An outdoor unit for an air conditioner

Abstract

The present invention relates to an outdoor unit for an air conditioner. The outdoor unit comprising a casing, a fan and a grille (100) for covering an air discharge port by having a frame (140) fitted thereon. The grille (100) comprising an inner rim (110), a plurality of circular ribs (101) within the inner rim (110) and an outer rim (120) provided surrounding the inner rim (110). The grille (100) further comprising a plurality of peripheral guide members (130) disposed between the inner rim (110) and the outer rim (120) with each of them tilted at a predetermined angle, and having an outwardly curved surface on a first lateral side (131) and an inwardly curved surface on a second lateral side (132).

Description

[0001] AN OUTDOOR UNIT FOR AN AIR CONDITIONER

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an outdoor unit for an air conditioner, and more particularly, to an outdoor unit provided with a grille for improving air blowing performance and reducing air blowing noise for an air conditioner.

[0004] BACKGROUND OF THE INVENTION

[0005] An outdoor unit for an air conditioner is generally equipped with a grille in front of an outdoor fan. The grille serves as a physical barrier that protects human fingers from accidental contact with rotating blades of the outdoor fan and also protects the outdoor fan and other electrical components of the outdoor unit from being hit by large objects. It is also useful to reduce dust from entering and clogging up the outdoor fan.

[0006] There have been a number of grille structures available over the prior art aiming to provide an optimal air flow and noise reduction. One of them is disclosed in CN102758802B which provides a protective fan cover for an outdoor unit of the air conditioner. The protective fan cover is having an air guide assembly which comprises a plurality of guide vanes with each of them having the middle part protruding forward towards a counter-clockwise direction. The plurality of guide vanes are formed to be inclined in an opposite direction from that of the impeller blades. Nevertheless, the discharged air is unable to flow towards a radial direction which corresponds to the direction where the impeller rotates. Fundamentally, whenever there is an air stream being forced to change its flow direction, energy loss will occur due to presence of air resistance and drag when the air stream passes through the air guide assembly. The air stream will be deflected and changed to flow in axial direction by the air guide assembly, causing the air unable to be smoothly delivered across the air guide assembly. Prior art document CN202382333U discloses another grille for use in an outdoor unit of an air conditioner, in which the grille is having an outer frame body, a middle grille and a plurality of wind guiding grilles disposed between the outer frame body and the middle grille. The wind guiding grilles are formed by sequentially arranging a plurality of arc sweep forward guide vanes which can be used for deflecting air current flowing through a periphery of the grille to flow in axial direction as much as possible and leading out the deflecting air current. The two ends of each arc sweep forward guide vane are respectively connected to the middle grille and the outer frame body. Similar to the aforementioned prior art, the configuration of the grille does not allow the air to flow towards a radial direction which corresponds to the direction of the fan rotation. This may lead to certain energy loss when the air flow is deflected into another direction. At the same time, the air flow may not be able to be led out smoothly due to presence of air resistance and drag.

[0007] Another prior art document US201 1000653A1 further discloses a different grille for an outdoor unit of an air conditioner, in which the grille is provided with a plurality of slit-like openings on its right frame wall portion, upper and lower frame wall portions. A predetermined amount of air is blown from the openings of the right frame wall portion, the upper frame wall portion and the lower frame wall portion as sub-streams. On the other hand, the prior art document does not provide further disclosure on how the openings on the frame wall portions are useful or beneficial in improving the air flow performance at a periphery of the grille.

[0008] Accordingly, it can be seen in the prior art documents that there exists a need to provide a grille for an outdoor unit of an air conditioner which is capable of producing an optimal air flow by allowing air to flow smoothly across a periphery of the grille and significantly lowering air flow resistance, thereby reducing noise of the outdoor unit.

[0009] SUMMARY OF INVENTION An object of the present invention is to provide a grille for an outdoor unit of an air conditioner for optimizing air flow across the grille and lowering noise of the outdoor unit.

[0010] Another object of the present invention is to provide a grille for an outdoor unit of an air conditioner that is capable of facilitating radial air flow across a periphery of the grille, thereby lowering air resistance at the periphery of the grille.

