Self-cleaning fan air duct structure of range hood and cleaning method

Abstract

The invention discloses a self-cleaning fan air duct structure of a range hood and a cleaning method, and the self-cleaning fan air duct structure comprises an air duct which is provided with a first through hole; the fan is arranged in the air duct, and the outer wall of the fan does not abut against the inner wall of the air duct; the upper edge of the fan cover is connected with the lower edge of the fan, and the lower edge of the fan cover is connected with the lower edge of the air duct inlet; the outer edge and the inner edge of the annular plate are fixedly connected with the inner wall of the air duct and the outer wall of the fan cover correspondingly, and the annular plate is located on one side of the first through hole; the collecting box is fixed to the outer wall of the air duct and located on the other side of the first through hole; and the heating equipment is arranged in the air duct and is positioned above the fan. Due to the addition of the fan cover and the annular plate, the outer wall of the fan does not abut against the inner wall of the air duct, the heated liquid oil smoke does not fall onto the fan, and the oil smoke is prevented from being thrown out of the range hood by the fan when the range hood is started next time. And the difficulty of cleaning the air duct is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of range hoods, and in particular to a self-cleaning fan duct structure of a range hood and a cleaning method. Background Art

[0002] The range hood duct, in simple terms, is the passage connecting the range hood to the outdoor space. During the cooking process in the kitchen, the fumes need to be discharged outdoors in time through this passage to keep the kitchen environment clean.

[0003] After the range hood has been used for a long time, solid oil smoke will accumulate on the inner wall of the air duct. When the accumulation reaches a certain level, it will affect the air outlet. Therefore, the air duct needs to be cleaned to remove the oil smoke on the inner wall of the air duct to ensure that the vent is unobstructed. When cleaning the air duct, the corresponding fan needs to be removed, and the maintenance personnel enter the air duct from the fan to clean it. However, due to the complicated connection and installation method of the range hood, professional maintenance personnel are required to clean it. In addition, due to the long-term accumulation of oil smoke, the cleaning time is long, which affects the user experience. Summary of the invention

[0004] In view of the above-mentioned defects, the purpose of the present invention is to provide a self-cleaning fan duct structure and cleaning method for a range hood, so as to realize automatic cleaning of the range hood duct and reduce the difficulty of cleaning the duct.

[0005] To achieve this purpose, the present invention adopts the following technical solution: A self-cleaning fan duct structure of a range hood comprises:

[0006] An air duct, wherein the air duct is provided with a first through hole;

[0007] A fan is arranged in the air duct, and the outer wall of the fan does not abut against the inner wall of the air duct;

[0008] A wind shield, wherein the upper edge of the wind shield is connected to the lower edge of the fan, and the lower edge of the wind shield is connected to the lower edge of the air duct inlet;

[0009] an annular plate, the outer edge and the inner edge of the annular plate are respectively fixedly connected to the inner wall of the air duct and the outer wall of the air cover, and the annular plate is located on one side of the first through hole;

[0010] A collection box is fixed to the outer wall of the air duct, and the collection box is located on the other side of the first through hole;

[0011] The heating device is arranged in the air duct and located above the fan.

[0012] Preferably, it further comprises a camera and a light tube, wherein the light tube and the camera are arranged at the same horizontal position in the air duct and above the heating device, and the distance from the camera to the heating device is equal to the distance from the heating device to the wind shield;

[0013] It also includes an image processing module, which is electrically connected to the camera, the light tube, the heating device and the fan.

[0014] Preferably, the annular plate is arranged to be inclined, and the first through hole is located on the side of the lowest horizontal position of the inclined annular plate.

[0015] Preferably, the air duct is further provided with a second through hole, the second through hole is located on one side of the highest horizontal position of the inclination of the annular plate, and a baffle is hinged on the other side of the second through hole.

[0016] Preferably, the collection box comprises a collection portion and a connection portion, wherein the connection portion is arranged above the collection portion, and the connection portion is fixedly connected to the outer wall of the air duct by bolts;

[0017] The top of the collecting portion is flush with or lower than the first through hole.

