Electric appliance box assembly and duct type air conditioner

Abstract

The invention relates to the technical field of air conditioners, in particular to an electric appliance box assembly and a duct type air conditioner. The air duct type air conditioner aims at solving the problems that an existing air duct type air conditioner is insufficient in air volume, and the energy efficiency is affected. In order to achieve the purpose, the electric appliance box assembly and the duct type air conditioner are provided, the electric appliance box assembly is arranged on one side of the duct type air conditioner in the length direction, the electric appliance box assembly comprises an electric appliance box body and an electric appliance box cover, and the electric appliance box cover is detachably connected with the electric appliance box body. The air guide wall, extending in the air inlet direction, of the electric appliance box body is used for arranging a circuit board, and the air guide wall is obliquely arranged so that the section of the electric appliance box body can form a trapezoidal structure. With the adoption of the technical scheme, for the duct type air conditioner with the same volume, the air guide wall on the electric appliance box body is obliquely arranged, so that the area occupied by the electric appliance box assembly in the air inlet direction can be reduced under the condition of ensuring the installation of a circuit board, the air volume is improved, a premise is provided for a heat exchanger in the duct type air conditioner to play all roles, and the service life of the air conditioner is prolonged. The heat exchange efficiency of the heat exchanger is ensured and the energy efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and particularly relates to an electric appliance box assembly and an air duct machine. Background Art

[0002] As an air conditioning system, an air duct machine can deliver cold and hot air to each room through an air duct. Compared with a general indoor unit of an air conditioner, the air duct machine has the advantages of being beautiful and concealed, and uniform air supply. And with the development of technology, miniaturizing the air duct machine has gradually become a trend.

[0003] However, in the process of miniaturizing the air duct machine, it will cause the reduction of the air inlet area of the air duct machine and the decrease of the air volume of the air duct machine. At this time, it will also cause the heat exchanger in the air duct machine to not play its full role, thereby affecting the heat exchange efficiency of the heat exchanger and reducing the energy efficiency of the air conditioner.

[0004] Correspondingly, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0005] In order to solve at least one of the above problems in the prior art, that is, to solve the problems of insufficient air volume and affecting energy efficiency existing in the existing air duct machine, the present application provides an electric appliance box assembly (1). The electric appliance box assembly (1) is arranged on one side in the length direction of the air duct machine. The electric appliance box assembly (1) includes an electric appliance box body (11) and an electric appliance box cover (12). The electric appliance box cover (12) is detachably connected to the electric appliance box body (11);

[0006] The air guiding wall (111) of the electric appliance box body (11) extending along the air inlet direction is used for arranging a circuit board (13), and the air guiding wall (111) is inclined so that the cross section of the electric appliance box body (11) forms a trapezoidal structure.

[0007] In the case of adopting the above technical solution, inclining the air guiding wall (111) on the electric appliance box body (11) can reduce the area occupied by the electric appliance box assembly (1) in the air inlet direction while ensuring the installation of the circuit board (13), thereby increasing the air volume, providing a prerequisite for the heat exchanger in the air duct machine to play its full role, ensuring the heat exchange efficiency of the heat exchanger, and improving the energy efficiency.

[0008] In a preferred technical solution of the above electric appliance box assembly (1), an included angle exists between the air guiding wall (111) and the air inlet direction, and the projected shape of the electric appliance box body (11) in the vertical direction is trapezoidal, and the thickness of the electric appliance box body (11) gradually increases along the air inlet direction.

[0009] In the case of adopting the above technical solution, the setting of the electrical appliance box body (11) can not only increase the air inlet area, but also make the whole air duct of the air duct machine form a Venturi effect, thereby increasing the wind speed, further improving the heat exchange efficiency, and improving the energy efficiency.

[0010] In a preferred technical solution of the above electrical appliance box assembly (1), the minimum thickness of the electrical appliance box assembly (1) is greater than or equal to 40 mm; and / or

[0011] The maximum thickness of the electrical appliance box assembly (1) is greater than or equal to 70 mm.

