Flue check valve capable of preventing smoke from flowing back

Abstract

The utility model discloses a flue check valve for preventing smoke backflow, which comprises a valve body pipeline with a 90-degree elbow structure, a smoke inlet of the valve body pipeline is horizontally arranged on an indoor smoke exhaust pipeline, a smoke outlet of the valve body pipeline is vertically arranged on a public smoke exhaust pipeline, a valve cover covers the smoke outlet, the valve cover is turned over upwards under the action of airflow, and the valve cover is arranged on the valve body pipeline. An annular lower sealing plate is coaxially arranged on the outer wall of a smoke outlet of the valve body pipeline, and an annular lower sealing groove is formed in the surface of the lower sealing plate. An upper sealing plate is installed on the inner side face, facing the valve body pipeline, of the valve deck, an upper sealing groove is formed in the upper sealing plate and used for covering the end of the smoke outlet, and an annular sealing baffle is installed on the outer edge of the upper sealing plate and used for stretching into the lower sealing groove. According to the flue check valve, on the basis of an existing check valve, the sealing structure is additionally arranged at the connecting position of the valve cover and the valve body, the smoke channeling prevention capacity of the valve body is greatly improved, and smoke in a public flue is prevented from flowing back into a room through the check valve.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of flue check valve, specifically, relate to a flue check valve of preventing flue gas backflow. BACKGROUND

[0002] The public vertical smoke exhaust system is a kind of ventilation and exhaust way commonly used in current residential kitchen, and the kitchen hood in the kitchen is communicated with the public flue through indoor smoke exhaust passage, in order to prevent oil fume backflow, the flue check valve is usually arranged between the public flue and indoor smoke exhaust passage, and the flue check valve has a check structure.The flue check valve is also called backflow valve, non-return valve, back pressure valve and one-way valve, and the function is to effectively block the waste gas and oil fume in the external environment from backflowing into the user's own home, thereby playing the role of protecting the indoor air quality and safety of the user.

[0003] At present, the conventional flue check valve is installed in the horizontal indoor passage, when discharging smoke into the public flue, the flue gas is horizontally discharged, and the flue gas directly impacts on the flue wall, which can easily cause the flue gas rebounding and affecting the smoke exhaust effect.Therefore, in order to solve the above problems, a check valve with 90 ° elbow structure is used in actual flue construction, as shown in the drawing, the smoke outlet thereof is installed in the public flue vertically upward and parallel to the public flue, and the flue gas injection on the wall surface is avoided. Figure 1 However, the valve cover of this type of check valve is a flat structure and is in a separated state with the valve body, the valve cover is opened and limited by the turnover structure arranged inside and outside the valve body, then the valve cover is covered on the opening of the valve body under the action of its own gravity to realize closing.The valve body is sealed only by the valve cover covering the smoke outlet of the valve body in the closed state, and the sealing performance is poor, and the valve cover will continuously collide with the metal end face of the valve body in the opening and closing process, which also causes the continuous abrasion of the sealing ring on the inner side of the valve cover, resulting in poor sealing performance.When the flue gas discharged from other floors, especially the lower floors, in the public flue, the flue gas can easily flow into the valve body from the lower edge of the valve cover, and finally backflow into the room.

[0004] Therefore, the present application is proposed. UTILITY MODEL CONTENTS

[0005] The technical problem to be solved by the utility model is the poor sealing performance of the valve cover and the valve body of the existing flue check valve, and the utility model aims to provide a flue check valve for preventing flue gas backflow, which greatly improves the anti-channeling capability of the valve body by increasing the sealing structure at the connection between the valve cover and the valve body, and avoids the flue gas in the public flue backflowing into the room.

