Sealing structure of a lifting range hood, design method and lifting range hood

Abstract

The application relates to a sealing structure and a design method of a lifting type range hood, and the lifting type range hood comprises an upper box body with an open bottom, a lower box body constrained on the upper box body and capable of moving up and down relative to the upper box body, and the lower box body has a cavity with an open top, and the cavity is used for partially containing the box body; characterized in that: a surrounding edge is arranged around the outer peripheral wall of the upper box body in the cavity, and a gap is left between the surrounding edge and the outer peripheral wall of the upper box body; the sealing structure comprises a flexible connecting piece arranged in the cavity, and the upper end of the flexible connecting piece is capable of being sealingly connected with the upper box body and is configured to be sealingly connected with the bottom of the surrounding edge when the lower box body moves to the lowest position. The advantage is that the sealing between the lower box body and the upper box body is realized through the flexible connecting piece, the airflow in the gap is cut off, and the howling sound generated by the airflow through the gap is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil fume purification, and particularly relates to a sealing structure of a lifting type range hood, a design method and the lifting type range hood. BACKGROUND

[0002] The volume of the traditional ceiling type range hood is large, and a cook is prone to bumping his head. If the distance between the air inlet of the range hood and the oil fume generation area is large, the oil fume suction path is long, and the suction time is increased, so that the oil fume escape phenomenon is prone to occur during cooking. If the installation height of the range hood is reduced, and the smoke inlet is as close to the smoke source as possible, the negative pressure is expanded, which is beneficial to improving the oil fume suction effect, but the cooking space is too small, the head of the cook is prone to accidentally bumping the smoke collection cover, and after the installation height is reduced, the line of sight and the overall appearance of the kitchen are also affected.

[0003] To solve the above technical problems, the applicant previously applied for a Chinese invention patent with the application number CN202410004983.X (application publication number CN117847164A) for a lifting mechanism and a range hood applying the lifting mechanism. The range hood wraps the lower box outside the upper box, and the air inlet body is contained in the lower box. During work, under the drive of the lifting mechanism, the lower box and the air inlet body are both lowered to the lowest position, the upper part of the lower box is connected with the lower part of the upper box, the upper part of the air inlet body is connected with the lower part of the lower box, and the air inlet on the front side of the air inlet body is exposed below the lower box as a whole. The negative pressure area is lowered, and the oil fume suction effect is improved. When the machine is turned off, under the drive of the lifting mechanism, the lower box and the air inlet body are both raised to the highest position. At this time, the upper box partially extends into the lower box, and the air inlet body extends into the lower box as a whole. The height of the whole machine is reduced, the structure of the whole machine is more compact, the effect of embedding flat with the bottom surface of the cabinet can be achieved, and the aesthetic degree is improved.

[0004] Although the above lifting type range hood can expand the negative pressure, which is beneficial to improving the oil fume suction effect, in order to realize the lifting movement of the lower box relative to the upper box, the lower box and the upper box cannot be directly fixed and connected, but a certain gap is left to allow the lifting of the lower box. Due to the operation of the fan system in the range hood, there is a pressure difference between the inside and outside of the range hood, and the flow rate of the airflow through the gap increases sharply, and a howling sound is generated, which affects the user experience. Therefore, further improvement is needed for the prior art. SUMMARY

[0005] The first technical problem to be solved by the present application is to provide a sealing structure of a lifting type range hood capable of eliminating the howling sound generated by the airflow.

[0006] The second technical problem to be solved by the present application is to provide a design method of the sealing structure of the above lifting type range hood.

[0007] The third technical problem to be solved by the present application is to provide a lifting type range hood with the sealing structure.

[0008] The technical scheme adopted by the present application to solve the first technical problem is a sealing structure of a lifting type range hood, wherein the lifting type range hood comprises:

[0009] an upper cabinet with an open bottom;

[0010] a lower cabinet constrained on the upper cabinet and capable of moving up and down relative to the upper cabinet, wherein the lower cabinet has a cavity with an open top, and the cavity is used for at least partially accommodating the upper cabinet;

[0011] characterized in that a surrounding edge is arranged around the outer peripheral wall of the upper cabinet in the cavity, and a gap is left between the surrounding edge and the outer peripheral wall of the upper cabinet, and the sealing structure comprises:

[0012] a flexible connecting member arranged in the cavity, wherein the upper end of the flexible connecting member is capable of being sealingly connected with the upper cabinet, and the lower end of the flexible connecting member is capable of being sealingly connected with the bottom of the surrounding edge when the lower cabinet moves to the lowest position.