[0012] In the case of adopting the above technical solution, it is possible to reduce the air inlet area occupied by the electrical appliance box assembly (1) while ensuring the normal installation of each component in the electrical appliance box assembly (1).

[0013] In a preferred technical solution of the above electrical appliance box assembly (1), at least part of the outer wall (121) of the electrical appliance box cover (12) extends outward to form a boss (1221).

[0014] In the case of adopting the above technical solution, through the setting of the boss (1221), the thickness of the electrical appliance box can be further reduced, thereby further increasing the air inlet area, ensuring the heat exchange efficiency of the heat exchanger, and improving the energy efficiency.

[0015] In a preferred technical solution of the above electrical appliance box assembly (1), the depth of the boss (1221) is greater than or equal to 5 mm.

[0016] This application also provides an air duct machine, and the air duct machine includes the electrical appliance box assembly (1) described in any one of the above.

[0017] In the case of adopting the above technical solution, for an air duct machine of the same volume, setting the air guiding wall (111) on the electrical appliance box body (11) obliquely can reduce the area occupied by the electrical appliance box assembly (1) in the air inlet direction while ensuring the installation of the circuit board (13), thereby increasing the air volume, providing a prerequisite for the full play of the heat exchanger in the air duct machine, ensuring the heat exchange efficiency of the heat exchanger, and improving the energy efficiency.

[0018] In a preferred technical solution of the above air duct machine, the air duct machine includes a cover plate (2), a chassis (4), side plates (3) and a partition plate (5). The cover plate (2) and the chassis (4) are oppositely arranged in the height direction, the side plates (3) and the electrical appliance box assembly (1) are oppositely arranged in the length direction, and the partition plate (5) is arranged on one side in the width direction of the cover plate (2);

[0019] At least part of the cover plate (2), at least part of the chassis (4), at least part of the side plates (3), the electrical appliance box assembly (1) and the partition plate (5) enclose to form an air inlet cavity.

[0020] In the preferred technical solution of the above air duct machine, the electrical appliance box body (11) further includes a face wind wall (112) perpendicular to the air inlet direction, the electrical appliance box cover (12) further includes an upper wall (122), the shape of the upper wall (122) is trapezoidal, and the upper wall (122) is adapted to the cover plate (2);

[0021] The air guide wall (111), the face wind wall (112), the upper wall (122), the outer wall (121), part of the partition plate (5) and part of the chassis (4) jointly enclose to form an installation cavity (14), and the circuit board (13) is arranged in the installation cavity (14).

[0022] In the case of adopting the above technical solution, enclosing to form the installation cavity (14) by each component is beneficial to reducing the volume and weight of the whole machine while ensuring the size of the installation cavity (14).

[0023] In the preferred technical solution of the above air duct machine, the two ends in the length direction of the cover plate (2) are respectively connected to the side plate (3) and the electrical appliance box assembly (1), and the two ends in the length direction of the chassis (4) are respectively connected to the side plate (3) and the electrical appliance box assembly (1).

[0024] In the preferred technical solution of the above air duct machine, the cover plate (2) is folded downwards to form a first folded edge (21), the side plate (3) is folded inwards to form a second folded edge (31), the chassis (4) is folded upwards to form a third folded edge (41), and the first folded edge (21), the second folded edge (31), and the third folded edge (41) are all on the windward side;

[0025] Preferably, the width of the first folded edge (21) is less than or equal to 10 mm; and / or

[0026] the width of the second folded edge (31) is less than or equal to 10 mm; and / or

[0027] the width of the third folded edge (41) is less than or equal to 15 mm.

[0028] In the case of adopting the above technical solution, the installation of the air inlet panel can be realized through the first folded edge (21), the second folded edge (31), the third folded edge (41) and the electrical appliance box body (11), the air inlet panel can filter impurities in the air, and the settings of the first folded edge (21), the second folded edge (31) and the third folded edge (41) can reduce their influence on the air inlet area. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following describes the air duct machine of the present application with reference to the drawings. In the drawings:

[0030] Figure 1 Structural diagram of the air duct machine of the present application;

[0031] Figure 2 Top view of the air duct machine of the present application;

[0032] Figure 3 Structural diagram of the air duct machine of the prior art.