[0018] A method for cleaning a self-cleaning fan duct of a range hood, using the self-cleaning fan duct structure of the range hood, comprises the following steps:

[0019] Set the self-test cycle;

[0020] When the self-check cycle is reached, the camera and the light tube are started to obtain the image inside the air duct;

[0021] Processing the image to obtain grayscale parameters in the image, and setting a start-up time of the heating device based on the grayscale parameters and a preset grayscale value;

[0022] The heating device is started, and after the start-up time is reached, the heating device is turned off.

[0023] Preferably, based on the grayscale parameter and the preset grayscale value, the steps of setting the start-up time of the heating device are as follows:

[0024] The image is divided into a plurality of regional images according to a preset ratio, and the median of the grayscale value in each regional image is counted, and the median is used as the grayscale parameter of the regional image;

[0025] Obtaining the highest value of the grayscale parameter in the regional image, determining whether the highest value of the grayscale parameter is greater than a first preset grayscale value, and if it is less than or equal to the first preset grayscale value, not starting the heating device;

[0026] If it is greater than the first preset grayscale value, then determine whether the highest value of the grayscale parameter is greater than the second preset grayscale value; if it is less than the second preset grayscale value, then use the minimum preset time as the startup duration;

[0027] If it is greater than the second preset grayscale value, a spare grayscale parameter is obtained by subtracting the third preset grayscale value from the highest value of the grayscale parameter, and the number of regional screens whose grayscale parameters are greater than the spare grayscale parameter is counted, and it is determined whether the number of regional screens is greater than the number threshold. If it is greater than the number threshold, the startup duration is obtained according to the highest value of the grayscale parameter;

[0028] If it is less than the quantity threshold, the startup duration is obtained according to the second highest value of the grayscale parameter or the third highest value of the intensity parameter.

[0029] Preferably, the steps of obtaining the startup duration according to the maximum value of the grayscale parameter are as follows:

[0030] The thickness of oil smoke in the image is obtained based on the linear relationship between the gray value and the thickness of oil smoke;

[0031] Estimate the quality of the oil smoke in the image through the thickness and density of the oil smoke;

[0032] Get the set heating temperature of the heating device and the distance from the heating device to the camera;

[0033] The startup duration is calculated based on the oil fume mass, heating temperature and distance.

[0034] Preferably, the startup duration calculation formula is as follows:

[0035] Where m is the mass of oil smoke in the area, c is the specific heat of oil smoke, k is the thermal conductivity of air, s is the area of ​​one unit length of the air duct, T me is the melting temperature of oil smoke, T in is the initial temperature in the duct, T he is the heating temperature, T sm is the temperature change in the air duct after the heating equipment is started per unit time, and D is the distance.

[0036] One of the above technical solutions has the following advantages or beneficial effects: the present invention can realize simple cleaning of oil smoke in the air duct by installing a heating device and an annular plate in the air duct, and at the same time, due to the addition of the wind cover and the annular plate, the outer wall of the fan does not collide with the inner wall of the air duct, and the heated liquid oil smoke does not fall onto the fan, so that the fan is prevented from throwing the oil smoke out of the range hood when it is started next time. The difficulty of cleaning the air duct is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1It is a cross-sectional view of an embodiment of the air duct structure of the present invention.

[0038] Figure 2 yes Figure 1 Enlarged view of point A in the middle.

[0039] Figure 3 yes Figure 1 Enlarged view of point B in the middle.

[0040] Figure 4 is a flow chart of an embodiment of the method of the present invention.

[0041] Among them: air duct 1, fan 2, wind cover 3, annular plate 4, collecting box 5, connecting part 5a, collecting part 5b, heating device 6, camera 7, light tube 8, first through hole 9, baffle 10. DETAILED DESCRIPTION

[0042] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0043] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] like Figures 1 to 4 As shown, a self-cleaning fan duct structure of a range hood includes:

[0046] An air duct (1), wherein the air duct (1) is provided with a first through hole (9);

[0047] The fan (2) is arranged in the air duct (1), and the outer wall of the fan (2) does not abut against the inner wall of the air duct (1);

[0048] A wind shield (3), wherein the upper edge of the wind shield (3) is connected to the lower edge of the fan (2), and the lower edge of the wind shield (3) is connected to the lower edge of the entrance of the air duct (1);

[0049] an annular plate (4), the outer edge and the inner edge of the annular plate (4) being respectively fixedly connected to the inner wall of the air duct (1) and the outer wall of the air cover (3), and the annular plate (4) being located on one side of the first through hole (9);

[0050] A collection box (5) is fixed to the outer wall of the air duct (1), and the collection box (5) is located on the other side of the first through hole (9);

[0051] The heating device (6) is arranged in the air duct (1) and is located above the fan (2).

