A washing machine

Abstract

The application discloses a washing machine, which comprises an outer drum, an exhaust hole arranged on the rear wall of the outer drum and used for connecting the inside of the outer drum with the outside, and a flow guide structure arranged at the exhaust hole and used for guiding water flow into the outer drum. The application can keep the air pressure inside and outside the outer drum stable during use, and when washing clothes, the flow guide structure can guide the generated turbulent water flow through the exhaust hole again, so that the washing water is guided into the outer drum again, the washing water is prevented from directly flowing out of the exhaust hole and water resource waste is avoided, and the use effect of the equipment is improved.

Description

Technical Field

[0001] This invention belongs to the field of clothing processing equipment, and more specifically, relates to a washing machine. Background Technology

[0002] With the rapid development of washing machines, while the washing drum assembly is sealed during operation, the air pressure inside can cause inlet and outlet failures, necessitating a drainage overflow structure. Therefore, an overflow hole is located at the top of the outer drum, primarily for drainage and to facilitate atmospheric pressure control. Current washing machines use a single hole at the back of the outer drum for overflow. During specific washing programs, water overflows through this hole, leading to water waste.

[0003] Chinese Patent Application No. CN107177962A discloses an overflow venting assembly for a washing machine and a wall-mounted washing machine having the same. The overflow venting assembly includes an overflow pipe and a venting component. One end of the overflow pipe is adapted to connect to the rear outer tub of the washing machine, and the other end is connected to the outside to drain water or foam. The venting component has a bent structure, with one side connected to the overflow pipe, and the bent structure is not lower than the connection point between the venting component and the overflow pipe in the vertical direction. According to the washing machine overflow venting assembly of the present invention, by providing a venting component with a bent structure, and setting the bent structure not lower than the connection point between the overflow pipe and the venting component in the vertical direction, foam entering the venting component gradually rises to the bent structure and bursts in large quantities at the bent structure. This achieves both pressure balance inside and outside the rear outer tub and prevents foam overflow from the tub and thus avoids pollution. Although it can achieve pressure balance between the inside and outside of the outer tub and prevent foam from overflowing, water or foam inside the tub will still be discharged through the overflow pipe when the washing machine performs a vibrating wash, thus wasting water resources and reducing the washing effect.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a washing machine that, by setting a diversion structure on the outer drum, guides the washing water through the drum into the washing tub when washing clothes, reducing the flow of water through the vent and avoiding water waste. At the same time, the vent in the diversion structure prevents the washing machine from being completely sealed inside when it is working, maintains stable air pressure inside and outside the outer drum, and avoids noise caused by air suction during drainage.

[0006] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is to provide a washing machine, including an outer drum;

[0007] An exhaust port is provided on the rear wall of the outer cylinder to connect the inside of the outer cylinder with the outside.

[0008] A flow-guiding structure is provided at the vent hole to guide water flow into the outer cylinder.

[0009] Furthermore, the vent hole is disposed through the rear wall of the outer cylinder, near the upper part of the rear wall of the outer cylinder;

[0010] The drainage structure is located on the inner side of the rear wall of the outer cylinder and communicates with the exhaust hole.

[0011] Furthermore, the drainage structure is a receiving cavity, which is disposed on the inner side of the rear wall;

[0012] One end of the vent is connected to the bottom of the receiving cavity.

[0013] Furthermore, the outer side of the rear wall of the outer cylinder is provided with a protrusion, and the exhaust hole is disposed in the protrusion.

[0014] Furthermore, the protrusion is also provided with a connecting pipe, one end of which is connected to the exhaust hole, and the other end extends outward from the exhaust hole for connection with the exhaust pipe.

[0015] Furthermore, it also includes a guide section, which is disposed in the receiving cavity of the drainage structure and connected to the vent hole, for guiding the water in the vent hole to the drainage structure.

