Vortex cooling assembly and dust collector

Abstract

The invention relates to the technical field of battery pack cooling, and discloses a vortex cooling assembly which comprises an air guide pipe, a cold air pipe, a hot air pipe and the like, high-pressure airflow tangentially enters a vortex chamber through a vortex air inlet duct, is accelerated by a vortex plate and then rapidly rotates in the vortex chamber to form free vortex, and through internal energy conversion, the free vortex is formed. Cold air is generated at the cold air outlet end, and hot air is generated at the hot air outlet end; the invention further discloses a dust collector adopting the vortex cooling assembly, when the motor assembly works, high-pressure airflow generated in a motor air outlet chamber can achieve cold and hot air separation through the vortex cooling assembly, generated cold air is guided into the battery pack assembly to cool and dissipate heat of a battery pack in the battery pack assembly, and the lithium electrochemical reaction rate is reduced, so that the lithium battery pack is cooled. According to the dust collector, the battery pack is cooled, the endurance time is prolonged, heated air is exhausted to the external environment, the cost of cooling the battery pack by the dust collector is low, and the dust collector has a good cooling effect.

Description

Technical Field

[0001] The present invention relates to the technical field of battery pack cooling, and in particular to a vortex cooling assembly and a vacuum cleaner. Background Art

[0002] With the development of science and technology, many household appliances have gotten rid of the constraints of power cords, making them more convenient and more flexible to operate; for example, cordless handheld vacuum cleaners are mainly powered by battery packs, which drive the vacuum motor to rotate at high speed, forming negative pressure inside the vacuum cleaner. This negative pressure will generate strong suction, which will suck dust, garbage, hair and other debris into the dust cup of the vacuum cleaner through the suction head.

[0003] If the vacuum cleaner continues to operate at high power, the heat generated by the battery pack will continue to accumulate. Since the heat dissipation rate of the battery pack is limited to a certain extent, the temperature of the battery pack will gradually increase over time. For example, when cleaning a large area of ​​carpet, if the vacuum cleaner is always in high power mode, the temperature inside the battery pack may rise by more than ten degrees Celsius or even higher within a few minutes.

[0004] When the temperature of the battery pack rises, the activity of the chemical substances inside it will also change. For lithium batteries, excessively high temperatures may cause the decomposition of the electrolyte inside the battery to accelerate, which will not only further aggravate the heating of the battery, but may also reduce the performance and life of the battery. In addition, excessively high temperatures may also cause safety problems in the battery pack, such as battery bulging, or even dangerous situations such as fire and explosion. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a vortex cooling assembly, in which a high-pressure airflow enters a vortex chamber tangentially through a vortex air inlet duct and rapidly rotates to form a free vortex, and through internal energy conversion, cold air is generated at the cold air outlet end and hot air is generated at the hot air outlet end; and the generated cold air is discharged into the battery pack to cool and dissipate the heat of the internal battery pack.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: A vortex cooling component comprises an air guide duct, wherein an inner cavity and a vortex air inlet duct are provided inside the air guide duct, a cold air duct and a hot air duct are arranged relatively in the inner cavity, and a vortex chamber is enclosed between the opposite ends of the two and the side wall of the inner cavity; an air inlet hole is provided on the side wall of the inner cavity, one end of the vortex air inlet duct is provided with a vortex air inlet, and the other end is tangentially connected with the vortex chamber through the air inlet hole; a cold end air duct is provided inside the cold air duct, a vortex plate for generating a free vortex is provided at one end of the cold end air duct, and a cold air outlet is provided at the other end, the vortex plate is located in the vortex chamber, and the cold end air duct is connected with the vortex chamber through the vortex plate; a hot end air duct is provided inside the hot air duct, one end of the hot end air duct is connected with the vortex chamber, and the other end is provided with a hot air outlet, a vortex block is inserted at the center of the hot end air duct, and the inner diameter of the hot end air duct is larger than the inner diameter of the cold end air duct.

