CN112178716B

CN112178716B - Oil smoke escape prevention structure and range hood with same

Info

Publication number: CN112178716B
Application number: CN202010980822.6A
Authority: CN
Inventors: 杨伟刚
Original assignee: Ningbo Fotile Kitchen Ware Co Ltd
Current assignee: Ningbo Fotile Kitchen Ware Co Ltd
Priority date: 2020-09-17
Filing date: 2020-09-17
Publication date: 2022-05-17
Anticipated expiration: 2040-09-17
Also published as: CN112178716A

Abstract

The invention discloses a structure for preventing oil smoke from escaping, which is characterized in that: the oil fume flow guide device comprises a fluid inlet and a guide vane, wherein the guide vane is provided with at least two outer pipes forming an annular shape, a gap between every two adjacent guide vanes forms a fluid outlet, and the guide vane is used for guiding oil fume flow entering from the fluid inlet to flow out from the fluid outlet to form a convoluted airflow on the periphery of the guide vane. Also discloses a range hood applying the oil smoke escape preventing structure. Compared with the prior art, the invention has the advantages that: through setting up the water conservancy diversion piece, the fluid outlet that communicates with fluid inlet is formed at the clearance between the water conservancy diversion piece, can control fluid flow direction export in the fluid route to form the coanda effect of control oil smoke, the fluid forms the air current at the water conservancy diversion piece surface and revolves, can pull back the oil smoke that has escaped back into the suction chamber negative pressure within range again, and the air current is not directly blowing to the outside space, and culinary art person's operation experience is good.

Description

Oil smoke escape prevention structure and range hood with same

Technical Field

The invention relates to an oil fume purification device, in particular to an oil fume escape prevention structure and a range hood applying the oil fume escape prevention structure.

Background

The range hood has become one of the indispensable kitchen household electrical appliances in modern families. The range hood works by utilizing the fluid dynamics principle, sucks and exhausts oil smoke through a centrifugal fan arranged in the range hood, and filters partial grease particles by using a filter screen. The centrifugal fan comprises a volute, an impeller arranged in the volute and a motor driving the impeller to rotate. When the impeller rotates, negative pressure suction is generated in the center of the fan, oil smoke below the range hood is sucked into the fan, accelerated by the fan and then collected and guided by the volute to be discharged out of a room.

Currently, the common range hoods on the market include a top suction type, a side suction type and a bottom suction type. The top-suction type range hood adopts an oil smoke rising principle, generates a negative pressure area right above a cooking bench, and sucks and exhausts naturally rising oil smoke generated during cooking.

The side-suction type range hood has the advantages that the side-suction type range hood is thin in body and not easy to touch the head when in operation, and has a good range hood effect because the installation height is low and the negative pressure area is close to a smoke source in a cooking state with small oil smoke amount.

The suction inlet of the downdraft range hood is closer to a cooking bench, the negative pressure area is close to a smoke source, the path of the movement of the smoke is reduced, and compared with other two forms, the downdraft range hood has a better smoke absorption effect, but has the following problems: firstly, under the condition of large oil smoke such as stir-frying, because the distribution range of the inlet negative pressure area is smaller, the capacity of capturing the oil smoke which is fried at high speed is poor, and the oil smoke is easy to escape to the periphery. When the top spoon is operated and the cooking is carried out in a high-pressure cooker (steamer), the installation height of the suction inlet from the cooking bench is 380 plus 420mm, the operation space is limited, certain depression is achieved, and bad experience is brought to users.

In a conventional range hood, for example, a range hood disclosed in chinese patent application No. 201410704669.9, an exhaust inlet is formed in a fume collecting hood, so that external oil fume is sucked into the interior. The negative pressure area of the top-suction type range hood is mainly concentrated under the smoke collecting cavity, the negative pressure at the edge is limited, the smoke control capability is weak, the anti-interference capability is poor, and the phenomenon of smoke leakage at the edge cannot be effectively prevented.

