A hood

Abstract

The present invention provides a hood, comprising an outer air guide, a guide body, and an inner air guide; wherein the outer air guide cover is arranged on the upper outer side of the hood connecting pipe, and an upward exhaust passage is formed inside the outer air guide, and the guide body is supported on the outer air guide and is located in the exhaust passage; wherein the guide body is arranged on one side above the smoke exhaust port at the top of the hood connecting pipe, and the inner air guide extends upward along the upper end surface of the guide body, forming a side wall that can receive rebound wind or rainwater after falling to the inner wall of the outer air guide, and a drainage section that passes through the exhaust from top to bottom is formed between the side wall and the inner wall of the outer air guide; wherein the smoke discharged from the smoke exhaust port at the top of the hood connecting pipe is bent after passing through the guide body, and after passing through the drainage section, it is discharged from the top outlet of the outer air guide. The present invention can not only prevent the falling backflow of wind or rainwater, but also prevent the rebound backflow of wind or rainwater, and completely solve the backflow problem of the hood.

Description

Technical Field

[0001] The present invention relates to the technical field of building exhaust ducts, and in particular to a backflow prevention hood, in particular a hood capable of preventing rebound wind or rain from falling into an exhaust duct after impact caused by strong winds or rain with large kinetic energy. Background Art

[0002] At present, the hoods installed at the roof outlets of residential exhaust duct systems can be divided into the following three categories: the first type of hood is to set a flat or umbrella-shaped top cover plate just above the outlet, and the smoke is discharged from the bottom of the top cover plate to the periphery. The disadvantages of this type of hood are: the structure is too simple, and when encountering oblique wind and cross-rain, wind and rain can easily flow back into the exhaust duct, which not only hinders the normal discharge of smoke in the exhaust duct, but also rainwater will flow into the room along the exhaust duct. The second type of hood is an improvement on the first type of hood, which is to install rainproof shutters at the exhaust port below the top cover plate. This improves the rainproof performance of the hood to a certain extent, but significantly reduces the effective ventilation area of ​​the exhaust port, reduces the air flow velocity at the exhaust port, and significantly increases the exhaust wind resistance of the hood, resulting in poor exhaust. In order to solve this problem, it is necessary to significantly increase the size of the shutters, resulting in a waste of building space and unsightly appearance. The third type of hood is also an improvement on the first type of hood. A circle of windshield side plates is installed on the outside of the exhaust port under the flat cover or umbrella-shaped cover, and the smoke is discharged outward from the gap between the cover and the side plates. If the gap between the windshield side plates of the hood and the cover is too small, the exhaust wind resistance will be large, making it difficult to exhaust smoke and exhaust; if the gap between the windshield side plates of the hood and the cover is too large, in the case of slanting wind and rain, it is inevitable that wind and rain will flow back into the exhaust duct.

[0003] In response to the defects in the above-mentioned prior art, the applicant has conducted many experiments and proposed improvements (application number is 201821919248.8). By providing a top cover and a wind and rainproof outer cover that cooperate with each other, it is possible to prevent wind and rain from backflowing into the exhaust duct. In most cases, it has a nearly complete ability to prevent wind and rain from backflowing. However, it is found in practice that when used in areas where storms and rainstorms often occur, there is still a phenomenon of wind or rain backflowing into the exhaust duct. The applicant has conducted many on-site observations and tests and found that the wind or rain that backflows into the exhaust duct is rebound wind or rain. When the wind or rain has a large kinetic energy, a small part of the wind or rain will bounce back after the impact, changing the original motion trajectory and rebounding and splashing into the exhaust duct.

[0004] At present, there is no solution to the problem of rebounding wind or rain in the exhaust duct field, and it has not even been discovered that wind or rain can rebound and cause backflow. Summary of the invention

[0005] In view of the defects of the prior art, the present invention provides a wind hood that can not only prevent the wind or rain from falling and flowing back, but also prevent the wind or rain from rebounding and flowing back, thus completely solving the problem of backflow of the wind hood.

[0006] The first object of the present invention is to provide a hood, comprising an outer air guide tube, a guide body, and an inner air guide tube;

[0007] The outer air guide cover is arranged on the upper outer side of the hood connecting pipe, and an upward exhaust passage is formed inside the outer air guide cover, and the guide body is supported on the outer air guide cover and is located in the exhaust passage;

[0008] The guide body is arranged on one side above the smoke exhaust port at the top of the hood connecting pipe, and the inner air guide tube extends upward along the upper end surface of the guide body to form a side wall capable of receiving rebound wind or rainwater generated after falling onto the inner wall of the outer air guide tube, and a drainage section for exhausting air through the upper and lower parts is formed between the side wall and the inner wall of the outer air guide tube;

[0009] The smoke exhausted from the smoke exhaust port at the top of the hood connecting pipe is bent after passing through the guide body, passes through the guide section, and is exhausted from the top outlet of the outer air guide tube.