[0011] A further object of the present invention is to provide a grille for an outdoor unit of an air conditioner that is capable of reducing resistance of axial air flow by having a plurality of customized openings at different regions of the grille for optimizing air flow.

[0012] It is another object of the present invention to provide a grille for an outdoor unit of an air conditioner that is capable of reducing flow separation across a periphery of the grille, contributing to lesser turbulence and air resistance.

[0013] It is a further object of the present invention to provide a grille for an outdoor unit of an air conditioner with a relatively rigid outer peripheral structure that allows a technician to grip thereon, thereby contributing to a better ergonomics during installing and removing the grille.

[0014] Accordingly, these objects are achievable by following the disclosure and teachings of the present invention. The present invention relates to an outdoor unit for an air conditioner, in which the outdoor unit comprising a casing, a fan disposed to be accommodated in the casing, an air discharge port formed on the casing for discharging an air flow generated by the fan, and a grille having a frame for covering the air discharge port by having the frame fitted thereon.

[0015] In the present invention, the grille is preferably comprising an inner rim, a plurality of circular ribs disposed concentrically at predetermined intervals within the inner rim, and a plurality of radial crosspieces intersecting the circular ribs and disposed radially from a center of the grille to the inner rim. The grille further comprises an outer rim with a greater diameter than the inner rim and disposed surrounding the inner rim. Furthermore, the grille preferably comprising a plurality of peripheral guide members that is disposed radially between the inner rim and the outer rim with each peripheral guide member having an outwardly curved surface on a first lateral side and an inwardly curved surface on a second lateral side opposing the first lateral side. The plurality of peripheral guide members is formed to be tilted at a predetermined angle that corresponds to a direction of the air flow generated by the fan.

[0016] In a preferred embodiment of the present invention, the frame of the grille is disposed behind the outer rim and the inner rim of the grille, and there is a plurality of side openings disposed between the outer rim of the grille and the frame of the grille. The plurality of side openings is formed by having the plurality of peripheral guide members to further extend from the outer rim and the inner rim towards the frame of the grille in a substantially rearward direction. Preferably, the plurality of peripheral guide members comprising a lateral cross-section of a substantially triangular shape or a substantially trapezoid shape.

[0017] Moreover, the inner rim of the grille may be having a diameter smaller than that of the frame of the grille. In a different embodiment of the present invention, the inner rim of the grille may be having a diameter substantially equal to that of the frame of the grille. On the other hand, the outer rim of the grille is disposed to extend over the frame of the grille to provide an outwardly protruding peripheral edge. The outwardly protruding peripheral edge of the outer rim comprising a lateral cross-section of a substantially triangular shape.

[0018] Furthermore, the plurality of peripheral guide members is formed to be tilted at the predetermined angle towards a counter-clockwise direction or a clockwise direction according to the direction of the air flow generated by the fan. The predetermined angle is preferably within a range of 20° to 30° relative to a reference line which is extending radially from the center of the fan. In each peripheral guide member of the present invention, the outwardly curved surface on the first lateral side thereof and the inwardly curved surface on the second lateral side thereof comprise at least two arc segments with different curvatures respectively.

[0019] In a preferred embodiment of the present invention, each of the plurality of circular ribs comprising an aerofoil-shaped cross-section, and the plurality of circular ribs is inclined at a predetermined angle that corresponds to the direction of the air flow generated by the fan. The predetermined angle is preferably within a range of 0° to 15° relative to the axis of the fan. On the other hand, each of the plurality of radial crosspieces comprising an aerofoil-shaped cross-section, and the plurality of radial crosspieces is inclined at a predetermined angle that corresponds to the direction to the air flow generated by the fan. Preferably, the predetermined angle is within a range of 20° to 30° relative to the axis of the fan.

[0020] In a further preferred embodiment of the present invention, the plurality of circular ribs is spaced apart from each other with multiple predetermined intervals. Further, the predetermined intervals of the circular ribs are gradually increasing from the inner rim towards the center of the grille. On the other hand, at least a middle region of the circular ribs between the inner rim and the center of the grille is having a greater depth dimension.