As disclosed in the chinese patent with application number 201020166285.3, blowing ports are provided at four corners of the range hood to form an air curtain surrounding the range; as also disclosed in chinese patent application nos. 201610461717.5 and 201720787123.3, it is also the principle of blowing air curtain at the edge to cover the cooking range to prevent oil smoke from escaping. Form the air curtain above cooking utensils and can prevent to a certain extent from running the cigarette, but the principle of air curtain sets up and blows, and the air curtain can seal the oil smoke at the cigarette machine suction chamber negative pressure space to a certain extent, but it can not pull back the oil smoke that blows off again, and the wind that blows off is well to the culinary art person, and this will reduce culinary art person's environmental comfort.

Disclosure of Invention

The first technical problem to be solved by the present invention is to provide an oil smoke escape prevention structure, which can lock escaping oil smoke by swirling air flow, in order to overcome the above-mentioned shortcomings of the prior art.

The second technical problem to be solved by the invention is to provide a range hood which is applied with the oil smoke escape prevention device.

The technical scheme adopted by the invention for solving the first technical problem is as follows: the utility model provides a grease proofing cigarette escape structure which characterized in that: the oil fume flow guide device comprises a fluid inlet and a guide vane, wherein the guide vane is provided with at least two outer pipes forming an annular shape, a gap between every two adjacent guide vanes forms a fluid outlet, and the guide vane is used for guiding oil fume flow entering from the fluid inlet to flow out from the fluid outlet to form a convoluted airflow on the periphery of the guide vane.

Preferably, in order to facilitate guiding the air flow in the outer pipe to flow out to the outer periphery of the outer pipe to form a convoluted air flow around the outer periphery of the outer pipe, the cross section of each guide vane is in the shape of an airfoil, and the leading edge of each guide vane is located inside the trailing edge of the adjacent guide vane.

Preferably, in order to ensure that the airflow flowing out of the inner pipe does not flow off the surface of the outer pipe, on the cross section of the outer pipe, the center of the leading edge of each guide vane is a, the center of the trailing edge of each guide vane is B, the center of the outer pipe is O, a connecting line between the center of the leading edge and the center of the trailing edge forms a chord, a connecting line between the center of the leading edge and the center of the outer pipe forms a first straight line, a connecting line between the center of the trailing edge and the center of the outer pipe forms a second straight line, and an included angle theta between the chord and the first straight line is theta₁And theta₁The value range of (a) is 75-80 degrees, and the included angle between the first straight line and the second straight line is theta₂And theta₂The value range of (1) is 30-40 degrees, and the placing radius R of the chord₁＝8～12mm。

Preferably, in order to facilitate connection of the flow deflectors and simultaneously ensure that the airflow between the flow deflectors can effectively form a wall attachment effect and ensure the speed of airflow convolution, so as to lock the oil smoke escaping from the front edge of the first air inlet, the outer tube further comprises a connecting column, the connecting column is connected between the front edge of each flow deflector and the tail edge of the adjacent flow deflector, the length of the connecting column is d, and the value range of d is 2mm or more and is less than or equal to d and is less than or equal to 4 mm.

In order to facilitate the oil fume flow from the fluid inlet to be uniformly diffused to the outer pipe, inner pipes communicated with the fluid inlet are arranged in the outer pipe at intervals, and through holes are formed in the pipe walls of the inner pipes, so that the oil fume flow from the fluid inlet is diffused between the outer pipe and the inner pipe.

Preferably, in order to facilitate uniform diffusion of the gas flow in the inner tube between the inner tube and the outer tube, the inner tube comprises two first tube segments and two second tube segments, the two first tube segments and the two second tube segments are both in the shape of truncated cones, the two second tube segments are arranged coaxially and adjacently, and each first tube segment is arranged at a position where the corresponding second tube segment is far away from the other second tube segment.

In order to further ensure that the airflow in the inner pipe is uniformly diffused between the inner pipe and the outer pipe, the radius of one end of the first pipe section far away from the second pipe section is R₂And the radius of one end close to the second pipe section is R₃The radius of the end of the second pipe sections close to each other is R₂The radius of the ends far away from each other is also R₃And satisfies the conditions that R2 is 4-5.8 mm, R3 is 6-8.5 mm, and the diffusion ratio delta is 2.25-4.5.