[0007] Optionally, the vortex plate includes a plate body connected to the cold air duct, a through hole connected to the cold end air duct is opened at the center position of the plate body, and a plurality of raised vortex blocks are arranged at the edge of the plate body, and the plurality of vortex blocks are distributed in a circular array around the axis of the cold air duct on the surrounding side of the through hole.

[0008] A vacuum cleaner using a vortex cooling assembly comprises a body assembly, a motor assembly, a battery pack assembly and a vortex cooling assembly, wherein the vortex cooling assembly, the motor assembly and the battery pack assembly are all mounted on the body assembly, and the vortex cooling assembly is located between the motor assembly and the battery pack assembly.

[0009] Optionally, the motor assembly includes a motor air outlet chamber, the battery pack assembly includes a shell connected to the fuselage assembly, a battery pack is installed inside the shell, and a battery pack air inlet and a battery pack air outlet are provided on the shell; the vortex air inlet and hot air outlet of the vortex cooling assembly are both connected to the motor air outlet chamber, and the cold air outlet of the vortex cooling assembly is connected to the battery pack air inlet.

[0010] Optionally, a vortex air outlet duct is provided on the air guide pipe, the hot air outlet is connected with the motor air outlet chamber through the vortex air outlet duct, and vortex air outlets connected to the outside are also provided at both ends of the vortex air outlet duct.

[0011] Optionally, the lower end of the vortex stopper is embedded in the hot end air duct, the upper end of the vortex stopper is located at the bottom of the motor air outlet chamber, and the radial size of the vortex stopper increases from bottom to top.

[0012] Optionally, the body assembly includes a handle, both ends of the handle are respectively connected to the motor assembly and the battery pack assembly, and the vortex cooling assembly is installed inside the handle.

[0013] Optionally, the body assembly includes a handle, a support rod is provided on the front side of the handle, both ends of the support rod are respectively connected to the motor assembly and the battery pack assembly, and the vortex cooling assembly is installed inside the support rod.

[0014] Optionally, a sealing ring for sealing and isolating the vortex air inlet duct and the vortex air outlet duct is provided on the top of the air guide duct.

[0015] Optionally, the cold air duct is located below the hot air duct, and the cold end air duct and the hot end air duct are both coaxial with the inner cavity.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The high-pressure airflow enters the vortex chamber tangentially through the vortex air inlet duct, and after being accelerated by the vortex plate, it quickly rotates in the vortex chamber to form a free vortex. Through internal energy conversion, cold air is generated at the cold air outlet and hot air is generated at the hot air outlet. The structure of this component is ingenious and simple. It can separate the cold and hot air of the high-pressure airflow only through its own mechanical structure. The cost of use is low, and the cold air generated can play a role in heat dissipation and cooling of the corresponding components. (2) When the motor assembly is working, the high-pressure airflow generated in the motor air outlet chamber can be separated into hot and cold air through the vortex cooling assembly, and the generated cold air is introduced into the battery pack assembly to cool the battery pack therein, thereby reducing the lithium electrochemical reaction rate and increasing its battery life. The heated air is discharged into the external environment; (3) In order to prevent the high-pressure airflow in the motor air outlet chamber from entering the hot-end air duct and affecting the exhaust effect of the hot air, the two ends of the vortex block are respectively located inside the motor air outlet chamber and the hot-end air duct, and the radial size of the vortex block increases from bottom to top. In this way, it will not affect the exhaust of hot air from the hot-end air duct, and the high-pressure airflow in the motor air outlet chamber can pass around it and enter the vortex air inlet duct. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a vortex cooling assembly according to an embodiment of the present invention; Figure 2 is a schematic diagram of the internal structure of an eddy current cooling assembly according to an embodiment of the present invention; Figure 3 is a schematic structural diagram of a vortex plate in an embodiment of the present invention; Figure 4 is a schematic structural diagram of a vacuum cleaner using a vortex cooling assembly according to an embodiment of the present invention; Figure 5 is a schematic diagram of the explosion structure of a vacuum cleaner in an embodiment of the present invention; Figure 6is a schematic diagram of the internal structure of a vacuum cleaner in an embodiment of the present invention; Figure 7 is a schematic diagram of the position structure of the eddy current cooling component and the dust collector in an embodiment of the present invention; Among them, 1. air guide duct; 101. vortex air inlet duct; 102. air inlet hole; 103. vortex air inlet; 104. vortex air outlet duct; 105. vortex air outlet; 2. Cold air duct; 201. Cold end air duct; 202. Cold air outlet; 3. eddy current plate; 301. plate body; 302. through hole; 303. eddy current block; 4. Hot air pipe; 401. Hot end air duct; 402. Hot air outlet; 5. Vortex chamber; 6. Body assembly; 601. Handle; 7. Motor assembly; 701. Motor air outlet chamber; 702. Eddy current block; 8. Dust cup assembly; 9. Battery pack assembly; 901. Battery pack air inlet; 902. Battery pack air outlet; 903. Housing; 10. Sealing ring. DETAILED DESCRIPTION