[0010] In the above technical scheme of the present invention, the structure of the outer air guide tube and the guide body cooperate to form a main air guiding part. The smoke discharged from the smoke exhaust port at the top of the wind hood connecting pipe is turned upward after passing through the guide body and discharged from the top outlet of the outer air guide tube; the main purpose of the inner air guide tube is to prevent wind and rain backflow, especially in cases where the wind is strong and the rain is heavy (with large kinetic energy). At this time, the wind or rain poured into it from the top outlet of the outer air guide tube can produce rebound wind or rain after hitting the inner wall of the outer air guide tube. At this time, the guide body of the conventional structure cannot receive this part of the rebound wind or rain (for example, the applicant's previous application 201821919248.8). In this case, the rebound wind or rain will flow back into the wind hood connecting pipe, causing backflow, which has an adverse effect on the smoke and exhaust in the exhaust duct. The above-mentioned backflow phenomenon is the main problem that the wind hood needs to solve in the current prior art.

[0011] Furthermore, in order to receive the rebound wind or rainwater that causes the backflow phenomenon mentioned above, the applicant, after a large number of experiments, set up an inner air guide tube above the guide body. On the one hand, it can guide the smoke discharged from the smoke exhaust port on the top of the hood connecting pipe, and on the other hand, it is used to receive the rebound wind or rainwater generated after falling to the inner wall of the outer air guide tube, so that the rebound wind or rainwater dissipates energy and stays away from the top smoke exhaust port of the hood connecting pipe. Specifically, the wind or rainwater after energy dissipation flows downward along the side wall.

[0012] Among them, in order to reduce the space occupied by the hood, the height of the side wall is set so that it can receive at least one rebound wind or rain, that is, the wind or rain that can fall from the top outlet of the outer air duct will hit the side wall after one rebound and cannot directly rebound to the top smoke exhaust port of the hood connecting pipe. After a large number of experiments by the applicant, it was found that the energy dissipation rate of the rebound wind or rain after receiving it once exceeded half, and after rebounding again, it is completely or almost completely unable to rebound for the next time. Therefore, setting the side wall height that can receive the rebound wind or rain once can effectively prevent the rebound wind or rain from backflowing.

[0013] The height of the side wall can be adaptively adjusted according to the specifications of the product.

[0014] In order to prevent the inner air duct from causing unnecessary wind resistance to the smoke exhaust process, preferably, the side walls of the inner air duct are arranged to be vertical or inwardly inclined so that the effective flow area of ​​the drainage section will not decrease along the smoke exhaust direction, and may even gradually increase, so as to quickly exhaust the smoke.

[0015] Specifically, in the present invention, smoke is discharged from the top outlet of the outer air duct, and the outer wall thereof is more regular, which is convenient for production and manufacturing processes, avoids unnecessary assembly processes, and is conducive to productization.

[0016] According to another specific embodiment of the present invention, the surface of the side wall is provided with a buffer structure capable of absorbing rebound wind or rainwater, for example, a layer of absorbent cotton is pasted on it, and a porous (blind hole) structure or a tiny protrusion structure is set on the surface of the side wall to improve the energy dissipation rate of the side wall to rebound wind or rainwater, so that the rebound wind or rainwater can dissipate energy better and be discharged quickly.

[0017] According to another specific embodiment of the present invention, the outer air guide tube is supported on the hood connecting pipe or on the hood base of the roof floor through a bracket.

[0018] According to another specific embodiment of the present invention, the guide body is a square cone, a circular cone or a wedge-shaped cone with a small lower end and a large upper end to better form a wind-inducing effect. The guide body guides the smoke in the hood connecting pipe to change direction to eliminate the vortex phenomenon, thereby reducing wind resistance and achieving a smooth discharge process of the smoke.

[0019] According to another specific embodiment of the present invention, a chamfered portion is formed at the connection between the body guide and the inner air guide tube, and a drip line is provided at the bottom of the side wall. The drip line is configured to extend downward from the lower end of the side wall and does not exceed the chamfered portion, wherein rainwater gathered downward along the side wall directly drips from the drip line without sliding onto the body guide.