In order to introduce air flow in the fan system into the inner pipe, the oil smoke escape prevention structure further comprises an air inlet pipeline, one end of the air inlet pipeline forms an air inlet serving as a fluid inlet, the other end of the air inlet pipeline is connected to the inner pipe, and an oil net is arranged at the air inlet.

To ensure that the high-speed air flow in the fan system is effectively guided into the inner pipe through the air inlet pipe, the diameter of the air inlet pipe is d₁，d₁The value range of (A) is 10-15 mm.

In order to enable the range hood to have the advantages of low suction, side suction and top suction and increase the negative pressure of the suction inlet, the lower part of the shell is respectively recessed from front to back at the positions close to the left side and the right side to form a second air inlet.

The technical scheme adopted by the invention for solving the second technical problem is as follows: the utility model provides a range hood, includes the casing, sets up fan system and the air intake in the casing, its characterized in that: the range hood further comprises the oil smoke escape prevention structure, a fluid inlet of the oil smoke escape prevention structure is located in the fan system, and a fluid outlet of the oil smoke escape prevention structure is located at the air inlet.

The shell upper portion front side is provided with the air inlet subassembly, first air intake has been seted up to the bottom of air inlet subassembly, first air intake and the interior fluid intercommunication of casing, the outer tube sets up the front side at first air intake.

The lower part of the shell is respectively recessed from front to back at the positions close to the left side and the right side to form a second air inlet.

Compared with the prior art, the invention has the advantages that: through setting up the water conservancy diversion piece, the fluid outlet that communicates with fluid inlet is formed at the clearance between the water conservancy diversion piece, can control fluid flow direction export in the fluid route to form the coanda effect of control oil smoke, the fluid forms the air current at the water conservancy diversion piece surface and revolves, can pull back the oil smoke that has escaped back into the suction chamber negative pressure within range again, and the air current is not directly blowing to the outside space, and culinary art person's operation experience is good.

Drawings

Fig. 1 is a schematic front view of a range hood according to an embodiment of the present invention;

FIG. 2 is a side view of a range hood according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view of a range hood in accordance with an embodiment of the present invention;

fig. 4 is a schematic view of a smoke escape prevention structure of the range hood according to the embodiment of the invention;

fig. 5 is an exploded schematic view of the air intake duct and the air inlet hidden in the oil smoke escape preventing structure of the range hood according to the embodiment of the present invention;

FIG. 6 is a side view of the outer tube of the oil smoke escape prevention structure of the range hood according to the embodiment of the present invention;

fig. 7 is a front view of the inner tube of the oil smoke escape prevention structure of the range hood according to the embodiment of the present invention;

fig. 8 is an enlarged view of a portion i of fig. 3.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar functions.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and to simplify the description, but are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and that the directional terms are used for purposes of illustration and are not to be construed as limiting, for example, because the disclosed embodiments of the present invention may be oriented in different directions, "lower" is not necessarily limited to a direction opposite to or coincident with the direction of gravity. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

Referring to fig. 1 to 3, a range hood includes a housing 1, a fan system 2 disposed in the housing 1, and an oil cup 3 disposed at the bottom of the housing 1.

The upper front side of the shell 1 is provided with an air inlet assembly 4, the air inlet assembly 4 comprises a first baffle plate 41 positioned on the front side and second baffle plates 42 positioned on the left and right sides of the first baffle plate 41, the top of the first baffle plate 41 can be fixedly connected with the shell 1, the first baffle plate 41 is gradually inclined forwards from top to bottom, the second baffle plates 42 can be roughly triangular and gradually increase from top to bottom, the bottom of the second baffle plates 42 can be an arc protruding downwards, and a space between the first baffle plate 41 and the second baffle plates 42 forms a cavity for holding cigarettes together. A first air inlet 43 is formed between the bottom of the first baffle 41 and the corresponding position of the housing 1, a first filter screen 44 may be disposed at the first air inlet 43, the first filter screen 44 may also be in an arc shape protruding downwards, and the left and right sides of the first filter screen 44 are respectively connected with the second baffle 42 at the corresponding position. The intake assembly 4 is in fluid communication with the interior of the housing 1.