[0018] The present invention will now be further described in detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0019] Embodiment 1, as Figure 1-Figure 3 As shown, a vortex cooling component includes an air guide 1, an inner cavity and a vortex air inlet duct 101 are provided inside the air guide 1, a cold air duct 2 and a hot air duct 4 are arranged in the inner cavity, and a vortex chamber 5 is formed between the opposite ends of the two and the side wall of the inner cavity; an air inlet hole 102 is provided on the side wall of the inner cavity, a vortex air inlet port 103 is provided at one end of the vortex air inlet duct 101, and the other end is tangentially connected to the vortex chamber 5 through the air inlet hole 102; a cold end air duct 201 is provided inside the cold air duct 2, and a hot air duct 4 is arranged in the inner cavity ... A vortex plate 3 for generating a free vortex is provided at one end of 201, and a cold air outlet 202 is provided at the other end. The vortex plate 3 is located in the vortex chamber 5, and the cold end air duct 201 is connected with the vortex chamber 5 through the vortex plate 3; a hot end air duct 401 is opened inside the hot air pipe 4, one end of the hot end air duct 401 is connected with the vortex chamber 5, and a hot air outlet 402 is provided at the other end. A vortex block 702 is inserted at the center of the hot end air duct 401, and the inner diameter of the hot end air duct 401 is larger than the inner diameter of the cold end air duct 201.

[0020] The high-pressure airflow passes through the vortex air inlet 103 and enters the vortex air inlet duct 101, and then passes through the air inlet hole 102 and enters the vortex chamber 5 along the tangent direction. The airflow speeds up when passing through the vortex plate 3. The accelerated airflow rotates rapidly in the vortex chamber 5 to form a free vortex. Through internal energy conversion, cold air is generated at one end and hot air is generated at the other end.

[0021] The high-pressure airflow that enters the vortex chamber 5 tangentially through the air inlet 102 rotates rapidly under the action of the vortex plate 3 to form a free vortex, and diffuses upward along the hot end air duct 401 with a larger diameter. The airflow near the center of the free vortex has a large angular velocity of rotation, and rubs against the outer airflow, and transfers energy to the outer airflow, thereby weakening its own energy, slowing down its speed, and reducing its temperature.

[0022] The air close to the tube wall not only obtains energy from the air in the center, but also rubs against the tube wall, causing the temperature to continue to rise and the speed to increase, thereby becoming hot air and being ejected; the air with a low temperature in the center of the inner layer will be blocked by the vortex block 702 in the hot end air duct 401 when moving forward with the hot air, and then rebound and turn, entering the cold end air duct 201, and flowing out through the cold air outlet 202, thereby realizing the separation of hot and cold air.

[0023] The structure of the vortex cooling component is ingenious and simple. It can separate hot and cold air from the high-pressure airflow only through its own mechanical structure. It has low cost of use, and the generated cold air can heat and cool the corresponding components.

