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

Abstract

A bellmouth structure (20) is provided. The bellmouth structure (20) includes a cylindrical portion (21) configured to surround the fan 12, a base portion (30) extending outward from one end of the cylindrical portion, and a plurality of reinforcing members (33 / 35) protruding downward from a surface forming the base portion (30). The plurality of reinforcing members (33 / 35) are provided at a plurality of positions around the cylindrical portion (21) in directions that are approximately symmetrical with respect to the center (O) of the cylindrical portion (20) in a plan view of the base portion (30), and each of the plurality of reinforcing members (33 / 35) has a shape that is curved with respect to the center of the cylindrical portion (21).

Description

[Technical Field]

[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. [Background technology]

[0002] Conventionally, top-flow outdoor units have been known in which a roughly cylindrical bell mouth is installed at the top of the outdoor unit of an air conditioner such as a multi-air conditioner for buildings, surrounding a fan installed at the air outlet. In recent years, to reduce costs, a configuration has also been adopted in which the bell mouth and the shroud of the outdoor unit of the air conditioner are molded as a single unit.

[0003] In the above-mentioned top-flow type outdoor units, the fan diameter and the number of fans are being increased to improve air blowing performance. To efficiently install the outdoor unit in a limited installation space, it is desirable to keep the product's footprint as small as possible, so the fan diameter is often enlarged as much as possible within the product's footprint. As a result, the bell-mouth structure that forms the upper part of the outdoor unit's housing loses rigidity in the area where the cylindrical part (circular duct part) and the outer edge of the housing are close to each other, which may result in increased vibration.

[0004] Furthermore, in the above-mentioned top-flow type outdoor unit, it is expected that the efficiency of the fan will be improved by extending the height of the cylindrical part of the bell mouth, but there are generally restrictions on the height in product design, and if the thickness of the base part is made relatively thin in order to extend the cylindrical part while maintaining the overall height of the bell mouth, there is a concern that the rigidity will decrease.

[0005] Incidentally, the temperature range at the outdoor unit's air outlet is wide, from approximately -40°C to approximately +60°C, and when using ordinary resin materials, thermal expansion can cause expansion or contraction of ± several mm per meter of dimension. While adding reinforcing members or increasing plate thickness can improve rigidity, blindly increasing rigidity can generate stress due to differences in the linear expansion coefficient at fastening points such as screws between the bell mouth structure and the metal parts of the housing, which could lead to damage. The higher the rigidity, the greater the stress.

[0006] Furthermore, since the shroud is also a design component, the placement of a reinforcing member on the outer surface is undesirable because it significantly impairs the design.

[0007] Japanese Utility Model Application Publication No. 60-101464 (Patent Document 1) is known in relation to a bellmouth structure. The prior art in Patent Document 1 discloses a fan shroud having a cylindrical portion extending to surround the outer periphery of the outer ring of the cooling fan, and a funnel-shaped bellmouth portion extending toward the air intake of the cylindrical portion. In the fan shroud in Patent Document 1, a convex rib portion is provided extending diagonally across the upper region of the bellmouth portion, which prevents rainwater, snow, etc. from entering the opening of the bellmouth portion from the top surface of the fan shroud and prevents malfunctions or damage due to freezing, etc.

[0008] Another known bellmouth structure is Japanese Patent No. 7442727 (Patent Document 1). Patent Document 2 discloses a bellmouth structure that includes 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 that connects to the base portion and the cylindrical portion. In the technology of Patent Document 2, the reinforcing member extends continuously from the base portion along the cylindrical portion's outer wall surface from one end to the other in the central axial direction of the cylindrical portion, displacing circumferentially of the cylindrical portion.

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

[0010] In light of the above technical background, there has been a need for the development of a bell mouth structure that achieves both high rigidity and thermal stress suppression, particularly in the base portion, without compromising design. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Application No. 60-101464 [Patent Document 2] Patent No. 7442727 Summary of the Invention [Problem to be solved by the invention]

[0012] The present disclosure has been made in consideration of the above points, and has an object to provide a bell-mouth structure that is reinforced so as to achieve both high rigidity in the base portion and suppression of thermal stress without compromising design, a shroud that has the bell-mouth structure, and an outdoor unit for an air conditioner, an air conditioner, and a refrigeration cycle apparatus that are equipped with the bell-mouth structure. [Means for solving the problem]

[0013] In order to solve the above problems, the present disclosure provides a bellmouth structure having the following characteristics. The bellmouth 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 protruding downward from the surface forming the base. In this bellmouth structure, the multiple reinforcing members are provided at multiple positions around the periphery of the cylindrical portion in directions that are approximately symmetrical about the center of the cylindrical portion when the base portion is viewed in plan, and each of the multiple reinforcing members has a shape that is curved relative to the center of the cylindrical portion.