The lower part of the casing 1 is recessed from front to back at positions close to the left and right sides to form second air inlets 11, and each second air inlet 11 is provided with a first sub air inlet 111, a second sub air inlet 112 and a third sub air inlet 113 which are arranged at an angle, so that the second air inlets 11 with three air inlet sides are formed. The first branch air inlet 111 is forward, and is inclined backward from top to bottom. The second sub-inlet 112 and the third sub-inlet 113 of the left second inlet 11 face to the left, and the second sub-inlet 112 and the third sub-inlet 113 of the right second inlet 11 face to the right. The second sub air inlet 112 and the third sub air inlet 113 may have a triangular shape. The second sub air inlet 112 is inclined gradually from the side surface of the housing 1 to the middle from top to bottom, the rear side of the second sub air inlet 112 is connected with one side of the first sub air inlet 111 facing the middle, the bottom of the second sub air inlet 112 is inclined gradually from front to back, and the air inlet area of the second sub air inlet 112 is gradually increased from top to bottom. The front side of the second sub-air inlet 112 is gradually inclined from top to bottom. The third minute air intake 113 is located the below that the second divides air intake 112, and the top that the third divides air intake 113 is connected with the bottom that the second divides air intake 112, and the third divides air intake 113 from top to bottom slopes to the centre gradually, and the inclination of third minute air intake 113 is less than the second and divides air intake 112, and the rear side and the first one side that divides air intake 111 to be connected towards the centre of third minute air intake 113, and the bottom that the third divides air intake 113 extends to the bottom of casing 1, and the air inlet area that the third divides air intake 113 from top to bottom crescent.

The portion of the casing 1 between the front sides of the two second air inlets 11 forms a front side wall 13 that is inclined gradually backward from top to bottom. The bottom of the housing 1 is provided with a bottom wall 14 which is gradually inclined downwards from front to back, and the bottom wall 14 is located between the two second air inlets 11.

The fan system 2 includes a volute 21, an impeller 22 disposed within the volute 21, and a motor 23 for driving the impeller 22 to rotate.

In this embodiment, both the second screen 12 and the first screen 44 may be a grill screen.

Through the second air inlet 11 and the second air inlet 44, the whole machine has three air inlets, and has the advantages of top suction, side suction and low suction. The three-side air inlet design of the second air inlet 11 can ensure that effective negative pressure is distributed above the pot. The second air inlet 44 can effectively capture escaping oil smoke in a cooking state with large oil smoke such as quick-fried oil smoke.

Due to the inclined design of the front side wall 13 and the first baffle plate 41 and the arrangement of the second filter screen 12 and the first filter screen 44, the grease in the shell 1 can be ensured to flow into the oil cup 3 downwards along the front side wall 13, the first baffle plate 41, the two filter screens and the bottom wall 14, the grease separation degree is improved, the excessive grease is prevented from being accumulated on the surface of the motor of the fan system 2, and the service life of the fan system 2 is prolonged.

During the installation, range hood can be installed in the below of cupboard as a whole, does not keep off the sight moreover, and operating space is big, and user's culinary art is experienced.