[0052] In order to reduce the difficulty of cleaning the air duct (1) and realize the self-cleaning function of the air duct (1), in the present invention, a wind cover (3) is arranged between the fan (2) and the air duct (1). At the same time, a heating device (6) is installed in the air duct (1). By remotely controlling the workpiece to issue a start command to the heating device (6), the heating device (6) can heat the air duct (1) to heat the solid oil smoke and turn it into a liquid form. At this time, the liquid oil smoke will flow downward along the inner wall of the air duct (1) due to gravity, and then stay on the annular plate (4) above the wind cover (3). The air duct (1) is provided with a first through hole (9) on one side of the annular plate (4), and a collection box (5) is arranged on the other side of the first through hole (9). When the liquid oil smoke accumulates on the annular plate (4) to a certain extent, it will flow into the collection box (5) from the first through hole (9), so as to realize the cleaning of the oil smoke in the air duct (1) and the collection of the cleaned oil smoke.

[0053] The present invention can achieve simple cleaning of the oil smoke in the air duct (1) by installing a heating device (6) and an annular plate (4) in the air duct (1). At the same time, due to the addition of the wind cover (3) and the annular plate (4), the outer wall of the fan (2) does not collide with the inner wall of the air duct (1), and the heated liquid oil smoke will not fall onto the fan (2), thereby preventing the fan (2) from throwing the oil smoke out of the range hood when it is started next time. The difficulty of cleaning the air duct (1) is greatly reduced.

[0054] It is worth mentioning that the heating device (6) can be a heating wire.

[0055] Preferably, it further comprises a camera (7) and a light tube (8), wherein the light tube (8) and the camera (7) are arranged at the same horizontal position in the air duct (1) and are located above the heating device (6), and the distance between the camera (7) and the heating device (6) is equal to the distance between the heating device (6) and the wind shield (3);

[0056] It also includes an image processing module, which is electrically connected to the camera (7), the light tube (8), the heating device (6) and the fan (2).

[0057] In order to realize the automatic cleaning function, the present invention further provides an external image processing module, which can collect images captured by the camera (7) and determine the extent to which the oil smoke accumulation in the air duct (1) needs to be cleaned by means of image recognition. Since the internal environment of the air duct (1) is relatively dark, the present invention further provides a lamp tube (8), which can increase the brightness in the air duct (1) when shooting, thereby making the image captured by the camera (7) clearer.

[0058] In order to prevent the heating device (6) from affecting the normal operation of the camera (7), the camera (7) needs to be arranged above the heating device (6). When the heating device (6) is heating, it determines the heating time according to the image captured by the camera (7), so that the oil smoke at the location captured by the camera (7) can be dissolved and dripped. When the distance from the camera (7) to the heating device (6) is equal to the distance from the heating device (6) to the wind cover (3), it can ensure that the oil smoke under the air duct (1) can also be dissolved, thereby ensuring the cleanliness of the air duct (1).

[0059] Preferably, the annular plate (4) is arranged to be inclined, and the first through hole (9) is located on the side of the lowest horizontal position of the inclination of the annular plate (4).

[0060] like Figure 1 As shown, after the annular plate (4) is tilted, the oil smoke dripping on the annular plate (4) can gradually slide down to the side of the lowest horizontal position of the annular plate (4) along the tilted direction, thereby better collecting the oil smoke.

[0061] Preferably, the air duct (1) is further provided with a second through hole, the second through hole being located on one side of the highest horizontal position of the inclination of the annular plate (4), and a baffle (10) being hingedly connected to the other side of the second through hole.

[0062] Although the oil smoke will flow out of the first through hole (9) along the inclination direction of the annular plate (4), the oil smoke has a certain viscosity and is easy to adhere to the annular plate (4) when the temperature drops. Long-term use will cause the oil smoke to accumulate on the annular plate (4). This affects the subsequent movement of the oil smoke on its surface. In order to solve this problem, the invention provides a second through hole on the side of the highest horizontal position of the inclination of the annular plate (4). When cleaning the annular plate (4), the baffle (10) can be opened to expose the second through hole, and hot water and an active agent can be poured into the second through hole to allow the oil smoke to be detached from the attachment of the annular plate (4). Then, the oil smoke flows from the first through hole (9) into the collection box (5). The cleaning of the annular plate (4) is simply completed.

