A range hood and a control method thereof

Abstract

The present application relates to a kind of range hood and its control method, range hood includes casing and fan being arranged in casing, oil fume parameter detector is arranged in casing, oil fume parameter detector includes optical signal sensor, oil fume parameter detector also includes venturi and the vortex motion of making fluid to spin, the vortex generator is set in venturi and is adjacent to the inlet end of venturi and is arranged, optical signal sensor is located in the airflow direction downstream of vortex generator.This range hood can realize oil fume concentration and airflow speed detection simultaneously without additional flow sensor, and the separation of oil fume and air is increased by vortex generator, and the detectability of oil fume change is further improved by venturi acceleration, and the rotation separation of air and oil fume is also strengthened by "vortex core" helical precession around axis, the action intensity of oil fume to light is enhanced, so that it is more convenient to expand the detection of small smoke, reach wide range, high linearity, more reliable detection purpose.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil fume purification, and particularly relates to an extractor hood and a control method thereof. BACKGROUND

[0002] The extractor hood is an essential kitchen appliance for every family, which completes the purification of kitchen air by sucking oil fume from an air inlet into a volute through a high-speed rotating impeller, filtering the oil fume by the impeller, and discharging the filtered oil fume from an air outlet.

[0003] The fan of the traditional extractor hood runs at a fixed gear or speed, and cannot automatically adjust the gear of the fan according to the amount of oil fume in different cooking scenes. In order to realize oil fume detection, the prior art often simply uses the principle that oil fume affects the refractive index of light in the air to realize the judgment of the size of oil fume, but is not associated with the current airflow speed, has slow response speed, and even needs to be matched with an additional flow sensor to judge whether the current oil fume and airflow speed match, but this method has high cost, low intelligence, and is not very convenient for users to operate. Furthermore, there is also a light projection principle, but it often does not reflect in time when detecting weak oil fume, and is inaccurate in judging the initial cooking or small smoke state of the user, which is slow in response and not intelligent. In addition, some use light scattering, which reflects in time for small smoke and is easy to exceed the range for large smoke, and does not reflect linearly for large smoke. Therefore, the prior art needs to be further improved. SUMMARY

[0004] The first technical problem to be solved by the present application is to provide an extractor hood capable of simultaneously detecting oil fume concentration and airflow speed without an additional flow sensor.

[0005] The second technical problem to be solved by the present application is to provide a control method for the above-mentioned extractor hood, which can accurately adjust the speed of the fan to make the airflow speed and the oil fume concentration have a higher matching degree.

[0006] The technical solution adopted by the present application to solve the above-mentioned first technical problem is an extractor hood, which comprises a casing and a fan arranged in the casing, and an oil fume parameter detector arranged in the casing, wherein the oil fume parameter detector comprises a light signal sensor, characterized in that the oil fume parameter detector further comprises a Venturi tube and a vortex generator for generating vortex motion of fluid, the vortex generator is arranged in the Venturi tube and adjacent to the inlet end of the Venturi tube, and the light signal sensor is located downstream of the airflow direction of the vortex generator.

[0007] In order to facilitate detection of the oil fume signal, the light signal sensor comprises a light emitter and a light receiver, the light emitter and the light receiver are respectively arranged on two opposite inner wall surfaces of the Venturi tube, and the light receiver faces the light emitter in a direction perpendicular to the airflow direction.

[0008] Preferably, the cyclone device comprises a plurality of cyclone blades extending along the airflow direction, each of the cyclone blades extending radially outward from the middle and arranged radially, each of the cyclone blades is arc-shaped, and all of the cyclone blades are clockwise or counterclockwise in overall rotation direction.

[0009] In order to ensure the consistency of the oil fume flow direction before flowing through the cyclone device, and thus to obtain more accurate oil fume signal and airflow speed, the oil fume parameter detector further comprises a straightening module for straightening the oil fume flow direction, the straightening module is arranged upstream of the airflow direction of the Venturi tube.