[0013] Preferably, the flexible connecting member is a flexible film, the flexible film extends along the moving direction of the lower cabinet, the upper edge of the flexible film is attached to the inner wall of the upper cabinet, and the lower end of the flexible film is provided with a hook portion, and when the lower cabinet moves to the lowest position, the bottom of the surrounding edge is placed in the hook portion to form a sealing connection between the surrounding edge and the lower end of the flexible film. In this way, the gap left between the surrounding edge and the outer peripheral wall of the upper cabinet can be closed by the flexible film to cut off the airflow at the gap, thereby avoiding the howling sound generated during the use of the range hood.

[0014] Further preferably, the lower end of the flexible film is outwardly turned to form the hook portion. In this way, the bottom of the surrounding edge can be installed on one hand, and better sealing effect can be achieved on the other hand.

[0015] In order to enable the lower cabinet to move smoothly, a guide rail is installed between the upper cabinet and the lower cabinet, and the lower cabinet moves up and down relative to the upper cabinet along the guide rail. The lower cabinet can move up and down relative to the upper cabinet under the drive of a driving mechanism, or can be manually pushed to move up and down.

[0016] Further preferably, the upper cabinet and the lower cabinet are both square-shaped, and the guide rail is arranged on the rear side plate of the upper cabinet and the rear plate of the lower cabinet.

[0017] Further preferably, the three surrounding edges are respectively a first surrounding edge arranged on the periphery of the left side plate of the upper cabinet, a second surrounding edge arranged on the periphery of the front side plate of the upper cabinet, and a third surrounding edge arranged on the periphery of the right side plate of the upper cabinet, all of which together with the rear plate of the lower cabinet form the above-mentioned cavity, and correspondingly, the three flexible films are respectively a first flexible film for sealing the first surrounding edge and the left side plate of the upper cabinet, a second flexible film for sealing the second surrounding edge and the front side plate of the upper cabinet, and a third flexible film for sealing the third surrounding edge and the right side plate of the upper cabinet.

[0018] In order to further improve the sealing performance, the first flexible film, the second flexible film and the third flexible film are sequentially connected to form a U-shaped flexible connecting piece. In this way, the three surrounding edges of the cavity can be sealed.

[0019] In order to prevent the rear end of the flexible connecting piece from separating from the rear plate of the lower cabinet, the sealing structure further comprises flexible magnets respectively constrained on the rear side of the first flexible film and the rear side of the third flexible film, the rear plate of the lower cabinet is made of a magnetic material, and the first flexible film and the third flexible film can be magnetically attracted to the rear plate of the lower cabinet by means of the respective flexible magnets, thereby maintaining the sealing connection with the rear plate of the lower cabinet.

[0020] In order to ensure sealing, the first flexible film and the third flexible film are further respectively provided with inclined portions near the rear end thereof, and each inclined portion gradually inclines outward from the center of the corresponding flexible film to the rear end thereof.

[0021] The technical solution adopted by the present application to solve the above-mentioned second technical problem is: a design method of the sealing structure of the above-mentioned lifting type range hood, characterized in that it comprises: obtaining the attractive force provided by the flexible magnet in combination with the stress condition of the flexible film, and calculating the magnetic force between the flexible magnet and the rear side plate of the lower cabinet according to the attractive force provided by the flexible magnet, and finally designing the size of the flexible magnet according to the magnetic force between the flexible magnet and the rear side plate of the lower cabinet.

[0022] In order to compensate for errors and ensure reliability, the formula for calculating the magnetic force between the flexible magnet and the rear side plate of the lower cabinet is:

[0023] F = K * F4

[0024] Wherein, K is the safety factor, and F4 is the attractive force provided by the flexible magnet.

[0025] Preferably, the size design process of the flexible magnet is:

[0026] Step 1, obtain the magnetization M of the flexible magnet;

[0027] Step 2, the magnetic field strength H of the flexible magnet is calculated according to the magnetization M of the flexible magnet;

[0028] Step 3, the magnetic induction B in the rear side plate of the lower box is calculated according to the magnetic field strength H of the flexible magnet;

[0029] Step 4, the magnetic force F between the flexible magnet and the rear side plate of the lower box is calculated according to the following formula:

[0030] F=B*A*t*μ0 / (2*μr)

[0031] Wherein, A is the surface area of the face closest to the flexible magnet and parallel to the rear side plate of the lower box; t is the thickness of the flexible magnet, μ0 is the magnetic permeability in vacuum, and μr is the relative magnetic permeability of the flexible magnet;

[0032] Step 5, the magnetic force F between the flexible magnet and the rear side plate of the lower box is calculated according to the attractive force given by the flexible magnet, and the calculation formula in step 4 is substituted, that is, A is obtained.