[0014] The present disclosure also provides a shroud having the above-described bellmouth structure, an outdoor unit of an air conditioning system including the above-described bellmouth structure, an air conditioning system including an indoor unit and the above-described outdoor unit, and a refrigeration cycle apparatus including the above-described bellmouth structure. [Effects of the Invention]

[0015] With the above configuration, it is possible to reinforce the bellmouth structure by achieving both high rigidity in the base portion and suppression of thermal stress without compromising the design. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing 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] FIG. 2 is a diagram showing a schematic configuration of an outdoor unit of an air conditioning system equipped with a bellmouth structure according to one or more embodiments of the present disclosure. [Figure 3] FIG. 3 shows a top perspective view (A) and a side view (B) of a shroud having a bellmouth structure according to one or more embodiments. [Figure 4] FIG. 4 shows a perspective view (A) and a bottom view (B) from below of a shroud having a bellmouth structure according to a first embodiment of the present disclosure. [Figure 5]FIG. 5 shows a perspective view (A) and a bottom view (B) from below of a shroud having a bellmouth structure according to a second embodiment of the present disclosure. [Figure 6] FIG. 6 shows a perspective view (A) and a bottom view (B) from below of a shroud having a bellmouth structure according to a third embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram illustrating the symmetry of rib location in a shroud having a bellmouth structure in accordance with one or more embodiments of the present disclosure. [Figure 8] FIG. 8 is a diagram illustrating the function of curved ribs of a shroud having a bellmouth structure according to one or more embodiments of the present disclosure. [Figure 9] FIG. 9 is a diagram illustrating 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] FIG. 10 is a diagram illustrating an example arrangement of a shroud and a propeller fan having a bellmouth structure according to one or more embodiments of the present disclosure. [Figure 11] FIG. 11 illustrates simulated performance of a shroud with a bellmouth design in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

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

[0018] The present disclosure relates to a bellmouth structure, a shroud having the bellmouth structure, an outdoor unit of an air conditioning system including the bellmouth structure, an air conditioning system including the outdoor unit, and a refrigeration cycle apparatus including the bellmouth structure.

[0019] A bellmouth structure according to an 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 protruding downward from the surface forming the base portion. The reinforcing members are provided at a plurality of positions around the periphery of the cylindrical portion in directions that are substantially symmetrical about the center of the cylindrical portion when the base portion is viewed in plan, and each of the reinforcing members has a shape that is curved with respect to the center of the cylindrical portion.

[0020] With the above configuration, it is possible to reinforce the bellmouth structure by achieving both high rigidity in the base portion and suppression of thermal stress without compromising the design.

[0021] In a preferred embodiment, the curved shape protrudes toward the center of the cylindrical portion at its center when the base is viewed in plan view, thereby making it possible to reinforce the base portion by achieving both high rigidity and thermal stress suppression while preventing interference between the bellmouth structure and the main body on which it is mounted.

[0022] In a preferred embodiment, the base has a generally rectangular shape with four vertices, and the positions are located between the center of the cylindrical portion and the four vertices of the rectangle. In this arrangement, the positions are oriented in directions that have approximately four-fold rotational symmetry. In this manner, by providing a reinforcing member that is curved relative to the center of the cylindrical portion on the flat portion of the base, the rigidity of the flat portion is improved and thermal stress is reduced.

[0023] In a preferred embodiment, the base portion has a generally rectangular shape with four sides, and the plurality of positions are located between the center of the tubular portion and positions approximately midway between the four sides of the rectangle. In this arrangement, the plurality of positions are in directions with four-fold rotational symmetry. This reinforcement provides sufficient escape routes for thermal expansion and contraction, minimizing increases 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 includes 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 positions and the second positions are each located at positions having four-fold rotational symmetry, and the plurality of positions, including the first positions and the second positions, are located in directions having eight-fold rotational symmetry. This allows for a synergistic effect to be obtained 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 bellmouth structure to the housing, and each of the plurality of reinforcing members is configured so that a straight line connecting two of the plurality of fastening portions on both sides of the reinforcing member intersects with an arc defining the curved shape of the reinforcing member at two points. This allows the reinforcing member to function as a flexible structure with respect to thermal expansion and contraction, while providing high rigidity to the flat portion.

[0026] In a specific embodiment, the tubular portion, the base portion, and the plurality of reinforcing members are integrally molded from resin.

[0027] A shroud according to an embodiment of the present disclosure includes the bellmouth structure described above.

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

[0029] In a specific embodiment, the outdoor unit includes a fan and a pair of bellmouth structures, and when the base is viewed from above, the outer edge of the outdoor unit housing and the cylindrical portion of the bellmouth structure are adjacent to each other at approximately the center of the long side of the housing. The bellmouth structure of the present disclosure is useful in such a configuration.