[0021] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0022] The features of the invention will be more readily understood and appreciated from the following detailed description when read in conjunction with the accompanying drawings of the preferred embodiment of the present invention, in which:

[0023] Figure 1 (a) illustrates a perspective view of an outdoor unit of an air conditioner according to a preferred embodiment of the present invention. Figure 1 (b) illustrates a side view of an outdoor unit of an air conditioner according to a preferred embodiment of the present invention.

[0024] Figure 2 illustrates a close-up front view of a grille for an outdoor unit of an air conditioner according to a preferred embodiment of the present invention.

[0025] Figure 3 illustrates a close-up view showing a peripheral guide member of a grille for an outdoor unit of an air conditioner according to a preferred embodiment of the present invention.

[0026] Figure 4 illustrates a side perspective view a grille for an outdoor unit of an air conditioner according to a preferred embodiment of the present invention.

[0027] Figure 5 illustrates a cross-sectional view of a grille for an outdoor unit of an air conditioner taken along line A-A.

[0028] Figure 6 illustrates a partial cross-sectional view of a grille for an outdoor unit of an air conditioner taken along line A-A of Figure 5.

[0029] Figure 7 illustrates a cross-sectional view of a portion of a grille for an outdoor unit of an air conditioner taken long line B-B.

[0030] Figure 8(a) shows a conventional grille and a partial front view of simulated air flow pattern across a periphery of the conventional grille.

[0031] Figure 8(b) shows a grille according to the present invention and a partial front view of simulated air flow pattern across a periphery of the grille.

[0032] Figure 9 is a line chart showing respective sound performance for a conventional grille and a grille according to the present invention over different air flow rate. Figure 10(a) shows a partial top cross-sectional view of simulated air flow pattern for a prior art grille.

[0033] Figure 10(b) shows a partial top cross-sectional view of simulated air flow pattern for a grille of the present invention.

[0034] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] The abovementioned and other features and objects of this invention will become more apparent and better understood by reference to the following detailed description. It should be understood that the detailed description made known below is not intended to be exhaustive or limit the invention to the precise form disclosed as the invention may assume various alternative forms. All the relevant modifications and alterations made to the present invention as covered in the detailed description should be construed to fall within the scope of the appended claims. Therefore, the configuration of the invention is not limited to the configuration mentioned in the following description.

[0036] Figure 1 shows a preferred embodiment of the present invention. The present invention provides an outdoor unit of an air conditioner, in which the outdoor unit comprises a casing, a fan disposed to be accommodated in the casing, and an air discharge port formed on the casing for discharging an air flow generated by the fan. The outdoor unit is furnished with a grille (100) for covering the air discharge port, in which the grille (100) has a frame (140) to be fitted onto the air discharge port.

[0037] Figure 2 shows a front view of the grille (100) and a close-up view showing a portion of the grille (100) according to a preferred embodiment of the present invention. As shown in Figure 2, the grille (100) is having an inner rim (1 10), a plurality of circular ribs (101 ) disposed concentrically at predetermined intervals within the inner rim (110) with a connecting means connecting the circular ribs from the center of the grille (100) to the inner rim (1 10). The grille (100) is also having an outer rim (120) with a greater diameter than the inner rim (1 10) surrounding the inner rim (1 10). Preferably, the connecting means comprises a plurality of radial crosspieces (102) intersecting the circular ribs (101 ) and disposed radially from the center of the grille (100) to the inner rim (1 10).

[0038] In a preferred embodiment of the present invention, the grille (100) further comprising a plurality of peripheral guide members (130) that is disposed radially between the inner rim (110) and the outer rim (120). Each peripheral guide member (130) is having a first lateral side (131 ) and a second lateral side (132) opposing the first lateral side (131 ), in which the first lateral side (131 ) is provided with an outwardly curved surface, while the second lateral side (132) is provided with an inwardly curved surface.