In order to prevent the oil smoke from escaping from the front edge of the air inlet component 4, an oil smoke escape preventing structure is also arranged. Referring to fig. 3 to 8, the oil and smoke escape preventing structure includes an air inlet duct 51, an outer duct 52 and an inner duct 53 disposed in the outer duct 52, wherein the outer duct 52 and the inner duct 53 are disposed at the bottom front side of the air intake assembly 4, that is, at the junction of the bottom end of the first baffle 41 and the front end of the first air inlet 43. One end of the air inlet duct 51 extends into the volute 21 of the fan system 2 and forms an air inlet 511 at that end, an oil screen 512 is provided at the air inlet 511 for filtering grease, and the other end of the air inlet duct 51 extends into the inner tube 53 and is in fluid communication with the interior of the inner tube 53. The air inlet 511 is located at a position where the volute casing 21 has a high-speed airflow inside, such as a position located in the middle of the air outlet of the volute casing 21, and the position and the size of the air inlet 511 can be designed according to the size of the fan system 2. The outer tube 52 and the inner tube 53 are both hollow tubes, and the inner tube 53 is arranged at intervals inside the outer tube 52 and is in fluid communication with the inside of the fan system 2. The airflow passes through the intake duct 51 from the intake port 511 to reach the inner pipe 53. The air flow is rectified in the inner tube 53 and then sent between the outer tube 52 and the inner tube 53, and finally, the air flow is controlled by the tube wall of the outer tube 52 to form a spiral flow, so that the oil smoke at the front edge of the first baffle 41 is locked, and the principle is described in detail below. Both ends of the outer tube 52 are provided with end caps 54 so as to close the inner space inside the outer tube 52.

The outer tube 52 includes at least two flow deflectors 521 and a connection column 522 connecting the flow deflectors 521 end to end, each flow deflector 521 is in a shape of a long strip, and the connection column 522 is in a shape of a column, and may have a plurality of flow deflectors, which are arranged at intervals along the length direction of the flow deflectors 521. The guide vanes 521 are approximately cylindrical, and the connecting column 522 is connected to the head and the tail of two circumferentially adjacent guide vanes 521, so as to support the flow channel between the guide vanes 521 to form an airflow coanda effect. The cross section (the plane perpendicular to the axial direction and the radial direction of the outer pipe 52) of each guide vane 521 is in an airfoil shape, the leading edge of the airfoil shape of each guide vane 521 is positioned inside the trailing edge of the airfoil shape of the adjacent guide vane 521, and the connecting column 522 is connected between the leading edge of each guide vane 521 and the trailing edge of the adjacent guide vane 521.

In cross section, the center of the leading edge of each guide vane 521 is a, the center of the trailing edge of each guide vane 521 is B, the center of the entire outer tube 52 is O, a line connecting the leading edge center a and the trailing edge center B forms a chord AB, the line connecting the leading edge center a and the center O of the outer tube 52 forms a first straight line OA, the line connecting the trailing edge center B and the center O of the outer tube 52 forms a second straight line OB, and the included angle θ between the chord AB and the first straight line OA is θ₁And theta₁Preferably 75-80 DEG, and the placement radius R of the chord₁Within the parameter range, the air flow flowing out of the inner pipe 53 can be ensured not to flow off the surface of the outer pipe 52. The first line OA and the second line OB have an angle θ₂And theta₂The value range of (A) is preferably 30 to 40 degrees. The length of the connecting column 522 is d, and d is preferably in a range of 2mm or more and 4mm or less, and in the gap range, airflow between the wing profiles can effectively form a wall attachment effect, so that the speed of the airflow rotating is ensured, and the oil smoke escaping from the front edge of the first air inlet 43 is locked. The airfoil can be a common airfoil or other streamline airfoils, such as a circular arc airfoil, a NACA airfoil and the like. Alternatively, the guide vanes 521 may not be airfoil-shaped, but may be arc-shaped, so long as the guide vanes 521 can guide the air flow and have a passage for the air flow to pass through between the guide vanes 521.