[0063] Preferably, the collection box (5) comprises a collection portion (5b) and a connection portion (5a), wherein the connection portion (5a) is arranged above the collection portion (5b), and the connection portion (5a) is fixedly connected to the outer wall of the air duct (1) by means of bolts;

[0064] The top of the collecting portion (5b) is flush with the first through hole (9) or lower than the first through hole (9).

[0065] In the present invention, the collection box (5) is simply and quickly installed by means of bolts, which is convenient for users to disassemble. Moreover, the bolts have a certain strength and can support the collection part (5b) carrying the oil smoke, so that the collection box (5) can be firmly installed on the outer wall of the air duct (1) without falling off.

[0066] A method for cleaning a self-cleaning fan duct of a range hood, using the self-cleaning fan duct structure of the range hood, comprises the following steps:

[0067] Set the self-test cycle;

[0068] When the self-check cycle is reached, the camera and the light tube are started to obtain the image inside the air duct;

[0069] Processing the image to obtain grayscale parameters in the image, and setting a start-up time of the heating device based on the grayscale parameters and a preset grayscale value;

[0070] The heating device is started, and after the start-up time is reached, the heating device is turned off.

[0071] In the present invention, the heating device is a constant temperature electric heating wire. Before self-cleaning, a self-check cycle can be set to the image processing module. When the self-check cycle time is reached, the camera and the lamp are started to shoot and obtain the image in the air duct. Since the camera is set in the air duct, the oil smoke will also adhere to the camera, which will affect the grayscale value presented by the image. Therefore, the attachment thickness of the oil smoke can be roughly estimated by the grayscale value presented by the image, and the constant temperature heating device can heat and dissolve the oil smoke in a certain period of time, so that the startup time of the constant temperature electric heating wire can be determined by the grayscale parameter. After the startup time is reached, the heating device can be turned off to achieve self-cleaning of the air duct.

[0072] Preferably, based on the grayscale parameter and the preset grayscale value, the steps of setting the start-up time of the heating device are as follows:

[0073] The image is divided into a plurality of regional images according to a preset ratio, and the median of the grayscale value in each regional image is counted, and the median is used as the grayscale parameter of the regional image;

[0074] Obtaining the highest value of the grayscale parameter in the regional image, determining whether the highest value of the grayscale parameter is greater than a first preset grayscale value, and if it is less than or equal to the first preset grayscale value, not starting the heating device;

[0075] If it is greater than the first preset grayscale value, then determine whether the highest value of the grayscale parameter is greater than the second preset grayscale value; if it is less than the second preset grayscale value, then use the minimum preset time as the startup duration;

[0076] If it is greater than the second preset grayscale value, a spare grayscale parameter is obtained by subtracting the third preset grayscale value from the highest value of the grayscale parameter, and the number of regional screens whose grayscale parameters are greater than the spare grayscale parameter is counted, and it is determined whether the number of regional screens is greater than the number threshold. If it is greater than the number threshold, the startup duration is obtained according to the highest value of the grayscale parameter;

[0077] If it is less than the quantity threshold, the startup duration is obtained according to the second highest value of the grayscale parameter or the third highest value of the intensity parameter.

[0078] In the present invention, the image is divided into a pair of regional images. It is convenient to process multiple regional images concurrently and improve the calculation speed. Then the median of the grayscale value of each image area is counted. The median grayscale value is a robust statistic that can better reflect the overall brightness level of the regional image and is not easily affected by extreme values ​​(such as dust). The grayscale parameters of the regional image can effectively reflect the thickness of the oil smoke.

