structure.

[0064] As another example, both the positive pressure side (61) and the negative pressure side (62) may be made of porous material. In this case, at least one of the average pore diameter and the number of pores per unit area on the outer surface may be different from each other. Furthermore, the air permeability resistance per unit thickness may be different from each other.

[0065] As yet another example, both the positive pressure side (61) and the negative pressure side (62) may have a through-hole structure with multiple through-holes in the thickness direction of the blade (35). In this case, at least one of the number of holes per unit area on the outer surface (or a cross section perpendicular to the direction in which the through-holes extend) and the average hole diameter may be different from each other.

[0066] With any of the above configurations, the airflow resistance, pressure loss characteristics, or pressure loss in the positive pressure side (61) and the negative pressure side (62) can be set individually. Furthermore, by setting the number, diameter, and arrangement density of holes on the negative pressure surface (53) side of the negative pressure side (62), a uniform air layer can be achieved through airflow. As a result, fan noise is reduced.

[0067] (First variation) Figure 4 shows a schematic cross-section of the wing (35) of the first modified example of the present disclosure. Figure 4 shows the cross-section corresponding to Figure 3.

[0068] In the example shown in Figure 3, the communication section (60) has a structure that includes a positive pressure side (61) and a negative pressure side (62) made of a separate component from the wing (35). In contrast, in Modification 1, the positive pressure side (61a) is made of a component common to the other parts of the wing (35).

[0069] More specifically, a recess (63) is provided in a predetermined region on the negative pressure side (53) of the wing (35), and a porous structure is placed in the recess (63) to form the negative pressure side portion (62). In addition, a positive pressure side portion (61a) of the through-hole structure is formed by providing a plurality of through holes that extend from the bottom of the recess (63) in the wing (35) to the positive pressure side (51).

[0070] The positive pressure side portion (61a) of the through-hole structure can be formed simultaneously when manufacturing the main body of the wing (35). For example, when manufacturing the wing (35) by molding using a mold, it can be formed by providing multiple needle-like shapes in the location of the mold corresponding to the positive pressure side portion (61a). In this case, the mold is also provided with a shape corresponding to the recess (63).

[0071] This configuration also allows air to pass from the positive pressure side (51) to the negative pressure side (62) through the connecting section (60), while simultaneously adjusting the flow rate and velocity in the negative pressure side (62) and creating a uniform air layer.

[0072] Furthermore, since the positive pressure side portion (61a) is integrally formed with a component common to the wing (35), the number of components is reduced compared to forming the positive pressure side portion (61) with a separate component as shown in Figure 3, thereby reducing manufacturing man-hours and costs.

[0073] Conversely to the example in Figure 4, it is also possible to construct the negative pressure side (62) from a component common to the other parts of the wing (35), and form the positive pressure side (61) from a different component.

[0074] (Second variation) Figure 5 shows a schematic cross-section of the wing (35) of the second modified example of the present disclosure. Figure 4 shows a cross-section corresponding to Figure 3. In the wing (35) of the second modified example, the communication portion (60) has a hollow portion (64) between the positive pressure side portion (61) and the negative pressure side portion (62).

[0075] In this modified example as well, the negative pressure side (62) is controlled so that the airflow flowing out to the negative pressure side (62) forms a uniform air layer. For this purpose, for example, in a porous structure or a through-hole structure, the diameter and number of pores or through-holes are set.

[0076] Furthermore, the positive pressure side (61) and the hollow section (64), similar to the positive pressure side (61) in Figure 3, uniformly distribute the airflow from the positive pressure surface (51) to the negative pressure side (62) and adjust it to the desired flow velocity and flow rate. Pressure loss in the positive pressure side (61) depends not only on the diameter and number of holes but also on their thickness. Therefore, in addition to the structure in Figure 3, in which the thickness direction of the blade (35) is filled with a positive pressure side (61) and a negative pressure side (62), a structure with a hollow section (64) as shown in Figure 5 can be provided, which increases the design flexibility.

[0077] In addition, in the second modification, the positive pressure side portion (61) may be integrally formed with a member common to the other parts of the wing (35), similar to the first modification.

[0078] - Turbo Fan - In the above, the case of an axial fan (31) was described as an example of a fan (31). However, the fan of this disclosure may be of other types, and may be applied to a turbo fan, for example.

[0079] Figure 6 illustrates a turbofan. The turbofan (70) shown in Figure 6 comprises one plate-shaped member (71), one shroud (72), and five blade members (73). The number of blade members (73) is merely an example.

[0080] The plate-shaped member (71) is a disc-shaped member with a recess in the center. The drive shaft of a fan motor (not shown) is connected to the plate-shaped member (71). The plate-shaped member (71) is positioned coaxially with the drive shaft of the fan motor. The central axis of the plate-shaped member (71) is the rotational axis of the turbo fan (70). The central axis of the plate-shaped member (71) substantially coincides with the central axis of the drive shaft of the fan motor.