[0010] Preferably, the straightening module comprises a base body, a plurality of channels extending along the airflow direction are formed in the base body, and the outlets of the channels face the inlet end of the Venturi tube.

[0011] In order to eliminate the influence of backflow on the oil fume, the oil fume parameter detector further comprises a backflow eliminator, the backflow eliminator is arranged in the Venturi tube and adjacent to the outlet end of the Venturi tube, and the backflow eliminator is arranged downstream of the light signal sensor.

[0012] Preferably, the backflow eliminator comprises a plurality of grid plates extending along the airflow direction, each of the grid plates extends radially outward from the middle and is arranged radially, and a backflow elimination channel is formed between adjacent two grid plates.

[0013] In order to improve the installation stability of the grid plates, the backflow eliminator further comprises a plurality of connecting plates extending along the airflow direction, each of the connecting plates is arranged between adjacent two grid plates, and each of the connecting plates is arc-shaped, and the overall cross section enclosed by all of the connecting plates is circular.

[0014] Preferably, the Venturi tube comprises a straight cylinder structure in the middle and a horn-shaped structure gradually expanding in diameter from both ends of the straight cylinder structure, the ends of the two horn-shaped structures away from the straight cylinder structure are respectively the inlet end of the Venturi tube and the outlet end of the Venturi tube, and the light signal sensor is arranged on the straight cylinder structure.

[0015] In order to improve the control accuracy of the range hood, a pressure sensor for detecting the pressure in the Venturi tube is further arranged on the Venturi tube, and the detection position of the pressure sensor is located on the plane where the light emitted by the light emitter is located.

[0016] The technical solution adopted by the present application to solve the above-mentioned second technical problem is: a control method of the above-mentioned range hood, characterized in that comprising:

[0017] Step 1, obtaining the oil fume signal value detected by the light signal sensor according to the first sampling period, and averaging the oil fume signal values collected within the first set time to obtain an average value of the oil fume △P1;

[0018] Step 2, judging whether △P1 is greater than the oil fume reference threshold Pa, if yes, controlling the fan in the range hood to start to a preset gear or maintaining the fan start state, and turning to step 3; if no, determining that there is no obvious oil fume or water vapor, and closing or maintaining the fan closed state after waiting for a second set time, and turning to step 1;

[0019] Step 3, determining the current oil fume scene of the range hood according to △P1, and finding the maximum speed Vb and the minimum speed Va under the corresponding oil fume scene according to the current oil fume scene of the range hood;

[0020] Step 4, performing Fourier transform processing on the oil fume signal values collected within the set time, and then obtaining the main frequency f of the oil fume flowing through the vortex center, and calculating the air flow speed V according to K=f / V, K being a basic parameter calibrated before the range hood is shipped;

[0021] Step 5, comparing the calculated air flow speed V with the maximum speed Vb and the minimum speed Va, and adjusting the fan speed according to the comparison result.

[0022] Preferably, the specific process of determining the current oil fume scene of the range hood in step 3 is as follows:

[0023] Comparing △P1 with the first oil fume set value Pb and the second oil fume set value Pc respectively, Pb

[0024] If △P1

[0025] If Pb≤△P1≤Pc, it means that the current oil fume scene of the range hood is a medium oil fume scene;

[0026] If △P1>Pc, it means that the current oil fume scene of the range hood is a large oil fume scene.

[0027] Preferably, the specific comparison process in step 5 is as follows:

[0028] If V

[0029] If Va≤V≤Vb, maintain the current fan speed;

[0030] If V>Vb, reduce the current fan speed.

[0031] Preferably, before searching for the maximum speed Vb and the minimum speed Va under the corresponding oil fume scene according to the oil fume scene where the current range hood is located in step 3, the method further comprises the following steps:

[0032] The pressure value detected by the pressure sensor is acquired according to a second sampling period, and the pressure values collected within a second set time are averaged to obtain a pressure average value △F1;

[0033] It is judged whether △F1 is greater than the first pressure reference threshold Fa, if yes, it is determined that the fan has been running, if no, it is determined that the fan has not been running, and the fan in the range hood is controlled to start to a preset gear.