[0033] Preferably, the flexible magnet is square, that is, the magnetic field strength H of the flexible magnet in step 2 is calculated according to the formula:

[0034] H=M / d

[0035] Wherein, d is the distance between the flexible magnet and the rear side plate of the lower box.

[0036] Specifically, the magnetic induction B in the rear side plate of the lower box in step 3 is calculated according to the formula:

[0037] B=μ*H

[0038] Wherein, μ is the magnetic permeability of the magnetic material used in the rear side plate of the lower box.

[0039] Further preferably, the height L of the flexible magnet is substantially close to the height of the flexible film, and the width B0 of the flexible magnet is calculated according to the following formula:

[0040] B0=A / L.

[0041] The technical solution adopted by the present application to solve the third technical problem is: a lifting type range hood characterized in that the sealing structure as described above is applied.

[0042] Compared with the prior art, the advantages of the present invention are as follows: by setting a flexible connector within the cavity, the upper end of the flexible connector can be sealed to the upper housing, and when the lower housing is in its lowest position, the lower end of the flexible connector can be sealed to the bottom of the surrounding edge. This arrangement achieves a seal between the lower and upper housings through the flexible connector, cutting off airflow within the gap and preventing whistling noise caused by airflow passing through the gap. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the lift-up range hood in an embodiment of the present invention;

[0044] Figure 2 for Figure 1 Exploded view;

[0045] Figure 3 For along Figure 1 Cross-sectional view along the AA direction;

[0046] Figure 4 For along Figure 1 Cross-sectional view along the BB direction;

[0047] Figure 5 This is a schematic diagram of the sealing structure in an embodiment of the present invention;

[0048] Figure 6 This is a force analysis diagram of the flexible film in an embodiment of the present invention. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0050] like Figure 1 and Figure 2 As shown, the lift-type range hood in this embodiment includes an upper housing 1 and a lower housing 2. The upper housing 1 has an open bottom, and the lower housing 2 is constrained to the upper housing 1 and can move up and down relative to the upper housing 1. The lower housing 2 has a cavity 21 with an open top, which is used to accommodate at least part of the upper housing 1. An air inlet 20 is provided at the bottom of the lower housing 2. The lower housing 2 is the smoke collection hood of the range hood, and the upper housing 1 is the fan frame of the range hood. The lift-type range hood in this embodiment can be referred to the content disclosed in the applicant's earlier application, application number CN202410004983.X (application publication number CN117847164A), "A Lifting Mechanism and a Range Hood Using the Lifting Mechanism," which will not be elaborated upon here.

[0051] In order to enable the lower box 2 to move up and down relative to the upper box 1, the lower box 2 and the upper box 1 cannot be directly fixedly connected, but a certain gap is left, such as... Figure 2As shown, in this embodiment, the cavity 21 is provided with a surrounding edge arranged around the outer peripheral wall of the upper box 1, and a gap is left between the surrounding edge and the outer peripheral wall of the upper box 1.

[0052] A guide rail 4 is installed between the upper housing 1 and the lower housing 2. The lower housing 2 moves up and down relative to the upper housing 1 along the guide rail. Figure 2 As shown, in this embodiment, both the upper housing 1 and the lower housing 2 are square, and the guide rail 4 is disposed on the rear side plate 11 of the upper housing 1 and the rear plate 2a of the lower housing 2; Figure 2 As shown, there are three surrounding edges in this embodiment: a first surrounding edge 211 located around the left side plate 12 of the upper box 1, a second surrounding edge 212 located around the front side plate 13 of the upper box 1, and a third surrounding edge 213 located around the right side plate 14 of the upper box 1. All surrounding edges together with the rear plate 2a of the lower box 2 form the aforementioned cavity 21.

[0053] Because the operation of the fan system in a range hood causes a pressure difference between the inside and outside of the range hood, the airflow velocity will surge when passing through the gaps, and a whistling sound will be generated, which will affect the user experience. Therefore, this embodiment also involves a sealing structure for a liftable range hood. This sealing structure avoids the generation of whistling noise by cutting off the airflow.