[0039] Figure 3 shows a peripheral guide member (130) of the grille (100) in a close-up view according to a preferred embodiment of the present invention. The peripheral guide member (130) is preferably tilted at a predetermined angle that corresponds to a direction of the air flow generated by the fan. In particular, a first line connecting two endpoints along the first lateral side (131 ) and a second line connecting two endpoints along the second lateral side (132) are disposed to be substantially parallel to each other and both of them are tilted at the predetermined angles, as denoted by 0Oand 0i in Figure 3, which is preferably within a range of 20° to 30° relative to a reference line extended radially from center of the fan. More preferably, the predetermined angle is 27° relative to the reference line extended radially from center of the fan. In a further embodiment of the present invention, the plurality of peripheral guide members (130) is tilted towards a direction that corresponds to the direction of the air flow generated by the fan. For instance, the plurality of peripheral guide members (130) is tilted towards a counter-clockwise direction when the air flow generated by the fan is in counter-clockwise direction, and vice versa. In another embodiment of the present invention, the peripheral guide members (130) and the radial crosspieces (102) are tilted towards a direction corresponding to the direction of the air flow generated by the fan. In a preferred embodiment of the present invention, the outwardly curved surface on the first lateral side (131 ) and the inwardly curved surface on the second lateral side (132) for each of the peripheral guide members (130) are having at least two arc segments with different curvatures. As shown in Figure 3, the outwardly curved surface on the first lateral side (131 ) comprising at least a first arc segment having a radius of curvature denoted by Roi, and a second arc segment having a radius of curvature denoted by R02. Preferably, the first arc segment is having a smaller radius of curvature than that of the second arc segment (R01 < R02).

[0040] On the other hand, the inwardly curved surface on the second lateral side (132) comprising at least a first arc segment having a radius of curvature denoted by Rii, and a second arc segment having a radius of curvature denoted by Ri2. Preferably, the first arc segment is having a smaller radius of curvature than that of the second arc segment (RM < Ri2).

[0041] In a further embodiment of the present invention, the first arc segment of the second lateral side (132) is having a greater radius of curvature as compared to that of the first arc segment of the first lateral side (131 ) (R > R01), while the second arc segment of the second lateral side (132) is having a greater radius of curvature as compared to that of the second arc segment of the first lateral side (131 ) (Ri2> R02).

[0042] Figure 4 shows a side perspective view of the grille according to a preferred embodiment of the present invention. Referring to Figure 4, the frame (140) of the grille (100) is disposed behind the outer rim (120) and the inner rim (1 10) of the grille (100). The grille (100) is further provided with a plurality of side openings (142) disposed between the outer rim (120) and the frame (140) of the grille (100), in which the plurality of side openings (142) is formed by having the plurality of peripheral guide members (130) extended from the outer rim (120) and the inner rim (110) towards the frame (140) of the grille (100) in a substantially rearward direction. Preferably, the plurality of peripheral guide members (130) comprising a lateral cross-section of a substantially triangular shape or a substantially trapezoid shape.

[0043] Figure 5 shows a cross-sectional view of the grille (100) taken along line A-A according to a preferred embodiment of the present invention. The inner rim (1 10) of the grille (100) is preferably having a diameter smaller than that of the frame (140) of the grille (100) such that the frame (140) is located between the outer rim (120) and the inner rim (1 10) of the grille (100). Meanwhile, the outer rim (120) of the grille (100) is preferably disposed to extend over the frame (140) of the grille (100) to provide an outwardly protruding peripheral edge. The outwardly protruding peripheral edge of the outer rim (120) is having a lateral cross-section of a substantially triangular shape. In a different embodiment of the present invention, the inner rim (110) of the grille (100) may be having a diameter equal to that of the frame (140) of the grille (100).

[0044] Figure 6 shows a cross-section for the plurality of the circular ribs (101 ) of the grille (100) taken along the line A-A of Figure 5. The plurality of circular ribs (101 ) comprising an aerofoil-shaped cross-section, in which the leading edges of the circular ribs (101 ) are directed towards the fan while the trailing edges of the circular ribs (101 ) are directed towards an outdoor environment where the outdoor unit is located. Also, the plurality of circular ribs (101 ) is inclined at a predetermined angle as denoted by a in Figure 6. The predetermined angle corresponds to the direction of the air flow generated by the fan. Preferably, the predetermined angle is within a range of 0° to 15° relative to the rotational axis of the fan, and more preferably, the predetermined angle is 10° relative to the rotational axis of the fan.