[0006] The utility model is implemented by the following technical scheme:

[0007] The flue check valve for preventing flue gas backflow comprises a valve body pipeline in 90-degree elbow structure, the one end of the valve body pipeline is horizontally arranged in the indoor exhaust pipeline, the other end is vertically arranged in the public exhaust pipeline, a valve cover is arranged above the exhaust outlet, the valve cover is turned up under the action of air flow, a lower annular sealing plate is coaxially arranged on the outer wall of the exhaust outlet of the valve body pipeline, and a lower annular sealing groove is arranged on the surface of the lower sealing plate;

[0008] An upper sealing plate is arranged on the inner side of the valve cover, an upper sealing groove is arranged on the upper sealing plate, the upper sealing groove is used for covering the end of the exhaust outlet, and a ring-shaped sealing baffle is arranged on the outer edge of the upper sealing plate and used for extending into the lower sealing groove.

[0009] The check valve currently used is in 90-degree elbow structure, the exhaust outlet is vertically upward and parallel to the public flue, the valve cover is in flat plate structure and is separated from the valve body, when exhausting, the valve cover is turned up and opened under the action of air flow through the turning structure arranged inside and outside the valve body, after exhausting, the valve cover is covered on the opening of the valve body under the action of gravity, the diameter of the valve cover is slightly larger than that of the exhaust outlet, so as to completely cover the exhaust outlet, and a rubber layer is arranged on the inner side of the valve cover and is in contact with the end surface of the exhaust outlet, so as to realize the sealing of the exhaust outlet and the buffering when the valve cover falls back.

[0010] Obviously, the closing structure of the valve cover and the valve body is difficult to well seal the exhaust outlet, and the valve body is generally made of stainless steel, so that the valve cover collides with the metal end surface of the valve body when falling and closing, the rubber layer is abraded and cannot be well in contact with the exhaust outlet, and the sealing performance of the valve cover is further reduced.

[0011] Therefore, the flue check valve of the utility model, on the basis of the existing check valve, increases the sealing structure at the connecting position of the valve cover and the valve body, greatly improves the anti-channeling ability of the valve body, and avoids that the flue gas in the public flue flows back to the indoor through the check valve.

[0012] The flue check valve of the utility model, lower sealing plate is arranged on the outer wall of the smoke outlet of the valve body pipeline, the top surface of the inner side of the lower sealing groove is slightly lower than the end surface of the smoke outlet, in the closed state, the upper sealing groove of the upper sealing plate covers the end surface of the smoke outlet, the bottom surface of the upper sealing plate can just contact with the top surface of the lower sealing plate of the inner side of the lower sealing groove, thereby the smoke outlet is closed between the first double sealing structure formed by the upper sealing groove and the lower sealing plate, the flue gas can be avoided from entering the smoke outlet from outside; meanwhile the sealing baffle of the outer edge of the upper sealing plate is located in the lower sealing groove and is attached to the bottom surface of the lower sealing groove, so that the sealing baffle and the lower sealing groove form the second double sealing structure, the flue gas can be avoided from drilling into the upper sealing groove from below when moving from below to above.

[0013] In a specific embodiment, the lower sealing groove separates the lower sealing plate into an inner ring plate, an outer ring plate, and a connecting bottom plate connecting the inner ring plate and the outer ring plate, and the outer ring plate has a tapered cylinder structure with a large upper part and a small lower part.

[0014] The outer ring plate is designed as a tapered cylinder structure with a large upper part and a small lower part, so when the flue gas moves from below to above and contacts the lower sealing plate, it will move upward along the outer edge of the outer ring plate, thereby guiding the flue gas to move away from the sealing baffle, avoiding the flue gas staying at the sealing part of the sealing baffle and the lower sealing groove.

[0015] The width of the lower sealing groove is greater than the thickness of the sealing baffle, and the inner diameter of the sealing baffle is slightly larger than the outer diameter of the inner ring plate. The sealing baffle is arranged on the lower sealing groove, and the inner wall and the outer wall of the sealing baffle do not have surface contact with the inner ring plate and the outer ring plate. In this way, the friction between the sealing baffle and the lower sealing plate can be avoided, which affects the opening and closing of the valve cover.

