Bell-mouth structure, shroud, outdoor unit, air-conditioning system, and refrigeration cycle device

Abstract

Provided is a bell-mouth structure (20). The bell-mouth structure (20) comprises: a cylindrical part (21) constructed so as to surround a fan 12; a base part (30) extending outward from one end of the cylindrical part; and a plurality of reinforcement members (33 / 35) protruding downward from a surface forming the base part (30). The plurality of reinforcement members (33 / 35) are provided at a plurality of positions around the cylindrical part (21) in directions generally symmetric with respect to the center (O) of the cylindrical part (20) in a plan view of the base part (30). The plurality of reinforcement members (33 / 35) each have a shape that is curved with respect to the center of the cylindrical part (21).

Description

Bellmouth structure, shroud, outdoor unit, air conditioning system, and refrigeration cycle device

[0001] The present disclosure relates to a bellmouth structure, a shroud, an outdoor unit of an air conditioning system, an air conditioning system, and a refrigeration cycle device.

[0002] Conventionally, a top-flow type outdoor unit has been known in which a substantially cylindrical bellmouth is installed so as to surround a fan installed at an air outlet on the upper part of an outdoor unit of an air conditioner such as a multi-air conditioner for buildings. In recent years, in order to reduce costs, a configuration in which the bellmouth and the shroud of the outdoor unit of the air conditioner are integrally formed has also been adopted.

[0003] In the above-described top-flow type outdoor unit, in order to improve the blowing performance, the diameter of the fan is increased and the number of fans is increased. In order to efficiently install the outdoor unit in a limited installation space, it is desirable that the footprint of the product be as small as possible, so the fan diameter is often expanded as much as possible within the range of the product's footprint. As a result, the rigidity of the bellmouth structure that constitutes the upper part of the housing of the outdoor unit decreases at the part where the cylindrical part (circular duct part) and the outer edge of the housing are close to each other, which may cause an increase in vibration.

[0004] Also, in the above-described top-flow type outdoor unit, it is expected to improve the efficiency of the fan by extending the height of the cylindrical part of the bellmouth, but generally there are restrictions on the height in product design. If the thickness of the base part is relatively reduced in order to extend the cylindrical part while maintaining the overall height of the bellmouth, there is a concern about a decrease in rigidity.

[0005] By the way, the temperature range at the air outlet of the outdoor unit is as wide as about -40°C to about +60°C. When a general resin material is used, expansion and contraction of ± several mm per meter of dimension may occur due to thermal expansion. Although an improvement in rigidity can be expected by adding a reinforcing member or increasing the plate thickness, if the rigidity is increased arbitrarily, stress may occur due to the difference in the linear expansion coefficient at the fastening points such as screws between the bellmouth structure and the sheet metal parts of the housing, leading to the risk of breakage. The higher the rigidity, the greater the stress will be.

[0006] Furthermore, since the shroud is also a design component, placing reinforcing members on the outer surface is undesirable as it would significantly detract from its aesthetic appeal.

[0007] Conventionally, in relation to bell mouth structures, Japanese Utility Model Application No. 60-101464 (Patent Document 1) is known. The prior art of Patent Document 1 discloses a fan shroud having a cylindrical portion that extends to surround the outer circumference of the outer ring of a cooling fan, and a funnel-shaped bell mouth portion that extends to the side of the air intake of the cylindrical portion. In the fan shroud of Patent Document 1, a convex ridge is provided that extends diagonally across the upper region of the bell mouth portion, thereby preventing rainwater, snow, etc. from flowing from the upper surface of the fan shroud into the opening of the bell mouth portion, and preventing malfunctions and damage due to freezing, etc.

[0008] In addition, Japanese Patent No. 7442727 (Patent Document 1) is known in relation to bell mouth structures. Patent Document 2 discloses a bell mouth structure comprising a cylindrical portion having an outer wall surface and configured to surround a fan, a base portion extending outward from one end of the cylindrical portion, and a reinforcing member connected to the base portion and the cylindrical portion. In the technology of Patent Document 2, the reinforcing member extends continuously from the base portion, from one end to the other in the central axis direction of the cylindrical portion, along the outer wall surface of the cylindrical portion, while being displaced in the circumferential direction of the cylindrical portion.

[0009] Patent Document 1 does not disclose any technology for improving the rigidity of the bell mouth or for dealing with thermal stress. The technology in Patent Document 2 was not necessarily sufficient for reinforcing the base of the bell mouth. Furthermore, the reinforcing member in Patent Document 2 is visible on the outer surface of the bell mouth, making it undesirable as a design component.

[0010] Given the technological background described above, there was a need to develop a bellmouth structure that could achieve both high rigidity and suppression of thermal stress, particularly in the base portion, without compromising aesthetic appeal.

[0011] Utility Application No. 60-101464 Patent No. 7442727 Publication

[0012] This disclosure has been made in view of the above points, and aims to provide a bell mouth structure reinforced to achieve both increased rigidity of the base portion and suppression of thermal stress without impairing the design, a shroud having the bell mouth structure, an outdoor unit for an air conditioner, an air conditioner, and a refrigeration cycle device equipped with the bell mouth structure.

[0013] In order to solve the above problems, this disclosure provides a bell mouth structure having the following features. The bell mouth structure includes a cylindrical portion configured to surround a fan, a base portion extending outward from one end of the cylindrical portion, and a plurality of reinforcing members projecting downward from the surface forming the base portion. In this bell mouth structure, the plurality of reinforcing members are provided at multiple positions around the cylindrical portion in a direction substantially symmetrical with respect to the center of the cylindrical portion, when the base portion is viewed in plan, and each of the plurality of reinforcing members has a curved shape with respect to the center of the cylindrical portion.

[0014] The present disclosure also provides a shroud having the bellmouth structure, an outdoor unit of an air conditioning system comprising the bellmouth structure, an air conditioning system comprising an indoor unit and the outdoor unit, and a refrigeration cycle device comprising the bellmouth structure.

[0015] With the above configuration, it becomes possible to reinforce the bellmouth structure while simultaneously increasing the rigidity of its base and suppressing thermal stress without compromising its aesthetic appeal.