[0020] Correspondingly, the drip line is not arranged to extend downward beyond the chamfered portion, thereby preventing the drip line from hindering the air guiding effect of the guide body.

[0021] According to another specific embodiment of the present invention, the effective flow area of ​​the drainage section is not less than the effective flow area of ​​the smoke exhaust port at the top of the hood connecting pipe.

[0022] According to another specific embodiment of the present invention, the cross-section of the outer air duct is circular, square or regular polygonal, and the cross-section of the inner air duct is circular, square or regular polygonal that matches the outer air duct. In this solution, the outer four sides of the regular outer air duct can be used for advertising, and the appearance is beautiful, and the smoke exhaust outlet of the hood cannot be seen on the side and below.

[0023] According to another specific embodiment of the present invention, the top of the inner air guide tube is closed to form a top cover, and a centrally protruding sloped rain dispersion structure is provided on the upper outer side of the top cover to quickly drain and discharge rainwater falling on the top cover.

[0024] According to another specific embodiment of the present invention, the upper end of the outer air duct is narrowed inward to form a conical rainproof platform, and the conical rainproof platform is inclined in a narrowed form from bottom to top to prevent rainwater from tilting and falling directly into the gap space between the guide body and the wind cap connecting pipe and entering the exhaust duct. In addition, the height of the entire outer air duct can also be reduced to save space.

[0025] The second object of the present invention is to provide a hood, comprising a hood connecting pipe, an outer air guide tube covering the smoke exhaust port at the top of the hood connecting pipe, and a guide body arranged in the outer air guide tube, wherein a vertical inner air guide tube is provided above the guide body, and the side wall of the inner air guide tube can receive rebound wind or rainwater generated after falling to the inner wall of the outer air guide tube, so that the rebound wind or rainwater dissipates energy and stays away from the top smoke exhaust port of the hood connecting pipe.

[0026] The present invention has the following beneficial effects:

[0027] The hood of the present invention adopts an outer air guide tube, and an inner and outer set between the inner air guide tube and the guide body. The smoke has fewer turns when flowing in the hood, the wind resistance is also small, and the smoke exhaust is smoother; wherein, the smoke is discharged high into the sky, which is not only suitable for floors where people do not walk, but also more suitable for floors where people walk, and does not affect the use function of the floor.

[0028] In addition, the inner air duct of the present invention has a side wall that can receive rebound wind or rainwater that falls on the inner wall of the outer air duct, so that the rebound wind or rainwater is discharged downward along the side wall after dissipating energy, and away from the top smoke exhaust port of the hood connecting pipe, thereby avoiding the phenomenon of rebound wind or rainwater backflowing into the exhaust duct and solving the problem of wind and rain rebounding and backflowing.

[0029] In addition, the side wall of the present invention is provided with a drip line, and the drip line is arranged to extend downward from the lower end of the side wall and not exceed the chamfered portion between the guide body and the inner air guide tube, so that rainwater gathered downward along the side wall drips directly from the drip line without sliding onto the guide body.

[0030] In addition, the upper end of the outer air duct of the present invention is closed inward to form a conical rainproof platform, thereby reducing the height of the entire outer air duct to save space.

[0031] In addition, the hood material of the present invention can be metal, such as stainless steel, galvanized steel plate, aluminum alloy, anti-corrosion carbon steel, etc.; it can also be non-metal, such as fiberglass, concrete, plastic, etc.

[0032] In addition, the wind hood of the present invention has extremely wide applicability. It is not only suitable for wind and rain protection of terminal exhaust ports of residential exhaust ducts, but also for wind and rain protection of smoke exhaust ports of large-scale catering industries. It is also suitable for terminal wind and rain protection design of smoke exhaust systems in the field of building ventilation and chemical, metallurgical and other industrial fields.

[0033] In addition, the hood of the present invention has a regular structure, the smoke exhaust port is located at the upper end, the lower end can be closed (leaving only a rainwater outlet) or not, and its outer surroundings can be used for advertising, with an aesthetic appearance, and the smoke exhaust port cannot be seen from the side or below.