[0034] Preferably, after it is determined that there is no obvious oil fume or water vapor in step 2, the method further comprises the following steps:

[0035] Step a, reading current fan running information, judging whether the current fan is running, if yes, the current fan is adjusted to the lowest gear, and step b is entered, if no, step 1 is entered;

[0036] Step b, acquiring the pressure value detected by the pressure sensor according to a second sampling period, and averaging the pressure values collected within a second set time to obtain a pressure average value △F1;

[0037] It is judged whether △F1 is greater than the second pressure reference threshold Fb, if yes, the fan continues to run at the current gear, and step 1 is entered, if no, the fan is turned off, and step 1 is entered.

[0038] Compared with the prior art, the advantages of the present application are that: by setting the spin generator and the Venturi tube, the spin generator forces the fluid medium to produce regular and violent vortex flow movement, when the regular vortex movement medium enters the contraction section of the Venturi tube, the flow rate is strengthened, finally the fluid flows through the diffusion section of the Venturi tube, the fluid flow rate is reduced, and under the action of pressure, backflow is generated, forming a phenomenon similar to the vortex shedding of bluff body vortex street, and the "vortex core" of the vortex flow makes spiral precession around the axis under the action of backflow. Therefore, the spin generator increases the separation of oil fume and air, and the Venturi tube further enhances the detectability of oil fume change, and the "vortex core" makes spiral precession around the axis, which strengthens the rotational separation of air and oil fume, so that the oil fume parameter detector has a three-fold amplification effect, enhances the action intensity of oil fume on light, makes it easier to expand the detection of small smoke, achieves wide range and high linearity, and more reliable detection purpose; in addition, the frequency of the "vortex core" making spiral precession around the axis is proportional to the speed of the fluid. Therefore, the precession frequency of the precession vortex is measured to calculate the airflow speed, and the oil fume concentration and airflow speed detection can be realized at the same time without additional flow detection module. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 This is a schematic diagram of the range hood in Embodiment 1 of the present invention;

[0040] Figure 2 for Figure 1 Schematic diagram of the structure of the oil fume parameter detector;

[0041] Figure 3 for Figure 2 A sectional view;

[0042] Figure 4 for Figure 2 Exploded view;

[0043] Figure 5 This is a state diagram of oil fumes passing through an oil fume parameter detector in Embodiment 1 of the present invention;

[0044] Figure 6 This is a flowchart of the range hood control method in Embodiment 1 of the present invention;

[0045] Figure 7 This is a schematic diagram of the oil fume parameter detector in Embodiment 2 of the present invention;

[0046] Figure 8 This is a flowchart of the range hood control method in Embodiment 2 of the present invention. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0048] Example 1:

[0049] like Figures 1 to 5 As shown, the range hood in this embodiment includes a housing 1 and a fan 2 disposed within the housing 1. An oil fume parameter detector 3 is installed inside the housing 1, which can be used to detect the oil fume concentration and airflow velocity. In this embodiment, the oil fume parameter detector 3 is disposed on the inner wall of the housing 1, facing the lower part of the air inlet of the fan 2. Since the oil fumes drawn by the range hood inevitably pass through this location, placing the oil fume parameter detector 3 at this position allows for more accurate data detection.

[0050] The oil fume parameter detector 3 includes a light signal sensor 31, a venturi tube 32, a vortex generator 33, a rectifier module 34, and a backflow eliminator 35. The vortex generator 33 causes the fluid to generate vortex motion, the rectifier module 34 is used to rectify the direction of oil fume flow, the vortex generator 33 is located inside the venturi tube 32 and adjacent to the inlet end of the venturi tube 32, the light signal sensor 31 is located downstream of the airflow direction of the vortex generator 33, and the rectifier module 34 is located upstream of the airflow direction of the venturi tube 32; the backflow eliminator 35 is located inside the venturi tube 32 and adjacent to the outlet end of the venturi tube 32, and the backflow eliminator 35 is located downstream of the light signal sensor 31.