[0016] In a specific embodiment, the sealing baffle also has a tapered cylinder structure with a large upper part and a small lower part, and the taper of the sealing baffle is greater than or equal to the taper of the outer ring plate.

[0017] By arranging the sealing baffle with an upper large and lower small structure, the sealing surface of the lower end of the sealing baffle and the bottom surface of the lower sealing groove is closer to the inner side, making it more difficult for the flue gas to reach. Secondly, when the taper of the sealing baffle is equal to the taper of the outer ring plate, the two are inclined parallel but not attached, forming an inclined upward ring gap, making it difficult for the flue gas to move downward from above the ring gap to the lower end of the sealing baffle. When the taper of the sealing baffle is greater than the taper of the outer ring plate, the outer wall of the sealing baffle can be attached to the top end of the outer ring plate, thereby forming a third double sealing structure, further improving the sealing performance. The taper of the sealing baffle and the outer ring plate can be determined according to the design size of the lower sealing plate and the upper sealing plate, but the taper should not be too large, and the taper of the outer ring plate is preferably within 45°.

[0018] In a specific embodiment, the lower sealing plate and the upper sealing plate are made of rubber or silicone material. The rubber or silicone material has a certain softness, which can buffer the impact force when the valve cover is closed, and the lower sealing plate and the upper sealing plate form a soft contact and are not easy to wear each other.

[0019] In a specific embodiment, the upper sealing groove penetrates the side of the upper sealing plate, and the side opening is covered with a rubber thin layer of annular structure. The upper sealing groove is sleeved on the valve cover from the outer side of the valve cover.

[0020] The flue check valve of the utility model, since the turnover structure for realizing the opening and closing of the valve is detachably installed on the valve body and the valve cover through bolts and other components, the upper sealing plate can be sleeved on the valve cover from the outer side of the valve cover after the turnover structure is detached, and the existing check valve can be directly modified.

[0021] In a specific embodiment, the lower sealing plate is provided with a joint, and the two ends of the joint are provided with matched buckle structures. By setting the lower sealing plate as a detachable structure, the lower sealing plate can be directly installed on the outer wall of the smoke outlet through the buckle structure, which is more convenient to install, or the lower sealing plate can be directly an integral structure and be sleeved into the smoke outlet from the upper end of the smoke outlet. The buckle structure can be a plug and a slot structure, and then be fixed through bolts and the like, so as to stagger the connection at the joint and improve the sealing performance at the joint. The detachable upper sealing plate and lower sealing plate structure in combination with the selection of materials can directly modify the structure of the existing check valve, which is low in modification cost and does not need to be re-manufactured.

[0022] In a specific embodiment, a flow guide cylinder is arranged in the vertical section of the valve body pipeline, the flow guide cylinder has a structure of being small at the top and large at the bottom, the lower end of the flow guide cylinder is tightly connected with the inner wall of the valve body pipeline, and the upper end of the flow guide cylinder is located below the smoke outlet.

[0023] In a specific embodiment, the diameter of the opening at the upper end of the flow guide cylinder is 1 / 3-1 / 2 of the diameter of the smoke outlet.

[0024] The vertical section of the valve body pipeline is provided with the flow guide cylinder, the airflow enters the flow guide cylinder from the bottom to the top, the flow area of the airflow gradually decreases, the pressure of the airflow continuously increases, the impact force on the valve cover is enhanced, and the opening of the valve cover is more sensitive. In addition, the flow guide cylinder is arranged in the vertical section, and the opening at the top of the flow guide cylinder is small. Therefore, even if a small amount of flue gas enters the valve body pipeline, the flow guide cylinder can isolate most of the flue gas above the flow guide cylinder, so that the flue gas is difficult to enter the indoor flue, and the ability to prevent the flue gas from flowing back to the indoor is improved. The flow guide cylinder can be installed in the valve body pipeline by welding, or the flow guide cylinder can be integrally formed with the valve body pipeline.

[0025] In a specific embodiment, the inner wall of the sealing baffle has a sawtooth structure, which makes the sealing baffle lighter without reducing the overall thickness of the sealing baffle.