[0054] like Figures 2 to 5 As shown, the sealing structure includes a flexible connector 3 disposed within the cavity 21. The upper end of the flexible connector 3 can be sealed to the upper housing 1, and is configured such that when the lower housing 2 is in its lowest position, one end of the flexible connector 3 can be sealed to the bottom of the surrounding edge. In this embodiment, the flexible connector 3 is a flexible film that extends along the movement direction of the lower housing 2. The upper edge of the flexible film adheres to the inner wall of the upper housing 1, and a hook portion is provided on the outer side of the lower end of the flexible film. When the lower housing 2 is in its lowest position, the bottom of the surrounding edge is placed within the hook portion, so that the surrounding edge 211 and the lower end of the flexible film form a sealed connection. To ensure sealing, the lower end of the flexible film is turned outward to form the aforementioned hook portion.

[0055] To achieve a seal between the cavity 21 and the upper housing 1, this embodiment uses three flexible films: a first flexible film 31 for sealing the first perimeter 211 and the left side plate 12 of the upper housing 1; a second flexible film 32 for sealing the second perimeter 212 and the front side plate 13 of the upper housing 1; and a third flexible film 33 for sealing the third perimeter 213 and the right side plate 14 of the upper housing 1. Furthermore, the first flexible film 31, the second flexible film 32, and the third flexible film 33 are sequentially connected to form a U-shaped flexible connector 3. There are three hook portions: a first hook portion 311 at the lower end of the first flexible film 31, a second hook portion 321 at the lower end of the second flexible film 32, and a third hook portion 331 at the lower end of the third flexible film 33.

[0056] Since the lower cabinet 2 is connected with the rear side of the upper cabinet 1 by the guide rail 4, the first flexible film 31, the second flexible film 32 and the third flexible film 33 are mainly used to solve the sealing problem of the first surrounding edge 211 and the left side plate 12 of the upper cabinet 1, the second surrounding edge 212 and the front side plate 13 of the upper cabinet 1, and the third surrounding edge 213 and the right side plate 14 of the upper cabinet 1 respectively in the embodiment. However, a gap will appear on the rear side of the upper cabinet 1. Therefore, in order to ensure the sealing of the rear side of the upper cabinet 1, the sealing structure of the embodiment further comprises flexible magnets 5 which are respectively constrained on the rear side of the first flexible film 31 and the rear side of the third flexible film 33. The rear plate 2a of the lower cabinet 2 is made of a magnetic material. The first flexible film 31 and the third flexible film 33 can be magnetically attracted to the rear plate 2a of the lower cabinet 2 by the respective flexible magnets 5, thereby maintaining the sealing connection with the rear plate 2a of the lower cabinet 2. In the embodiment, the flexible magnets are wrapped in the flexible films, which does not affect the flexibility of the flexible films. The flexible magnets themselves have good bendability and durability. The end is closed by magnetic force. Even if the original fit state of the flexible film is destroyed during movement, the flexible film will eventually stabilize in a new fit state under the action of magnetic force.

[0057] In addition, the first flexible film 31 and the third flexible film 33 are respectively provided with inclined portions 34 near the rear ends thereof. Each inclined portion 34 gradually inclines outward from the center of the corresponding flexible film to the rear end thereof. In this way, the sealing of the flexible film and the corresponding surrounding edge is further utilized by the inclined portions 34.

[0058] In the embodiment, it is desirable to use the smallest flexible magnet possible to reduce costs. However, if the magnet is too small, its magnetic force will be insufficient to counteract the force generated by the pressure difference between the inside and outside of the range hood, and the flexible film cannot be closed at the end. Therefore, it is necessary to determine at least how large the magnetic force should be to ensure the sealing effect. The design method of the sealing structure of the lifting type range hood in the embodiment comprises: obtaining the suction force provided by the flexible magnet in combination with the stress condition of the flexible film, calculating the magnetic force between the flexible magnet and the rear side plate of the lower cabinet according to the suction force provided by the flexible magnet, and finally designing the size of the flexible magnet according to the magnetic force between the flexible magnet and the rear side plate of the lower cabinet.