[0051] As Figure 3 shown, the light signal sensor 31 in this embodiment includes a light emitter 311 and a light receiver 312, which are respectively arranged on two opposite inner wall surfaces of the Venturi tube 32, and the light receiver 312 faces the light emitter 311 in a direction perpendicular to the airflow direction. In addition, the rectifying module 34 includes a base body, in which a plurality of passages 341 extending along the airflow direction are formed, and the outlets of the passages 341 face the inlet end of the Venturi tube 32.

[0052] As Figure 4 shown, the vortex generator 33 includes a plurality of vortex blades 331 extending along the airflow direction, each of which extends radially outward from the middle and is arranged in a radial pattern, each of which is arc-shaped, and all of which have a clockwise or counterclockwise rotation direction as a whole. In addition, the backflow eliminator 35 includes a plurality of grid plates 351 extending along the airflow direction and a plurality of connecting plates 353 extending along the airflow direction, each of the grid plates 351 extends radially outward from the middle and is arranged in a radial pattern, and a backflow elimination passage 352 is formed between adjacent two grid plates 351; each of the connecting plates 353 is arranged between adjacent two grid plates 351, and each of the connecting plates 353 is arc-shaped, and the whole cross section enclosed by all the connecting plates 353 is circular.

[0053] The Venturi tube 32 in this embodiment includes a straight cylinder structure 321 in the middle and two horn-shaped structures 322 gradually expanding in diameter outward from the two ends of the straight cylinder structure 321, the ends of the two horn-shaped structures 322 away from the straight cylinder structure 321 are respectively the inlet end of the Venturi tube 32 and the outlet end of the Venturi tube 32, and the light signal sensor 31 is arranged on the straight cylinder structure 321.

[0054] As Figure 5 shown, when the range hood is working, the chaotic airflow entering from the air inlet of the range hood first passes through the rectifying module 34 to be rectified into standard airflow and then enters the Venturi tube 32, first passes through the vortex generator 33 to force the fluid medium to produce regular and violent vortex flow movement, when the regular vortex movement medium enters the horn-shaped structure 322 (i.e. the contraction section) at the most upstream of the Venturi tube 32, the flow rate thereof will be strengthened; finally, the fluid flows through the straight cylinder structure 321 and the horn-shaped structure 322 (i.e. the diffusion section) at the most downstream, the fluid flow rate is reduced, and backflow is generated under the action of pressure, forming a phenomenon similar to the vortex shedding of bluff body vortex street, and the "vortex core" of the vortex flow makes spiral precession around the axis under the action of backflow, and the precession frequency is proportional to the fluid velocity. Therefore, the precession frequency of the precession vortex can be measured to know the fluid flow, and there is good linearity in the flow measurement range, and the pressure or vortex precession frequency f in the flow field has the following relationship with the inlet flow rate v: K = f / v, which is obtained by testing and simulation at the factory.

[0055] Because the fluid passing through the swirler itself enhances the oil fume and air separation, and the Venturi tube acceleration further enhances the detectability of oil fume change, and the "vortex core" around the axis does helical precession, which also strengthens the rotational separation of air and oil fume, so that the oil fume parameter detector 3 has three effects of vortex, Venturi acceleration and central flow periodic rotation promotion, enhances the action intensity of oil fume on light, makes it easier to expand the detection of small smoke, achieves wide range, high linearity and more reliable detection purpose.

[0056] And the central flow around the axis does helical precession, which will show periodicity for fixed detection position, so that the fundamental frequency component obtained by Fourier transform of the light receiving signal can be used to obtain the pressure or vortex precession frequency f in the flow field. According to the pre-calibrated K, the air flow velocity v can be obtained by K=f / V, and then the actual flow of the current range hood can be obtained by looking up the table based on this reference, or the flow Q can be obtained directly by looking up the table according to f and flow Q, so that there is no need to set an additional flow detection module, and the flow rate and oil fume detection are in the same position, which is more referential for judgment than the separated flow rate sensor.