[0026] In a specific embodiment, a sticky layer is coated between the inner wall of the lower sealing plate and the outer wall of the valve body pipeline, which improves the stability of the installation of the lower sealing plate and the valve body pipeline.

[0027] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0028] 1. The flue check valve for preventing flue gas backflow provided by the utility model embodiment, by increasing the sealing structure at the valve cover and valve body connecting part of the existing check valve, greatly improves the anti-channeling ability of the valve body, avoids the flue gas in the public flue from backflowing to the indoor through the check valve;

[0029] 2. The flue check valve for preventing flue gas backflow provided by the utility model embodiment, by improving the specific structure of the lower sealing plate and the upper sealing plate, can form a multiple sealing structure at the valve cover and valve body flue outlet, further improves the sealing performance, and prevents the flue gas from channeling and backflowing;

[0030] 3. The flue check valve for preventing flue gas backflow provided by the utility model embodiment, by the detachable upper sealing plate and lower sealing plate structure, combined with the selection of materials, can directly perform structural modification on the basis of the existing check valve, and the modification cost is low, and it is unnecessary to re-customize and manufacture. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical scheme of the exemplary embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some embodiments of the utility model, and should not be regarded as the limitation to the scope, and for the ordinary skilled person in the art, other related drawings can also be obtained according to these drawings without the creative labor.

[0032] Figure 1 The existing flue check valve structure schematic diagram provided by the utility model;

[0033] Figure 2 The overall structure schematic diagram of the flue check valve provided by the utility model embodiment;

[0034] Figure 3 The upper sealing plate structure schematic diagram provided by the utility model embodiment;

[0035] Figure 4 The lower sealing plate structure schematic diagram provided by the utility model embodiment;

[0036] Figure 5 The sealing structure under the closed state of the flue check valve is shown in the schematic view of the utility model embodiment.

[0037] Markings in the drawings and corresponding component names:

[0038] 1-valve body pipeline, 2-valve cover, 3-lower sealing plate, 31-lower sealing groove, 301-inner ring plate, 302-outer ring plate, 303-connection inner ring plate, 4-upper sealing plate, 41-upper sealing groove, 42-sealing baffle, 43-rubber thin layer, 5-flow guide cylinder. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the utility model clearer and more apparent, the utility model will be further described in detail below in combination with embodiments and drawings, and the schematic implementation mode and the description thereof of the utility model are only used to explain the utility model, and not as a limitation on the utility model.

[0040] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the utility model. However, it is apparent to those skilled in the art that the utility model can be practiced without these specific details. In other embodiments, well-known structures are not specifically described in order to avoid obscuring the utility model.

[0041] In the entire description, the mention of "one embodiment", "embodiment", "one example" or "example" means that the specific features, structures or characteristics described in combination with the embodiment or example are included in at least one embodiment of the utility model. Therefore, the phrases "one embodiment", "embodiment", "one example" or "example" appearing in various places throughout the description are not necessarily all referring to the same embodiment or example. In addition, specific features, structures or characteristics can be combined in one or more embodiments or examples in any appropriate combination and / or subcombination. In addition, those skilled in the art should understand that the drawings provided herein are for illustrative purposes only, and the drawings are not necessarily drawn to scale. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0042] In the description of the utility model, the orientation or position relationship indicated by the terms "front", "back", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", "outer" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the protection scope of the utility model.

[0043] Embodiment 1

[0044] like Figures 2-5 As shown in the figure, this utility model provides a flue gas backflow prevention check valve, which includes a valve body pipe 1 with a 90° bend structure. The inlet end of the valve body pipe 1 is horizontally installed in the indoor exhaust pipe, and the outlet end is vertically installed in the public exhaust pipe. A valve cover 2 is covered above the outlet. The valve cover 2 flips upward under the action of airflow. The feature is that an annular lower sealing plate 3 is coaxially arranged on the outer wall of the outlet of the valve body pipe 1, and an annular lower sealing groove 31 is opened on the surface of the lower sealing plate 3.