[0024] As described above, the vortex plate 3 includes a plate body 301 connected to the cold air duct 2, a through hole 302 connected to the cold end air duct 201 is opened at the center position of the plate body 301, and a plurality of raised vortex blocks 303 are arranged at the edge of the plate body 301, and the plurality of vortex blocks 303 are distributed in a circular array around the axis of the cold air duct 2 on the circumferential side of the through hole 302.

[0025] There is a gap between two adjacent vortex blocks 303, the gap distance is smaller than the diameter of the air inlet hole 102, and the side of the vortex block 303 on the plate body 301 close to the through hole 302 is generally distributed in a vortex shape. After the high-pressure airflow enters the vortex chamber 5, it passes through the gap, the flow rate increases, and then passes through the guidance of the side of the vortex block 303 to form a free vortex; after the cold and hot air are separated, the cold air blocked by the rebound passes through the through hole 302 and enters the cold end air duct 201.

[0026] Embodiment 2. Based on Embodiment 1, the present invention further proposes a vacuum cleaner using a vortex cooling component, which separates the high-pressure airflow originally discharged directly from the vacuum cleaner into cold and hot air. The cold air is introduced into the battery pack to cool the lithium battery, while the hot air continues to be discharged into the external environment.

[0027] like Figure 5-Figure 7 As shown, a vacuum cleaner using a vortex cooling assembly includes a body assembly 6, on which a motor assembly 7, a battery pack assembly 9 and a vortex cooling assembly are installed, a dust cup assembly 8 is connected to the motor assembly 7, the vortex cooling assembly is located between the motor assembly 7 and the battery pack assembly 9, and the hot air end of the vortex cooling assembly is connected to the motor assembly 7, and the cold air end is connected to the battery pack assembly 9.

[0028] The battery pack assembly 9 is used to provide power to the motor assembly 7. After power is supplied, the motor assembly 7 generates vacuum negative pressure suction to suck external dirt into the dust cup assembly 8 to separate the dirt from the airflow. The dust cup assembly 8 is a prior art, so it will not be described in detail here.

[0029] The motor assembly 7 includes a casing, and a vacuum motor is installed inside the casing. When working, the vacuum motor forms negative pressure suction by generating high-pressure airflow, and the generated high-pressure airflow first enters the motor outlet chamber 701; the battery pack assembly 9 includes a shell 903 connected to the body assembly 6, and a battery pack is installed inside the shell 903. The existing battery packs are mostly composed of lithium batteries, and the shell 903 is provided with a battery pack air inlet 901 and a battery pack air outlet 902.

[0030] The fuselage assembly 6 is mainly used for the installation of the motor assembly 7 and the battery pack assembly 9; wherein the cold air duct 2 is located below the hot air duct 4, and the cold end air duct 201 and the hot end air duct 401 are both coaxial with the inner cavity; the vortex air inlet 103 and the hot air outlet 402 are both connected to the motor air outlet chamber 701, and the cold air outlet 202 is connected to the battery pack air inlet 901; therefore, the high-pressure airflow in the motor air outlet chamber 701 can enter the vortex air inlet duct 101 through the vortex air inlet 103, and after the vortex cooling assembly separates the hot and cold air, the cold air passes through the cold air outlet 202 and the battery pack air inlet 901 along the cold end air duct 201 and enters the interior of the shell 903, and is discharged from the battery pack air outlet 902 after heat exchange with the internal battery pack, thereby achieving the purpose of cooling and dissipating the heat of the battery pack.

[0031] In order to improve the cooling effect, the battery pack air inlet 901 and the battery pack air outlet 902 are respectively arranged at the top and bottom of the shell 903, and the cooling effect is improved by extending the path of cold air in the shell 903.

[0032] Furthermore, a vortex outlet duct 104 is provided on the air guide 1, and the hot air outlet 402 is connected to the motor outlet chamber 701 through the vortex outlet duct 104, and vortex outlets 105 connected to the outside are also provided at both ends of the vortex outlet duct 104.