[0059] Firstly, the stress analysis of the flexible film is carried out. In the state of starting the range hood, the self-gravity of the flexible film can be ignored. The fastening force provided by the connection part of the upper cabinet 1 and the flexible film to the flexible film is F1, the fastening force provided by the surrounding edge to the flexible film is F2, the pressure generated by the pressure difference between the inside and outside of the range hood is F3, and the suction force provided by the flexible magnet is F4. Since the actual stress condition of the flexible film is extremely complex, the stress condition is simplified as follows for the convenience of analysis and calculation. Figure 6The shown approximate model, the process is simplified as follows, force analysis will be flexible film as a rigid body, ignoring the non-major direction of the force.

[0060] Wherein: as shown in the coordinate system is established as Figure 6 AB is Y axis, AE is Z axis, the line through A point and perpendicular to the plane ABDE is X axis, AE and DB = H, ED = AB = W, DC = V and DC is the vertical plane ABDE, H is the height difference between the surrounding edge bottom and the upper box bottom, W is the width of the upper box W, V is the distance between the upper box and the surrounding edge, then the coordinates of A point (0, 0, 0); the coordinates of B point (0, W, 0); the coordinates of C point (V, W, H); the coordinates of D point (0, W, H); the coordinates of E point (0, 0, H);

[0061] The direction of F4 is along the X axis, and the action point is the midpoint of AE (0, 0, H / 2), the direction of F3 is perpendicular to the plane ABCE, and the action point is the intersection of the diagonal lines of the plane ABCE (V / 2, W / 2, H / 2), the size of F3 can be obtained by multiplying the area of the plane ABCE by the pressure difference inside and outside the range hood, and the area can be easily obtained under the condition that the coordinates of the four vertices are known, which will not be repeated. The inside and outside pressure difference under the working condition of the range hood is usually between 80pa and 220pa, and the accurate value can be further determined by experiment. Therefore, the size, direction and action point of F3 are known, and the components of F3 in X, Y and Z directions are also known, that is, F3x, F3y and F3z are known in subsequent calculation, F3x is the component of F3 in X direction, F3y is the component of F3 in Y direction, and F3z is the component of F3 in Z direction. In order to reduce the number of unknowns, it is assumed that the size of the components of F1 and F2 in Y direction is equal, the action point of F1 is the midpoint of EC (V / 2, W / 2, H), and the action point of F2 is the midpoint of AB (0, W / 2, 0). After the above simplifying assumptions, there are six unknowns, F1x, F1y = F2y, F1z, F2x, F2z and F4, F1x is the component of F1 in Y direction, F1y is the component of F1 in Y direction, F1z is the component of F1 in Z direction, F2x is the component of F2 in X direction, F2y is the component of F2 in Y direction, and F2z is the component of F2 in Z direction.

[0062] ΣFx = 0, that is: F3x - F1x - F2x - F4 = 0

[0063] ΣFy = 0, that is: F1y + F2y - F3y = 0

[0064] ΣFz = 0, that is: F1z + F2z - F3z = 0

[0065] ΣFz = 0, that is: F1z + F2z - F3z = 0

[0066] From the moment balance, we have (clockwise is positive, counterclockwise is negative)

[0067] ΣMx=0, i.e.: F1y*H-F1z*W / 2+F2z*W / 2-F3y*H / 2+F3z*w / 2=0

[0068] ΣMy=0, i.e.: -F1x*H-F1z*V / 2+F3x*H / 2+F3x*V / 2-F4*H / 2=0

[0069] ΣMz=0, i.e.: -F1x*W / 2-F1y*V / 2-F2x*W / 2+F3x*W / 2+F3y*V / 2=0

[0070] The above Mx is the moment of force in the X direction, My is the moment of force in the Y direction, and Mz is the moment of force in the Z direction.

[0071] The above six equations can be solved to obtain the six unknowns, i.e. the value of F4.

[0072] Since the model is simplified, a safety factor K is multiplied to compensate for the error and ensure reliability when calculating the magnetic force between the flexible magnet and the rear side plate of the lower box, i.e. F=K*F4, K is usually between 3 and 5.

[0073] The size design process of the flexible magnet is as follows:

[0074] Step 1, obtain the magnetization M of the flexible magnet;

[0075] In this embodiment, the magnetization M of the flexible magnet is a inherent property of the flexible magnet, which can be queried after selecting the type of flexible magnet. Commonly used flexible magnets in industry include rubber magnets, compressible ferrite magnets, silicon steel magnets, and permanent magnet rubber magnets.