[0016] Furthermore, the flow guide includes,

[0017] A first guide section, one end of which is connected to one end of the exhaust hole, and the other end extends into the receiving cavity;

[0018] The second guide section has one end connected to the other end of the first guide section, and the other end extends toward the central axis of the exhaust hole.

[0019] Furthermore, the first guide portion is an arc-shaped plate with a certain extension length, and one end of the arc-shaped plate is connected to the inner peripheral wall of the upper end of the exhaust hole;

[0020] The second guide portion is a flat plate, which extends downward from the other end of the arc-shaped plate, and the arc-shaped plate is perpendicularly connected to the flat plate.

[0021] Furthermore, the receiving cavity includes a first sidewall that extends obliquely downward from the bottom of the receiving cavity toward the interior of the outer cylinder;

[0022] The second sidewall is disposed vertically opposite to the first sidewall, and extends obliquely upward from the bottom of the receiving cavity toward the interior of the outer cylinder.

[0023] Furthermore, the tilt angle of the first sidewall is smaller than the tilt angle of the second sidewall.

[0024] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0025] (1) The present invention provides an exhaust hole on the rear wall of the outer drum to keep the air pressure inside the outer drum balanced with the outside air pressure, thereby avoiding noise during drainage. The drainage structure is set at the exhaust hole to reduce water flow out of the outer drum during washing. When the washing machine is washing clothes, the drainage structure will generate agitated washing water. When the washing water passes through the drainage structure, it can be guided back into the washing drum, thus preventing the washing water from flowing out of the exhaust hole of the outer drum and causing water waste.

[0026] (2) By setting a guide part inside the diversion structure and connecting it with the vent hole in the diversion structure, when the water flow passes through the diversion structure, if the water flow is too turbulent, the guide part can reduce the water flow when passing through the vent hole on the diversion structure, prevent the water flow from flowing directly out of the vent hole, increase the obstruction effect on the water flow, reduce water waste, and improve the washing performance of clothes.

[0027] (3) The drainage structure is set to accommodate the cavity, and the first sidewall and the second sidewall of the cavity are set at an inclination. The inclination angle of the first sidewall is greater than that of the second sidewall. When the water flows through the cavity, the first sidewall and the second sidewall are set at an inclination, which prevents water from remaining in the cavity. After the turbulent water flows through and is blocked by the protective cap, the washing water is better guided to the inner drum, which improves the drainage effect of the drainage structure, improves the cleaning effect, and prevents bacterial growth.

[0028] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0029] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0030] Figure 1 This is a schematic diagram of the outer drum structure of a washing machine according to the present invention;

[0031] Figure 2 This is the present invention. Figure 1 Enlarged view at point E;

[0032] Figure 3 This is the present invention. Figure 1 A structural diagram from another angle;

[0033] Figure 4 This is the present invention. Figure 3 Enlarged view of point F in the image;

[0034] Figure 5 This is the present invention. Figure 1 Side view;

[0035] Figure 6 This is the present invention. Figure 5 Sectional view at point BB;

[0036] Figure 7 This is the present invention. Figure 6 A magnified view of point G in the middle.

[0037] In the figure: 1. Outer cylinder; 11. Rear wall; 2. Drainage structure; 21. Receiving cavity; 211. First side wall; 212. Second side wall; 213. Third side wall; 214. Fourth side wall; 3. Exhaust hole; 4. Guide section; 41. First guide section; 42. Second guide section; 5. Protrusion; 6. Connecting pipe.

[0038] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0040] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] like Figures 1 to 7 As shown, the washing machine of the present invention includes an outer drum 1, a flow guiding structure 2, and an exhaust port 3.

[0043] The vent 3 is located on the rear wall of the outer cylinder 1, and is used to connect the inside of the outer cylinder 1 with the outside.

[0044] The flow-guiding structure 2 is located at the vent 3 and is used to guide water flow into the outer cylinder 1.