[0034] When the downwardly inclined natural wind blows on the inner side of the outer air guide, the present invention will rebound to the inner air guide, and then flow downward along the inner air guide without backflow into the exhaust duct, thereby solving the defect of natural wind rebounding and backflow occurring in the existing anti-backflow hood due to the lack of an inner air guide. When raindrops fall on the top cover, it will scatter in all directions. When encountering heavy rain, the rainwater will directly hit the inner wall of the outer air guide, and a part of the rainwater after the impact will splash and rebound to the side wall of the inner air guide, and then flow along the side wall of the inner air guide through the drip line, through the gap between the outer air guide of the hood and the hood connecting pipe, and drip onto the floor outside the hood. As the existing anti-backflow hood has no inner air guide, after the rainwater hits the inner wall of the outer air guide, a small amount of rainwater will rebound and splash into the exhaust duct, resulting in the occurrence of backflow.

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of the hood of the present invention;

[0037] Figure 2 yes Figure 1 An enlarged schematic diagram of the middle drip line;

[0038] Figure 3 It is a schematic diagram of the installation of the hood of the present invention;

[0039] Figure 4 It is a schematic diagram of the working principle of the wind cap of the present invention to prevent horizontal wind backflow;

[0040] Figure 5 It is a schematic diagram of the working principle of the wind cap preventing the tilted wind backflow of the present invention;

[0041] Figure 6 It is a schematic diagram of the working principle of the wind cap of the present invention to prevent rainwater from flowing back;

[0042] Figure 7 is a top view schematic diagram of the square structure of the hood of the present invention;

[0043] Figure 8 is a top view schematic diagram of the circular structure of the hood of the present invention;

[0044] Fig. 9 It is a schematic structural diagram of another outer air guide tube of the hood of the present invention;

[0045] Fig.10 It is a structural schematic diagram of another hood connecting pipe of the present invention;

[0046] Fig.11 This is a schematic diagram of the structure of the double-sided wall installation of the present invention;

[0047] Fig.12 It is a structural schematic diagram of the present invention installed on one side against the wall. DETAILED DESCRIPTION

[0048] A hood comprises an outer air guide tube 10, a body guide 20 and an inner air guide tube 30.

[0049] See also Figure 1 The outer air guide tube 10 is covered on the upper outer side of the hood connecting pipe 40, and an upward exhaust passage 10a is formed inside the outer air guide tube 10. The guide body 20 is supported on the outer air guide tube 10 and is located in the exhaust passage 10a. The outer air guide tube 10 is supported on the hood connecting pipe 40 or on the hood base of the roof floor through a bracket 11. Figure 3 As shown, the outer air guide tube 10 is supported on the hood connecting tube 40 through the bracket 11;

[0050] Among them, see again Figure 1 The bracket 11 has a certain distance from the top smoke exhaust port of the hood connecting pipe 40. When rain drops on the bracket 11, it will not splash into the hood connecting pipe 40. Preferably, the bracket 11 can also be a cylindrical support rod, which can firmly support the outer air guide tube 10 while avoiding the splashing of rainwater; more preferably, the bracket 11 can also be arranged at an angle so that the dripping rainwater splashes in the direction away from the top smoke exhaust port of the hood connecting pipe 40.

[0051] The guide body 20 is arranged on the upper side of the smoke exhaust port at the top of the hood connecting tube 40, and the inner air guide tube 30 extends upward along the upper end surface of the guide body 20 to form a side wall 30a that can receive rebound wind or rainwater that falls on the inner wall of the outer air guide tube 10, and a drainage section 12 that passes through the exhaust from top to bottom is formed between the side wall 30a and the inner wall of the outer air guide tube 10, wherein the effective flow area of ​​the drainage section 12 is not less than the effective flow area of ​​the smoke exhaust port at the top of the hood connecting tube 40; the smoke discharged from the smoke exhaust port at the top of the hood connecting tube 40 is bent after passing through the guide body 20, and after passing through the drainage section 12, it is discharged from the top outlet of the outer air guide tube 10.

[0052] Among them, the guide body 20 is a square cone, a circular cone or a wedge-shaped cone with a small lower end and a large upper end, so as to better form a wind-inducing effect, guide the smoke to flow obliquely upward, and reduce the smoke exhaust wind resistance. The guide body 20 guides the smoke in the wind hood connecting pipe 40 to change direction to eliminate the vortex phenomenon, thereby reducing wind resistance and realizing the smooth discharge of smoke.

[0053] In other examples of the present invention, the surface of the side wall 30a of the inner air guide tube 30 is provided with a buffer structure capable of absorbing rebound wind or rainwater, such as pasting a layer of absorbent cotton, or the surface of the side wall 30a is provided with a porous (blind hole) structure or a tiny protrusion structure, etc., so that the rebound wind or rainwater can better dissipate energy and be discharged quickly.