[0033] List of reference numerals

[0034] 1. Electric box assembly; 11. Electric box body; 111. Air guide wall; 112. Front air wall; 12. Electric box cover; 121. Outer wall; 122. Upper wall; 1221. Boss; 13. Circuit board; 14. Installation cavity; 2. Cover plate; 21. First folded edge; 3. Side plate; 31. Second folded edge; 4. Chassis; 41. Third folded edge; 5. Partition; 7. Electric box; 8. Connecting plate. Detailed implementation manners

[0035] The preferred implementation manners of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principle of the present application and are not intended to limit the protection scope of the present application. For example, although the electric box assembly (1) in this implementation manner is introduced in combination with the air duct machine with rear air return, this is not intended to limit the protection scope of the present application. Without departing from the principle of the present application, those skilled in the art can adjust it as needed. For example, applying the electric box assembly (1) in this implementation manner to the air duct machine with downward air return or the vertical air duct machine. Another example is that although there is a boss (1221) provided on the outer wall of the electric box cover (12) in this implementation manner, this is not intended to limit the protection scope of the present application. Those skilled in the art can choose whether to provide the boss (1221) and change the depth of the boss (1221) according to the needs.

[0036] It should be noted that in the description of the present application, the terms indicating directions or positional relationships such as "up", "down", "vertical", "horizontal", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0037] In addition, it should be noted that in the description of the present application, unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0038] As described in the background art, as an air-conditioning system, an air duct machine can deliver cold and hot air to each room through an air duct. Compared with a general indoor air conditioner, the air duct machine has the advantages of being beautiful and concealed, and uniform air supply. And with the development of technology, miniaturizing the air duct machine has gradually become a trend.

[0039] However, in the process of miniaturizing the air duct machine, it will lead to a reduction in the air inlet area of the air duct machine and a decrease in the air volume of the air duct machine. At this time, it will also cause the heat exchanger in the air duct machine to not fully play its role, thereby affecting the heat exchange efficiency of the heat exchanger and reducing the air-conditioning energy efficiency.

[0040] To solve the problems of insufficient air volume and affecting energy efficiency existing in the existing air duct machines, the present application provides an electrical box assembly (1). The electrical box assembly (1) is arranged on one side in the length direction of the air duct machine. The electrical box assembly (1) includes an electrical box body (11) and an electrical box cover (12), and the electrical box cover (12) is detachably connected to the electrical box body (11). A wind guiding wall (111) of the electrical box body (11) extending along the air inlet direction is used to arrange a circuit board (13), and the wind guiding wall (111) is inclined so that the cross-section of the electrical box body (11) forms a trapezoidal structure.

[0041] In the case of adopting the above technical solution, for an air duct machine of the same volume, inclining the wind guiding wall (111) on the electrical box body (11) can reduce the area occupied by the electrical box assembly (1) in the air inlet direction while ensuring the installation of the circuit board (13), thereby increasing the air volume, providing a prerequisite for the heat exchanger in the air duct machine to fully play its role, ensuring the heat exchange efficiency of the heat exchanger, and improving the energy efficiency.

[0042] Next, with reference to Figures 1 to 3 , the electrical box assembly and the air duct machine of the present application will be described. Among them, Figure 1 is the structural diagram of the air duct machine of the present application; Figure 2 is the top view of the air duct machine of the present application; Figure 3 is the structural diagram of the air duct machine of the prior art.

[0043] As shown in Figure 1 and Figure 2As shown, in a preferred embodiment, the air duct machine includes an electric appliance box assembly (1), a cover plate (2), side plates (3), a chassis (4), and a partition plate (5). Among them, taking Figure 1 the shown direction as an example, the cover plate (2) and the chassis (4) are oppositely arranged along the height direction of the air duct machine, the side plates (3) and the electric appliance box assembly (1) are oppositely arranged along the length direction of the air duct machine, and the partition plate (5) is arranged on one side in the width direction of the cover plate (2). The two ends in the length direction of the cover plate (2) are respectively connected to the side plates (3) and the electric appliance box assembly (1), the two ends in the length direction of the chassis (4) are respectively connected to the side plates (3) and the electric appliance box assembly (1), the partition plate (5) is connected to the cover plate (2), the chassis (4), the side plates (3), and the electric appliance box assembly (1), and at least part of the cover plate (2), at least part of the chassis (4), at least part of the side plates (3), the electric appliance box assembly (1), and the partition plate (5) enclose to form an air inlet cavity. Moreover, the cover plate (2) is folded downwards to form a first folded edge (21), the side plates (3) are folded inwards to form a second folded edge (31), the chassis (4) is folded upwards to form a third folded edge (41), and the first folded edge (21), the second folded edge (31), and the third folded edge (41) are all on the windward side.