[0045] This invention provides an exhaust vent 3 on the rear wall 11 of the outer drum 1 and a flow guiding structure 2 at the exhaust vent 3. During use, this can maintain stable air pressure inside and outside the outer drum 1. At the same time, when washing clothes, if agitated water flow is generated, the flow guiding structure 2 can guide the agitated water flow back into the washing drum after passing through the exhaust vent 3, thus preventing the washing water from flowing out of the exhaust vent 3 on the flow guiding structure 2 and causing water waste.

[0046] Furthermore, the exhaust port 3 is disposed through the rear wall 11 of the outer cylinder 1, near the upper part of the rear wall 11 of the outer cylinder 1.

[0047] The drainage structure 2 is located on the inner side of the rear wall 11 of the outer cylinder 1 and communicates with the exhaust hole 3.

[0048] By setting the drainage structure 2 on the inner side of the rear wall 11 of the outer drum 1 and connecting it with the exhaust hole 3, the drainage structure 2 and the exhaust hole 3 work together to achieve the effect of drainage and maintaining stable air pressure inside and outside the washing drum, and increase the drainage area of ​​the drainage structure 2. When the washing machine is washing, the washing water has a buffer state when passing through the exhaust hole 3, reducing the washing water from being directly discharged from the exhaust hole 3 when passing through the outer drum 1, thereby draining the washing water in the washing drum and avoiding waste of water resources in the washing drum.

[0049] Specifically, this invention, by setting the vent 3 on the rear wall 11 and extending it through the upper part of the rear wall 11, can balance the air pressure between the inside and outside of the outer drum 1 during drainage, avoiding an imbalance of internal and external air pressure that would prevent drainage. The drainage structure 2 is set at the vent 3 on the rear wall 11 and extends from the inner circumference of the rear wall 11 to the outside of the rear wall 11 and communicates with the vent 3. When the washing machine is washing, as the washing drum rotates, the movement effect of the washing water at both ends is greater than the movement effect on the back plate 11 of the outer drum 1. By minimizing the movement effect of the washing water on the rear wall 11 of the outer drum 1, the water-saving effect is improved. In conjunction with the vent 3 on the drainage structure 2, the effects of saving water resources and stabilizing the internal and external air pressure in the outer drum 1 are achieved.

[0050] Furthermore, the drainage structure 2 is a cavity 21, which is located on the inner side of the rear wall 11.

[0051] One end of the vent 3 is connected to the bottom of the receiving cavity 21.

[0052] This invention sets the drainage structure 2 as a receiving cavity 21 to facilitate the guidance of water flow. One end of the vent 3 is connected to the bottom of the receiving cavity 21. In use, the other end of the vent 3 is connected to the vent pipe to balance the internal and external air pressure of the outer cylinder 1. It also ensures that when the turbulent water flow passes through the vent pipe, the water flow first passes through the receiving cavity 21, so that the water flow has a buffer in the receiving cavity 21 when passing through the drainage structure 2, avoiding direct flow out from the vent 3 and causing waste of water resources.

[0053] Furthermore, the outer side of the rear wall 11 of the outer cylinder 1 is provided with a protrusion 5, and the exhaust hole 3 is disposed through the protrusion 5.

[0054] The present invention provides a protrusion 5 on the outer side of the rear wall 11, through which the exhaust hole 3 is disposed, which facilitates the connection between the exhaust hole 3 and the exhaust pipe, thereby achieving the balance of internal and external air pressure in the washing drum.

[0055] Specifically, the protrusion 5 on the rear wall 11 is formed by the outward protrusion of the receiving cavity 21.

[0056] Furthermore, the protrusion 5 is also provided with a connecting pipe 6, one end of which is connected to the exhaust hole 3, and the other end extends outward from the exhaust hole 3 for connection with the exhaust pipe.