[0054] For further information, see Figure 2 The body guide 20 in the present invention is formed with a chamfered portion 21 at the connection with the inner air guide tube 30, and a drip line 31 is provided at the bottom of the side wall 30a. The drip line 31 is configured to extend downward from the lower end of the side wall 30a and does not exceed the chamfered portion 21, wherein rainwater gathered downward along the side wall 30a directly drips from the drip line 31 without sliding onto the body guide 20.

[0055] Accordingly, the drip line 31 does not extend downward beyond the chamfered portion 21, see Figure 2 The dotted line in the figure can prevent the drip line 31 from hindering the wind guiding effect of the guide body 20.

[0056] Furthermore, in order to reduce wind resistance, the body guide 20 and the inner air guide tube 30 are arranged in such a manner: a plurality of connecting rods 13, for example four, are arranged, which are evenly distributed on the outer periphery of the inner air guide tube 30, and one end of the connecting rod 13 is connected to the inner air guide tube 30, and the other end of the connecting rod 13 is connected to the outer air guide tube 10, so as to fix the inner air guide tube 30 and the body guide 20; wherein the connecting rod 13 can be a horizontal rod or an inclined rod.

[0057] In the present invention, the cross section of the outer air duct 10 is circular, square or regular polygonal, and the cross section of the inner air duct 30 is circular, square or regular polygonal that matches the outer air duct 10, for example Figure 7 The square shown, for example Figure 8 The circle shown.

[0058] In other preferred examples of the present invention, the outer air guide cylinder 10 may also be in a frustum shape in the vertical direction, for example Fig. 9 As shown, it includes an upper section 10b and a lower section 10c. The upper section 10b and the lower section 10c are symmetrical. The upper section 10b is a conical tube with a lower upper end and a larger lower end, and the lower section 10c is a conical tube with a larger upper end and a smaller lower end. At this time, the inner air guide tube 30 is preferably a circular structure.

[0059] Correspondingly, the outer air duct 10 can also be a conical tube with a small upper end and a large lower end, or a partially smaller conical structure can be set. For example, the upper end of the outer air duct 10 is narrowed inward to form a conical rainproof platform 14. The conical rainproof platform 14 is inclined from bottom to top in a convergent manner to prevent rainwater from tilting and directly falling into the gap space between the guide body 20 and the hood connecting pipe 40 and entering the exhaust duct. In addition, the height of the entire outer air duct 10 can also be lowered to save space.

[0060] For another example, the bottom of the outer air guide tube 10 is closed inwardly to form a cone shape to facilitate the discharge of collected rainwater and prevent rainwater from falling on the roof hood mounting base from splashing in.

[0061] In the present invention, the outer periphery of the regular outer air duct 10 can be used for advertising, and the appearance is beautiful, and the smoke exhaust outlet of the hood cannot be seen on the side and below.

[0062] Specifically, the top of the inner air duct 30 is closed to form a top cover 32, and a centrally protruding sloped rain-scattering structure is provided on the upper outer side of the top cover 32 to quickly drain and discharge rainwater falling on the top cover 32, wherein the sloped rain-scattering structure can be in the shape of a triangular cone, a frustum, or a step, etc., as long as it can guide the rainwater to be discharged.

[0063] The hood connecting pipe 40 of the present invention can be Figure 1 The straight pipe shown in the figure has an air inlet size greater than or equal to the size of the exhaust duct. The erected portion of the mounting flange 50 is located inside the connecting pipe to prevent rainwater from entering the exhaust duct. The hood portion is mounted and fixed on the hood mounting base on the roof through the hood connecting pipe 40 and the mounting flange 50. Figure 3 shown.

[0064] In other examples of the present invention, the hood connecting pipe 40 may also be a tapered pipe with a large upper end and a small lower end, such as Fig.10 As shown, the size of the air inlet at the lower end is greater than or equal to the specification size of the exhaust duct; the mounting flange 50 is located inside the connecting pipe to prevent rainwater from entering the exhaust duct.

[0065] See also Figure 4 -6, which shows the process of the present invention to prevent wind and rain.

[0066] Figure 4 The working principle of the windproof horizontal natural wind backflow is shown in the figure. The horizontal natural wind blows through the outer air guide tube 10 of the wind hood and spreads to the surroundings. It will not backflow into the inside of the wind hood and will not hinder the emission of smoke.

