Check valve and range hood applying same

Abstract

The invention discloses a check valve and a range hood with the check valve. The check valve comprises a shell (1) and a valve plate (2). The laval pipe (3) is arranged in the channel (13) of the shell (1), an air inlet pipe opening (31) and an air outlet pipe opening (32) are formed in the two ends of the laval pipe (3) respectively, and the air inlet pipe opening (31) is in butt joint with the first port (11) of the shell (1); a reducing section (33) is arranged in the middle of the Laval pipe (3) in the oil smoke discharging direction; the valve plate (2) is arranged at an air outlet pipe opening (32) of the Laval pipe (3) and is configured to rotate in a single direction under the flowing action of oil smoke so as to open the air outlet pipe opening (32). By arranging the Laval pipe in the channel of the shell, oil smoke is accelerated after entering the Laval pipe, so that oil smoke disorder can be reduced, and the oil smoke can be conveniently discharged out of the check valve.

Description

Technical Field

[0001] The present invention relates to the technical field of check valves, and in particular to a check valve and a range hood using the check valve. Background Art

[0002] As an indispensable kitchen installation device for modern floor public flues, the check valve plays a decisive role in blocking the reflux of oil smoke and preventing the backflow of oil smoke. For example, the Chinese invention patent with the authorization number CN106065964B previously applied by the applicant discloses "A check valve", which includes a cover body and a valve plate arranged in the cover body and capable of rotating relative to the cover body, a driving mechanism for driving the valve plate to rotate is installed on the cover body, an installation cavity is provided inside the cover body, the driving mechanism is installed in the installation cavity, and the driving mechanism includes a driving rod extending from the installation cavity and used to drive the valve plate to rotate.

[0003] However, the check valve in the above patent has the following problems:

[0004] First, the oil smoke does not have a certain movement direction in the hood, which will cause a certain amount of oil smoke disorder, which is not conducive to the discharge of oil smoke;

[0005] Second, in order to promote the exhaust of oil smoke and to prevent the backflow of oil smoke from the public flue, the fan of the range hood needs to run at a higher power, which is not conducive to energy saving and building a green exhaust mode;

[0006] Third, when the oil fume pressure is high, the valve plate of the check valve may hit other parts when it flips open, causing a knocking sound and generating a loud noise. Summary of the invention

[0007] The first technical problem to be solved by the present invention is to provide a check valve for facilitating the discharge of oil smoke in view of the current status of the prior art.

[0008] The second technical problem to be solved by the present invention is to provide a check valve which is beneficial to energy saving.

[0009] The third technical problem to be solved by the present invention is to provide a check valve with lower noise.

[0010] The fourth technical problem to be solved by the present invention is to provide a range hood.

[0011] The technical solution adopted by the present invention to solve the above-mentioned first technical problem is: a check valve, comprising a housing and a valve plate, wherein the housing has a through channel, and two ends of the channel are respectively a first port and a second port;

[0012] It is characterized by: it also includes

[0013] A Rafale tube is arranged in the channel of the shell, and the two ends of the Rafale tube are respectively an air inlet and an air outlet, and the air inlet is connected to the first port of the shell;

[0014] Along the direction of oil smoke discharge, the middle part of the Rafale tube has a reduced diameter section;

[0015] The valve plate is arranged at the air outlet of the Rafale tube, and is configured to rotate in one direction under the action of the flow of oil smoke to open the air outlet.

[0016] In order to further facilitate the exhaust of oil smoke, along the flow direction of the oil smoke, the Rafale tube includes a lower diameter expansion section located downstream of the diameter reduction section;

[0017] An annular limiting portion is provided on the middle inner wall surface of the lower diameter expansion section at a position adjacent to the air outlet. Along the flow direction of the oil smoke, the annular limiting portion is located upstream of the valve plate and abuts against the valve plate in a state of closing the air outlet.