[0030] In a specific embodiment, the outdoor unit includes multiple pairs of fans and bellmouth structures aligned in the longitudinal direction of the housing, and in a plan view of the base, the outer edge of the outdoor unit housing and the cylindrical portion of the bellmouth structure are adjacent to each other at approximately the center of the short side of the housing. The bellmouth structure of the present disclosure is useful in such a configuration.

[0031] In a specific embodiment, the bellmouth 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 toward the area where the cylindrical portion and the outdoor unit housing are close to each other. The bellmouth structure of the present disclosure is useful in such a configuration.

[0032] An air conditioning system according to the present disclosure includes the outdoor unit and indoor unit described above.

[0033] A refrigeration cycle device according to the present disclosure includes the above-described bellmouth structure.

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

[0035] Referring to FIG. 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 FIG. 1, the air conditioning system 1 includes one or more indoor units 4 (4a, 4b, etc.) that are each installed indoors (air-conditioned spaces), and an outdoor unit 10 that is installed outdoors. The one or more indoor units 4a, 4b, etc. and the outdoor unit 10 are connected via refrigerant piping 2. For example, a hydrofluorocarbon such as R410a or R32 can be used as the refrigerant.

[0036] During operation, the indoor unit 4 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 equipped with an indoor heat exchanger and an indoor blower such as a crossflow fan in the refrigeration cycle of the air conditioning system 1.

[0037] The outdoor unit 10 starts up upon receiving instructions from a control device, and controls the operation of the compressor and outdoor fan according to the operation mode set by an operating device, which includes a remote controller, a central control device, etc.

[0038] 1 shows two indoor units 4a and 4b as the indoor units 4, the number of indoor units 4 is not particularly limited and may be one, or three or more. Also, the number of outdoor units 10 is shown as one, but is not limited to one.

[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 may be connected to the indoor unit 4 via the communication line in the room where the indoor unit 4 is installed. Furthermore, a centralized controller that centrally controls one or more indoor units 4a, 4b and the outdoor unit 10 may be connected via the communication line.

[0040] 1, the air conditioning system 1 is depicted as an embodiment of a multi-air conditioner for a building equipped with an up-blowing type outdoor unit 10. The bell-mouth structure according to the embodiment of the present disclosure is suitably applicable to up-blowing type outdoor units, but in the embodiment of the present disclosure, the form of the air conditioning system 1 is not necessarily limited to this and may also be directed to a packaged air conditioner.

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

[0042] 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 in a refrigeration cycle.

[0043] 2 is configured to include a compressor 16 arranged in a housing 19, an outdoor heat exchanger 17, an electrical component box 18 arranged 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 placed over the housing 19. In the embodiment to be described, the shroud 20 is integrated with a bell mouth of the outdoor unit and configures a bell mouth structure according to an embodiment of the present disclosure.

[0044] Blower 11 is configured to include a propeller fan (propeller) 12 and a motor 13 that drives propeller fan 12. Propeller fan 12 has blades that rotate and blow air around a rotation axis, and the number of blades is not particularly limited, but may be three, for example. When propeller fan 12 of blower 11 is rotated by motor 13, outdoor unit 10 draws air from outside housing 19 through the side of outdoor heat exchanger 17, as shown by the thick arrow in Figure 2, performs heat exchange in outdoor heat exchanger 17, and discharges the air into the atmosphere from the upper opening of shroud 20.

[0045] As described above, in the outdoor unit 10 of the air conditioning system 1, increasing the height of the cylindrical portion of the bellmouth structure of the shroud 20 is expected to improve the efficiency of the fan. However, because height is generally limited by product design, it is desirable to increase the cylindrical portion while maintaining the overall height of the bellmouth structure of the shroud 20. To achieve this, it is necessary to reinforce the base of the bellmouth structure of the shroud 20 to address the reduction in thickness. Furthermore, from the perspective of the design of the shroud 20, it is desirable to place reinforcing members on parts of the shroud 20 that are not visible, other than the outer surface.

[0046] The rigidity of the bellmouth structure can be broadly classified into the ring rigidity of the tubular portion and the flat rigidity of the base portion. If there is even a portion with low rigidity relative to the entire circumference, the tubular portion is prone to elliptical deformation starting from that portion, resulting in an extreme decrease in ring rigidity. The decrease in rigidity in the portion where the outer edge of the base portion and the tubular portion are close to each other is particularly problematic. Meanwhile, with regard to the base portion, it is important to ensure the rigidity of the flat portion away from the tubular portion in addition to the portion where the outer edge of the base portion and the tubular portion are close to each other. Therefore, if the height of the base portion needs to be kept low, it is difficult to ensure sufficient reinforcement height.