[0057] As shown in Figure 6 , the control method of the above range hood in the embodiment includes:

[0058] Step 1, obtaining the oil fume signal value detected by the light signal sensor according to the first sampling period, and performing average calculation on the oil fume signal values collected within the first set time to obtain the oil fume average value △P1;

[0059] The first sampling period is a set value, which can be determined according to experiments or experience;

[0060] In the embodiment, before step 1, it also includes controlling whether the range hood is started in manual operation or intelligent mode. If the intelligent mode is started, the intelligent monitoring mode is started, and step 1 is entered.

[0061] Step 2, judging whether △P1 is greater than the oil fume reference threshold Pa. If yes, the fan in the range hood is controlled to start to a preset gear or keep the fan in the starting state, and step 3 is entered. If no, it is determined that there is no obvious oil fume or water vapor, and the fan is closed or kept in the closed state after waiting for a second set time, and step 1 is entered.

[0062] The oil fume reference threshold Pa is a set value, which can be determined according to experiments or experience;

[0063] Step 3, determining the oil fume scene where the current range hood is located according to △P1, and finding the maximum speed Vb and the minimum speed Va under the corresponding oil fume scene without smoke according to the oil fume scene where the current range hood is located.

[0064] The specific process of determining the oil fume scene where the current range hood is located is as follows:

[0065] The ΔP1 is compared with the first oil fume set value Pb and the second oil fume set value Pc respectively, and Pb

[0066] If the ΔP1 is less than Pb, it indicates that the oil fume scene where the current range hood is located is a small oil fume scene.

[0067] If Pb is less than or equal to the ΔP1 and the ΔP1 is less than or equal to Pc, it indicates that the oil fume scene where the current range hood is located is a medium oil fume scene.

[0068] If the ΔP1 is greater than Pc, it indicates that the oil fume scene where the current range hood is located is a large oil fume scene.

[0069] The small oil fume scene, the medium oil fume scene and the large oil fume scene are determined according to the oil fume amount, and the values of Pb and Pc can be adaptively changed according to actual application scenes.

[0070] In the embodiment, a memory is arranged in the range hood, and a table for storing the maximum speed Vb and the minimum speed Va of the range hood in the oil fume scene where the range hood is located is pre-set in the memory, so that the maximum speed Vb and the minimum speed Va of the range hood in the oil fume scene where the range hood is located are obtained by table lookup.

[0071] Step 4, Fourier transform processing is performed on the oil fume signal values collected in the set time, and then the main frequency f of the oil fume flowing through the vortex center is obtained, and the speed V of the air flow is calculated according to K = f / V, K being a basic parameter calibrated before the range hood is shipped.

[0072] Step 5, the calculated air flow speed V is compared with the maximum speed Vb and the minimum speed Va respectively, and the fan speed is adjusted according to the comparison result.

[0073] The specific comparison process is as follows: if V is less than Va, the speed of the current fan is increased; if Va is less than or equal to V and V is less than or equal to Vb, the speed of the current fan is maintained; and if V is greater than Vb, the speed of the current fan is reduced.

[0074] Embodiment Two

[0075] As shown in Figure 7 Unlike the embodiment one, the Venturi tube 32 in the embodiment is additionally provided with a pressure sensor 4 for detecting the pressure in the Venturi tube 32, and the detection position of the pressure sensor 4 is located on the plane where the light emitted by the light emitter 311 is located.

[0076] As shown in Figure 8 Unlike the embodiment one, the control method of the range hood in the embodiment further comprises:

[0077] Before finding the maximum speed Vb and the minimum speed Va in step 3, the following steps are further included:

[0078] The pressure value detected by the pressure sensor is acquired according to the second sampling period, and the pressure values collected within the second set time are averaged to obtain the pressure average value △F1.

[0079] It is judged whether △F1 is greater than the first pressure reference threshold Fa. If yes, it is determined that the fan is running. If no, it is determined that the fan is not running, and the fan in the range hood is controlled to start to the preset gear.