[0018] In this way, by setting the annular limiting part, on the one hand, it is convenient for the valve plate to abut and limit the valve plate, and on the other hand, the position of the annular limiting part is equivalent to a reduced diameter section, which is similar to forming a small Rafale tube near the air outlet, thereby further facilitating the discharge of oil smoke.

[0019] To further solve the second technical problem of the present application, preferably, the housing includes

[0020] cylindrical body;

[0021] An outer annular ring, the outer peripheral edge of which is connected to the inner peripheral wall surface of the cylindrical body, and the outer annular ring has a windward surface;

[0022] The inner annular ring is located in the space surrounded by the outer annular ring and connected to the inner periphery of the outer annular ring. The inner annular ring is bent toward the air outlet relative to the windward surface of the outer annular ring. The inner annular ring surrounds an air inlet cavity, and the free end of the inner annular ring is the first port.

[0023] The inner wall surface of the cylindrical body, the inner wall surface of the outer annular ring and the inner wall surface of the inner annular ring form the channel, and the inner annular ring has ventilation holes penetrating through the wall thickness thereof, and the ventilation holes are respectively connected to the channel and the air inlet cavity;

[0024] A shielding member is movably constrained on the inner annular ring and is located in the air inlet cavity and is used to adjust the size of the area covering the first port; the back side of the shielding member is opposite to the ventilation hole, and the back side of the shielding member is affected by the return air entering the ventilation hole from the channel, and moves toward a position that reduces the area covering the first port.

[0025] When the pressure in the public flue is relatively high, there may be backflow of oil smoke (return air) entering the channel of the shell and reaching the ventilation hole. The backflow of oil smoke acts on the back of the shielding member and drives the shielding member to move toward a position that reduces the area of ​​the first port covered. The air inlet area of ​​the first port becomes larger, and the air intake volume in the Rafale tube becomes larger. Correspondingly, the exhaust volume of the air outlet of the Rafale tube increases, and the volume of the aerosol wall formed at the air outlet is relatively large, which blocks the backflow of oil smoke in the public flue. In this way, according to the backflow of oil smoke in the channel, the shielding member can adjust the size of the area covering the first port and automatically adjust the amount of oil smoke entering the Rafale tube, so that the oil smoke reaches the fan at the air inlet of the Rafale tube. When the working power is relatively low, the oil smoke can be discharged from the check valve, which is beneficial to energy saving.

[0026] In order to facilitate pushing the shielding member, the shielding member is arc-shaped and moves circumferentially along the wall surface where the air inlet cavity is located after being subjected to force;

[0027] The ventilation hole is in a strip shape, and its length direction forms an acute angle with the tangent direction of the shielding member, and the ventilation hole is inclined in a direction in which the shielding member reduces the area of ​​the first port covered by the ventilation hole.

[0028] In this way, the backflowing oil smoke entering the ventilation hole can push the shielding piece to move.

[0029] In order to facilitate pushing the shielding member, the back side of the shielding member is provided with a guide groove connected to the ventilation hole. By providing the guide groove, the backflowing oil smoke entering the ventilation hole is concentrated in the guide groove, which facilitates the backflowing oil smoke to push the shielding member.

[0030] In order to facilitate the pushing of the shielding member, a guide plate partially shielding the ventilation hole is provided at the ventilation hole, and the guide plate divides the ventilation hole into a first half through hole that is shielded and a second half through hole that is not shielded. Along the moving direction of the shielding member to reduce the area of ​​the first port covered, the second half through hole is located downstream of the first half through hole. The guide plate guides the backflow oil smoke from the public flue to concentrate on one side of the second half through hole, thereby facilitating the pushing of the shielding member.

[0031] In order to facilitate pushing the shielding member, a mounting tube is coaxially installed in the ventilation hole, the mounting tube is opposite to the guide groove, and the guide plate is rotatably connected to the mounting tube and has at least two states:

[0032] In the first state, the guide plate blocks the first half through hole;

[0033] In the second state, the guide plate is turned over to open the first half through hole, and is turned over to abut against or approach the guide groove.