[0016] Figure 1 shows a schematic configuration of an air conditioning system that may include a bellmouth structure according to one or more embodiments of the present disclosure. Figure 2 shows a schematic configuration of an outdoor unit of an air conditioning system that includes a bellmouth structure according to one or more embodiments of the present disclosure. Figure 3 shows an overhead perspective view (A) and a side view (B) of a shroud having a bellmouth structure according to one or more embodiments. Figure 4 shows a downward perspective view (A) and a bottom view (B) of a shroud having a bellmouth structure according to a first embodiment of the present disclosure. Figure 5 shows a downward perspective view (A) and a bottom view (B) of a shroud having a bellmouth structure according to a second embodiment of the present disclosure. Figure 6 shows a downward perspective view (A) and a bottom view (B) of a shroud having a bellmouth structure according to a third embodiment of the present disclosure. Figure 7 is a diagram illustrating the symmetry of the rib positions of a shroud having a bellmouth structure according to one or more embodiments of the present disclosure. Figure 8 is a diagram illustrating the function of the curved ribs of a shroud having a bellmouth structure according to one or more embodiments of the present disclosure. Figure 9 illustrates a coupling structure between a shroud having a bellmouth structure according to one or more embodiments of the present disclosure and a housing-side member. Figure 10 illustrates an example of the arrangement of a shroud having a bellmouth structure and a propeller fan according to one or more embodiments of the present disclosure. Figure 11 shows the results of simulating the characteristics of a shroud having a bellmouth structure according to one or more embodiments of the present disclosure.

[0017] The embodiments of this disclosure will be described below with reference to the drawings, but the embodiments of this disclosure are not limited to the specific embodiments described below. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0018] This disclosure covers a bell mouth structure, a shroud having the bell mouth structure, an outdoor unit of an air conditioning system comprising the bell mouth structure, an air conditioning system comprising the outdoor unit, and a refrigeration cycle device comprising the bell mouth structure.

[0019] The bell mouth structure according to the embodiment of the present disclosure includes a cylindrical portion configured to surround a fan (propeller), a base portion extending outward from one end of the cylindrical portion, and a plurality of reinforcing members projecting downward from the surface forming the base portion. The plurality of reinforcing members are provided at multiple positions around the cylindrical portion in a direction substantially symmetrical with respect to the center of the cylindrical portion, when the base portion is viewed in plan, and each of the plurality of reinforcing members has a curved shape with respect to the center of the cylindrical portion.

[0020] With the above configuration, it becomes possible to reinforce the bellmouth structure while simultaneously increasing the rigidity of its base and suppressing thermal stress without compromising its aesthetic appeal.

[0021] In a preferred embodiment, the curved shape protrudes from the center of the curved shape, approaching the center of the cylindrical portion when the base is viewed from above. This makes it possible to reinforce the base portion while simultaneously increasing its rigidity and suppressing thermal stress, while preventing interference between the bell mouth structure and the main body on which it is mounted.

[0022] In a preferred embodiment, the base portion has a substantially rectangular shape with four vertices, and the multiple positions are located between the center of the cylindrical portion and the four vertices of the rectangle. In this arrangement, the multiple positions are in a direction having approximately four-fold rotational symmetry. By providing the flat plate portion of the base portion with a reinforcing member that is curved relative to the center of the cylindrical portion in this way, the rigidity of the flat plate portion is improved and thermal stress is reduced.

[0023] In a preferred embodiment, the base portion has a substantially rectangular shape with four sides, and the multiple positions are located between the center of the cylindrical portion and the approximately midpoints of the four sides of the rectangle. In this arrangement, the multiple positions are in a direction having four-fold rotational symmetry. This reinforcement provides sufficient room for thermal expansion and contraction, thereby minimizing the increase in thermal stress.

[0024] In a preferred embodiment, the base portion has a substantially rectangular shape with four vertices and four sides, and the plurality of positions include a plurality of first positions located between the center of the cylindrical portion and the four vertices of the rectangle, and a plurality of second positions located between the center of the cylindrical portion and positions approximately midway between the four sides of the rectangle. In this arrangement, the first and second positions are each in positions with four-fold rotational symmetry, and the plurality of positions, including the first and second positions, are in a direction with eight-fold rotational symmetry. This makes it possible to obtain a synergistic effect between the reinforcing members provided at the first positions and the reinforcing members provided at the second positions.

[0025] In a preferred embodiment, the base portion has a plurality of fastening portions for fixing the bell mouth structure to the housing, and each of the plurality of reinforcing members is configured such that a straight line connecting two of the plurality of fastening portions on both sides of the reinforcing member intersects at two points with an arc defining the curved shape of the reinforcing member. In this way, the reinforcing member functions to act as a flexible structure against thermal expansion and contraction while providing high rigidity to the flat portion.

[0026] In a particular embodiment, the cylindrical portion, the base portion, and the multiple reinforcing members are integrally molded from resin.

[0027] The shroud according to the embodiments of this disclosure includes the bell mouth structure described above.

[0028] The outdoor unit of the air conditioning system according to the embodiment of the present disclosure comprises a substantially rectangular parallelepiped housing, the bell mouth structure described above, and a fan, which are provided above the housing.

[0029] In a particular embodiment, the outdoor unit comprises a pair of fans and a bellmouth structure, and when the base is viewed from above, the outer edge of the outdoor unit's housing and the cylindrical portion of the bellmouth structure are in close proximity at approximately the center of the long side of the housing. The bellmouth structure of this disclosure is useful in such a configuration.

[0030] In certain embodiments, the outdoor unit comprises multiple pairs of fans and bellmouth structures arranged longitudinally along the housing, and, with a plan view of the base, the outer edge of the outdoor unit housing and the cylindrical portion of the bellmouth structure are in close proximity at approximately the center of the short side of the housing. The bellmouth structure of this disclosure is useful in such a configuration.

[0031] In certain embodiments, the bell mouth structure has a rounded portion at the boundary between the cylindrical portion and the base portion, and the rounded portion has a radius of curvature that gradually decreases as it approaches the portion where the cylindrical portion and the outdoor unit housing are in close proximity. The bell mouth structure of the present disclosure is useful in such a configuration.

[0032] The air conditioning system described herein includes the outdoor unit and indoor unit described above.

[0033] The refrigeration cycle device according to this disclosure comprises the bell mouth structure described above.