[0047] Therefore, a simple approach to improving the rigidity of the bellmouth structure would be to provide reinforcing members such as ribs around the entire circumference of the cylindrical portion, including both the adjacent and flat portions. However, providing ribs around the entire circumference, including both the adjacent and flat portions, would increase rigidity but also significantly increase thermal stress, as described below. This is because the amount of expansion and contraction due to differences in thermal expansion coefficients (linear expansion coefficients) is determined by the original length x the linear expansion coefficient x temperature change, regardless of the rigidity of the material. The greater the rigidity, the greater the force generated at constraint points such as screws, resulting in worsening of the condition. In other words, high rigidity and low thermal stress are inversely related, and increasing overall rigidity actually increases thermal stress.

[0048] For this reason, there is a need to reinforce the base of the bellmouth structure while simultaneously increasing its rigidity and suppressing thermal stress by placing reinforcing members locally and effectively, rather than all over the surface, in areas that cannot be seen other than the outer surface.

[0049] Therefore, this embodiment employs a configuration that includes a cylindrical circular duct (tubular portion) configured to surround the propeller fan, a base extending outward from the bottom end of the circular duct, and multiple ribs (reinforcing members) protruding downward from the surface forming the base, with the multiple ribs being provided at multiple positions around the circular duct in directions that are approximately symmetrical with respect to the center of the circular duct when the base is viewed from above, and each of the multiple ribs has a curved shape with respect to the center of the circular duct. This aims to reinforce the base portion of the bellmouth structure so that it both increases the rigidity and suppresses thermal stress without compromising design.

[0050] Hereinafter, the configuration of a shroud having a bellmouth structure according to one or more embodiments of the present disclosure will be described in more detail with reference to FIGS.

[0051] Fig. 3 shows a perspective view (A) from above and a front view (B) of a shroud having a bellmouth structure according to the first to third embodiments of the present disclosure. Figs. 4 to 6 show a perspective view (A) from below and a bottom view (B) of a shroud having a bellmouth structure according to the first to third embodiments of the present disclosure. Figs. 7(A) to 7(C) are diagrams explaining the symmetry of the rib positions of a shroud having a bellmouth structure according to the first to third embodiments of the present disclosure. Fig. 8 is a diagram explaining the function of the ribs of a shroud having a bellmouth structure according to the first to third embodiments of the present disclosure.

[0052] A shroud 20 having a bellmouth structure according to a 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] 3 and 4 includes 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 generally cylindrical shape that is open at the upper end U and the lower end L.

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

[0055] More specifically, the circular duct portion 21 includes a round portion 22, an intermediate portion 23, and an expanded diameter portion 24. The round portion 22 is the boundary between the circular duct portion 21 and the base portion 30, and smoothly connects the base portion 30, which expands in a planar direction with a predetermined radius of curvature, to the cylindrical circular duct portion 21, which extends perpendicular to the plane of the base portion 30. The intermediate portion 23 is a cylindrical portion located above the round portion 22 and has a substantially constant diameter to ensure the above-mentioned clearance. As shown in FIG. 2, the propeller fan 12 is mainly housed inside this intermediate portion 23. The circular duct portion 21 constitutes the tubular portion in this embodiment.

[0056] In the embodiment being described, the circular duct portion 21 has an expanded diameter portion 24, and employs a structure in which the diameter expands stepwise from the center, a so-called multi-stage expansion structure. A bell mouth equipped with such an expanded diameter portion 24 is also called a long bell mouth. By employing this long bell mouth configuration, the air flow is smoothed, fan input is reduced, and high efficiency and improved performance over a wide operating range are achieved.

[0057] The base 30 has a substantially 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 FIG. 2). The base 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 substantially rectangular shape. In the embodiment to be described, the rectangle of the base 30 is roughly close to a square, but has a substantially rectangular shape with long and short sides. The base 30 is open where the circular duct portion 21 is provided. The base 30 constitutes the base in this embodiment.

[0058] The base 30 is provided with a mechanism for fastening to a member (e.g., a metal plate) on the housing 19 side, and in the embodiment described, screw holes 31a to 31h are formed in recesses at a total of eight locations, two at each of the four corners of the substantially rectangular shape (one on each side of each vertex). By inserting screws through the screw holes 31a to 31h and fastening them to the housing 19, the shroud 20 and the housing 19 are fixed together.

[0059] As shown in Fig. 4(B) surrounded by dashed and dot-dash line rings, the base portion 30 has two main portions. The first portion is the portion (proximal portion) 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 close to each other, shown surrounded by dashed line rings, and four proximal portions are shown in Fig. 4(B). The second portion is the portion (flat portion) at the four corners away from the circular duct portion 21, shown surrounded by dash-dotted line rings, and four flat portion are shown in Fig. 4(B). It is important for the shroud 20 to ensure the rigidity of the proximal portion and the flat portion.