[0034] In this way, the guide plate abuts against or is close to the guide groove, and the guide plate divides the guide groove into two sections, which is conducive to concentrating the backflow oil smoke from the public flue in one section of the guide groove, thereby facilitating the pushing of the shielding member.

[0035] There may be various matching structures between the shielding member and the inner annular ring. Preferably, the inner annular ring is provided with a fixing member located in the air inlet cavity, and an arc-shaped slot opening along the circumference of the inner annular ring is formed between the fixing member and the inner annular ring.

[0036] The shielding member is arc-shaped, and is inserted into the arc-shaped slot and moves along the arc-shaped slot.

[0037] In this way, when the shielding member is inserted into the arc-shaped groove, the shielding member shields the first port less, and the air inlet area of ​​the first port becomes larger, which is beneficial to increase the air inlet volume at the first port.

[0038] In order to further facilitate the exhaust of oil smoke, the fixing member and the shielding member are inclined in the direction of expanding the first port, counter to the flow direction of the oil smoke.

[0039] In this way, the positions of the fixing member and the shielding member are similar to the expansion section, and the first port is contracted, which is similar to forming a small Rafale tube, thereby further facilitating the discharge of oil smoke.

[0040] In order to facilitate the automatic resetting of the shielding member, the shielding member has a first position and a second position to which the back side thereof moves due to the effect of the return air entering the ventilation hole from the passage;

[0041] The check valve also includes a first elastic member acting on the shielding member. When the shielding member is in the second position, the first elastic member is in an energy storage state. The first elastic member has a tendency to release energy to restore the shielding member from the second position to the first position.

[0042] The first elastic member is provided to facilitate automatic reset of the shielding member.

[0043] To further solve the third technical problem of the present application, preferably, a noise reduction ring is connected between the Rafale tube and the first port of the shell, and the noise reduction ring extends into the channel, or a noise reduction ring located in the channel is sleeved on the outer periphery of the Rafale tube;

[0044] The noise reduction ring is adjacent to the first port of the shell and has a noise reduction hole communicated with the channel at a position located in the channel.

[0045] By setting a noise reduction ring, it is helpful to reduce noise.

[0046] There can be various installation structures for the valve plate. Preferably, a connecting shaft is provided in the air outlet, the valve plate is rotatably provided on the connecting shaft, and a second elastic member is provided on the connecting shaft for releasing energy to restore the valve plate to the tendency of closing the air outlet.

[0047] The technical solution adopted by the present invention to solve the fourth technical problem is: a range hood, characterized in that: the check valve as mentioned above is adopted.

[0048] Compared with the prior art, the advantages of the present invention are: by arranging a Rafale tube in the channel of the shell, the oil smoke is accelerated after entering the Rafale tube, which can reduce the turbulence of the oil smoke, thereby facilitating the oil smoke to be discharged from the check valve; at the same time, the oil smoke forms an aerosol wall at the air outlet of the Rafale tube, which is beneficial to preventing the backflow of oil smoke in the public flue. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of a check valve according to an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a check valve from another angle according to an embodiment of the present invention;

[0051] Figure 3 It is a cross-sectional view of a check valve according to an embodiment of the present invention;

[0052] Figure 4 This is an exploded view of a check valve according to a first embodiment of the present invention;

[0053] Figure 5 Another exploded view of a check valve according to an embodiment of the present invention;

[0054] Figure 6 This is a schematic diagram of the assembly of the shielding member and the fixing member in the first embodiment of the present invention;

[0055] Figure 7 for Figure 6 A schematic diagram of another angle of the middle component;

[0056] Figure 8 for Figure 6 Exploded view of the components in the

[0057] Fig. 9 This is an exploded view of a check valve from another angle according to an embodiment of the present invention;