[0045] An upper sealing plate 4 is installed on the inner side of the valve cover 2 facing the valve body pipe 1. An upper sealing groove 41 is provided on the upper sealing plate 4. The upper sealing groove 41 is used to cover the end of the smoke outlet. An annular sealing baffle 42 is installed on the outer edge of the upper sealing plate 4. The sealing baffle 42 is used to extend into the lower sealing groove 31.

[0046] The current check valve structure is as follows: Figure 1 As shown, the check valve has a 90° bend structure with its smoke outlet vertically upward and parallel to the common flue. The valve cover is a flat plate structure and is separate from the valve body. During smoke exhaust, the valve cover flips upward and opens under the action of airflow through the flipping structure set inside and outside the valve body. After the smoke exhaust is completed, the valve cover covers the valve body opening under its own weight. The diameter of the valve cover is slightly larger than the diameter of the smoke outlet to completely cover the smoke outlet. A rubber layer is covered on the inner side of the valve cover, which contacts and fits against the end face of the smoke outlet to achieve sealing of the smoke outlet and buffering when the valve cover falls back.

[0047] It is obvious that this valve cover and valve body closure structure is difficult to seal the smoke outlet well. Moreover, the valve body is generally made of stainless steel. Therefore, when the valve cover falls and closes, it will collide with the metal end face of the valve body, causing the rubber layer to wear and failing to form a good fit with the smoke outlet, further reducing the sealing performance of the valve cover.

[0048] Therefore, the flue gas check valve of this utility model, based on the existing check valve, greatly improves the valve body's ability to prevent smoke backflow by adding a sealing structure at the connection between the valve cover and the valve body, thus preventing the flue gas in the public flue from flowing back into the room through the check valve.

[0049] The flue check valve of the utility model, lower sealing plate is arranged on the outer wall of the smoke outlet of the valve body pipeline, the top surface of the inner side of the lower sealing groove is slightly lower than the end surface of the smoke outlet, the upper sealing groove of the upper sealing plate covers the end surface of the smoke outlet in the closed state, the bottom surface of the upper sealing plate can be in contact with the top surface of the lower sealing plate of the inner side of the lower sealing groove, so that the smoke outlet is closed between the first double sealing structure formed by the upper sealing groove and the lower sealing plate, and smoke from the outside can be avoided from entering the smoke outlet; meanwhile, the sealing baffle of the outer edge of the upper sealing plate is located in the lower sealing groove and is attached to the bottom surface of the lower sealing groove, so that the sealing baffle and the lower sealing groove form the second double sealing structure, and smoke can be avoided from drilling into the upper sealing groove from below when moving upwards from below.

[0050] In a specific embodiment, the lower sealing groove 31 separates the lower sealing plate 3 into an inner ring plate 301, an outer ring plate 302 and a connecting bottom plate 303 connecting the inner ring plate 301 and the outer ring plate 302, and the outer ring plate 302 is in the form of a tapered cylinder structure with a large upper part and a small lower part.

[0051] The utility model discloses the outer ring plate is designed into the tapered cylinder structure with a large upper part and a small lower part, so when smoke moves upwards and contacts the lower sealing plate, the smoke will move upwards along the outer edge of the outer ring plate, thereby guiding the smoke to move away from the sealing baffle, so as to avoid the smoke from staying at the sealing place of the sealing baffle and the lower sealing groove.

[0052] The width of the lower sealing groove is greater than the thickness of the sealing baffle, and the inner diameter of the sealing baffle is slightly greater than the outer diameter of the inner ring plate, the sealing baffle is arranged on the lower sealing groove, and the inner wall and the outer wall of the sealing baffle do not have surface contact with the inner ring plate and the outer ring plate, so as to avoid the friction between the sealing baffle and the lower sealing plate affecting the opening and closing of the valve cover.