[0079] When the highest value of the grayscale parameter is greater than the first preset grayscale value, it means that there is no oil smoke attached in the air duct, and there is no need to start the heating equipment for cleaning. When it is greater than the first preset grayscale value, it will be judged whether it is greater than the second preset grayscale value, where the second preset grayscale value is greater than the first preset grayscale value. If it is not greater than, it means that the amount of oil smoke attached is small. At this time, due to the small grayscale parameter, it is difficult to convert it into the corresponding oil smoke thickness, so the minimum preset time is used as the startup time. When the highest value of the grayscale parameter is greater than the second preset grayscale value, it is necessary to go back to the spare grayscale parameter, and then the number of regional screens with grayscale parameters greater than the spare grayscale parameter will be obtained. The number of regional screens determines which grayscale parameter to use to calculate the startup time. Because in addition to oil smoke attached to the inside of the air duct, there is also a small amount of dust attached to the oil smoke. At this time, the grayscale value of the dust after image processing is higher than the grayscale value of the oil smoke. If the highest value of the grayscale parameter is directly used to obtain the startup time, it is possible that the dust is used as the thickness of the oil smoke, which will extend the startup time and cause a waste of electric energy. Therefore, it is necessary to determine whether the highest value of the grayscale parameter is caused by dust by the number of regional images. The third preset grayscale value is less than the first preset grayscale value. The spare grayscale parameter is obtained by subtracting the third preset grayscale value from the highest value of the grayscale parameter. The spare grayscale parameter is a range value close to the highest value of the grayscale parameter. When the number of regional images is greater than the number threshold, it means that most of the grayscale parameters in the image are close to the highest value of the grayscale parameter. At this time, it can be considered that the highest value of the grayscale parameter is the grayscale parameter obtained by the attachment of oil smoke. At this time, it is necessary to determine the startup time by the highest value of the grayscale parameter. When the number of regional images is less than the number threshold, there are fewer regional images close to the highest value of the grayscale parameter at this time. It can be considered that the highest value of the grayscale parameter is the grayscale parameter obtained by the attachment of dust. In order to reduce the startup time, the startup time can be obtained by the second highest value of the grayscale parameter or the third highest value of the grayscale parameter. Of course, if the user feels that he uses the kitchen to cook more frequently, he can use the second highest value of the grayscale parameter to obtain the startup time, and if the kitchen is used less frequently for cooking, the third highest value of the grayscale parameter can be used to obtain the startup time.

[0080] Preferably, the steps of obtaining the startup duration according to the maximum value of the grayscale parameter are as follows:

[0081] The thickness of oil smoke in the image is obtained based on the linear relationship between the gray value and the thickness of oil smoke;

[0082] Estimate the quality of the oil smoke in the image through the thickness and density of the oil smoke;

[0083] Get the set heating temperature of the heating device and the distance from the heating device to the camera;

[0084] The startup duration is calculated based on the oil fume mass, heating temperature and distance.

[0085] Since the change in grayscale value is caused by the oil smoke adhering to the camera, there is a linear relationship between the thickness of the oil smoke and the change in grayscale. Therefore, different grayscale values ​​and the thickness of the oil smoke adhesion can be obtained in the simulated light and dark environment in the air duct, so as to obtain the corresponding linear relationship. Then, the thickness of the oil smoke in the image can be obtained by calculating the linear relationship and the highest value of the grayscale parameter. The corresponding volume of the oil smoke can be determined by the thickness of the oil smoke and the size of the image, and the quality of the oil smoke in the image can be known by the volume of the oil smoke and its density. The image is obtained by shooting horizontally with the camera, so if the oil smoke needs to be dissolved, it is necessary to consider the distance from the heating equipment to the camera and the heat conduction of the air at this distance. The parameters such as the oil smoke quality, heating temperature and distance can be used to accurately calculate the time for the oil smoke to dissolve, and this time is used as the startup time to avoid unnecessary energy waste, thereby achieving the goal of efficient energy saving.

[0086] Preferably, the startup duration calculation formula is as follows:

[0087] Where m is the mass of oil smoke in the area, c is the specific heat of oil smoke, k is the thermal conductivity of air, s is the area of ​​one unit length of the air duct, T me is the melting temperature of oil smoke, T in is the initial temperature in the duct, T he is the heating temperature, T sm is the temperature change in the air duct after the heating equipment is started per unit time, and D is the distance.