[0058] Fig.10 for Fig. 9 A magnified schematic diagram of part I in the middle;

[0059] Fig.11 Another cross-sectional view of a check valve according to an embodiment of the present invention;

[0060] Fig.12 for Fig.11 A magnified schematic diagram of the middle part II;

[0061] Fig.13 for Fig.11 Exploded diagram of

[0062] Fig.14 for Fig.11 Another exploded view of ;

[0063] Fig.15 It is another cross-sectional view of a check valve according to an embodiment of the present invention;

[0064] Fig.16 This is a schematic diagram of the relationship between the oil smoke ejected from the Rafale pipe and the oil smoke in the public flue in Example 1 of the present invention;

[0065] Fig.17 It is a schematic diagram of the assembly of the shielding member, the fixing member and the first elastic member in the second embodiment of the present invention. DETAILED DESCRIPTION

[0066] The present invention is further described in detail below with reference to the accompanying drawings.

[0067] Embodiment 1:

[0068] See also Figures 1 to 16 The check valve comprises a housing 1, a valve plate 2, a Lafarge tube 3, a shielding member 4, a fixing member 5, a first elastic member 6, a guide plate 7, a noise reduction ring 9 and other main components.

[0069] Among them, see Figure 1 to Figure 5 , Figure 11 to Figure 15 The shell 1 has a through passage 13, and the two ends of the passage 13 are respectively a first port 11 and a second port 12, and the first port 11 is used for air intake. The shell 1 is divided into a first part 17 and a second part 18 which are connected, and the first part 17 includes a cylindrical body 14, an outer annular ring 15, and an inner annular ring 16. The shell 1 can also be a one-piece piece. Specifically, the outer peripheral edge of the outer annular ring 15 is connected to the inner peripheral wall surface of the cylindrical body 14, and the outer annular ring 15 has a windward surface 151; the inner annular ring 16 is located in the space surrounded by the outer annular ring 15, and is connected to the inner peripheral edge of the outer annular ring 15, and the inner annular ring 16 is bent toward the air outlet 32 ​​relative to the windward surface 151 of the outer annular ring 15, and the inner annular ring 16 encloses an air inlet cavity 162 ( Figure 3 , Fig.15), the free end of the inner annular ring 16 is the first port 11; the inner wall surface of the cylindrical body 14, the inner wall surface of the outer annular ring 15 and the inner wall surface of the inner annular ring 16 form a channel 13, and the inner wall surface of the cylindrical body 14 forms a first space, which is the channel 13 after removing the air inlet cavity 162. The inner annular ring 16 has a ventilation hole 161 that penetrates its wall thickness, and the ventilation hole 161 is respectively connected to the channel 13 and the air inlet cavity 162.

[0070] See also Figure 2 The valve plate 2 is arranged at the air outlet 32 ​​of the Rafale tube 3, and is configured to rotate unidirectionally 32 under the action of the oil smoke flow to open the air outlet 32. Specifically, a connecting shaft 30 is arranged in the air outlet 32, and the valve plate 2 is rotatably arranged on the connecting shaft 30. The connecting shaft 30 is provided with a second elastic member 20 that releases energy to restore the valve plate 2 to the trend of closing the air outlet 32. The second elastic member 20 is, for example, a torsion spring.

[0071] See also Figure 1 to Figure 5 , Figure 11 to Figure 15 The Rafale tube 3 is arranged in the channel 13 of the shell 1, and the two ends of the Rafale tube 3 are respectively an air inlet port 31 and an air outlet port 32, and the air inlet port 31 is connected to the first port 11 of the shell 1; along the flow direction of the oil smoke, the middle part of the Rafale tube 3 has a reduced diameter section 33; the Rafale tube 3 includes a lower expanded diameter section 35 located downstream of the reduced diameter section 33, and an upper expanded diameter section 34 located upstream of the reduced diameter section 33; the middle inner wall surface of the lower expanded diameter section 35 is provided with an annular limiting portion 351 at a position adjacent to the air outlet port 32, and along the flow direction of the oil smoke, the annular limiting portion 351 is located upstream of the valve plate 2, and is against the valve plate 2 in a state of closing the air outlet port 32.