[0060] As shown in FIGS. 4(A) and 4(B), the shroud 20 according to the first embodiment further includes a plurality of ribs 33 protruding downward from the surface (or plane) 32 forming the base portion 30. In the embodiment being described, four ribs 33a to 33d are provided. The plurality of ribs 33 constitute a reinforcing member in the embodiment of the present disclosure. If there is even a portion with low rigidity relative to the entire circumference, the circular duct portion 21 becomes prone to elliptical deformation starting from that portion, resulting in an extreme decrease in ring rigidity. Therefore, the plurality of ribs 33 according to the first embodiment are reinforcing members that particularly improve the rigidity of the portion near the base portion 30, which is prone to low rigidity and is indicated by the dashed ring in FIG. 4(B).

[0061] The four ribs 33a to 33d are positioned around the circular duct portion 21 (more specifically, outside the circle formed by the minimum diameter of the cylindrical shape of the circular duct portion 21) when the base portion 30 is viewed in plan (the bottom view shown in FIG. 4(B)), and are located between the center indicated by O of the circular duct portion 21 and approximately the middle positions of the four sides of the rectangle of the base portion 30. Each of the four ribs 33a to 33d has a curved shape with respect to the center O of the circular duct portion 21 when the base portion 30 is viewed in plan, and in the described embodiment, the ribs protrude convexly from the center O of the circular duct portion 21 so that the central portion of the curved shape approaches the center O of the circular duct portion 21. The curved rib 33 locally reinforces the area between the fastening points 31 on both sides of the rib 33 rather than reinforcing the entire area.

[0062] 4(A) and 4(B), flat ribs 34a to 34d are provided on the outer edge of the base 30 of each of the curved ribs 33a to 33d, connecting to both ends of each curved rib 33. The curved rib 33 and the flat rib 34 form a half-moon shape. The flat rib 34 is a rib for preventing air leakage and may not be provided.

[0063] 7A is a diagram illustrating the symmetry of the rib arrangement of 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 FIGS. 3 and 4, the positions at which the curved ribs 33a to 33d are arranged generally coincide with directions having four-fold rotational symmetry with the center O of the circular duct portion 21 as the rotation axis. The positions of the 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 the ribs 33a and 33c are mirror-symmetric with respect to a plane m2 passing through the center O of the circular duct portion 21. In this way, the ribs 33a to 33d are provided at positions around the circular duct portion 21 in directions that are approximately symmetric with respect to the center O of the circular duct portion 21, when the base portion 30 is viewed from above. Here, the rectangular shape of the base 30 is a rectangle that is roughly close to a square, and the "direction having substantial symmetry" means that it is acceptable that the direction may not strictly coincide with the position having the above symmetry (rotational symmetry or mirror symmetry) depending on the degree to which the rectangular shape of the base 30 deviates from a square in design and due to manufacturing errors. Also, the "position where the rib is disposed" 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 (shown as B in FIG. 3(B)) formed by the bottom of the side surface (shown as 30a in FIG. 3(B)) of the base 30, as long as it does not interfere with the components of the housing 19 on which the base 30 is mounted. On the other hand, at the position where the rib 33 comes into contact with the components of the housing 19 on which the base 30 is mounted, the height of the rib 33 is kept within a range that does not interfere with the components of the housing 19.

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

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

[0067] If the entire area between fastening points 31L and 31R were reinforced with a straight rib R' as shown in FIG. 8(A), there would be no escape route for thermal expansion and contraction S, resulting in increased thermal stress. In contrast, as shown in FIG. 8(B), by adopting the configuration of the first embodiment of the present disclosure and locally reinforcing the area between 31L and 31R with a curved rib R, there would be sufficient escape route for thermal expansion and contraction S, and the increase in thermal stress could be minimized. This allows the rigidity of the base portion 30 of the shroud 20 to be improved while minimizing the increase in thermal stress. Consequently, it is possible to provide a shroud 20 that satisfies thermal stress requirements and has improved rigidity.

[0068] Moreover, according to the first embodiment, the design is not impaired by providing the ribs 33 that protrude downward from the base 30. Furthermore, according to the first embodiment, the base 30 can be reinforced efficiently, so there is no need to increase the overall thickness, and therefore the total weight of the resin used can be reduced, leading to cost reductions.

[0069] A shroud 20A having a bellmouth structure according to a second embodiment of the present 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 are designated by the same reference numerals.

[0070] 3 and 5, similar to the first embodiment, the shroud 20A includes a circular duct portion 21 including a round portion 22, an intermediate portion 23, and an expanded diameter portion 24, and a base portion 30 having a substantially rectangular shape and extending outward from a lower end L of the circular duct portion 21. The base portion 30 is provided with screw holes 31a to 31h at the same positions as in the first embodiment. The following description will focus on differences from the first embodiment, and unless otherwise specified, the shroud 20A will be considered to have the same configuration as the first embodiment to the extent that there is no contradiction.