[0034] Hereinafter, with reference to Figures 1 to 10, an air conditioning system equipped with a bell mouth structure according to an embodiment of the present disclosure will be described, using an air conditioning system 1 equipped with a shroud 20 and its outdoor unit 10 as an example.

[0035] Referring to Figure 1, a schematic configuration of an air conditioning system 1 that may include a shroud 20 according to one or more embodiments of the present disclosure will be described. The air conditioning system 1 is a device that performs air conditioning by circulating a refrigerant in a refrigeration cycle. As shown in Figure 1, the air conditioning system 1 comprises one or more indoor units 4 (4a, 4b…) installed in a room (air-conditioned space), and an outdoor unit 10 installed outdoors. The one or more indoor units 4a, 4b… and the outdoor unit 10 are connected via refrigerant piping 2. As the refrigerant, hydrofluorocarbons such as R410a and R32 may be used.

[0036] The indoor unit 4 is a device that, during operation, takes in indoor air, exchanges heat between the taken-in air and the refrigerant supplied from the outdoor unit 10, and blows out cooled or heated air to cool or heat the indoor space to a set temperature. The indoor unit 4 is part of the refrigeration cycle of the air conditioning system 1 and includes an indoor heat exchanger and an indoor blower such as a cross-flow fan.

[0037] The outdoor unit 10 is started upon receiving a specification from the control device and controls the operation of the compressor and outdoor fan according to the operating mode set by the operating device. Such operating devices include remote controllers and centralized control equipment.

[0038] In Figure 1, two indoor units 4a and 4b are shown as indoor units 4, but the number of indoor units 4 is not particularly limited; it may be one unit or three or more units. Similarly, although one outdoor unit 10 is shown as an example, it is not limited to one unit.

[0039] In the air conditioning system 1, the indoor unit 4 and the outdoor unit 10 are connected via a communication line (not shown). In addition, an operating device such as a remote controller for operating the indoor unit 4 via the communication line may be connected to the room in which the indoor unit 4 is installed. Furthermore, a central controller for centrally controlling one or more indoor units 4a, 4b and the outdoor unit 10 may be connected via the communication line.

[0040] In the example shown in Figure 1, the air conditioning system 1 is depicted as an example of a multi-split air conditioner for a building equipped with an upward-blowing type outdoor unit 10. While the bell mouth structure according to the embodiment of this disclosure can be suitably applied to an upward-blowing type outdoor unit, the form of the air conditioning system 1 in the embodiment of this disclosure is not necessarily limited to this, and may also be applied to a packaged air conditioner.

[0041] Next, with reference to Figure 2, the schematic configuration of the outdoor unit 10 of the air conditioning system 1 equipped with a shroud 20 according to one or more embodiments of the present disclosure will be described.

[0042] In the refrigeration cycle, the outdoor unit 10 includes a blower 11, a compressor 16, an outdoor heat exchanger 17, a four-way valve (not shown), and an expansion valve.

[0043] The outdoor unit 10 shown in FIG. 2 includes a compressor 16 disposed within a housing 19, an outdoor heat exchanger 17, an electrical component box 18 disposed above the compressor 16, a stay 14 to which the electrical component box 18 is attached, a blower 11 fixed to the stay 14, and a shroud 20 provided on the outer periphery of the blower 11 and covering the housing 19. In the described embodiment, the shroud 20 is integrated with the bellmouth of the outdoor unit and constitutes the bellmouth structure according to the embodiment of the present disclosure.

[0044] The blower 11 includes a propeller fan (propeller) 12 and a motor 13 that drives the propeller fan 12. The propeller fan 12 has blades that cause air to flow while swirling along the rotation axis, and the number thereof is not particularly limited, but for example, it is composed of three blades. When the propeller fan 12 of the blower 11 is rotated by the motor 13 in the outdoor unit 10, as indicated by the thick arrow in FIG. 2, air is sucked from outside the housing 19 through the side surface of the outdoor heat exchanger 17, heat exchange is performed in the outdoor heat exchanger 17, and the air is discharged into the atmosphere from the upper opening of the shroud 20.

[0045] As described above, in the outdoor unit 10 of the air conditioning system 1, it is expected to improve the efficiency of the fan by extending the height of the cylindrical portion of the bellmouth structure of the shroud 20. However, generally, there are restrictions on the height in product design, so it is desirable to extend the cylindrical portion while maintaining the overall height of the bellmouth structure of the shroud 20. For this purpose, it is required to cope with and reinforce the reduction in the thickness of the base portion of the shroud 20 bellmouth structure. Also, in terms of the designability of the shroud 20 during reinforcement, it is desirable to arrange the reinforcing members in the invisible portions other than the outer surface of the shroud 20.

[0046] Regarding the rigidity of the bellows structure, it can be roughly classified into the annular rigidity of the cylindrical part and the flat rigidity of the base part. If there is a part with low rigidity even in part of the entire circumference for the annular rigidity, the cylindrical part is likely to deform into an elliptical shape starting from that part, and the rigidity will extremely decrease. In particular, the decrease in rigidity at the part where the outer edge of the base part and the cylindrical part are close to each other becomes a problem. On the other hand, regarding the base part, in addition to the proximity part where the outer edge of the base part and the cylindrical part are close to each other, it is also important to ensure the rigidity of the flat part away from the cylindrical part. When it is desired to keep the height of the base part low, it is difficult to ensure a sufficient height of the reinforcing material.

[0047] Therefore, in order to improve the rigidity of the bellows structure, simply providing reinforcing members such as ribs over the entire circumference of the cylindrical part including both the proximity part and the flat part can be considered. However, when ribs are provided over the entire circumference including both the proximity part and the flat part, as will be described later, although the rigidity increases, the thermal stress also increases significantly. This is because the amount of expansion and contraction caused by the difference in the coefficient of thermal expansion (linear expansion coefficient) is determined by the original length × linear expansion coefficient × temperature change regardless of the rigidity of the member. The higher the rigidity, the greater the excessive force generated at the restraint points such as screws, resulting in rather a worsening result. That is, high rigidity and low thermal stress are in a contradictory relationship, and an overall increase in rigidity rather brings an increase in thermal stress.

[0048] Therefore, it is required to reinforce both the high rigidity and thermal stress suppression of the base part of the bellows structure by arranging the reinforcing members locally and effectively rather than globally on the invisible parts other than the outer surface.