[0044] The electric appliance box assembly (1) is arranged on one side in the length direction of the air duct machine. The electric appliance box assembly (1) includes an electric appliance box body (11) and an electric appliance box cover (12), and the electric appliance box cover (12) is detachably connected to the electric appliance box body (11). The electric appliance box body (11) includes a face wind wall (112) perpendicular to the air inlet direction and a wind guiding wall (111) extending along the air inlet direction. The electric appliance box cover (12) includes an outer wall (121) and an upper wall (122), and the upper wall (122) is adapted to the cover plate (2). The wind guiding wall (111), the face wind wall (112), the upper wall (122), the outer wall (121), part of the partition plate (5), and part of the chassis (4) jointly enclose to form an installation cavity (14), and a circuit board (13) is arranged in the installation cavity (14). Specifically, the wind guiding wall (111) is used for arranging the circuit board (13). And the wind guiding wall (111) is inclined. Specifically, there is an included angle between the wind guiding wall (111) and the air inlet direction. The projected shape of the electric appliance box body (11) in the vertical direction is trapezoidal. That is to say, the shape of the upper wall (122) is trapezoidal, and the thickness of the electric appliance box body (11) (i.e., the width of the electric appliance box body (11) in the width direction of the air duct machine) gradually increases along the air inlet direction, that is, the thickness of the electric appliance box body (11) is the largest near the partition plate (5). In addition, at least part of the outer wall (121) of the electric appliance box cover (12) extends outwards to form a boss (1221).

[0045] In this embodiment, the width of the first hem (21) is less than or equal to 10 mm, the width of the second hem (31) is less than or equal to 10 mm, the width of the third hem (41) is less than or equal to 15 mm, and the depth of the boss (1221) is greater than or equal to 5 mm. The minimum thickness of the electrical box assembly (1) is greater than or equal to 40 mm, and the maximum thickness of the electrical box assembly (1) is greater than or equal to 70 mm. That is to say, in order to ensure the installation of components inside the electrical box assembly (1), corresponding to the smallest components, the minimum thickness of the electrical box assembly (1) should be not less than 40 mm, and corresponding to the largest components, the maximum thickness of the electrical box assembly (1) should be not less than 70 mm. Specifically, as Figure 2 shown, when installing each component inside the electrical box assembly (1), larger components are arranged at positions closer to the partition (5).

[0046] It should be explained that, for the convenience of understanding, Figure 1 and Figure 2 only show some components inside the air duct machine, and the settings of components such as the heat exchanger, the cover plate above the heat exchanger, and the side plate on the other side of the air duct machine are omitted. During the operation of the air duct machine, the fan sucks indoor air, and the air exchanges heat with the heat exchanger after passing through the ventilation holes on the partition (5), and the heated air then enters the room again.

[0047] In addition, as Figure 3 shown, in the prior art, the electrical box (7) is generally rectangular in structure as a whole, and a connecting plate (8) is provided on the air duct machine. The connecting plate (8) is set in an L shape. The upper part of the connecting plate (8) is used to connect with the cover plate (2) and the electrical box (7) respectively, and the side part of the connecting plate (8) is used to connect with the air inlet panel (not shown in the figure). Here, the air inlet panel is used to filter the air sucked into the air inlet.