[0072] See also Figure 1 , Figure 3 to Figure 9 , the shielding member 4 is movably constrained in the air inlet cavity 162 of the inner annular ring 16, and the shielding member 4 is used to adjust the size of the area covering the first port 11. Specifically, the fixing member 5 is arranged on the inner annular ring 16 and is located in the air inlet cavity 162, and an arc-shaped slot 10 opening along the circumference of the inner annular ring 16 is formed between the fixing member 5 and the inner annular ring 16; the shielding member 4 is arc-shaped, and the shielding member 4 is inserted into the arc-shaped slot 10 and moves along the arc-shaped slot 10; the inner annular ring 16 is provided with a guide rail 40 ( Figure 4), the shielding member 4 is movably mounted on the guide rail 40. The back of the shielding member 4 is opposite to the ventilation hole 161, and the back of the shielding member 4 is affected by the return air (backflow oil smoke from the public flue) entering the ventilation hole 161 from the channel 13, and moves toward a position where the area of ​​the first port 11 covered is reduced, that is, the first port 11 of the shell 1 becomes larger. After being subjected to force, the shielding member 4 moves circumferentially along the wall surface where the air inlet cavity 162 is located; the ventilation hole 161 is strip-shaped, and its length direction forms an acute angle with the tangent direction of the shielding member 4, and the ventilation hole 61 is inclined in the direction in which the shielding member 4 reduces the area of ​​the first port 11 covered. See Figure 7 , Figure 8 , Fig.12 The back of the shielding member 4 has a guide groove 41 connected to the ventilation hole 161. Against the flow direction of the oil smoke, the fixing member 5 and the shielding member 4 are inclined toward the direction of expanding the first port 11, which is similar to a small Rafale tube, which is conducive to promoting the discharge of oil smoke.

[0073] See also Figure 7 to Figure 10 , see Figure 12 to Figure 14 , a guide plate 7 partially shielding the ventilation hole 161 is provided at the ventilation hole 161, and the guide plate 7 divides the ventilation hole 161 into a first half through hole 1611 that is shielded and a second half through hole 1612 that is not shielded. Along the moving direction of the shielding member 4 to reduce the area of ​​the first port 11 covered, the second half through hole 1612 is located downstream of the first half through hole 1611. Specifically, a mounting tube 8 is coaxially installed in the ventilation hole 161, and the mounting tube 8 is opposite to the guide groove 41. The guide plate 7 is rotatably connected to the mounting tube 8 and has two states: see Figure 8 In the first state, the guide plate 7 blocks the first half through hole 1611; in the second state, the guide plate 7 flips over to open the first half through hole 1611, and flips over to abut against or approach the guide groove 41, so that after the backflowing oil smoke enters the ventilation hole 161 from the channel 13, the guide plate 7 flips over to abut against the guide groove 41 and divides the guide groove 41 into two sections, and the backflowing oil smoke is concentrated in one section of the guide groove 41, which is convenient for pushing the shielding member 4 to move.

[0074] See also Figure 2 to Figure 5 , Figure 11 to Figure 14 The noise reduction ring 9 is butted between the Rafale tube 3 and the first port 11 of the housing 1, the noise reduction ring 9 extends into the channel 13, the noise reduction ring 9 is adjacent to the first port 11 of the housing 1, and has a noise reduction hole 91 in communication with the channel 13 at a position in the channel 13. Alternatively, the noise reduction ring 9 is sleeved on the outer periphery of the Rafale tube 3.