[0080] In addition, if it is determined that there is no obvious oil fume or water vapor in step 2, the following steps are further included:

[0081] Step a, read the current fan running information, judge whether the current fan is running, if yes, adjust the current fan to the lowest gear, and turn to step b; if no, turn to step 1;

[0082] Step b, acquire the pressure value detected by the pressure sensor according to the second sampling period, and average the pressure values collected within the second set time to obtain the pressure average value △F1.

[0083] It is judged whether △F1 is greater than the second pressure reference threshold Fb. If yes, the fan continues to run at the current gear, and turns to step 1. If no, the fan is turned off, and turns to step 1.

[0084] The second sampling period, the first pressure reference threshold Fa and the second pressure reference threshold Fb are set values, which can be determined according to experiments or experience.

[0085] In the embodiment, through the detection of the pressure value, a more intelligent experience of cleaning the oil after cooking and then shutting down can be realized. In the above embodiment one, the delay shutdown is adopted to absorb the heat. In the embodiment, the air temperature is slightly higher and the density is slightly lower when there is residual heat in the lower cooking area, and the pressure value is less than the calibration value. Whether the temperature is reduced to the safety value is distinguished by reference to the reference value, and the intelligent experience is improved.

[0086] Directional terms as used in describing the various example structural parts and elements of the application, such as "front", "back", "up", "down", "left", "right", "side", "top", "bottom", and the like are made only for the purpose of convenience in describing the illustrations and are determined based on the example orientation of the illustrations shown in the drawings. Since the embodiments disclosed herein can be positioned in different orientations, these directional terms are used only for the purpose of description and should not be construed as limiting, such as "up", "down" are not necessarily limited to the direction opposite or consistent with the direction of gravity.

Claims

1. A range hood, comprising a housing (1) and a fan (2) disposed within the housing (1), wherein a fume parameter detector (3) is disposed within the housing (1), the fume parameter detector (3) comprising an optical signal sensor (31), characterized in that: The oil fume parameter detector (3) also includes a venturi tube (32) and a vortex generator (33) that causes the fluid to swirl. The vortex generator (33) is located inside the venturi tube (32) and adjacent to the inlet end of the venturi tube (32). The optical signal sensor (31) is located downstream of the airflow direction of the vortex generator (33). The optical signal sensor (31) includes an optical transmitter (311) and an optical receiver (312). The optical transmitter (311) and the optical receiver (312) are respectively disposed on two opposite inner wall surfaces of the venturi tube (32), and the optical receiver (312) faces the optical transmitter (311) in a direction perpendicular to the airflow direction. The Venturi tube (32) is also equipped with a pressure sensor (4) for detecting the pressure inside the Venturi tube (32). The detection position of the pressure sensor (4) is located on the plane where the light emitted by the light emitter (311) is located.

2. The range hood according to claim 1, characterized in that: The swirl generator (33) includes multiple swirl vanes (331) extending along the airflow direction. Each swirl vane (331) extends radially outward from the center and is arranged in a radial pattern. Each swirl vane (331) is arc-shaped, and all swirl vanes (331) are generally swirling clockwise or counterclockwise.

3. The range hood according to claim 1 or 2, characterized in that: The oil fume parameter detector (3) also includes a rectification module (34) for rectifying the direction of oil fume flow, the rectification module (34) being located upstream of the airflow direction of the venturi tube (32).

4. The range hood according to claim 3, characterized in that: The rectifier module (34) includes a base, in which multiple channels (341) extending along the airflow direction are opened, and the outlet of the channels (341) faces the inlet end of the venturi tube (32).

5. The range hood according to claim 3, characterized in that: The oil fume parameter detector (3) also includes a backflow eliminator (35), which is located inside the venturi tube (32) and adjacent to the outlet end of the venturi tube (32). The backflow eliminator (35) is located downstream of the optical signal sensor (31).

6. The range hood according to claim 5, characterized in that: The backflow eliminator (35) includes a plurality of grid plates (351) extending along the airflow direction. Each grid plate (351) extends radially outward from the center and is arranged in a radial pattern. A backflow elimination channel (352) is formed between two adjacent grid plates (351).