[0053] In a specific embodiment, the sealing baffle 42 is also in the form of a tapered cylinder structure with a large upper part and a small lower part, and the taper of the sealing baffle 42 is greater than or equal to the taper of the outer ring plate 302.

[0054] The utility model discloses a sealing baffle of big upper and small lower structure is set up, first make the sealing baffle lower extreme and the sealing face of lower sealing groove bottom more close to the inside, and the flue gas is more difficult to reach, second, when the taper of sealing baffle is equal to the taper of outer ring plate, the both oblique parallel but do not adhere to, form a oblique upwards ring gap, make the flue gas difficult to move from the ring gap above obliquely downwards to sealing baffle lower extreme, when the taper of sealing baffle is greater than the taper of outer ring plate, the outer wall of sealing baffle can adhere to the top of outer ring plate, to form third heavy sealing structure again, further improve, sealing performance.

[0055] In a specific embodiment, the lower sealing plate 3 and the upper sealing plate 4 are made of rubber or silicone material. The use of rubber or silicone material with certain softness can not only buffer the impact force when the valve cover is closed, but also form a soft contact between the lower sealing plate and the upper sealing plate, and the two plates are not easy to wear out.

[0056] In a specific embodiment, the upper sealing groove 41 penetrates the side surface of the upper sealing plate 4, and the side surface opening is covered with a rubber thin layer 43 of annular structure. The upper sealing groove 41 is sleeved on the valve cover 2 from the outer side surface of the valve cover 2.

[0057] The flue check valve of the utility model, since the turnover structure for realizing the opening and closing of the valve is detachably installed on the valve body and the valve cover through bolts and other components, the upper sealing plate can be sleeved on the valve cover from the outer side of the valve cover after the turnover structure is detached. Thus, the existing check valve can be directly modified.

[0058] In a specific embodiment, the lower sealing plate 3 is provided with a joint, and the two ends of the joint are provided with matching buckle structures. By setting the lower sealing plate as a detachable structure, the lower sealing plate can be directly installed on the outer wall of the smoke outlet through the buckle structures, which is more convenient to install. Alternatively, the lower sealing plate can be directly an integral structure and be sleeved on the smoke outlet from the upper end. The buckle structure can be a plug and a slot structure, which is then fixed by bolts. In this way, the connection at the joint can be staggered to improve the sealing performance of the joint. The detachable upper sealing plate and lower sealing plate structure, combined with the selection of materials, can directly modify the structure of the existing check valve, which is low in cost and does not require reordering and manufacturing.

[0059] In a specific embodiment, the inner diameter of the lower sealing plate can be slightly smaller than the outer wall diameter of the smoke outlet. Then, the lower sealing plate made of rubber material has a certain elasticity, and the lower sealing plate can be slowly sleeved on the outer wall of the smoke outlet for tight connection.

[0060] In a specific embodiment, the valve body pipeline 1 is provided with a flow guide cylinder 5 in the vertical section, the flow guide cylinder 5 is in a structure of small upper and large lower, the lower end of the flow guide cylinder 5 is tightly connected with the inner wall of the valve body pipeline 1, and the upper end of the flow guide cylinder 5 is below the smoke outlet.

[0061] In a specific embodiment, the diameter of the opening at the upper end of the flow guide cylinder 5 is 1 / 3-1 / 2 of the diameter of the smoke outlet.

[0062] The vertical section of the valve body pipeline is provided with a flow guide cylinder, the airflow enters the flow guide cylinder from bottom to top, the flow area of the airflow gradually decreases, the pressure of the airflow is continuously increased, the impact force on the valve cover is enhanced, and the opening of the valve cover is more sensitive. In addition, the flow guide cylinder is arranged in the vertical section, the opening at the top of the flow guide cylinder is small, therefore, even if a small amount of flue gas enters the valve body pipeline, the flow guide cylinder can isolate most of the flue gas above the flow guide cylinder, so that the flue gas is difficult to enter the indoor flue, and the ability of preventing the flue gas from flowing back to the indoor is improved. The flow guide cylinder can be installed in the valve body pipeline by welding, or the flow guide cylinder can be integrally formed with the valve body pipeline.