[0045] Further, the plurality of circular ribs (101 ) is preferably spaced at irregular intervals within the inner rim (101 ). The predetermined intervals may be formed by multiple irregular intervals, in which the predetermined interval may be different between each of the circular ribs (101 ). With reference to Figure 6, the predetermined intervals of the circular ribs (101 ) are gradually increasing from the inner rim (1 10) towards the center of the grille (100), for instance, p5<p4<p3<p2<p1 . The predetermined intervals of the circular ribs (101 ) near the inner rim (1 10) of the grille (100) are made to be relatively smaller such that a child finger test probe and an adult finger test probe cannot enter into any spacing of the circular ribs (101 ) so that they will not be able to reach the rotating blades of the fan. The rotating blades of the fan are angled such that the peripheral area has a steeper angle as compared to the center area, causing the peripheral area to be closer to the grille (100) while the center area is further apart from the grille (100).

[0046] On the other hand, the depth dimension of the circular ribs (101 ) may vary at different portions of the grille (100). With reference to Figure 6, at least a middle portion of the circular ribs (101 ) between the inner rim (1 10) and the center of the grille (100) is having a greater depth dimension as compared to the rest of the circular ribs (101 ). In a further preferred embodiment of the present invention, the middle portion of the circular ribs (101 ) between the inner rim (1 10) and the center of the grille (100) is provided with the greater depth dimension while being spaced with increasing predetermined intervals in a direction towards the center of the grille (100). As the predetermined intervals are made to be increased for improving air flow performance, the depth dimension of these circular ribs (101 ) is required to be made greater in order to ensure a child finger test probe and an adult finger test probe unable to reach and in contact with any part of the fan.

[0047] Figure 7 shows a cross-section of one radial crosspiece (102) of the grille (100) taken along line B-B. The plurality of the radial crosspieces (102) is preferably comprising an aerofoil-shaped cross-section, in which the leading edges of the radial crosspieces (102) are directed towards the fan while the trailing edges of the radial crosspieces (102) are directed towards the outdoor environment where the outdoor unit is located. Furthermore, the plurality of radial crosspieces (102) is inclined at a predetermined angle as denoted by [3 in Figure 7, in which the predetermined angle is set to correspond to the direction of the air flow. Preferably, the predetermined angle is within a range of 20° to 30° relative to the rotational axis of the fan, and more preferably, the predetermined angle is 25° relative to the rotational axis of the fan. Moreover, there are supplementary radial crosspieces arranged between each of the radial crosspieces (102) as shown in Figure 7. The supplementary radial crosspieces are provided in a staggered configuration, and they are shorter as compared to the radial crosspieces (102) which extend from center of the grille towards the inner rim (1 10). The supplementary radial crosspieces are beneficial in strengthening the overall structure of the grille (100) without causing much resistance to the air flow across the grille (100).

[0048] Table 1 shows comparison on air flow rate, power input and sound pressure level (SPL) between a conventional grille and a grille (100) of the present invention which are illustrated in Figures 8(a) and 8(b). The study was conducted when the fan of the outdoor unit is fixed to run at 1050 revolutions per minute (rpm). As shown in Figure 8(a), the conventional grille is having a different configuration of peripheral ribs, in which the peripheral ribs are formed to be protruded forward and slightly leaned towards the center of the grille. On the other hand, with reference to Figure 8(b), the grille (100) of the present invention is having the plurality of peripheral guide members (130) which is disposed to be substantially on the same plane relative to the center of the grille and further extending backwards towards the frame (140) of the grille (100), forming a plurality of front openings and a plurality of side openings.

[0049] Table 1 Comparison on air flow output, power input and sound pressure level between a conventional grille and a grille according to a preferred embodiment of the present invention

[0050] Based on Table 1 , the grille (100) of the present invention is having a higher air flow output as measured in cubic feet per minute (cfm) which is 900 cfm, while the conventional grille is having an air flow output of 896 cfm. Also, the grille (100) of the present invention requires a lower power input as measured in watts (W), which is 18.9 W; whereas the conventional grille requires a slightly higher power input of 19.1 W. It is apparent that the grille (100) of the present invention is capable of achieving an improvement of 0.5% in the air flow output and a reduction of 1.1 % in the power input, which contributes to an improvement of 1 .6 % in performance efficiency as compared to that of the conventional grille.