[0057] By setting a connecting pipe 6 and protruding part 5 on the outer peripheral wall of the back panel 11, it is convenient to connect with the exhaust pipe. One end of the exhaust pipe is connected to the connecting pipe 6 and the other end is connected to the water outlet, which facilitates the balance of air pressure inside and outside the washing drum during washing. At the same time, when a small amount of water flows through the exhaust hole 3, the exhaust pipe will discharge a small amount of water from the water outlet, thereby increasing the effectiveness of the device.

[0058] Furthermore, it also includes a guide section 4, which is disposed in the receiving cavity 21 of the drainage structure 2 and connected to the vent hole 3, for guiding the water in the vent hole 3 to the drainage structure 2.

[0059] The present invention provides a guide section 4 in the receiving cavity 21 of the flow-guiding structure 2 and connects it to the vent 3. This prevents the agitated water flow from flowing directly out of the vent 3 when washing clothes, thus obstructing the water flow and guiding the water flow through the vent 3 to the flow-guiding structure 2, avoiding water waste and improving equipment performance.

[0060] Furthermore, the flow guide 4 includes a first flow guide 41 and a second flow guide 42.

[0061] One end of the first guide portion 41 is connected to one end of the exhaust hole 3, and the other end extends into the receiving cavity 21.

[0062] One end of the second guide section 42 is connected to the other end of the first guide section 41, and the other end extends toward the central axis of the exhaust hole 3.

[0063] Specifically, such as Figures 1-2 As shown, the present invention provides a guide section 4 inside the receiving cavity 21 of the diversion structure 2, which is connected to the exhaust hole 3, but does not directly cover the exhaust hole 3. There is a gap between the second guide section 42 and the exhaust hole 3. When the washing water passes through the diversion structure 2, the water first flows through the receiving cavity 21. When it passes through the exhaust hole 3, the water flow is guided into the outer drum 1. When the water flows through the guide section 4 in the diversion structure 2, the area of ​​the water flow passing through the exhaust hole 3 is reduced, and the water flow efficiency is reduced, thereby achieving the effect of saving water. The second guide section 42 does not directly cover the exhaust hole 3. By extending the first guide section 41, the space between the second guide section 42 and the exhaust hole 3 is increased. This avoids the problem of insufficient space when achieving pressure balance between the inside and outside of the outer drum 1, which would cause the pressure to stabilize slowly. It also prevents pressure imbalance between the inside and outside of the outer drum 1, which could lead to drainage failure. The structure is simple, improves the performance of the washing machine, and enhances the user experience.

[0064] Furthermore, the first guide portion 41 is an arc-shaped plate with a certain extension length, and one end of the arc-shaped plate is connected to the inner peripheral wall of the upper end of the exhaust hole 3;

[0065] The second guide portion 42 is a flat plate that extends downward from the other end of the arc-shaped plate, and the arc-shaped plate is perpendicularly connected to the flat plate.

[0066] This invention connects one end of a first guide section 41 to one end of the vent 3, and extends the other end inward from the bottom of the receiving cavity 21. The first guide section 41 is an arc-shaped plate, which blocks the washing water when it enters the receiving cavity 21, preventing the washing water from passing directly through the vent 3. One end of a second guide section 42 is connected to the other end of the first guide section 41, and the other end extends from the connection point towards the central axis of the vent 3. The second guide section is a flat plate, and the first guide section 41 and the second guide section 42 are perpendicularly connected, so that there is a gap between the second guide section 42 and the vent 3. This avoids the second guide section 42 directly blocking the vent 3, causing an imbalance of internal and external air pressure, and causing drainage failure. At the same time, the guide section 4 is set in the receiving cavity 21 to further reduce water waste. When the water flows through the vent 3, the guide section 4 guides the water flow, reducing the efficiency of water flowing out of the vent 3 and saving water resources.

[0067] The projection of the second guide portion 42 on the bottom of the receiving cavity 21 at least partially covers the exhaust port 3.