[0049] Therefore, in this embodiment, a cylindrical circular duct section (tubular section) is provided to surround the propeller fan, a base section extending outward from the lower end of the circular duct section, and a plurality of ribs (reinforcement members) protruding downward from the surface forming the base section. The plurality of ribs are provided at multiple positions around the circular duct section, in a direction that is substantially symmetrical with respect to the center of the circular duct section, when the base section is viewed from above, and each of the plurality of ribs is configured to have a curved shape with respect to the center of the circular duct section. This aims to reinforce the base section of the bellmouth structure in a way that achieves both increased rigidity and suppression of thermal stress without compromising aesthetic appeal.

[0050] The configuration of a shroud having a bellmouth structure according to one or more embodiments of this disclosure will be described in more detail below with reference to Figures 3 to 8.

[0051] Figure 3 shows an overhead perspective view (A) and a front view (B) of a shroud having a bellmouth structure according to the first to third embodiments of this disclosure. Figures 4 to 6 show an overhead perspective view (A) and a bottom view (B) of a shroud having a bellmouth structure according to the first to third embodiments of this disclosure. Figures 7(A) to 7(C) illustrate the symmetry of the rib positions in a shroud having a bellmouth structure according to the first to third embodiments of this disclosure. Figure 8 illustrates the function of the ribs in a shroud having a bellmouth structure according to the first to third embodiments of this disclosure.

[0052] A shroud 20 having a bell mouth structure according to the first embodiment will be described with reference to Figures 3, 4, 7(A), 8(A), and 8(B). Figure 3(A) shows a perspective view of the shroud 20 from above. Figure 3(B) shows a side view of the shroud 20. Figure 4(A) shows a perspective view of the shroud 20 from below. Figure 4(B) shows a bottom view of the shroud 20.

[0053] The shroud 20 shown in Figures 3 and 4 comprises a circular duct portion 21 having an upper end U and a lower end L, and a base portion 30 extending radially outward from the lower end L of the circular duct portion 21. The circular duct portion 21 has a substantially cylindrical shape with openings on the upper end U side and the lower end L side.

[0054] The circular duct section 21 is configured such that air enters from the opening on the lower end L side of the base section 30, flows from bottom to top within the circular duct section 21, and is discharged from the opening on the upper end U side. In the embodiment described, the diameter of the cylindrical shape of the circular duct section 21 is smallest in the center. The circular duct section 21 is configured to have a diameter that ensures a certain clearance from the maximum diameter of the propeller fan 12 when the propeller fan 12 is installed in the blower 11.

[0055] The circular duct section 21 is more specifically composed of a rounded section 22, an intermediate section 23, and an enlarged diameter section 24. The rounded section 22 is the boundary portion between the circular duct section 21 and the base section 30, and smoothly connects the base section 30, which extends in the planar direction, to the cylindrical circular duct section 21, which extends perpendicular to the plane on which the base section 30 extends, with a predetermined radius of curvature. The intermediate section 23 is a cylindrical section above the rounded section 22, having a substantially constant diameter that ensures the aforementioned clearance, and as shown in Figure 2, the propeller fan 12 is mainly housed inside this intermediate section 23. The circular duct section 21 constitutes the cylindrical section in this embodiment.

[0056] Furthermore, in the embodiment described, the circular duct section 21 is equipped with an enlarged diameter section 24, and employs a structure in which the diameter gradually expands from the center, a so-called multi-stage enlargement structure. A bell mouth equipped with such an enlarged diameter section 24 is also called a long bell mouth. By adopting this long bell mouth configuration, the airflow is made smoother, fan input is reduced, and efficiency and performance over a wide operating range are improved.

[0057] The base portion 30 has a roughly rectangular shape and is configured so that the shroud 20 is placed on and fixed to the housing of the outdoor unit 10 (housing 19 in Figure 2). The base portion 30 has a circular duct portion 21 formed in the center, and extends outward (in the radial direction of the cylinder) from the lower end L of the circular duct portion 21 to form the roughly rectangular shape described above. In the embodiment described, the rectangle of the base portion 30 is generally close to a square, but has a roughly rectangular shape with a long side and a short side. The base portion 30 is open at the location where the circular duct portion 21 is provided. The base portion 30 constitutes the base portion in this embodiment.

[0058] The base portion 30 is provided with a mechanism for fastening to a component (for example, sheet metal) on the housing 19 side. In the embodiment described, there are a total of eight screw holes 31a to 31h formed in recesses, two at each of the four corners of the roughly rectangular shape (one on each side of the vertices). The shroud 20 and the housing 19 are fixed together by fastening screws to the housing 19 through the screw holes 31a to 31h.

[0059] As shown in Figure 4(B) enclosed by dashed and dotted lines, the base portion 30 mainly consists of two parts. The first part, enclosed by a dashed line, is the area (proximity area) where the circular duct portion 21 and the housing 19 of the outdoor unit 10 (i.e., the outer edge of the base portion 30) are in close proximity, and four proximity areas are shown in Figure 4(B). The second part, enclosed by a dotted line, is the flat plate portion at the four corners away from the circular duct portion 21, and four flat plate portions are shown in Figure 4(B). In the shroud 20, it is important to ensure the rigidity of these proximity areas and flat plate portions.

[0060] As shown in Figures 4(A) and 4(B), the shroud 20 according to the first embodiment further includes a plurality of ribs 33 that protrude downward from the surface (or plane) 32 forming the base portion 30. In the embodiment described, four ribs 33a to 33d are provided. The plurality of ribs 33 constitute a reinforcing member in the embodiment of this disclosure. The annular rigidity is extremely reduced if there is even a part with low rigidity around the entire circumference, as the circular duct portion 21 tends to deform into an elliptical shape starting from that part. The plurality of ribs 33 according to the first embodiment are reinforcing members that improve the rigidity of the part adjacent to the base portion 30, which tends to have low rigidity, as shown by the dashed ring in Figure 4(B).