[0051] Moreover, the grille (100) of the present invention is having a lower sound pressure level as measured in decibel (dB) which is 47.6 dB, while the conventional grille is contributing to a slightly higher sound pressure level of 47.8 dB as shown in Table 1 . The grille (100) of the present invention is thus capable of achieving a reduction of 0.2 dB in the sound pressure level despite providing a higher air flow output when compared to that of the conventional grille. Also, with reference to Figure 9, it can be clearly seen that the sound pressure level provided by the grille (100) of the present invention is consistently lower than that of the conventional grille over increasing air flow rates.

[0052] Furthermore, there was a simulation air flow study conducted to determine respective simulated air flow patterns across a periphery of the conventional grille and a periphery of the grille (100) of the present invention as shown in Figures 8(a) and 8(b). It can be seen that there is occurrence of erratic flow with severe flow separation regions at the peripheral ribs of the conventional grille. Flow separation occurs when the air flow is partially or substantially obstructed by the peripheral ribs of the conventional grille, and then split into separate flows across the obstruction. As a result, there are turbulences formed around the periphery of the conventional grille, affecting the air flow across thereof. It may be difficult to achieve a smooth air flow when there are severe flow separations regions turned up.

[0053] On the other hand, there is no flow separation occurred near the periphery of the grille (100) of the present invention when the main air stream is discharged to flow across thereof. In the present invention, the grille (100) is having a plurality of peripheral guide members (130) which is tilted at the predetermined angle that corresponds to a direction of the air flow generated by the fan. Moreover, each peripheral guide member (130) is having the first lateral side (131 ) with the outwardly curved surface and the second lateral side (132) with the inwardly curved surface. Such configuration is found to be beneficial in facilitating the air flow across the periphery of the grille (100) by eliminating flow separation and therefore the air is able to flow smoothly without encountering or causing any turbulence.

[0054] There is another simulation air flow study conducted to determine simulated axial air flow pattern when the air is discharged across a prior art grille and the grille (100) of the present invention. As shown in Figure 10(a), the prior art grille does not have peripheral ribs and side openings as the aforementioned conventional grille, and it can be seen that there is occurrence of erratic flow before the discharged air exiting the prior art grille due to built-up static pressure at the periphery of the prior art grille as indicated by a dotted circle. The built-up static pressure tends to push the air flow towards the center of the prior art grille as indicated by solid arrows in Figure 10(a), resulting that the air unable to flow smoothly across the prior art grille. On the other hand, there is no significant erratic flow occurred at the same region as shown in Figure 10(b) when the air is discharged across the grille (100) of the present invention. The grille (100) of the present invention is provided with the peripheral guide members (130) and the corresponding openings that significantly minimize occurrence of erratic flow at that particular region. Therefore, the grille (100) of the present invention is shown to be beneficial in facilitating the air movement across the periphery of the grille (100). Various modifications to these embodiments are apparent to those skilled in the art from the description and the accompanying drawings. The principles associated with the various embodiments described herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be providing broadest scope of consistent with the principles and the novel features disclosed or suggested herein. Accordingly, the invention is anticipated to hold on to all other such alternatives, modifications, and variations that fall within the scope of the present invention and appended claims.

Claims

CLAIMS:1 . An outdoor unit for an air conditioner, comprising a casing; a fan accommodated in the casing; an air discharge port formed on the casing for discharging an air flow generated by the fan; and a grille (100) having a frame (140) for covering the air discharge port by having the frame (140) fitted thereon; wherein the grille (100) comprising an inner rim (1 10), a plurality of circular ribs (101 ) disposed concentrically at predetermined intervals within the inner rim (110) with a connecting means connecting the circular ribs (101 ) from a center of the grille (100) to the inner rim (1 10), wherein the grille (100) further comprising an outer rim (120) with a greater diameter than the inner rim (1 10) surrounding the inner rim (1 10), and wherein the grille (100) further comprising a plurality of peripheral guide members (130) disposed radially between the inner rim (110) and the outer rim (120) with each peripheral guide member (130) having an outwardly curved surface on a first lateral side (131 ) and an inwardly curved surface on a second lateral side (132) opposing the first lateral side (131 ), and the plurality of peripheral guide members (130) is tilted at a predetermined angle that corresponds to a direction of the air flow generated by the fan.