[0063] In a specific embodiment, the inner wall of the sealing baffle 42 has a sawtooth structure, and the mass of the sealing baffle is as light as possible without reducing the overall thickness of the sealing baffle.

[0064] In a specific embodiment, the inner wall of the lower sealing plate 3 and the outer wall of the valve body pipeline 1 are further coated with an adhesive layer, and the stability of the installation of the lower sealing plate and the valve body pipeline is improved through the adhesive layer.

[0065] The above specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the utility model, and it should be understood that the above description is only a specific embodiment of the utility model, and is not used to limit the protection scope of the utility model, and any modification, equivalent replacement, improvement, etc. within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A flue check valve for preventing flue gas backflow, comprising a valve body pipe (1) in the form of a 90° elbow structure, the valve body pipe (1) being horizontally installed at one end into a room exhaust pipe and vertically installed at the other end into a public exhaust pipe, a valve cover (2) being covered above the exhaust end of the valve body pipe (1), the valve cover (2) being turned upward under the action of air flow, characterized in that, The outer wall of the smoke outlet of the valve body pipe (1) is coaxially provided with a lower sealing plate (3) in an annular shape, and the surface of the lower sealing plate (3) is provided with a lower sealing groove (31) in an annular shape. The inner side of the valve cover (2) towards the valve body pipe (1) is provided with an upper sealing plate (4), and the upper sealing plate (4) is provided with an upper sealing groove (41) for covering the end of the smoke outlet, and the outer edge of the upper sealing plate (4) is provided with a sealing baffle (42) in an annular shape for extending into the lower sealing groove (31).

2. A flue check valve to prevent flue gas backflow according to claim 1, characterized in that, The lower sealing groove (31) divides the lower sealing plate (3) into an inner ring plate (301), an outer ring plate (302) and a connecting bottom plate (303) connecting the inner ring plate (301) and the outer ring plate (302), and the outer ring plate (302) is in a tapered cylinder structure with a large upper part and a small lower part.

3. A flue check valve to prevent flue gas backflow according to claim 2, characterized in that, The sealing baffle (42) is also in a tapered cylinder structure with a large upper part and a small lower part, and the taper of the sealing baffle (42) is greater than or equal to the taper of the outer ring plate (302).

4. A flue check valve to prevent flue gas backflow according to claim 1, characterized in that, The lower sealing plate (3) and the upper sealing plate (4) are made of rubber or silicone material.

5. A flue backdraft prevention valve according to claim 4, wherein The upper sealing groove (41) penetrates the side surface of the upper sealing plate (4), and the side surface opening is covered with a rubber thin layer (43) in an annular structure, and the upper sealing groove (41) is sleeved on the valve cover (2) from the outer side surface of the valve cover (2).

6. A flue check valve to prevent flue gas backflow according to claim 4, characterized in that, The lower sealing plate (3) is provided with a joint, and the two ends of the joint are provided with matching buckle structures.

7. A flue check valve to prevent flue gas backflow according to claim 1, characterized in that, A flow guide cylinder (5) is arranged in the vertical section of the valve body pipe (1), the flow guide cylinder (5) is in a structure with a small upper part and a large lower part, the lower end of the flow guide cylinder (5) is connected with the inner wall of the valve body pipe (1), and the upper end of the flow guide cylinder (5) is located below the smoke outlet.

8. A flue backdraft preventing check valve according to claim 7, wherein The diameter of the opening at the upper end of the flow guide cylinder (5) is 1 / 3-1 / 2 of the diameter of the smoke outlet.

9. A flue check valve to prevent flue gas backflow according to claim 1, characterized in that, The inner wall of the sealing baffle (42) has a sawtooth structure.

10. A flue check valve to prevent flue gas backflow according to claim 6, characterized in that, A glue layer is coated between the inner wall of the lower sealing plate (3) and the outer wall of the valve body pipe (1).

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