The inner tube 53 has through holes 531 formed in a wall thereof, and the through holes 531 are preferably uniformly arranged to uniformly deliver the duct airflow to the cavity between the outer tube 52 and the inner tube 53, so that the airflow is uniformly distributed along the length direction of the outer tube 52. The inner tube 53 constitutes a diffuser tube comprising a first tube segment 532 and a second tube segment 533, wherein the first tube segmentThe first pipe segment 532 is provided in two, the second pipe segment 533 is provided in two, and the first pipe segment 532 and the second pipe segment 533 are each of a truncated cone type. The second pipe segments 533 are coaxially and adjacently disposed, and each first pipe segment 532 is disposed at a position where the corresponding second pipe segment 533 is far away from another second pipe segment 533, that is, a first end of each second pipe segment 533 is connected with the first pipe segment 532, and the other end is connected with another second pipe segment 533. The radius of the end of the first pipe segment 532 remote from the second pipe segment 533 is R₂And the radius of the end near the second tube segment 533 is R₃The adjacent ends of the second pipe segments 533 have a radius R₂The radius of the ends far away from each other is also R₃. Preferably, the radius is selected from a range of R2 being 4 to 5.8mm, R3 being 6 to 8.5mm, and a diffusion ratio δ being 2.25 to 4.5, and the inner tube 53 is capable of uniformly delivering the duct airflow into the cavity between the outer tube 52 and the inner tube 53 within this diffusion ratio range. The diameter of the through hole 531 is d₂，d₂The preferable value range of (2) is 3-4 mm, so that the air flow is uniformly distributed along the length direction of the outer pipe 52. The inlet pipe 51 is connected to the inner pipe 53 at the large diameter end of the inner pipe 53 (where the first pipe segment 532 and the second pipe segment 533 are connected), and the diameter of the inlet pipe 51 is d₁，d₁The preferable value range of (1) is 10-15 mm, and in the parameter range, the high-speed airflow in the volute 21 can be ensured to be effectively introduced into the inner pipe 53 through the air inlet pipeline 51.

With the above arrangement of the structure for preventing oil smoke from escaping, the air inlet 511 forms a fluid inlet of the structure, and the gap between the guide vanes 521 forms a fluid outlet 523. The air flow enters from the air inlet 511, enters the inner pipe 53 through the air inlet pipe 51, is rectified by the inner pipe 53, and is uniformly sent to a cavity between the outer pipe 52 and the inner pipe 53, and finally forms an air flow convolution at the periphery of the guide vanes 521 (the air flow passes through between the adjacent guide vanes 521) under the control of the wing-shaped guide vanes 521 of the outer pipe 52, and the oil smoke at the front edge (the front side of the first air inlet 43) of the first baffle plate 41 of the range hood is locked by using the fluid wall attachment principle, as shown by an arrow in fig. 6. Therefore, the escaped oil smoke can be pulled back to be sucked into the negative pressure range, the air flow is not directly blown to the outer space, and the operation experience of a cooker is good.

The end cover 54 can be clamped with the second baffle 42, so that the oil smoke escape preventing structure is convenient to disassemble and assemble.

In this embodiment, the structure for preventing oil smoke from escaping is disposed at the first air inlet 43, and alternatively, may be disposed at the second air inlet 11, or disposed at an air inlet of a range hood of other forms.

The term "fluid communication" as used herein refers to a spatial relationship between two components or portions (hereinafter collectively referred to as a first portion and a second portion, respectively), i.e., a fluid (gas, liquid or a mixture of both) can flow along a flow path from the first portion and/or be transported to the second portion, and may be a direct communication between the first portion and the second portion, or an indirect communication between the first portion and the second portion via at least one third element, such as a fluid channel, e.g., a pipe, a channel, a duct, a flow guide, a hole, a groove, or a chamber that allows a fluid to flow through, or a combination thereof.

Claims

1. The utility model provides a grease proofing cigarette escape structure which characterized in that: the oil fume flow guide device comprises a fluid inlet and a flow guide sheet (521), wherein the flow guide sheet (521) is provided with at least two outer pipes (52) which form a ring shape, a gap between adjacent flow guide sheets (521) forms a fluid outlet (523), and the flow guide sheet (521) is used for guiding an oil fume flow entering from the fluid inlet to flow out of the fluid outlet (523) to form a convoluted airflow on the periphery of the flow guide sheet (521); the inner pipe (53) communicated with the fluid inlet is arranged in the outer pipe (52) at intervals, and the pipe wall of the inner pipe (53) is provided with through holes (531), so that the oil fume from the fluid inlet can diffuse between the outer pipe (52) and the inner pipe (53).