[0076] Step 2, calculate the magnetic field strength H of the flexible magnet according to the magnetization M of the flexible magnet;

[0077] The flexible magnet in this embodiment is square, i.e. the magnetic field strength H of the flexible magnet is calculated as follows:

[0078] H=M / d

[0079] Wherein, d is the distance between the flexible magnet and the rear side plate of the lower box; since the flexible magnet is embedded in the flexible film, d is usually half of the thickness of the flexible film, and the thickness of the flexible film is preferably in the range of 0.5-5mm;

[0080] Step 3, calculate the magnetic induction B in the rear side plate of the lower box according to the magnetic field strength H of the flexible magnet;

[0081] The magnetic induction intensity B in the back side plate of the lower box is calculated by the following formula:

[0082] B = μ*H

[0083] Wherein, μ is the magnetic permeability of the magnetic material used in the back side plate of the lower box; the back side plate of the lower box is made of sheet metal, and the specific value of μ can be found according to the properties of the sheet metal material;

[0084] Step 4, calculate the magnetic force between the flexible magnet and the back side plate of the lower box according to the following formula:

[0085] F = B*A*t*μ0 / (2*μr)

[0086] Wherein, A is the surface area of the face closest to the flexible magnet and parallel to the back side plate of the lower box; t is the thickness of the flexible magnet, μ0 is the magnetic permeability in vacuum, and μr is the relative magnetic permeability of the flexible magnet;

[0087] In this embodiment, t is a known value, and μr is determined by the type of the flexible magnet;

[0088] Step 5, replace the magnetic force F between the flexible magnet and the back side plate of the lower box calculated according to the suction force given by the flexible magnet into the calculation formula in step 4, that is, A is obtained.

[0089] In this embodiment, the height L of the flexible magnet is basically close to the height of the flexible film, and then the width B0 of the flexible magnet is obtained according to the following calculation formula: B0 = A / L.

[0090] In the specification and claims of the present application, terms indicating directions, such as "front", "back", "up", "down", "left", "right", "side", "top", "bottom", etc. are used to describe various example structural parts and elements of the present application, but these terms are used only for the purpose of convenient description and are determined based on the example orientation shown in the drawings. Since the disclosed embodiments of the present application can be arranged in different directions, these terms indicating directions are only for illustration and should not be considered as limitations, such as "up" and "down" are not necessarily limited to the direction opposite or consistent with the direction of gravity.

Claims

1. A sealing structure of a lifting type range hood, the lifting type range hood comprising: an upper cabinet (1) having an open bottom; a lower cabinet (2) constrained to the upper cabinet (1) and capable of lifting movement relative to the upper cabinet (1), the lower cabinet (2) having a cavity (21) with an open top, the cavity (21) being configured to at least partially accommodate the upper cabinet (1) therein; characterized in that the cavity (21) is provided with a surrounding edge (211, 212, 213) arranged around the outer peripheral wall of the upper cabinet (1), a gap being left between the surrounding edge (211, 212, 213) and the outer peripheral wall of the upper cabinet (1), the sealing structure comprising: a flexible connecting member (3) provided in the cavity (21), an upper end of the flexible connecting member (3) being capable of sealing connection with the upper cabinet (1) and being configured such that, in a state in which the lower cabinet (2) is moved to a lowest position, one end of the flexible connecting member (3) is capable of sealing connection with a bottom of the surrounding edge (211, 212, 213); the flexible connecting member (3) being a flexible film (31, 32, 33) extending in a direction of movement of the lower cabinet (2), an upper edge of the flexible film (31, 32, 33) being fitted to an inner wall of the upper cabinet (1), a lower end of the flexible film (31, 32, 33) being provided with a hook portion (311, 321, 331) on an outer side thereof, in a state in which the lower cabinet (2) is moved to the lowest position, the bottom of the surrounding edge (211, 212, 213) being placed in the hook portion (311, 321, 331) so as to form a sealing connection between the surrounding edge (211, 212, 213) and the lower end of the flexible film (31, 32, 33). The lower end of the flexible film (31, 32, 33) is outwardly turned to form the hook portion (311, 321, 331). A guide rail (4) is installed between the upper cabinet (1) and the lower cabinet (2), the lower cabinet (2) being capable of lifting movement relative to the upper cabinet (1) along the guide rail. The upper cabinet (1) and the lower cabinet (2) are both square-shaped, the guide rail (4) being provided on a rear side plate (11) of the upper cabinet (1) and a rear plate (2a) of the lower cabinet (2). ​ ​ 2. The seal structure of claim 1, wherein: ​ 3. The seal structure of claim 1, wherein: ​ 4. The seal structure of claim 3, wherein: ​ 5. The seal structure of claim 4, wherein: The three surrounding edges (211, 212, 213) are respectively a first surrounding edge (211) arranged on the periphery of the left side plate (12) of the upper cabinet (1), a second surrounding edge (212) arranged on the periphery of the front side plate (13) of the upper cabinet (1), and a third surrounding edge (213) arranged on the periphery of the right side plate (14) of the upper cabinet (1). All the surrounding edges (211, 212, 213) together with the rear plate (2a) of the lower cabinet (2) form the above-mentioned cavity (21). Correspondingly, the three flexible films are respectively a first flexible film (31) for sealing the first surrounding edge (211) and the left side plate (12) of the upper cabinet (1), a second flexible film (32) for sealing the second surrounding edge (212) and the front side plate (13) of the upper cabinet (1), and a third flexible film (33) for sealing the third surrounding edge (213) and the right side plate (14) of the upper cabinet (1).