[0061] The positions of the four ribs 33a to 33d are, when viewing the base portion 30 from above (as shown in the bottom view in Figure 4(B)), around the circular duct portion 21 (more specifically, outside the circle drawn by the smallest diameter of the cylindrical shape of the circular duct portion 21), and are located between the center of the circular duct portion 21, indicated by O, and approximately midway between the four sides of the rectangle of the base portion 30. Each of the four ribs 33a to 33d has a curved shape relative to the center O of the circular duct portion 21 when viewing the base portion 30 from above, and in the embodiment described, it protrudes convexly relative to the center O of the circular duct portion 21 so that the central part of the curved shape approaches the center O of the circular duct portion 21. The curved ribs 33 locally reinforce the area between the fastening points 31 adjacent to the ribs 33, rather than reinforcing the entire area.

[0062] In the embodiments shown in Figures 4(A) and 4(B), flat plate ribs 34a to 34d are provided on the outer edge side of the base portion 30 of each curved rib 33a to 33d, connected to both ends of each curved rib 33. The curved ribs 33 and the flat plate ribs 34 form a crescent shape. The flat plate ribs 34 are ribs that prevent air leakage and are not required to be provided.

[0063] Figure 7(A) is a diagram illustrating the symmetry of the rib arrangement in the shroud 20 according to the first embodiment of the present disclosure. In the shroud 20 according to the first embodiment described with reference to Figures 3 and 4, the multiple positions where the multiple curved ribs 33a to 33d are arranged generally coincide in a direction having four-fold rotational symmetry with respect to the center O of the circular duct portion 21 as the axis of rotation. Furthermore, the positions of ribs 33b and 33d are mirror-symmetric with respect to a plane m1 passing through the center O of the circular duct portion 21, and the positions of ribs 33a and 33c are mirror-symmetric with respect to a plane m2 passing through the center O of the circular duct portion 21. Thus, the multiple ribs 33a to 33d are provided at multiple positions around the circular duct portion 21, when the base portion 30 is viewed from above, in a direction having substantially symmetry with respect to the center O of the circular duct portion 21. Here, the rectangle of the base portion 30 is a rectangle that is roughly close to a square, and the "direction having approximate symmetry" means that it is permissible that it does not necessarily coincide exactly with the position having the above symmetry (rotational symmetry or mirror symmetry), depending on the degree to which the rectangle of the base portion 30 deviates from a square in the design, and due to manufacturing errors. Also, the "position where the rib is placed" means the approximate center of the curved shape of the rib.

[0064] Furthermore, the height of the rib 33, which affects the strength of the reinforcement, may protrude below the plane formed by the bottom of the side surface of the base portion 30 (indicated as 30a in Figure 3(B)) (indicated as B in Figure 3(B)), as long as it does not interfere with the member on the housing 19 side on which the base portion 30 is mounted. On the other hand, at the position where the base portion 30 is in contact with the member on the housing 19 side on which it is mounted, the height of the rib 33 is kept to a height that does not interfere with the member on the housing 19 side.

[0065] The circular duct portion 21, the base portion 30, and the multiple curved ribs 33 (and flat ribs 34) described above are preferably made of resin material, and in a more preferred embodiment, they are integrally molded from resin.

[0066] The advantages of the shroud 20 according to the first embodiment described with reference to Figures 3, 4, and 7(A) will be explained below with reference to Figures 8(A) and 8(B). Figure 8(A) is a diagram illustrating the case where the entire area between the two fastening points 31L and 31R is reinforced. Figure 8(B) is a diagram illustrating the case where the area between the fastening points 31L and 31R is reinforced locally, as in the first embodiment of this disclosure.

[0067] As shown in Figure 8(A), when the entire area between fastening points 31L and 31R is reinforced with a straight rib R', there is no room for thermal expansion and contraction S to escape, resulting in increased thermal stress. In contrast, as shown in Figure 8(B), by adopting the configuration of the first embodiment of this disclosure and locally reinforcing the area between 31L and 31R with a curved rib R, there is sufficient room for thermal expansion and contraction S to escape, thus minimizing the increase in thermal stress. This makes it possible to improve the rigidity of the base portion 30 of the shroud 20 while minimizing the increase in thermal stress. Ultimately, it is possible to provide a shroud 20 that satisfies the thermal stress requirements while improving rigidity.

[0068] Furthermore, according to the first embodiment, since the base portion 30 is provided with ribs 33 that protrude downward, the aesthetic design is not compromised. Moreover, according to the first embodiment, the base portion 30 can be efficiently reinforced, so there is no need to increase the overall thickness, which reduces the total weight of the resin used and lowers costs.

[0069] The shroud 20A having a bell mouth structure according to the second embodiment of this disclosure will be described below with reference to Figures 3, 5, 7(B), 8(C), and 8(D). Figure 5(A) shows a perspective view of the shroud 20A from below. Figure 5(B) shows a bottom view of the shroud 20A. Elements common to the first embodiment will be given the same reference numerals.

[0070] The shroud 20A shown in Figures 3 and 5 comprises a circular duct portion 21, which includes a round portion 22, an intermediate portion 23, and an enlarged diameter portion 24, similar to the first embodiment, and a base portion 30 that extends outward from the lower end L of the circular duct portion 21 and has a substantially rectangular shape. Screw holes 31a to 31h are provided in the same positions as in the first embodiment in the base portion 30. The following description will focus on the differences from the first embodiment, and unless otherwise specified, the configuration will be similar to that of the first embodiment to the extent that it is not inconsistent.

[0071] As shown in Figures 5(A) and 5(B), the shroud 20A, like the first embodiment, is provided with a plurality of ribs 35 that protrude downward from the surface 32 forming the base portion 30. In the embodiment described, four ribs 35a to 35d are provided at the four corners. When the largest possible circular duct portion 21 is provided approximately in the center of the substantially rectangular shape of the base portion 30, the four corners of the base portion 30 become flat plate portions, reducing the rigidity of these portions and causing increased vibration. The plurality of ribs 35 constitute reinforcing members in the embodiment of this disclosure, particularly for improving the rigidity of the flat plate portions of the base portion 30, which are shown as dotted lines in Figure 5(B).

[0072] The positions of the multiple ribs 35a to 35d differ from those of the first embodiment. More specifically, when viewing the base portion 30 from above (as shown in the bottom view in Figure 5(B)), they are positioned between the center O of the circular duct portion 21 and the four vertices of the rectangular shape of the base portion 30. Each of the multiple ribs 35a to 35d, as in the first embodiment, has a curved shape (bow or arch-like) relative to the center O of the circular duct portion 21 when viewing the base portion 30 from above. In the embodiment described, the central part of the curved shape protrudes convexly relative to the center O of the circular duct portion 21, approaching the center O of the circular duct portion 21.