[0048] It should be explained that referring back to Figure 1 , in this embodiment, an opening can be made on the side of the electrical box body (11) to directly connect the cover plate (2) to the electrical box body (11), and the air inlet panel can also be directly connected to the electrical box body (11). At this time, by omitting the setting of the connecting plate (8), the width of the air inlet can be increased, thereby increasing the air inlet area, improving the air volume, and in the case of omitting the setting of the connecting plate (8), not only can materials be saved and production costs be reduced, but also the risk of the air inlet panel falling off due to the detachment of the connecting plate (8) can be avoided.

[0049] It should also be explained that, compared with the prior art, when the air guide wall (111) is inclined along the air inlet direction, on the one hand, the inclined air guide wall (111) can increase the air inlet area by increasing the width at the air inlet, and on the other hand, it can further narrow the entire air duct of the air duct machine in the middle to form a Venturi effect, thereby increasing the air speed and air inlet volume.

[0050] Those skilled in the art can understand that although in this embodiment, when the air guide wall (111) is inclined along the air inlet direction, the air inlet area can be increased while the air speed is increased, the setting of the air guide wall (111) is not fixed. In an alternative embodiment, the air guide wall (111) can also be inclined along the vertical direction, that is, the shape of the air-facing wall (112) is trapezoidal at this time. At this time, the air inlet area can also be increased and the normal installation of the components on the circuit board (13) can be achieved. In addition, in this embodiment, the setting of the boss (1221) on the electrical box cover (12) can ensure the size of the installation cavity (14), so that the thickness of the electrical box body (11) is further reduced, that is, the width of the electrical box body (11) occupying the air inlet is further reduced, thereby increasing the air inlet area and air inlet volume. However, the setting of the boss (1221) is not fixed, and those skilled in the art can choose whether to set the boss (1221) and change the depth of the boss (1221) according to needs. Of course, the thickness of the electrical box assembly (1) is not fixed either, and those skilled in the art can change it according to needs.

[0051] Those skilled in the art can also understand that in this embodiment, components such as the electrical box assembly (1), the cover plate (2), the side plate (3), the chassis (4), and the partition plate (5) need to be assembled after being produced separately. Therefore, the shape of the cover plate (2) needs to be adapted to the upper wall (122). However, its setting is not fixed. In an alternative embodiment, the cover plate (2) and the upper wall (122) can be integrally formed, and at this time, the electrical box cover (12) only includes the outer wall (121). In addition, the connection method between each component is not fixed, and those skilled in the art can change its specific connection method. In an alternative embodiment, the chassis (4) and the electrical box body (11) can be integrally formed, or the electrical box body (11), the side plate (3), the chassis (4), and the partition plate (5) can also be integrally formed.

[0052] It should also be explained that the formation method of the installation cavity (14) is not fixed, and those skilled in the art can change its specific settings. In an alternative embodiment, the installation cavity (14) can be formed by an integrated electrical box assembly (1). However, in this embodiment, when the installation cavity (14) is formed by enclosing the electrical box body (11), the electrical box cover (12), a part of the chassis (4), and a part of the partition (5), compared with the integrated electrical box, it can reduce the occupied volume and mass, thereby reducing the mass of the whole air duct machine.

[0053] In addition, in this embodiment, the setting of the first folding edge (21) can realize the connection between the cover plate (2) and the side plate (3) and the electrical box body (11), the setting of the second folding edge (31) can realize the connection between the side plate (3) and the cover plate (2), and the setting of the third folding edge (41) can realize the connection between the chassis (4) and the electrical box body (11). In addition, the settings of the first folding edge (21), the second folding edge (31), the third folding edge (41), and the upper side holes of the electrical box body (11) can also realize the fixation of the air inlet panel. Since the first folding edge (21), the second folding edge (31), and the third folding edge (41) are all located on the windward side, the widths of the first folding edge (21), the second folding edge (31), and the third folding edge (41) will also affect the air inlet area. In this embodiment, restricting the widths of the first folding edge (21), the second folding edge (31), and the third folding edge (41) is beneficial to further increase the air inlet area of the air duct machine and improve the air volume. Moreover, when reducing the widths of the first folding edge (21), the second folding edge (31), and the third folding edge (41), it is also beneficial to reduce materials and costs. However, their settings are not fixed, and those skilled in the art can omit the setting of a certain folding edge or change the width of a certain folding edge according to requirements. For example, only the first folding edge (21) and the third folding edge (41) are set.