[0071] As shown in FIGS. 5A and 5B, the shroud 20A, like the first embodiment, is provided with multiple ribs 35 protruding downward from the surface 32 forming the base portion 30. In the embodiment being described, four ribs 35a to 35d are provided at the four corners. If 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 portions, reducing the rigidity of these areas and causing increased vibration. The multiple ribs 35 constitute reinforcing members in the embodiment of the present disclosure for improving the rigidity of the flat portions of the base portion 30, as indicated by the chain dotted line ring in FIG. 5B.

[0072] The positions of the multiple ribs 35a to 35d are different from those in the first embodiment, and more specifically, when the base 30 is viewed from above (the bottom view shown in FIG. 5(B)), the multiple ribs 35a to 35d are 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 30. As in the first embodiment, when the base 30 is viewed from above, each of the multiple ribs 35a to 35d has a curved shape (bow or arch shape) that is curved with respect to the center O of the circular duct portion 21, and in the embodiment being described, the ribs protrude convexly with respect to the center O of the circular duct portion 21 so that the central portion of the curved shape approaches the center O of the circular duct portion 21.

[0073] The base 30 has a plurality of fastening portions (31a to 31h) for fixing the shroud 20A to the housing. Each rib 35 is configured so that a straight line connecting two of the plurality of fastening portions on either side of the rib 35 intersects with an arc defining the curved shape of the rib 35 at two points. The curved rib 35 reinforces the areas between the fastening points 31 on both sides of each of the four corners.

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

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

[0076] Advantages of the shroud 20 according to the second embodiment described with reference to FIGS. 3, 5, and 7B will be described below with reference to FIGS. 8(C) and 8(D). FIG. 8(C) is a diagram illustrating a case in which the area between two fastening points 31T, 31U is reinforced with a curved rib 35, as in the second embodiment of the present disclosure. FIG. 8(D) is a diagram illustrating a comparison between a case in which the area between two fastening points 31T, 31U is reinforced with a curved rib 35 and a case in which the area is reinforced linearly.

[0077] As mentioned above, if the largest possible circular duct portion 21 is provided approximately at the center of the approximately rectangular base 30, the rigidity of the flat portion at the four corners of the base 30 decreases, resulting in increased vibration. Therefore, providing reinforcing members such as ribs on the flat portion is considered to increase rigidity. However, providing linear ribs at the fastening points, as shown on the left side of Figure 8(D), increases stress because there is no escape route for thermal expansion and contraction. In contrast, providing arch-shaped ribs 35 curved toward the center O of the circular duct portion 21 on the flat portion of the base 30, as shown on the right side of Figure 8(C) and Figure 8(D), improves the rigidity of the flat portion while reducing thermal stress. This is because the arch-shaped rib configuration between the fastening points allows the ribs 35 to act as a flexible structure against thermal expansion and contraction while providing high rigidity to the flat portion, as shown on the right side of Figure 8(D).

[0078] As described above, according to the second embodiment, it is possible to provide a shroud 20A that satisfies high rigidity while minimizing thermal stress. Also, according to the second embodiment, similar to the first embodiment, the design is not impaired. Furthermore, according to the second embodiment, since the base portion 30 can be efficiently reinforced, there is no need to increase the overall thickness, so the total weight of the resin used can be reduced, and costs can also be reduced.

[0079] A shroud 20B equipped with a bellmouth structure according to a third embodiment of the present disclosure will be described below 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 are designated by the same reference numerals.

[0080] 3 and 6 includes 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 base portion 30 at the same positions as in the first and second embodiments. The following description will focus on differences from the first and second embodiments, and unless otherwise specified, the shroud 20B will be considered to have the same configuration as the first or second embodiment to the extent that there is no contradiction.

[0081] As shown in FIGS. 6A and 6B, the shroud 20B is provided with a plurality of ribs 33 protruding downward from the surface 32 forming the base portion 30, similar to the first embodiment. Accordingly, flat ribs 34a to 34d are provided in addition to the curved ribs 33a to 33d, similar to the first embodiment. Furthermore, the shroud 20B is provided with a plurality of ribs 35 protruding downward from the surface 32 forming the base portion 30, similar to the second embodiment. The plurality of ribs 33 and ribs 35 constitute reinforcing members in the embodiment of the present disclosure. Similar to the first embodiment, the plurality of ribs 33 are reinforcing members for improving the rigidity of the adjacent portion of the base portion 30, indicated by the broken-line ring. Similarly to the second embodiment, the plurality of ribs 35 are reinforcing members for improving the rigidity of the flat portion of the base portion 30, indicated by the chain-dotted-line ring.

[0082] As in the first embodiment, the multiple ribs 33a to 33d are positioned between the center O of the circular duct portion 21 and the middle positions of the four sides of the rectangular shape of the base portion 30. On the other hand, as in the second embodiment, the multiple ribs 35a to 35d are positioned 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. As in the first and second embodiments, each of the multiple ribs 33a to 33d and 35a to 35d protrudes convexly from the center O of the circular duct portion 21 so as to approach the center O of the circular duct portion 21 at the center of its curved shape.