[0073] The base portion 30 has a plurality of fastening parts (31a to 31h) for fixing the shroud 20A to the housing. Each rib 35 is configured such that a straight line connecting two of the multiple fastening parts on either side of the rib 35 intersects at two points with an arc defining the curved shape of the rib 35. The curved ribs 35 reinforce the space between the fastening points 31 located on either side of each of the four corners.

[0074] Figure 7(B) is a diagram illustrating the symmetry of the rib arrangement in the shroud 20A according to the second embodiment of the present disclosure. In the shroud 20A according to the second embodiment described with reference to Figures 3 and 5, the multiple positions where the multiple curved ribs 35a to 35d are arranged generally coincide in a direction having four-fold rotational symmetry with respect to the center O of the circular duct portion 21 as the axis of rotation. Furthermore, the positions of ribs 35a, 35b and ribs 35d, 35c are mirror-symmetric with respect to a plane m1 passing through the center O of the circular duct portion 21. The positions of ribs 35a, 35d and ribs 35b, 35c are mirror-symmetric with respect to a plane m2 passing through the center O of the circular duct portion 21. Thus, the multiple ribs 35a to 35d are provided at multiple positions around the circular duct portion 21, in a direction having substantially symmetry with respect to the center O of the circular duct portion 21, when the base portion 30 is viewed from above.

[0075] Furthermore, the height of the ribs 33 is the same as in the first embodiment. The circular duct portion 21, the base portion 30, and the multiple ribs 35 are, as in the first embodiment, more preferably integrally molded from resin.

[0076] The advantages of the shroud 20 according to the second embodiment described with reference to Figures 3, 5, and 7(B) will be explained below with reference to Figures 8(C) and 8(D). Figure 8(C) is a diagram illustrating the case in which the space between two fastening points 31T and 31U is reinforced with a curved rib 35, as in the second embodiment of this disclosure. Figure 8(D) is a diagram illustrating the case in which the space between two fastening points 31T and 31U is reinforced with a curved rib 35 and the case in which it is reinforced linearly, in comparison.

[0077] As described above, if the largest possible circular duct section 21 is provided approximately in the center of the roughly rectangular shape of the base section 30, the rigidity of the flat plate sections at the four corners of the base section 30 decreases, causing increased vibration. Therefore, it is conceivable to increase the rigidity by providing reinforcing members such as ribs to the flat plate section. However, as shown on the left of Figure 8(D), if linear ribs are provided at the fastening points, there is no escape route for thermal expansion and contraction, resulting in increased stress. In contrast, as shown on the right side of Figure 8(C) and Figure 8(D), by providing arch-shaped ribs 35 that curve toward the center O of the circular duct section 21 on the flat plate section of the base section 30, it is possible to improve the rigidity of the flat plate section while reducing thermal stress. This is because, by using an arch-shaped rib configuration between the fastening points, as shown on the right side of Figure 8(D), the ribs 35 act as a flexible structure against thermal expansion and contraction while functioning to increase rigidity in the flat section.

[0078] Thus, according to the second embodiment, it is possible to provide a shroud 20A that satisfies both thermal stress and high rigidity. Furthermore, according to the second embodiment, the aesthetic appearance is not compromised, similar to the first embodiment. Moreover, according to the second embodiment, the base portion 30 can be reinforced efficiently, so there is no need to increase the overall thickness, which reduces the total weight of the resin used and thus lowers costs.

[0079] Hereinafter, a shroud 20B equipped with a bell mouth structure according to a third embodiment of this disclosure will be described with reference to Figures 3, 6, 7(C), and 8. Figure 6(A) shows a perspective view of the shroud 20B from below. Figure 6(B) shows a bottom view of the shroud 20B. Elements common to the first and second embodiments will be given the same reference numerals.

[0080] The shroud 20B shown in Figures 3 and 6 comprises a circular duct portion 21 and a base portion 30, similar to the first and second embodiments. Screw holes 31a to 31h are provided in the same positions as in the first and second embodiments in the base portion 30. The following description will focus on the differences from the first and second embodiments, and unless otherwise specified, the configuration will be similar to that of the first or second embodiment to the extent that it is not inconsistent.

[0081] As shown in Figures 6(A) and 6(B), the shroud 20B, like the first embodiment, is provided with a plurality of ribs 33 that protrude downward from the surface 32 forming the base portion 30. Accordingly, like the first embodiment, flat ribs 34a to 34d are provided in addition to the curved ribs 33a to 33d. Furthermore, like the second embodiment, the shroud 20B is provided with a plurality of ribs 35 that also protrude downward from the surface 32 forming the base portion 30. The plurality of ribs 33 and ribs 35 constitute reinforcing members in the embodiments of this disclosure. The plurality of ribs 33, like the first embodiment, are reinforcing members for improving the rigidity of the portion adjacent to the base portion 30, indicated by the dashed ring. On the other hand, the plurality of ribs 35, like the second embodiment, are reinforcing members for improving the rigidity of the flat portion of the base portion 30, indicated by the dashed ring.

[0082] The positions of the multiple ribs 33a to 33d are the same as in the first embodiment, located between the center O of the circular duct portion 21 and the midpoints of the four sides of the rectangular shape of the base portion 30. On the other hand, the positions of the multiple ribs 35a to 35d are the same as in the second embodiment, located between the center O of the circular duct portion 21 and the positions of the four vertices of the rectangular shape of the base portion 30. Each of the multiple ribs 33a to 33d and 35a to 35d protrudes convexly from the center O of the circular duct portion 21, as in the first and second embodiments, so that the central part of the curved shape approaches the center O of the circular duct portion 21.