[0075] This embodiment also includes a range hood, which uses the above-mentioned check valve. The check valve is installed on a vertically extending wall, and the installation position is as follows: Figure 1, the backflow oil smoke entering the public flue overcomes gravity and drives the shielding member 4 to rotate, and the shielding member 4 is reset by gravity. In order to maintain the shielding member 4 in the position when the range hood fan is not working, Figure 1 The shielding member 4 is in the required position as shown and does not fall. A limit block (not shown in the figure) is provided on the inner annular ring 16 and is located below the shielding member 4 to prevent the shielding member 4 from falling, or a first magnetic member is provided at the lower end of the shielding member 4, and the inner annular ring 16 is provided with a second magnetic member that repels the first magnetic member. The shielding member 4 is prevented from falling by the repulsive force between the two magnetic members.

[0076] The working principle and usage process are as follows.

[0077] After the oil smoke enters the Rafale tube 3, it is accelerated and pushes the valve plate 2 of the air outlet 32 ​​of the Rafale tube 3 to open unidirectionally toward the second port 12 of the housing 1, so that the oil smoke is discharged. The check valve is provided with a reduced diameter section 33, an annular limiter 351, and the fixing member 5 and the shielding member 4 are inclined in the direction of expanding the first port 11 against the flow direction of the oil smoke, which is equivalent to having three reduced diameter positions, and is equivalent to having three small Rafale tubes, which is conducive to the discharge of oil smoke. At the same time, the oil smoke forms an aerosol wall at the air outlet 32 ​​of the Rafale tube 3, which is conducive to blocking the backflow of oil smoke in the public flue.

[0078] The injection angle of the oil smoke at the air outlet 32 ​​of the Lafayette tube 3 is related to the inlet conditions (such as pressure and temperature), the properties of the gas, the desired injection velocity, the environmental conditions (such as the outlet pressure) and the injection angle. The outlet pressure of the air outlet 32 ​​of the Lafayette tube 3 can be obtained by the continuity equation, the Bernoulli equation, the isentropic flow relationship, etc.

[0079] The oil smoke outlet pressure of the air outlet 32 ​​of the Rafale tube 3 is recorded as Pa; the environmental pressure of the public flue is recorded as Pe. According to the relative size of Pa / Pe and the outlet inclination angle, the flow state of the oil smoke in the Rafale tube 3 is divided into the following three situations: Fig.16 shown.

[0080] 1) When the oil fume outlet pressure of the air outlet pipe 32 of the Lafarge tube 3 is greater than the public flue pressure, that is, Pa>Pe, it is an oversaturated state, and the area and boundary of the oil fume discharged from the Lafarge tube 3 are in the state shown by number A. At this time, the fan used to send the oil fume to the check valve can operate at a lower power, the air volume can be reduced, or the shielding member 4 moves to cover the first port 11 of the shell 1 to increase the area to reduce the air intake, and the oil fume discharged from the air outlet pipe 32 gradually tends to the area and boundary to be in the state shown by number B.

[0081] 2) When the oil fume outlet pressure at the air outlet pipe opening 32 of the Venturi tube 3 is equal to the common flue pressure, i.e., Pa = Pe, it is in a saturated state. The area and boundary of the oil fume discharged from the Venturi tube 3 are in the state shown by the number B. At this time, the fan of the range hood is in a balanced state, and the energy consumption of the fan reaches the optimal state.

[0082] 3) When the oil fume outlet pressure at the air outlet pipe opening 32 of the Venturi tube 3 is less than the common flue pressure, i.e., Pa < Pe, it is in an unsaturated state. The area and boundary of the oil fume discharged from the Venturi tube 3 are in the state shown by the number C. At this time, the oil fume in the common flue may flow back into the channel 13 of the housing 1. The path of the backflowing oil fume is as Fig.12 shown by the hollow arrow in the figure. The backflowing oil fume passes through the noise reduction holes 91, enters the ventilation holes 161, and then reaches the diversion groove 41, which pushes the shielding member 4 to move. The area of the shielding member 4 covering the first port 11 of the housing 1 decreases, which is beneficial to increasing the air intake volume into the Venturi tube 3. The area and boundary of the oil fume gradually tend to the state numbered B. At this time, the operating power of the fan can be not adjusted, which is beneficial to energy conservation. In the prior art in this case, it is necessary to increase the power of the fan to increase the air intake volume into the Venturi tube 3, and the energy consumption of the fan is relatively high, which is not conducive to energy conservation.