[0054] In addition, it should be explained that although the electrical box assembly (1) in this embodiment is introduced in combination with a rear-return air duct machine, this is not intended to limit the protection scope of this application. Without departing from the principle of this application, those skilled in the art can make adjustments according to needs. For example, applying the electrical box assembly (1) in this embodiment to a down-return air duct machine or a vertical air duct machine.

[0055] Those skilled in the art can understand that although some of the embodiments described herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of this application and forms different embodiments. For example, in the claims of this application, any one of the claimed embodiments can be used in any combination.

[0056] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easily understood by those skilled in the art that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principle of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present application.

Claims

1. An electrical box assembly (1), characterized in that, The electrical box assembly (1) is arranged on one side in the length direction of the air duct machine. The electrical box assembly (1) includes an electrical box body (11) and an electrical box cover (12), and the electrical box cover (12) is detachably connected to the electrical box body (11). The air guiding wall (111) of the electrical box body (11) extending along the air inlet direction is used for arranging the circuit board (13), and the air guiding wall (111) is inclined so that the cross section of the electrical box body (11) forms a trapezoidal structure.

2. The electrical box assembly (1) according to claim 1, wherein There is an included angle between the air guiding wall (111) and the air inlet direction, and the projected shape of the electrical box body (11) in the vertical direction is trapezoidal, and the thickness of the electrical box body (11) gradually increases along the air inlet direction.

3. The electrical box assembly (1) according to claim 2, characterized in that, The minimum thickness of the electrical box assembly (1) is greater than or equal to 40 mm; and / or The maximum thickness of the electrical box assembly (1) is greater than or equal to 70 mm.

4. The electrical box assembly (1) according to claim 1 or 2, characterized in that, At least part of the outer wall (121) of the electrical box cover (12) extends outward to form a boss (1221).

5. The electrical box assembly (1) according to claim 4, characterized in that, The depth of the boss (1221) is greater than or equal to 5 mm.

6. An air duct machine, characterized in that, The air duct machine includes the electrical box assembly (1) as described in any one of claims 1-5.

7. The air duct machine according to claim 6, characterized in that, The air duct machine includes a cover plate (2), a chassis (4), side plates (3) and a partition (5). The cover plate (2) and the chassis (4) are arranged opposite to each other in the height direction. The side plates (3) and the electrical box assembly (1) are arranged opposite to each other in the length direction. The partition (5) is arranged on one side in the width direction of the cover plate (2). At least part of the cover plate (2), at least part of the chassis (4), at least part of the side plates (3), the electrical box assembly (1) and the partition (5) enclose to form an air inlet cavity.

8. The air duct machine according to claim 7, characterized in that, The electrical box body (11) further includes a face air wall (112) perpendicular to the air inlet direction. The electrical box cover (12) further includes an upper wall (122). The shape of the upper wall (122) is trapezoidal, and the upper wall (122) is adapted to the cover plate (2). The air guiding wall (111), the face air wall (112), the upper wall (122), the outer wall (121), part of the partition (5) and part of the chassis (4) jointly enclose to form an installation cavity (14), and the circuit board (13) is arranged in the installation cavity (14).

9. The air duct machine according to claim 7, wherein Both ends in the length direction of the cover plate (2) are respectively connected to the side plates (3) and the electrical box assembly (1). Both ends in the length direction of the chassis (4) are respectively connected to the side plates (3) and the electrical box assembly (1).

10. The air duct machine according to claim 9, characterized in that, The cover plate (2) is folded down to form a first folded edge (21). The side plates (3) are folded inward to form a second folded edge (31). The chassis (4) is folded up to form a third folded edge (41). The first folded edge (21), the second folded edge (31) and the third folded edge (41) are all on the windward side; preferably, the width of the first folded edge (21) is less than or equal to 10 mm; and / or The width of the second folded edge (31) is less than or equal to 10 mm; and / or The width of the third folded edge (41) is less than or equal to 15 mm.

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