[0083] Figure 7(C) is a diagram illustrating the symmetry of the rib arrangement in the shroud 20B according to the third embodiment of the present disclosure. In the shroud 20B according to the third embodiment described with reference to Figures 3 and 6, the multiple positions where the multiple ribs 33a to 33d are arranged generally coincide in a direction having four-fold rotational symmetry with respect to the center O of the circular duct portion 21 as the axis of rotation. The multiple positions where the multiple ribs 35a to 35d are arranged generally coincide in a direction having four-fold rotational symmetry with respect to the center O of the circular duct portion 21 as the axis of rotation. Furthermore, the multiple positions where the multiple ribs 33a to 33d and 35a to 35d are arranged generally coincide in a direction having eight-fold rotational symmetry with respect to the center O of the circular duct portion 21 as the axis of rotation. Thus, the multiple ribs 33a to 33d and 35a to 35d are provided at multiple positions around the circular duct portion 21, when the base portion 30 is viewed from above, in a direction having substantially symmetry with respect to the center O of the circular duct portion 21.

[0084] Furthermore, the height of the ribs 33 (and 34), 35 is the same as in the first and second embodiments. The circular duct portion 21, the base portion 30, and the multiple ribs 33 (and 34), 35 are more preferably integrally molded from resin, as in the first and second embodiments.

[0085] The shroud 20B according to the third embodiment combines the advantages described with reference to Figures 8(A) and 8(B) for the first embodiment and the advantages described with reference to Figures 8(C) and 8(D) for the second embodiment.

[0086] Figure 9 illustrates the coupling structure between a shroud having a bellmouth structure according to one or more embodiments of the present disclosure and a housing-side member (e.g., a sheet metal member). Figure 9 illustrates the coupling structure of one corner of the rectangular base portion 30 of the shroud 20A according to the second embodiment. As shown in Figure 9, the rib 35 is configured such that its height H1 is greater than the thickness D of the base portion 30 itself, to the extent that it does not interfere with the housing-side member 19a on which the base portion 30 is mounted. On the other hand, at the position where the base portion 30 is in contact with the housing-side member 19a on which it is mounted (e.g., around the screw hole portion 31), the height H2 of the rib 33 is limited to a height (≤D) that does not interfere with the housing-side member 19a.

[0087] Hereinafter, with reference to Figure 10, examples of the arrangement of a shroud 20 (or 20A or 20B) having a bell mouth structure and a propeller fan 12 according to one or more embodiments of the present disclosure will be described. Figures 10(A) and 10(B) are plan views showing the arrangement of the shroud 20 and propeller fan 12 on the top surface of the outdoor unit 10. Figures 10(C) and 10(D) are perspective views of the outdoor unit 10 from above.

[0088] Figures 10(A) and 10(C) show an embodiment in which a pair of propeller fans 12 and shrouds 20 are provided. In the arrangement examples shown in Figures 10(A) and 10(C), the outer edge of the housing 19 of the outdoor unit 10 and the circular duct portion 21 of the shroud 20 are close together at approximately the center of the long side X of the housing 19, as shown by the dashed ring. The shrouds 20, 20A, and 20B according to the first to third embodiments of this disclosure are useful in the arrangement examples shown in Figures 10(A) and 10(C).

[0089] Figures 10(B) and 10(D) show another embodiment in which two pairs of propeller fans 12-1, 12-2 and shrouds 20-1, 20-2 are provided. In the arrangement example shown in Figures 10(B) and 10(D), the first pair of propeller fans 12-1 and shroud 20-1 and the second pair of propeller fans 12-2 and shroud 20-2 are arranged in the longitudinal direction of the housing 19, and the outer edge of the housing 19 of the outdoor unit 10 and the circular duct portions 21-1, 21-2 of the two shrouds 20-1, 20-2 are close together approximately in the center of the short side Y of the housing 19. The shrouds 20, 20A, and 20B according to the first to third embodiments of this disclosure are useful in the arrangement example shown in Figures 10(B) and 10(D).

[0090] In relation to the connection between the circular duct section 21 and the base section 30, the rounded section 22 connects the circular duct section 21 and the base section 30 with a predetermined radius of curvature, as described above. With respect to the proximity section represented by the dashed ring in Figure 10, the rounded section 22 has a basic radius of curvature (maximum value) for almost the entire circumference, and is configured to have a radius of curvature that gradually decreases as it approaches the proximity section indicated by the dashed ring, where the circular duct section 21 and the housing 19 of the outdoor unit 10 are in close proximity. In this way, a smooth shape is achieved by gradually reducing the curvature in narrow areas where sufficient space cannot be secured with the basic radius of curvature. The shrouds 20, 20A, and 20B according to the first to third embodiments of this disclosure are useful in configurations having a radius of curvature that gradually decreases as it approaches the proximity section indicated by the dashed ring.

[0091] The characteristics of the shrouds 20, 20A, and 20B according to the first to third embodiments described with reference to Figures 1 to 10 will be explained below with reference to Figure 11.

[0092] Figure 11 shows the simulation results of the characteristics of shrouds 20, 20A, and 20B having a bell mouth structure according to the first to third embodiments of this disclosure. Figure 11 also shows the simulation results of shrouds with other configurations for comparison. In Figure 5, the first column shows the experiment number, and the second column shows the shape of the model used in the simulation. The third to fifth columns show the simulation results, where the third column shows the annular stiffness, the fourth column shows the plate stiffness, and the fifth column shows the thermal stress. The stiffness was obtained from the square of the natural frequency ratio, since the natural frequency is proportional to the square root of the stiffness. In terms of interpretation of the results, it is desirable to improve the annular stiffness and plate stiffness while keeping the thermal stress within a predetermined range (for example, within a range of a maximum increase of 10%).

[0093] Experimental result number 1 shows the results for the baseline model without ribs. Experimental result number 2 shows the results for a comparative model with linear ribs around the entire circumference of the cylindrical shape. Experimental result number 3 shows the results for a model having the shape according to the first embodiment. Experimental result number 4 shows the results for a model having the shape according to the second embodiment. Experimental result number 5 shows the results for a model having the shape according to the third embodiment.

[0094] The experimental results for numbers 3 to 5 correspond to the configuration with curved ribs according to the embodiment of this disclosure. Experimental result number 1 serves as the baseline. As can be seen by referring to the table in Figure 11, in experimental result number 2, the annular stiffness improves to 816% and the plate stiffness to 1001% in the baseline model, but the thermal stress increases by 32%. The stiffness improves, but the thermal stress increases to an unacceptable level.