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

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

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

[0086] FIG. 9 is a diagram illustrating the connection 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). FIG. 9 illustrates the connection structure of one corner of the rectangular shape of base portion 30 of shroud 20A according to a second embodiment. As shown in FIG. 9, rib 35 is configured so that its height H1 is greater than the thickness D of base portion 30 itself, but within a range that does not interfere with member 19a of housing 19 on which base portion 30 is mounted. Meanwhile, at a position where base portion 30 comes into contact with member 19a of housing 19 on which base portion 30 is mounted (e.g., around screw hole portion 31), height H2 of rib 33 is kept within a height range (≦D) that does not interfere with member 19a of housing 19.

[0087] An example of the arrangement of the shroud 20 (or 20A or 20B) having a bellmouth structure and the propeller fan 12 according to one or more embodiments of the present disclosure will be described below with reference to Fig. 10. Figs. 10(A) and 10(B) show plan views illustrating the arrangement of the shroud 20 and the propeller fan 12 on the top surface of the outdoor unit 10. Figs. 10(C) and 10(D) show perspective views of the outdoor unit 10 from above.

[0088] 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 Fig. 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 to each other at approximately the center of the long side X of the housing 19, as indicated by the broken line ring. The shrouds 20, 20A, and 20B according to the first to third embodiments of the present disclosure are useful in the arrangement examples shown in Fig. 10(A) and 10(C).

[0089] 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 Fig. 10(B) and Fig. 10(D), a first pair of propeller fan 12-1 and shroud 20-1 and a second pair of propeller fan 12-2 and shroud 20-2 are aligned in the longitudinal direction of casing 19, and the outer edge of casing 19 of outdoor unit 10 and circular duct portions 21-1, 21-2 of the two shrouds 20-1, 20-2 are adjacent to each other at approximately the center of short side Y of casing 19. The shrouds 20, 20A, 20B according to the first to third embodiments of the present disclosure are useful in the arrangement examples shown in Fig. 10(B) and Fig. 10(D).

[0090] In connection with the connection between the circular duct portion 21 and the base portion 30, the rounded portion 22 connects the circular duct portion 21 and the base portion 30 with a predetermined radius of curvature as described above. Regarding the adjacent portion represented by the dashed-line ring in FIG. 10 , the rounded portion 22 has a basic radius of curvature (maximum value) over most of its circumference, and is configured to have a radius of curvature that gradually decreases toward the adjacent portion indicated by the dashed-line ring, where the circular duct portion 21 and the housing 19 of the outdoor unit 10 are adjacent. In this way, a smooth shape is achieved by gradually decreasing the curvature in a narrow region 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 the present disclosure are useful in such a configuration having a radius of curvature that gradually decreases toward the adjacent portion indicated by the dashed-line ring.

[0091] Hereinafter, the characteristics of the shrouds 20, 20A, 20B according to the first to third embodiments described with reference to FIGS. 1 to 10 will be described with reference to FIG.

[0092] FIG. 11 shows the results of simulating the characteristics of shrouds 20, 20A, and 20B equipped with the bellmouth structures according to the first to third embodiments of the present disclosure. For comparison, FIG. 11 also shows the results of simulations of shrouds equipped with other configurations. In FIG. 5, the first column indicates the experiment number, and the second column indicates the shape of the model used in the simulation. The third to fifth columns show the simulation results, where the third column indicates the ring stiffness, the fourth column indicates the plate stiffness, and the fifth column indicates the thermal stress. Note that the stiffness was calculated from the square of the natural frequency ratio, since the natural frequency is proportional to the square root of the stiffness. The results suggest that it is desirable to improve the ring stiffness and plate stiffness while keeping the thermal stress within a predetermined range (for example, a maximum increase of 10%).

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

[0094] The experimental results indicated by numbers 3 to 5 correspond to configurations including curved ribs according to embodiments of the present disclosure. The experimental result indicated by number 1 serves as the reference. As can be seen from the table in FIG. 11, the experimental result indicated by number 2 shows that the baseline model improved in ring stiffness by 816% and plate stiffness by 1001%, but the thermal stress also increased by 32%. Although the stiffness improved, the thermal stress increased to an unacceptable level.

[0095] In contrast, the experimental results for No. 3 showed that the ring stiffness was 217% and the plate stiffness was 222%, meaning that the stiffness in the ring and plate modes was approximately doubled, while the thermal stress increase was limited to about 12%. The experimental results for No. 4 showed that the ring stiffness was about 107%, but the plate stiffness was improved to 156%, meaning that the thermal stress decrease was about 8%. The experimental results for No. 5 showed that the ring stiffness was 225% and the plate stiffness was 295%, meaning that the stiffness in the ring and plate modes was more than doubled, while the thermal stress increase was limited to about 8%.