6. The seal structure of claim 5, wherein: The first flexible film (31), the second flexible film (32), and the third flexible film (33) are sequentially connected to form a U-shaped flexible connecting piece (3).

7. The sealed structure of claim 5, wherein: The sealing structure further comprises flexible magnets (5) respectively constrained on the rear side of the first flexible film (31) and the rear side of the third flexible film (33). The rear plate (2a) of the lower cabinet (2) is made of a magnetic material. The first flexible film (31) and the third flexible film (33) can be magnetically attracted to the rear plate (2a) of the lower cabinet (2) by means of the respective flexible magnets (5), thereby maintaining sealed connection with the rear plate (2a) of the lower cabinet (2).

8. The seal structure of claim 7, wherein: The first flexible film (31) and the third flexible film (33) are further respectively provided with inclined portions (34) near the rear ends thereof. Each inclined portion (34) gradually inclines outward from the center of the corresponding flexible film to the rear end thereof.

9. A method of designing a seal for a hood as claimed in claim 8, wherein It comprises: The magnetic force between the flexible magnet and the rear plate of the lower cabinet is calculated according to the magnetic force provided by the flexible magnet, and the size of the flexible magnet is finally designed according to the magnetic force between the flexible magnet and the rear plate of the lower cabinet.

10. The method of claim 9, wherein: The formula for calculating the magnetic force between the flexible magnet and the rear plate of the lower cabinet is: F =K*F4 Wherein, K is the safety factor, and F4 is the magnetic force provided by the flexible magnet.

11. The method of designing according to claim 10, wherein: The size design process of the flexible magnet is as follows: Step 1, obtain the magnetization intensity M of the flexible magnet; Step 2, calculate the magnetic field intensity H of the flexible magnet according to the magnetization intensity M of the flexible magnet; Step 3, calculate the magnetic induction intensity B in the rear plate of the lower cabinet according to the magnetic field intensity H of the flexible magnet; Step 4, calculate the magnetic force between the flexible magnet and the rear plate of the lower cabinet according to the following formula: F =B*A*t*μ0 / (2*μᵣ ) Wherein, A is the surface area of the face closest to the flexible magnet and parallel to the rear plate of the lower cabinet; t is the thickness of the flexible magnet, μ0 is the magnetic permeability in vacuum, and μᵣ is the relative magnetic permeability of the flexible magnet; Step 5, the magnetic force F between the flexible magnet and the back plate of the lower box is calculated according to the suction force given by the flexible magnet, and is substituted into the calculation formula in Step 4, that is, A is obtained.

12. The method of designing according to claim 11, wherein: The flexible magnet is square, that is, the magnetic field strength H of the flexible magnet in Step 2 is calculated according to the following formula: H = M / d Wherein, d is the distance between the flexible magnet and the back plate of the lower box.

13. The method of claim 11, wherein: The magnetic induction intensity B in the back plate of the lower box in Step 3 is calculated according to the following formula: B = μ*H Wherein, μ is the magnetic permeability of the magnetic material used in the back plate of the lower box.

14. The method of claim 12, wherein: The height L of the flexible magnet is basically close to the height of the flexible film, and the width B0 of the flexible magnet is obtained according to the following formula: B0 = A / L.

15. A ceiling-mounted range hood, characterized by: The sealing structure according to any one of claims 1-8 is applied.

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