[0068] By at least partially covering the exhaust hole 3 by projecting the second guide section 42 into the receiving cavity 21, the internal and external air pressure of the outer drum 1 is balanced while reducing water flow efficiency, preventing drainage failure or excessive noise during drainage. The structure is simple and the performance of the washing machine is improved.

[0069] Furthermore, the receiving cavity 21 includes a first sidewall 211 and a second sidewall 212.

[0070] The first sidewall 211 extends obliquely downward from the bottom of the receiving cavity 21 toward the interior of the outer cylinder 1.

[0071] The second sidewall 212 is arranged vertically opposite to the first sidewall 211, and the second sidewall 212 extends obliquely upward from the bottom of the receiving cavity 21 toward the interior of the outer cylinder 1.

[0072] The second sidewall 212 is located above the first sidewall 211.

[0073] This invention extends the first sidewall 211 and the second sidewall 212 of the receiving cavity 21 of the drainage structure 2 at an incline within the outer cylinder 1, with the second sidewall 212 positioned above the first sidewall 211. This incline angle between the first sidewall 211 and the second sidewall 212 when water flows through the drainage structure 2 prevents excessive washing water from flowing out of the vent hole 3 on the drainage structure 2, thus avoiding water waste. Furthermore, the relative arrangement of the second sidewall 212 and the first sidewall 211 increases the drainage area of ​​the drainage structure 2, improves the drainage effect, and saves water resources.

[0074] Furthermore, the tilt angle of the first sidewall 211 is greater than the tilt angle of the second sidewall 212.

[0075] This invention achieves this by setting the inclination angle of the first sidewall 211 to be greater than that of the second sidewall 212, and by placing the first sidewall 211 closer to the washing water and the second sidewall 212 further away from the washing water. During the drainage process, the washing water has a larger inclination angle when passing through the first sidewall 211, resulting in a shorter residence time of the washing water in the drainage structure 2. This reduces the time the water flows through the vent 3, thereby reducing excessive water outflow from the vent 3 in the washing drum and conserving water resources.

[0076] The receiving cavity 21 of the drainage structure 2 also includes a third sidewall 213 and a fourth sidewall 214.

[0077] The two ends of the third sidewall 213 are respectively connected to one end of the first sidewall 211 and one end of the second sidewall 212.

[0078] The fourth sidewall 214 is disposed opposite to the third sidewall 213, and the two ends of the fourth sidewall 214 are respectively connected to the other end of the first sidewall 211 and the other end of the second sidewall 212.

[0079] The third sidewall 213 and the fourth sidewall 214 are smoothly connected to the first sidewall 211 and the second sidewall 212.

[0080] By smoothly connecting the third sidewall 213, the fourth sidewall 214 with the first sidewall 211 and the second sidewall 212, the guiding effect of the drainage structure 2 is improved, and the foam or washing water formed by the washing liquid in the washing drum is prevented from being stored in the drainage structure 2. This prevents bacteria from growing in the drainage structure 2 or from being blocked by the vent hole 3 of the drainage structure 2 after long-term use.

[0081] Preferably, the receiving cavity 21 includes a groove.

[0082] By setting the receiving cavity 21 of the drainage structure 2 as a groove structure and setting the exhaust hole 3 at the bottom of the groove, the drainage structure 2 and the exhaust hole 3 can achieve the drainage effect, save water resources, and stabilize the air pressure in the outer drum 1 of the washing machine. The structure is simple.

[0083] Specifically, the present invention provides a drainage structure 2 at the vent 3 on the rear wall 11 of the outer drum 1, and connects the vent 3 to the bottom of the receiving cavity 21 to achieve pressure balance between the inside and outside of the outer drum 1, preventing drainage failure due to pressure imbalance during drainage. The first side wall 211 and the second side wall 212 of the receiving cavity 21 are inclined at a certain angle to expand the drainage space inside the groove. When the water flows through the groove during operation, the first side wall 211 and the second side wall 212 are inclined to prevent foam generated by washing water or washing liquid from being stored in the groove, thus preventing bacteria from growing in the outer drum 1 of the washing machine, improving the washing effect of clothes, and enhancing the user experience.