[0033] After the vortex cooling component separates the hot and cold air in the high-pressure air flow, the hot air first enters the vortex outlet duct 104 along the hot end duct 401 through the hot air outlet 402, and then passes through the vortex outlet duct 104 through the vortex outlet duct 105 at both ends and the air outlet grille on the casing to be discharged to the outside of the product.

[0034] In order to prevent leakage between the vortex air inlet duct 101 and the vortex air outlet duct 104 and affect the separation effect of cold and hot air, a sealing ring 10 is provided on the top of the air duct 1, and the sealing ring 10 is used to seal and isolate the vortex air inlet duct 101 and the vortex air outlet duct 104.

[0035] In order to prevent the high-pressure airflow from entering the hot-end air duct 401 from the motor air outlet chamber 701 and affecting the discharge of hot air, the lower end of the vortex block 702 is embedded in the hot-end air duct 401, and the upper end of the vortex block 702 is located at the bottom of the motor air outlet chamber 701, and the radial size of the vortex block 702 increases from bottom to top. In this way, the hot air is not affected from being discharged upward from the hot-end air duct 401, and the high-pressure airflow in the motor air outlet chamber 701 can pass through its periphery and enter the vortex air inlet duct 101.

[0036] Embodiment 3, based on Embodiment 1 and Embodiment 2, the body assembly 6 includes a handle 601, and the two ends of the handle 601 are respectively connected to the motor assembly 7 and the battery pack assembly 9, which is convenient for the user to hold, and the eddy current cooling assembly is installed inside the handle 601, and the two ends are respectively connected to the motor assembly 7 and the battery pack assembly 9, which does not take up additional space and is no different from a conventional vacuum cleaner in appearance.

[0037] Embodiment 4, on the basis of Embodiment 1 and Embodiment 2, the body assembly 6 includes a handle 601, and the two ends of the handle 601 are respectively connected to the motor assembly 7 and the battery pack assembly 9, that is, the motor assembly 7 and the battery pack assembly 9 are connected through the handle 601. In order to improve the stability of the connection between the two, a support rod is usually arranged on the front side of the handle 601, and the two ends of the support rod are also respectively connected to the motor assembly 7 and the battery pack assembly 9, which mainly plays a supporting role, so that the structure of the body assembly 6 is more stable.

[0038] At this time, the eddy current cooling assembly can be installed inside the support rod, which can also meet the cooling and heat dissipation requirements of the battery pack without taking up additional space.

[0039] That is to say, when the body assembly 6 of the vacuum cleaner has both a handle 601 and a support rod, the vortex cooling assembly can be installed inside the handle 601 or inside the support rod; the two ends of the vortex cooling assembly installed inside the support rod are also respectively connected to the motor assembly 7 and the battery pack assembly 9; it is only necessary to ensure that the hot air outlet and the vortex air inlet 103 of the vortex cooling assembly are connected to the motor air outlet chamber 701, and the cold air outlet 202 is connected to the battery pack air inlet 901, so as to improve the cooling effect of the battery pack.

[0040] In summary, the present invention proposes a vortex cooling assembly, which can separate cold and hot air from high-pressure airflow and make it flow in different directions; it also proposes a vacuum cleaner using a vortex cooling assembly to improve the cooling effect on the battery pack and improve the performance and life of the battery. The vortex cooling assembly here can be installed on the inside of the handle 601 of the vacuum cleaner, or it can be installed in the support rod on the front side of the handle 601. Compared with conventional vacuum cleaners, it can not only improve the cooling effect on the battery pack, but also will not take up too much space. It is suitable for different types of vacuum cleaners and has a low cooling cost.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0043] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A vortex cooling assembly, characterized in that: Comprising an air guide duct (1), wherein an inner cavity and a vortex air inlet duct (101) are provided inside the air guide duct (1), a cold air duct (2) and a hot air duct (4) are arranged opposite to each other in the inner cavity, and a vortex chamber (5) is formed between the opposite ends of the two and the side wall of the inner cavity; An air inlet hole (102) is provided on the side wall of the inner cavity, a vortex air inlet port (103) is provided at one end of the vortex air inlet duct (101), and the other end is tangentially connected to the vortex chamber (5) through the air inlet hole (102); A cold end air duct (201) is provided inside the cold air duct (2); a vortex plate (3) for generating a free vortex is provided at one end of the cold end air duct (201); a cold air outlet (202) is provided at the other end; the vortex plate (3) is located in the vortex chamber (5); and the cold end air duct (201) is connected to the vortex chamber (5) via the vortex plate (3); A hot end air duct (401) is provided inside the hot air pipe (4), one end of the hot end air duct (401) is connected to the vortex chamber (5), and the other end is provided with a hot air outlet (402), a vortex block (702) is inserted at the center of the hot end air duct (401), and the inner diameter of the hot end air duct (401) is greater than the inner diameter of the cold end air duct (201).