[0096] As described above, in the configurations (numbers 3 to 5) in which the curved ribs according to the embodiment of the present disclosure are provided on the base portion, it is possible to improve rigidity while suppressing an increase in thermal stress, and it is shown that the base portion can be reinforced by achieving both high rigidity and suppression of thermal stress without compromising design. In particular, in the configuration (number 5) in which both curved ribs 33 and 35 according to the embodiment of the present disclosure are provided, the synergistic effect of the reinforcement of the adjacent portion by the curved rib 33 and the reinforcement of the flat portion by the curved rib 35 allows the rigidity to be improved by two to three times while suppressing thermal stress, which is the most balanced.

[0097] As described above, according to the embodiments of the present disclosure, it is possible to provide a bellmouth structure that is reinforced so as to simultaneously increase the rigidity of the base portion and suppress thermal stress without compromising design, a shroud that has the bellmouth structure, and an outdoor unit for an air conditioner, an air conditioner, and a refrigeration cycle apparatus that are equipped with the bellmouth structure.

[0098] In the above-described embodiments, an air conditioning system or an air conditioner including an outdoor unit with the above-described bellmouth structure has been described as an example. However, the bellmouth structure according to this embodiment is not limited to an outdoor unit of an air conditioning system. In other embodiments, the bellmouth structure may be applied to a refrigeration cycle device other than an air conditioning system. Here, the refrigeration cycle device is also called a refrigeration air conditioning device, which collectively refers to devices that use a refrigerant and a refrigeration cycle, such as the air conditioning system described above, refrigerators, freezers, etc. More specifically, examples of refrigeration air conditioning devices include the above-described air conditioning systems such as package air conditioners and multi-air conditioners for buildings, heat source devices such as freezers and chilling units, commercial freezers such as showcases, refrigerator-freezers, unit coolers, and ice makers, transportation refrigeration devices such as car air conditioners, and heat pump water heaters.

[0099] It should be noted that the embodiments of the present disclosure are not limited to the above-described embodiments and may include various modifications. For example, the above-described embodiments have been described in detail for ease of understanding, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

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

Claims

1. A bell mouth structure, a cylindrical portion configured to surround the fan; a base portion extending outward from one end of the cylindrical portion; a plurality of reinforcing members protruding downward from a surface forming the base portion; the plurality of reinforcing members are provided at a plurality of positions around the tubular portion in directions that are approximately symmetrical about the center of the tubular portion in a plan view of the base portion, and each of the plurality of reinforcing members has a shape that is curved with respect to the center of the tubular portion, and the curved shape protrudes at a central portion of the curved shape so as to approach the center of the tubular portion in a plan view of the base portion.

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

3. 2. The bellmouth structure according to claim 1, wherein the base portion has a substantially rectangular shape having four sides, and the plurality of positions are located between the center of the cylindrical portion and positions that are substantially midpoints of the four sides of the rectangle.

4. 2. The bellmouth structure according to claim 1, wherein the base portion has a substantially rectangular shape 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 positions approximately midpoints of the four sides of the rectangle.

5. 2. The bellmouth structure according to claim 1, wherein the base portion has a plurality of fastening portions for fixing the bellmouth structure to a housing, and each of the plurality of reinforcing members is configured so that a straight line connecting two of the plurality of fastening portions on either side of the reinforcing member intersects at two points with an arc defining the curved shape of the reinforcing member.

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

7. The bellmouth structure according to claim 1 Shroud including.

8. A substantially rectangular parallelepiped housing; the bell-mouth structure according to claim 1 provided above the housing; The fan and An outdoor unit of an air conditioning system comprising:

9. The outdoor unit is 9. The outdoor unit according to claim 8, comprising a pair of the fan and the bell-mouth structure, wherein, in a plan view of the base, an outer edge of the housing of the outdoor unit and the cylindrical portion of the bell-mouth structure are adjacent to each other at approximately the center of a long side of the housing.

10. The outdoor unit is 9. The outdoor unit according to claim 8, comprising a plurality of pairs of the fan and the bellmouth structure arranged in the longitudinal direction of the housing, wherein, in a plan view of the base, an outer edge of the housing of the outdoor unit and the cylindrical portion of the bellmouth structure are adjacent to each other at approximately the center of a short side of the housing.

11. 9. The outdoor unit according to claim 8, wherein the bell-mouth structure has a rounded portion at a boundary between the cylindrical portion and the base portion, and the rounded portion has a radius of curvature that gradually decreases toward a portion where the cylindrical portion and the housing of the outdoor unit are close to each other.

12. An air conditioning system comprising an indoor unit and the outdoor unit according to claim 8.

13. A refrigeration cycle device comprising the bell mouth structure according to claim 1.

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