7. The range hood according to claim 6, characterized in that: The backflow eliminator (35) also includes connecting plates (353) extending along the airflow direction. Each connecting plate (353) is disposed between two adjacent grid plates (351), and each connecting plate (353) is arc-shaped. The overall cross-section formed by all connecting plates (353) is circular.

8. The range hood according to claim 5, characterized in that: The Venturi tube (32) includes a straight cylindrical structure (321) located in the middle and a flared structure (322) formed by gradually expanding the diameter from both ends of the straight cylindrical structure (321). The ends of the two flared structures (322) away from the straight cylindrical structure (321) correspond to the inlet end and the outlet end of the Venturi tube (32), respectively. The optical signal sensor (31) is located on the straight cylindrical structure (321).

9. A control method for a range hood as described in any one of claims 1 to 8, characterized in that... include: Step 1: Obtain the oil fume signal value detected by the optical signal sensor according to the first sampling period, and calculate the average value of the oil fume signal value collected within the first set time period to obtain the average value of oil fume △P1; Step 2: Determine whether △P1 is greater than the oil fume reference threshold Pa. If yes, control the fan in the range hood to start at the preset level or keep the fan running, and proceed to Step 3. If no, determine that there is no obvious oil fume or water vapor, and turn off or keep the fan off after waiting for the second set time, and proceed to Step 1. Step 3: Determine the current fume scene of the range hood based on △P1, and find the maximum speed Vb and minimum speed Va that do not escape the fume scene according to the current fume scene of the range hood. Step 4: Perform Fourier transform on the oil fume signal values ​​collected within the set time to obtain the main frequency f of the oil fume flow through the center of the vortex. Calculate the airflow velocity V according to K = f / V, where K is the basic parameter calibrated before the range hood leaves the factory. Step 5: Compare the calculated airflow velocity V with the maximum velocity Vb and the minimum velocity Va respectively, and adjust the fan speed according to the comparison results.

10. The control method according to claim 9, characterized in that: The specific process for determining the current oil fume scenario of the range hood in step 3 is as follows: Compare △P1 with the first oil fume setting value Pb and the second oil fume setting value Pc respectively, and Pb < Pc; If △P1<Pb, it means that the current range hood is in a low-smoke scenario. If Pb≤△P1≤Pc, it means that the current range hood is in a medium-level oil fume scenario. If △P1>Pc, it means that the current range hood is in a heavy oil fume scenario.

11. The control method according to claim 9, characterized in that: The specific comparison process in step 5 is as follows: If V < Va, then increase the current fan speed; If Va≤V≤Vb, then maintain the current fan speed; If V > Vb, then reduce the current fan speed.

12. The control method according to any one of claims 9 to 11, characterized in that: Before searching for the maximum speed Vb and minimum speed Va that prevents smoke from escaping in the current fume scenario according to the fume scenario of the range hood, step 3 also includes the following steps: The pressure value detected by the pressure sensor is obtained according to the second sampling period, and the average pressure value collected within the second set time is calculated to obtain the average pressure value ΔF1. Determine whether △F1 is greater than the first pressure reference threshold Fa. If so, the fan is determined to be running; otherwise, the fan is determined not to be running, and the fan in the range hood is controlled to start to the preset level.

13. The control method according to claim 12, characterized in that: If step 2 determines that there is no obvious oil fumes or water vapor, the following steps are also included: Step a: Read the current fan operation information and determine whether the fan is currently running. If yes, adjust the fan to the lowest setting and proceed to step b; otherwise, proceed to step 1. Step b: Obtain the pressure value detected by the pressure sensor according to the second sampling period, and calculate the average pressure value collected within the second set time period to obtain the average pressure value ΔF1; Determine whether ΔF1 is greater than the second pressure reference threshold Fb. If so, keep the fan running at the current speed and proceed to step 1; otherwise, turn off the fan and proceed to step 1.

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