[0083] In this way, the check valve can automatically adjust the position of the shielding member 4 according to the conditions of the common flue environment, etc., and automatically adjust the size of the area covering the first port 11 of the housing 1, so as to adjust the air intake volume into the Venturi tube 3 to maintain the best operating state.

[0084] In addition, by providing the Venturi exhaust pipe 3, the valve plate 2 is relatively far from the first port 11 of the housing 1, so that the noise generated when the valve plate 2 opens and closes is relatively behind. The provision of the noise reduction ring 9 is beneficial to absorbing noise.

[0085] Embodiment 2:

[0086] On the basis of the check valve in Embodiment 1, a first elastic member 6 is added. The shielding member 4 has a first position and a second position where it moves under the action of the return air entering the ventilation hole 161 from the channel 13 on its back. The first elastic member 6 acts on the shielding member 4. Refer to Fig.17 , the two ends of the first elastic member 6 are respectively connected to the shielding member 4 and the fixing member 5. When the shielding member 4 is in the second position, the first elastic member 6 is in an energy storage state, and the first elastic member 6 has a tendency to release energy and return the shielding member 4 from the second position to the first position. The first elastic member 6 is a spring or a spring piece. In this way, the check valve can be installed on a vertically extending wall in the direction shown Figure 1 in the figure, and can also be adjusted to other installation directions according to needs.

Claims

1. A check valve, comprising a housing (1) and a valve plate (2), wherein the housing (1) has a through passage (13), and two ends of the passage (13) are respectively a first port (11) and a second port (12); Features: Also includes A Rafale tube (3) is arranged in the channel (13) of the shell (1), the two ends of the Rafale tube (3) are respectively an air inlet port (31) and an air outlet port (32), and the air inlet port (31) is butt-jointed with the first port (11) of the shell (1); Along the flow direction of the oil smoke, the middle part of the Rafale tube (3) has a reduced diameter section (33); The valve plate (2) is arranged at the air outlet (32) of the Rafale tube (3), and is configured to rotate unidirectionally under the action of the flow of oil smoke to open the air outlet (32).

2. The check valve according to claim 1, characterized in that: Along the flow direction of the oil smoke, the Rafale tube (3) comprises a lower diameter expansion section (35) located downstream of the diameter reduction section (33); An annular limiting portion (351) is provided on the middle inner wall surface of the lower diameter expansion section (35) at a position adjacent to the air outlet pipe opening (32); along the direction of oil smoke flow, the annular limiting portion (351) is located upstream of the valve plate (2) and abuts against the valve plate (2) in a state of closing the air outlet pipe opening (32).

3. The check valve according to claim 1, characterized in that: The housing (1) comprises Tubular body (14); An outer annular ring (15), the outer peripheral edge of which is connected to the inner peripheral wall surface of the cylindrical body (14), and the outer annular ring (15) has a windward surface (151); The inner annular ring (16) is located in the space surrounded by the outer annular ring (15) and is connected to the inner periphery of the outer annular ring (15). The inner annular ring (16) is bent toward the air outlet (32) relative to the windward surface (151) of the outer annular ring (15). The inner annular ring (16) surrounds an air inlet cavity (162). The free end of the inner annular ring (16) is the first port (11); The inner wall surface of the cylindrical body (14), the inner wall surface of the outer annular ring (15) and the inner wall surface of the inner annular ring (16) form the channel (13); the inner annular ring (16) has a ventilation hole (161) penetrating the thickness of the inner annular ring; the ventilation hole (161) is respectively connected to the channel (13) and the air inlet chamber (162); A shielding member (4) is movably constrained on the inner annular ring (16) and is located in the air inlet cavity (162) and is used to adjust the size of the area covering the first port (11); the back side of the shielding member (4) is opposite to the ventilation hole (161), and the back side of the shielding member (4) is affected by the return air entering the ventilation hole (161) from the channel (13), so that it moves towards a position where the area covering the first port (11) is reduced.