2. The outdoor unit as claimed in claim 1 , wherein the frame (140) of the grille (100) is disposed behind the outer rim (120) and the inner rim (1 10) of the grille (100).

3. The outdoor unit as claimed in claim 1 , wherein the grille (100) is provided with a plurality of side openings (142) disposed between the outer rim (120) and the frame (140) of the grille (100).

4. The outdoor unit as claimed in claim 3, wherein the plurality of side openings (142) is formed by having the plurality of peripheral guide members (130)extended from the outer rim (120) and the inner rim (110) towards the frame (140) of the grille (100) in a substantially rearward direction.

5. The outdoor unit as claimed in claim 4, wherein the plurality of peripheral guide members (130) comprising a lateral cross-section of a substantially triangular shape or a substantially trapezoid shape.

6. The outdoor unit as claimed in claim 1 , wherein the inner rim (1 10) of the grille (100) is having a diameter smaller than that of the frame (140) of the grille (100).

7. The outdoor unit as claimed in claim 1 , wherein the outer rim (120) of the grille(100) is disposed to extend over the frame (140) of the grille (100) to provide an outwardly protruding peripheral edge.

8. The outdoor unit as claimed in claim 7, wherein the outwardly protruding peripheral edge of the outer rim (120) comprising a lateral cross-section of a substantially triangular shape.

9. The outdoor unit as claimed in claim 1 , wherein the plurality of peripheral guide members (130) is tilted towards a counter-clockwise direction when the air flow generated by the fan is in a counter-clockwise direction.

10. The outdoor unit as claimed in claim 1 , wherein the predetermined angle is within a range of 20° to 30° relative to a reference line extended radially from center of the fan.1 1 .The outdoor unit as claimed in claim 1 , wherein the outwardly curved surface on the first lateral side (131 ) and the inwardly curved surface on the second lateral side (132) for each of the peripheral guide members (130) comprising at least two arc segments with different curvatures.

12. The outdoor unit as claimed in claim 1 , wherein the plurality of circular ribs(101 ) comprising an aerofoil-shaped cross-section.

13. The outdoor unit as claimed in claim 1 , wherein the plurality of circular ribs (101 ) is inclined at a predetermined angle that corresponds to the direction of the air flow generated by the fan.

14. The outdoor unit as claimed in claim 13, wherein the predetermined angle is within a range of 0° to 15° relative to the axis of the fan.

15. The outdoor unit as claimed in claim 1 , wherein the connecting means comprises a plurality of radial crosspieces (102) intersecting the circular ribs (101 ) and disposed radially from the center of the grille (100) to the inner rim (1 10).

16. The outdoor unit as claimed in claim 15, wherein the plurality of radial crosspieces (102) comprising an aerofoil-shaped cross-section.

17. The outdoor unit as claimed in claim 15, wherein the plurality of radial crosspieces (102) is inclined at a predetermined angle that corresponds to the direction to the air flow generated by the fan.

18. The outdoor unit as claimed in claim 17, wherein the predetermined angle is within a range of 20° to 30° relative to the axis of the fan.

19. The outdoor unit as claimed in claim 1 , wherein the plurality of circular ribs (101 ) is spaced from each other with multiple predetermined intervals.

20. The outdoor unit as claimed in claim 19, wherein the predetermined intervals of the circular ribs (101 ) are gradually increasing from the inner rim (1 10) towards the center of the grille (100).21 .The outdoor unit as claimed in claim 1 , wherein at least a middle region of the circular ribs (101 ) between the inner rim (110) and the center of the grille (100) is having greater depth dimension.

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