[0067] Figure 5 The working principle of anti-wind backflow is shown in the figure. The natural wind that is inclined downward blows on the top cover 32 of the hood, spreads out to the surroundings, flows downward along the drainage section 12 between the inner air guide tube 30 of the hood and the outer air guide tube 10, and finally flows out of the hood from between the hood connecting pipe 40 and the outer air guide tube 10. It will not flow back into the exhaust duct. At this time, the drainage section 12 guides the wind entering the hood to be discharged vertically downward instead of being blown into the hood connecting pipe 40.

[0068] Figure 6 The working principle of anti-rainwater (anti-rebound wind) backflow is shown in the figure. If rainwater drops between the inner air duct 30 and the outer air duct 10 of the hood, it will directly pass through the exhaust duct 10a and fall onto the floor; if rainwater drops on the hood top cover 32, it will scatter along the top cover 32, among which the rainwater mainly flows downward along the inner air duct 30 and drips from the drip line 31, and the remaining rainwater directly hits the inner wall of the outer air duct 10 and then flows downward along the inner wall of the outer air duct; another part of the rainwater will rebound and splash onto the side wall 30a of the inner air duct 30 after hitting the inner wall of the outer air duct 10, flow along the side wall 30a of the inner air duct 30 to the drip line 31, and drip from the drip line 31 onto the floor outside the hood. During the whole process, no matter where the rainwater drops on the anti-backflow hood, it will not fall into the exhaust duct.

[0069] In other examples of the present invention, in order to adapt to the installation of the hood, a single-side wall installation or a double-side wall installation is performed, and only the various parts of the hood need to be adaptively adjusted. Taking the double-side wall installation as an example, see Fig.11 At this time, the hood connecting pipe 40 is close to the wall, and the outer air guide tube 10 can be directly fixed on the wall, or by using Figure 1 According to the fixing method of the bracket in the embodiment, the inner air guide tube 30 and the flow guide body 20 can be prefabricated on a side wall 10d of the outer air guide tube 10 for fixed installation.

[0070] At this time, the smoke discharged from the top smoke exhaust port of the hood connecting pipe 40 is discharged upward from the drainage section on the right side. The principle of preventing rebound wind or rainwater backflow is the same as that of Figure 1 The structure is the same as in, so I will not repeat it here; the structure with one side against the wall is as follows Fig.12As shown, it is only an adaptive change of the above structure, which will not be repeated here.

[0071] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the scope of the present invention. Any person skilled in the art can make some improvements without departing from the scope of the present invention, that is, all equivalent improvements made according to the present invention should be covered by the scope of the present invention.

Claims

1. A hood, characterized in that: include: External air duct; Conductor; as well as Internal air duct; The outer air guide cover is arranged on the upper outer side of the hood connecting pipe, and an upward exhaust passage is formed inside the outer air guide cover, and the guide body is supported on the outer air guide cover and is located in the exhaust passage; The guide body is arranged on one side above the smoke exhaust port at the top of the hood connecting pipe, and the inner air guide tube extends upward along the upper end surface of the guide body to form a side wall capable of receiving rebound wind or rainwater generated after falling onto the inner wall of the outer air guide tube, and a drainage section for exhaust gas passing through from top to bottom is formed between the side wall and the inner wall of the outer air guide tube; The smoke discharged from the smoke exhaust port at the top of the hood connecting pipe is deflected after passing through the guide body, passes through the guide section, and is discharged from the top outlet of the outer air guide tube; The body guide is a square cone, a circular cone or a wedge-shaped cone with a small lower end and a large upper end. The body guide is located at the connection with the inner air guide tube and a chamfer is formed. The bottom of the side wall is provided with a drip line, and the drip line is arranged to extend downward from the lower end of the side wall and not exceed the chamfer. The top of the inner air guide tube is closed to form a top cover, and a sloped rain dispersion structure with a protruding center is arranged on the upper outer side of the top cover.

2. The hood according to claim 1, characterized in that: The surface of the side wall is provided with a buffer structure capable of absorbing rebound wind or rainwater.

3. The hood according to claim 1, characterized in that: The outer air guide tube is supported on the hood connecting pipe or on the hood base of the roof floor through a bracket.

4. The hood according to claim 1, characterized in that: The effective flow area of ​​the diversion section is not less than the effective flow area of ​​the smoke exhaust port at the top of the hood connecting pipe.

5. The hood according to claim 1, characterized in that: The cross section of the outer air guide tube is a circle or a regular polygon, and the cross section of the inner air guide tube is a circle or a regular polygon matching the outer air guide tube.

6. The hood according to claim 1, characterized in that: The upper end of the outer air guide tube is closed inwardly to form a conical rainproof platform.

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