4. The check valve according to claim 3, characterized in that: The shielding member (4) is arc-shaped and moves circumferentially along the wall surface where the air inlet cavity (162) is located after receiving force; The ventilation hole (161) is strip-shaped, its length direction forms an acute angle with the tangent direction of the shielding member (4), and the ventilation hole (61) is inclined in the direction in which the shielding member (4) reduces the area of ​​the first port (11) covered by it.

5. The check valve according to claim 3, characterized in that: The back side of the shielding member (4) is provided with a guide groove (41) which is in communication with the ventilation hole (161).

6. The check valve according to claim 3, characterized in that: A guide plate (7) for partially shielding the ventilation hole (161) is provided at the ventilation hole (161), and the guide plate (7) divides the ventilation hole (161) into a first half through hole (1611) that is shielded and a second half through hole (1612) that is not shielded. Along the moving direction of the shielding member (4) to reduce the area of ​​the first port (11) covered, the second half through hole (1612) is located downstream of the first half through hole (1611).

7. The check valve according to claim 6, characterized in that: A mounting tube (8) is coaxially mounted in the ventilation hole (161), the mounting tube (8) being opposite to the guide groove (41), and the guide plate (7) is rotatably connected to the mounting tube (8) to have at least two states: In a first state, the guide plate (7) blocks the first half through hole (1611); In the second state, the guide plate (7) is turned over to open the first half through hole (1611), and is turned over to abut against or approach the guide groove (41).

8. The check valve according to claim 3, characterized in that: The inner annular ring (16) is provided with a fixing member (5) located in the air inlet cavity (162), and an arc-shaped slot (10) opening along the circumference of the inner annular ring (16) is formed between the fixing member (5) and the inner annular ring (16); The shielding member (4) is arc-shaped, and is inserted into the arc-shaped slot (10) and moves along the arc-shaped slot (10).

9. The check valve according to claim 8, characterized in that: In the opposite direction of the oil smoke flow, the fixing member (5) and the shielding member (4) are both inclined in the direction of expanding the first port (11).

10. The check valve according to claim 3, characterized in that: The shielding member (4) has a first position and a second position to which the back side thereof moves due to the effect of return air entering the ventilation hole (161) from the passage (13); The non-return valve further comprises a first elastic member (6) acting on the shielding member (4); when the shielding member (4) is in the second position, the first elastic member (6) is in an energy storage state, and the first elastic member (6) has a tendency to release energy and cause the shielding member (4) to return from the second position to the first position.

11. The check valve according to claim 1, characterized in that: A noise reduction ring (9) is butt-jointed between the Rafale tube (3) and the first port (11) of the housing (1), and the noise reduction ring (9) extends into the channel (13), or the outer periphery of the Rafale tube (3) is sleeved with a noise reduction ring (9) located in the channel (13); The noise reduction ring (9) is adjacent to the first port (11) of the housing (1), and has a noise reduction hole (91) in communication with the channel (13) at a position located inside the channel (13).

12. The check valve according to claim 1, characterized in that: A connecting shaft (30) is arranged in the air outlet pipe opening (32), the valve plate (2) is rotatably arranged on the connecting shaft (30), and a second elastic member (20) is arranged on the connecting shaft (30) for releasing energy to restore the valve plate (2) to a tendency to close the air outlet pipe opening (32).

13. A range hood, characterized in that: A check valve as claimed in any one of claims 1 to 12 is used.

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