[0088] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0089] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A self-cleaning fan duct structure for a range hood, characterized in that: include: An air duct, wherein the air duct is provided with a first through hole; A fan is arranged in the air duct, and the outer wall of the fan does not abut against the inner wall of the air duct; A wind shield, wherein the upper edge of the wind shield is connected to the lower edge of the fan, and the lower edge of the wind shield is connected to the lower edge of the air duct inlet; an annular plate, the outer edge and the inner edge of the annular plate are respectively fixedly connected to the inner wall of the air duct and the outer wall of the air cover, and the annular plate is located on one side of the first through hole; A collection box is fixed to the outer wall of the air duct, and the collection box is located on the other side of the first through hole; The heating device is arranged in the air duct and located above the fan.

2. The self-cleaning fan duct structure of a range hood according to claim 1, characterized in that: It also includes a camera and a light tube, wherein the light tube and the camera are arranged at the same horizontal position in the air duct and above the heating device, and the distance from the camera to the heating device is equal to the distance from the heating device to the wind shield; It also includes an image processing module, which is electrically connected to the camera, the light tube, the heating device and the fan.

3. The self-cleaning fan duct structure of a range hood according to claim 1, characterized in that: The annular plate is arranged tilted, and the first through hole is located on the side of the lowest horizontal position of the tilted annular plate.

4. The self-cleaning fan duct structure of a range hood according to claim 3, characterized in that: The air duct is further provided with a second through hole, which is located on one side of the highest horizontal position of the inclination of the annular plate, and a baffle is hinged on the other side of the second through hole.

5. The self-cleaning fan duct structure of a range hood according to claim 1, characterized in that: The collection box comprises a collection portion and a connection portion, wherein the connection portion is arranged above the collection portion and is fixedly connected to the outer wall of the air duct by bolts; The top of the collecting portion is flush with or lower than the first through hole.

6. A method for cleaning a self-cleaning fan duct of a range hood, using a self-cleaning fan duct structure of a range hood according to any one of claims 1 to 5, characterized in that: The steps include: Set the self-test cycle; When the self-check cycle is reached, the camera and the light tube are started to obtain the image inside the air duct; Processing the image to obtain grayscale parameters in the image, and setting a start-up time of the heating device based on the grayscale parameters and a preset grayscale value; The heating device is started, and after the start-up time is reached, the heating device is turned off.

7. A method for cleaning a self-cleaning fan duct of a range hood according to claim 6, characterized in that: Based on the grayscale parameters and the preset grayscale value, the steps for setting the start-up time of the heating device are as follows: The image is divided into a plurality of regional images according to a preset ratio, and the median of the grayscale value in each regional image is counted, and the median is used as the grayscale parameter of the regional image; Obtaining the highest value of the grayscale parameter in the regional image, determining whether the highest value of the grayscale parameter is greater than a first preset grayscale value, and if it is less than or equal to the first preset grayscale value, not starting the heating device; If it is greater than the first preset grayscale value, then determine whether the highest value of the grayscale parameter is greater than the second preset grayscale value; if it is less than the second preset grayscale value, then use the minimum preset time as the startup duration; If it is greater than the second preset grayscale value, a spare grayscale parameter is obtained by subtracting the third preset grayscale value from the highest value of the grayscale parameter, and the number of regional screens whose grayscale parameters are greater than the spare grayscale parameter is counted, and it is determined whether the number of regional screens is greater than the number threshold. If it is greater than the number threshold, the startup duration is obtained according to the highest value of the grayscale parameter; If it is less than the quantity threshold, the startup duration is obtained according to the second highest value of the grayscale parameter or the third highest value of the degree parameter.

8. The method for cleaning the self-cleaning fan duct of a range hood according to claim 7, characterized in that: The steps to obtain the startup duration based on the highest value of the grayscale parameter are as follows: The thickness of oil smoke in the image is obtained based on the linear relationship between the gray value and the thickness of oil smoke; Estimate the quality of the oil smoke in the image through the thickness and density of the oil smoke; Get the set heating temperature of the heating device and the distance from the heating device to the camera; The startup duration is calculated based on the oil fume mass, heating temperature and distance.

9. A method for cleaning a self-cleaning fan duct of a range hood according to claim 8, characterized in that: The startup duration calculation formula is as follows: Where m is the mass of oil smoke in the area, c is the specific heat of oil smoke, k is the thermal conductivity of air, s is the area of ​​one unit length of the air duct, T me is the melting temperature of oil smoke, T in is the initial temperature in the duct, T he is the heating temperature, T sm is the temperature change in the air duct after the heating equipment is started per unit time, and D is the distance.

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