[0081] The shroud (72) is an annular member. The shroud (72) is positioned opposite the plate-shaped member (71) at a distance. The shroud (72) is also positioned substantially coaxially with the plate-shaped member (71). The outer diameter of the shroud (72) is approximately equal to the outer diameter of the plate-shaped member (71). The inner edge of the shroud (72) protrudes away from the plate-shaped member (71). In the turbofan (70), the inner edge of the shroud (72) forms a blade member (73), and the outer edge of the plate-shaped member (71) and the outer edge of the shroud (72) form a blade member (77).

[0082] The wing members (73) are provided between the plate-shaped member (71) and the shroud (72). The wing members (73) are also positioned in the region near the outer edge of the plate-shaped member (71). The upper edge of the wing member (73) is fixed to the plate-shaped member (71), and the lower edge is fixed to the shroud (72). As shown in Figure 6, the five wing members (73) are arranged at predetermined angular intervals in the circumferential direction of the plate-shaped member (71) and the shroud (72). The angular intervals of these five wing members (73) are not constant. The leading edge (43) of the wing member (73), which is located in front of the rotation direction of the turbofan (70), is located closer to the center of the plate-shaped member (71) than the trailing edge (45) which is located behind the rotation direction of the turbofan (70).

[0083] By providing a connecting section (60) as illustrated in Figures 3 to 5, the blade member (73) of such a turbofan (70) can also be made to reduce noise and have other effects.

[0084] Although embodiments and modifications have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, elements of the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate. [Industrial applicability]

[0085] As explained above, this disclosure is useful for fans. [Explanation of Symbols]

[0086] 1. Air conditioning system 31 Axial flow fan (fan) 33 Hubs 35 wings 37 Shaft hole 41 wingtip 43 Leading edge 45 Trailing edge 51 Positive pressure surface 53 Suction surface 60 Communication part 61 Positive pressure side 61a Positive pressure side 62 Negative pressure side 63 recess 64 Hollow part 65 Airflow 70 Turbofan 71 Plate-shaped member 72 Shroud 73 Wing members

Claims

1. In a fan (31) equipped with a rotatable blade (35), The blade (35) includes a leading edge (43) located forward in the direction of rotation, a trailing edge (45) located backward in the direction of rotation, and a communication portion (60) that connects the positive pressure surface (51) and the negative pressure surface (53) of the blade (35). The communicating portion (60) is located in a part of the wing (35) between the leading edge (43) and the trailing edge (45), and includes a positive pressure side portion (61) located on the positive pressure side (51) of the wing (35) and a negative pressure side portion (62) located on the negative pressure side (53) of the wing (35). A fan (31) characterized in that the pressure loss characteristics on the positive pressure side (61) and the pressure loss characteristics on the negative pressure side (62) are different.

2. In the fan (31) described in claim 1, The fan (31) is characterized in that the pressure loss characteristics of the negative pressure side (62) are greater than those of the positive pressure side (61).

3. In the fan (31) described in claim 1, The fan (31) is characterized in that the thickness of the negative pressure side (62) is smaller than the thickness of the positive pressure side (61).

4. In the fan (31) described in claim 1, The fan (31) is characterized in that the pressure loss in the positive pressure side (61) is smaller than the pressure loss in the negative pressure side (62).

5. In the fan (31) described in claim 1, The fan (31) is characterized in that the pressure loss in the positive pressure side (61) is greater than the pressure loss in the negative pressure side (62).

6. In the fan (31) described in claim 1, The positive pressure side portion (61) is a through-hole structure having a plurality of through holes in the thickness direction of the blade (35), The fan (31) is characterized in that the negative pressure side portion (62) has a porous structure.

7. In the fan (31) described in claim 1, The fan (31) is characterized in that the positive pressure side portion (61) is made of a member common to the other parts of the blade (35).

8. In the fan (31) described in claim 1, The fan (31) is characterized in that both the positive pressure side (61) and the negative pressure side (62) have a porous structure and have different average pore diameters.

9. In the fan (31) described in claim 1, The fan (31) is characterized in that both the positive pressure side (61) and the negative pressure side (62) have a porous structure, and the number of pores per unit area on the outer surface is different from that of the other.

10. In the fan (31) described in claim 1, The fan (31) is characterized in that both the positive pressure side (61) and the negative pressure side (62) have a porous structure and have different airflow resistances per unit thickness.

11. In the fan (31) described in claim 1, The fan (31) is characterized in that both the positive pressure side (61) and the negative pressure side (62) are through-hole structures having a plurality of through holes in the thickness direction of the blade (35), and the average hole diameters are different from each other.

12. In the fan (31) described in claim 1, The fan (31) is characterized in that both the positive pressure side (61) and the negative pressure side (62) are through-hole structures having a plurality of through-holes in the thickness direction of the blade (35), and the number of holes per unit area on the outer surface is different from each other.

13. In the fan (31) described in claim 1, A fan (31) characterized in that a hollow portion is formed between the positive pressure side (61) and the negative pressure side (62).

14. In the fan (31) described in claim 1, A fan (31) characterized by being an axial flow fan (31) in which a plurality of the aforementioned blades (35) are attached to a hub.

15. In the fan (31) described in claim 1, A fan (31) characterized in that a plurality of the aforementioned blades (35) are arranged between a plate-shaped member and a shroud to form a turbofan (31).

16. An air conditioning device characterized by comprising the fan (31) described in claim 1.

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