[0095] In contrast, the experimental results for experiment number 3 showed an annular stiffness of 217% and a plate stiffness of 222%, with the stiffness of both the annular and plate modes increasing by approximately twofold, while the thermal stress was kept to an increase of about 12%. The experimental results for experiment number 4 showed an annular stiffness of approximately 107%, but the plate stiffness increased to 156%, and the thermal stress decreased by about 8%. The experimental results for experiment number 5 showed an annular stiffness of 225% and a plate stiffness of 295%, with the stiffness of both the annular and plate modes increasing by more than twofold, while the thermal stress was kept to an increase of about 8%.

[0096] Thus, in the configurations (numbers 3 to 5) according to the embodiments of this disclosure in which curved ribs are provided on the base portion, it is possible to improve rigidity while suppressing the increase in thermal stress, and it is shown that the base portion can be reinforced while simultaneously achieving high rigidity and suppressing thermal stress without compromising aesthetic appeal. In particular, in the configuration (number 5) according to the embodiments of this disclosure that includes both curved ribs 33 and 35, the synergistic effect of reinforcement of the adjacent portion by the curved rib 33 and reinforcement of the flat portion by the curved rib 35 makes it possible to improve rigidity by two to three times while suppressing thermal stress, and this configuration was the most balanced.

[0097] As described above, according to the embodiments of the present disclosure, it is possible to provide a bell mouth structure that is reinforced to achieve both increased rigidity of the base portion and suppression of thermal stress without impairing the design, a shroud having the bell mouth structure, an outdoor unit of an air conditioner, an air conditioner, and a refrigeration cycle device equipped with the bell mouth structure.

[0098] In the embodiments described above, an air conditioning system or air conditioner equipped with an outdoor unit having the bell mouth structure described above was explained as an example. However, the bell mouth structure according to this embodiment is not limited to that of an outdoor unit of an air conditioning system. In other embodiments, the bell mouth structure may be applied to refrigeration cycle devices other than air conditioning systems. Here, a refrigeration cycle device is also called a refrigeration and air conditioning device, and a refrigeration and air conditioning device is a general term for devices that utilize refrigerants and refrigeration cycles, such as refrigerators and freezers, in addition to the air conditioning systems described above. More specifically, examples of refrigeration and air conditioning devices may include the above-mentioned air conditioning systems such as packaged air conditioners and multi-split air conditioners for buildings, heat source equipment such as chillers and chilling units, commercial refrigeration equipment such as showcases, refrigerators and freezers, unit coolers and ice makers, transport refrigeration equipment such as car air conditioners, and heat pump water heaters.

[0099] It should be noted that the embodiments described herein are not limited to those described above, and may include various modifications. For example, the embodiments described above are described in detail for clarity and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0100] 1...Air conditioning system, 2...Refrigerant piping, 4...Indoor unit, 10...Outdoor unit, 11...Blower, 12...Propeller fan, 13...Motor, 14...Stay, 16...Compressor, 17...Outdoor heat exchanger, 18...Electrical box, 19...Housing, 20, 20A, 20B...Shroud, 21...Circular duct section, 22...Round section, 23...Intermediate section, 24...Enlarged diameter section, 30...Base section, 31...Screw hole, 32...Surface, 33, 35...Rib (curved rib), 34...Rib (flat rib)

Claims

1. A bell mouth structure comprising: a cylindrical portion configured to surround a fan; a base portion extending outward from one end of the cylindrical portion; and a plurality of reinforcing members projecting downward from the surface forming the base portion, wherein the plurality of reinforcing members are provided at multiple positions around the cylindrical portion in a direction substantially symmetrical with respect to the center of the cylindrical portion, when the base portion is viewed in plan, and each of the plurality of reinforcing members has a curved shape with respect to the center of the cylindrical portion.

2. The bell mouth structure according to claim 1, wherein the curved shape protrudes from the center of the curved shape, approaching the center of the cylindrical portion, when the base portion is viewed in plan.

3. The bell mouth structure according to claim 1, wherein the base portion has a substantially rectangular shape having four vertices, and the plurality of positions are located between the center of the cylindrical portion and the four vertices of the rectangle.

4. The bell mouth structure according to claim 1, wherein the base portion has a substantially rectangle having four sides, and the plurality of positions are located between the center of the cylindrical portion and the substantially midpoint positions of the four sides of the rectangle.

5. The bell mouth structure according to claim 1, wherein the base portion has a substantially rectangle having four vertices and four sides, and the plurality of positions include a plurality of first positions located between the center of the cylindrical portion and the four vertices of the rectangle, and a plurality of second positions located between the center of the cylindrical portion and substantially midway positions of the four sides of the rectangle.

6. The bell mouth structure according to claim 1, wherein the base portion has a plurality of fastening portions for fixing the bell mouth structure to the housing, and each of the plurality of reinforcing members is configured such that a straight line connecting two of the plurality of fastening portions on both sides of the reinforcing member intersects at two points with an arc defining the curved shape of the reinforcing member.

7. The bell mouth structure according to claim 1, wherein the cylindrical portion, the base portion, and the plurality of reinforcing members are integrally molded from resin.

8. A shroud comprising the bell mouth structure described in claim 1.

9. An outdoor unit for an air conditioning system comprising a substantially rectangular prism housing, a bell mouth structure according to claim 1 provided above the housing, and the fan.

10. The outdoor unit according to claim 9, wherein the outdoor unit comprises a pair of the fan and the bell mouth structure, and when the base is viewed from above, the outer edge of the housing of the outdoor unit and the cylindrical part of the bell mouth structure are in close proximity at approximately the center of the long side of the housing.

11. The outdoor unit according to claim 9, wherein the outdoor unit comprises a plurality of pairs of the fan and the bell mouth structure arranged in the longitudinal direction of the housing, and when the base is viewed from above, the outer edge of the housing of the outdoor unit and the cylindrical portion of the bell mouth structure are in close proximity at approximately the center of the short side of the housing.

12. The outdoor unit according to claim 9, wherein the bell mouth structure has a rounded portion at the boundary between the cylindrical portion and the base portion, and the rounded portion has a radius of curvature that gradually decreases as it approaches the portion where the cylindrical portion and the housing of the outdoor unit are in close proximity.

13. An air conditioning system comprising an indoor unit and an outdoor unit as described in claim 9.

14. A refrigeration cycle apparatus comprising the bell mouth structure described in claim 1.

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