2. The structure of preventing oil and smoke from escaping according to claim 1, characterized in that: the cross section of each guide vane (521) is airfoil-shaped, and the front edge of each guide vane (521) is positioned inside the tail edge of the adjacent guide vane (521).

3. The structure of preventing oil and smoke from escaping according to claim 2, characterized in that: across the outer tube (52)In cross section, the center of the leading edge of each guide vane (521) is A, the center of the trailing edge of each guide vane (521) is B, the center of the outer tube (52) is O, the connecting line between the center of the leading edge (A) and the center of the trailing edge (B) forms a chord (AB), the connecting line between the center of the leading edge (A) and the center of the outer tube (52) forms a first straight line (OA), the connecting line between the center of the trailing edge (B) and the center of the outer tube (52) forms a second straight line (OB), and the included angle between the chord (AB) and the first straight line (OA) is theta₁And theta₁Is 75-80 DEG, and the included angle between the first straight line (OA) and the second straight line (OB) is theta₂And theta₂The value range of (A) is 30-40 degrees, and the placing radius R of the chord (AB)₁＝8～12mm。

4. The structure of preventing oil and smoke from escaping according to claim 3, characterized in that: the outer pipe (2) further comprises a connecting column (522), the connecting column (522) is connected between the front edge of each guide vane (521) and the tail edge of the adjacent guide vane (521), the length of the connecting column (522) is d, and the value range of d is 2mm or more and 4mm or less.

5. The structure of preventing oil and smoke from escaping according to claim 1, characterized in that: the inner pipe (53) comprises a first pipe section (532) and a second pipe section (533), wherein the first pipe section (532) comprises two first pipe sections, the second pipe section (533) comprises two second pipe sections, the first pipe section (532) and the second pipe section (533) are in a truncated cone shape, the second pipe sections (533) are coaxially and adjacently arranged, and each first pipe section (532) is arranged at a position where the corresponding second pipe section (533) is far away from the other second pipe section (533).

6. The structure of preventing oil and smoke from escaping of claim 5, characterized in that: the radius of one end of the first pipe section (532) far away from the second pipe section (533) is R₂And the radius of one end close to the second pipe section (533) is R₃The radius of the end of the second pipe section (533) close to each other is R₂The radius of the ends far away from each other is also R₃And satisfies the conditions that R2 is 4-5.8 mm, R3 is 6-8.5 mm, and the diffusion ratio delta is 2.25-4.5.

7. The structure of preventing oil and smoke from escaping according to claim 1, characterized in that: the oil smoke escape preventing structure further comprises an air inlet pipeline (51), one end of the air inlet pipeline (51) forms an air inlet (511) serving as a fluid inlet, the other end of the air inlet pipeline is connected to the inner pipe (53), and an oil net (512) is arranged at the air inlet (511).

8. The structure of preventing oil and smoke from escaping according to claim 7, characterized in that: the diameter of the air inlet pipe (51) is d₁，d₁The value range of (A) is 10-15 mm.

9. The utility model provides a range hood, includes casing (1), sets up fan system (2) and the air intake in casing (1), its characterized in that: the range hood further comprises the oil smoke escape prevention structure according to any one of claims 1 to 8, wherein a fluid inlet of the oil smoke escape prevention structure is positioned in the fan system (2), and a fluid outlet (523) of the oil smoke escape prevention structure is positioned at an air inlet.

10. The range hood of claim 9, wherein: the utility model discloses a shell (1) is characterized in that casing (1) upper portion front side is provided with air inlet subassembly (4), first air intake (43) have been seted up to the bottom of air inlet subassembly (4), first air intake (43) and casing (1) interior fluid intercommunication, outer tube (52) set up the front side at first air intake (43).

11. The range hood of claim 9, wherein: the lower part of the shell (1) is respectively recessed from front to back at the positions close to the left side and the right side to form a second air inlet (11).