2. The eddy current cooling assembly according to claim 1, characterized in that: The vortex plate (3) comprises a plate body (301) connected to the cold air duct (2); a through hole (302) communicating with the cold end air duct (201) is provided at the center of the plate body (301); and a plurality of protruding vortex blocks (303) are provided at the edge of the plate body (301); the plurality of vortex blocks (303) are distributed around the axis of the cold air duct (2) in a circular array on the circumference of the through hole (302).

3. A vacuum cleaner using the vortex cooling assembly according to any one of claims 1 to 2, characterized in that: The invention comprises a body assembly (6), a motor assembly (7), a battery pack assembly (9) and an eddy current cooling assembly, wherein the eddy current cooling assembly, the motor assembly (7) and the battery pack assembly (9) are all mounted on the body assembly (6), and the eddy current cooling assembly is located between the motor assembly (7) and the battery pack assembly (9).

4. The vacuum cleaner according to claim 3, characterized in that: The motor assembly (7) comprises a motor air outlet chamber (701), the battery pack assembly (9) comprises a shell (903) connected to the fuselage assembly (6), a battery pack is installed inside the shell (903), and a battery pack air inlet (901) and a battery pack air outlet (902) are provided on the shell (903); The vortex air inlet (103) and the hot air outlet (402) of the vortex cooling assembly are both in communication with the motor air outlet chamber (701), and the cold air outlet (202) of the vortex cooling assembly is in communication with the battery pack air inlet (901).

5. The vacuum cleaner according to claim 3, characterized in that: The air guide pipe (1) is provided with a vortex air outlet duct (104), the hot air outlet (402) is connected to the motor air outlet chamber (701) through the vortex air outlet duct (104), and vortex air outlets (105) connected to the outside are also provided at both ends of the vortex air outlet duct (104).

6. The vacuum cleaner according to claim 5, characterized in that: The lower end of the vortex stopper (702) is embedded in the hot end air duct (401), the upper end of the vortex stopper (702) is located at the bottom of the motor air outlet chamber (701), and the radial dimension of the vortex stopper (702) increases from bottom to top.

7. The vacuum cleaner according to claim 3, characterized in that: The body assembly (6) comprises a handle (601), two ends of the handle (601) are respectively connected to the motor assembly (7) and the battery pack assembly (9), and the eddy current cooling assembly is installed inside the handle (601); or, The body assembly (6) comprises a handle (601), a support rod is provided on the front side of the handle (6), two ends of the support rod are respectively connected to the motor assembly (7) and the battery pack assembly (9), and the eddy current cooling assembly is installed inside the support rod.

8. The vacuum cleaner according to claim 5, characterized in that: A sealing ring (10) is provided at the top of the air guide duct (1) for sealing and isolating the vortex air inlet duct (101) and the vortex air outlet duct (104).

9. The vacuum cleaner according to any one of claims 4 to 8, characterized in that: The cold air pipe (2) is located below the hot air pipe (4), and the cold end air duct (201) and the hot end air duct (401) are both coaxial with the inner cavity.

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