[0084] This invention provides an exhaust vent 3 on the rear wall 11 of the outer drum 1 of a washing machine, extending through the rear wall 11. A flow guiding structure 2 is positioned at the exhaust vent 3 and configured as a receiving cavity 21. The exhaust vent 3 communicates with the bottom of the receiving cavity 21, balancing the internal and external air pressure of the outer drum 1. A flow guide 4 is provided inside the receiving cavity 21 and communicates with the exhaust vent 3. During washing, this prevents water or foam from flowing directly out of the exhaust vent 3, thus saving water resources. The second flow guide 42 does not completely cover the receiving cavity 21. The bottom-connected exhaust port 3 connects one end of the first guide section 41 to one end of the exhaust port 3, and the other end extends to the bottom of the receiving cavity 21. One end of the second guide section 42 is connected to the other end of the first guide section 41, and the other end extends towards the central axis of the exhaust port 3, increasing the space between the second guide section 42 and the exhaust port 3. This achieves air pressure balance between the inside and outside of the outer drum 1 during washing machine operation. The structure is simple, and it can achieve the performance of multiple washing machines, improve the washing effect of clothes, and enhance the user experience.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A washing machine, characterized in that: include, outer cylinder; An exhaust port is provided through the upper part of the rear wall of the outer cylinder to connect the inside of the outer cylinder with the outside. A flow-guiding structure is provided at the vent hole and on the inner side of the rear wall of the outer cylinder, communicating with the vent hole, for guiding water flow into the outer cylinder; The drainage structure is a receiving cavity, which includes a first sidewall that extends obliquely downward from the bottom of the receiving cavity toward the interior of the outer cylinder. One end of the vent hole is connected to the bottom of the receiving cavity; The guide section is disposed in the receiving cavity of the drainage structure and connected to the vent hole, and is used to guide the water in the vent hole to the drainage structure. The flow guide includes a first flow guide and a second flow guide. One end of the first flow guide is connected to one end of the exhaust hole, and the other end extends into the receiving cavity. One end of the second flow guide is connected to the other end of the first flow guide, and the other end extends toward the central axis of the exhaust hole.

2. A washing machine according to claim 1, characterized in that: The outer side of the rear wall of the outer cylinder is provided with a protrusion, and the exhaust hole is disposed through the protrusion.

3. A washing machine according to claim 2, characterized in that: The protrusion is also provided with a connecting pipe, one end of which is connected to the exhaust hole, and the other end extends outward from the exhaust hole to connect with the exhaust pipe.

4. A washing machine according to any one of claims 1-3, characterized in that: The first guide portion is an arc-shaped plate with a certain extension length, and one end of the arc-shaped plate is connected to the inner peripheral wall of the upper end of the exhaust hole; The second guide portion is a flat plate, which extends downward from the other end of the arc-shaped plate, and the arc-shaped plate is perpendicularly connected to the flat plate.

5. A washing machine according to any one of claims 1-3, characterized in that: The receiving cavity includes a second sidewall, which is disposed vertically opposite to the first sidewall. The second sidewall extends obliquely upward from the bottom of the receiving cavity toward the interior of the outer cylinder.

6. A washing machine according to claim 5, characterized in that: The tilt angle of the first sidewall is greater than that of the second sidewall.

7. A washing machine according to claim 5, characterized in that, The cavity includes a third sidewall and a fourth sidewall. The two ends of the third sidewall are respectively connected to one end of the first sidewall and one end of the second sidewall. The fourth sidewall is disposed opposite to the third sidewall, and the two ends of the fourth sidewall are respectively connected to the other end of the first sidewall and the other end of the second sidewall.

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