Air sensor mounting structure, range hood and control method of range hood

Abstract

The invention discloses an air sensor mounting structure, a range hood and a control method thereof, the air quality sensor mounting structure comprises a shell and an air quality sensor mounted in the shell, the shell is provided with an airflow channel communicating the interior and the exterior of the shell, a detection cavity is formed in the shell, and a cantilever beam is mounted in the detection cavity; the air quality sensor is installed at the end of the cantilever beam, the airflow channel is obliquely arranged downwards from inside to outside, the caliber of the airflow channel is gradually increased from inside to outside, and the air quality sensor is installed on a machine shell of the range hood. According to the range hood, the air quality sensor is installed on the cantilever beam with the specific inherent frequency, resonance is excited when the vibration frequency of the draught fan is matched with the inherent frequency of the cantilever beam by means of broadband vibration energy generated when the draught fan of the range hood operates, and the sensor generates high-frequency micro-amplitude vibration; passive mechanical stripping of oil stains on the surface of the sensor is realized, and the problems of inaccurate detection and shortened service life caused by oil stain attachment of a traditional sensor are solved.

Description

Technical Field

[0001] This invention relates to an oil fume purification device, and more particularly to an air sensor mounting structure, an oil fume extractor, and a control method thereof. Background Technology

[0002] With the continuous improvement of residents' living standards and the deepening of health consumption concepts, the potential impact of air quality in the kitchen, as the core area of ​​daily family activities, on human health has become a focus of social attention. Cooking fumes not only contain particulate matter (such as PM2.5), but also a large amount of total volatile organic compounds (TVOC) and irritating odors. Long-term exposure can damage the respiratory system and skin health, and even increase the risk of chronic diseases. Against this backdrop, the functional requirements of range hoods, as the core appliance for kitchen fume purification, have evolved from the traditional simple extraction of fumes to monitoring and proactively regulating the health environment.

[0003] To meet users' demands for a healthy kitchen environment, some range hoods on the market are now integrating air quality monitoring functions, such as "air management" systems. These systems use built-in sensors to monitor PM2.5, TVOC concentrations, and odor levels in the kitchen environment in real time, and automatically adjust the range hood's operating settings (such as airflow and fan speed) based on the monitoring data, achieving a dynamic response of purification as pollution occurs, thereby creating a healthier and more comfortable cooking environment. However, after long-term market application and technical verification, it has been found that existing range hoods with air quality detection functions still have many shortcomings in terms of technical implementation, resulting in monitoring accuracy, equipment stability, and user experience that fail to meet actual needs. Specific problems are as follows:

[0004] Firstly, the sensor installation layout is poorly designed, resulting in poor resistance to oil stains and a short lifespan. Currently, manufacturers generally place air quality monitoring sensors (such as PM2.5 and TVOC sensors) on the front panel of the range hood or near the air inlet. While this layout can shorten the distance between the sensor and the cooking area to some extent, theoretically allowing for rapid detection of pollutant concentration changes, the front panel and air inlet area are high-frequency areas for oil stain adhesion. Oil mist and smoke particles generated during cooking will directly deposit on the sensor surface, forming an oil stain layer. This problem leads to a significant decrease in sensor detection accuracy, and may even cause sensor failure. Simultaneously, oil stain corrosion will drastically shorten the sensor's lifespan, requiring users to frequently disassemble and replace sensors to maintain normal equipment function, increasing long-term operating costs.

[0005] Secondly, the single-point measurement mode of the sensor has sensitivity limitations, and the accompanying solution has additional drawbacks. Due to the significant uneven distribution of pollutants (such as cooking fumes and TVOCs) in the kitchen (e.g., high concentrations near the stove and low concentrations further away), the single-point sensor measurement method used in existing range hoods cannot comprehensively and accurately reflect the overall air quality of the kitchen, leading to data deviations and affecting the accuracy of the range hood's speed adjustment. To improve the measurement sensitivity of the single-point sensor, some manufacturers have attempted to add a small fan near the sensor, using the fan to guide the surrounding airflow and promote the mixing of pollutants in the area around the sensor, thereby improving detection sensitivity. However, this solution brings new problems: on the one hand, the operation of the additional fan increases the overall energy consumption of the range hood, contradicting the current industry trend of energy-saving appliances; on the other hand, the fan blades also accumulate grease during operation, requiring regular cleaning and maintenance, and may even cause fan malfunctions due to grease buildup, increasing the equipment's repair rate and further increasing the user's operating costs and maintenance burden. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide an air quality sensor mounting structure with strong resistance to oil pollution interference, in light of the above-mentioned existing technology.

[0007] The second technical problem to be solved by the present invention is to provide a range hood that can achieve sensor self-cleaning and high sensor detection accuracy, in light of the above-mentioned existing technology.

[0008] The third technical problem to be solved by the present invention is to provide a control method for the above-mentioned range hood, in view of the current state of the prior art.

[0009] The technical solution adopted by the present invention to solve the first technical problem mentioned above is as follows: an air quality sensor mounting structure, including a housing and an air quality sensor installed inside the housing, wherein the housing has an airflow channel connecting the inside of the housing and the outside, characterized in that: a detection cavity is formed inside the housing, a cantilever beam is installed inside the detection cavity, the air quality sensor is installed at the end of the cantilever beam, the airflow channel is arranged obliquely downward from the inside to the outside, and the diameter of the airflow channel gradually increases from the inside to the outside.

[0010] To prevent oil fumes from contaminating the air quality sensor, a protective grille is installed on the side of the housing, and the airflow channel is formed on the protective grille. The cantilever beam is installed on the inner side wall of the housing opposite to the protective grille.

[0011] Further preferably, the cantilever beam is horizontally positioned, and the outer diameter of the air quality sensor probe is larger than the outer diameter of the cantilever beam. This configuration can induce a vortex street similar to Karman's, enhancing local turbulence intensity and further improving gas mixing uniformity, thus increasing the effectiveness of the detection method.

[0012] The tilt angle and guide convergence angle of the airflow channel can have multiple different ranges. Preferably, the tilt angle α of the airflow channel relative to the horizontal plane is 15°≤α≤60°, and the guide convergence angle θ of the airflow channel is 3°≤α≤15°. This configuration allows gas to diffuse through the airflow channel into the housing, preventing large oil droplets from directly impacting the sensor, and guiding external airflow to accelerate through the airflow channel. It also allows the walls of the airflow channel to intercept large oil particles.

[0013] Further optimization is that the spacing between adjacent airflow channels is 1-2 mm.

[0014] The technical solution adopted by the present invention to solve the second technical problem mentioned above is as follows: a range hood, including a housing, a range hood fan installed inside the housing, an air quality sensor installed on the housing, and the air quality sensor connected to the outside of the housing through the airflow channel.

[0015] The air quality sensor can be installed in multiple different locations. Preferably, the housing includes an upper box and a lower box. The fume extractor is installed inside the upper box. A sensor mounting cavity is opened on the left or right side wall of the lower box. The outer shell of the air quality sensor mounting structure is located inside the sensor mounting cavity.

[0016] The technical solution adopted by the present invention to solve the third technical problem mentioned above is: a control method for a range hood, characterized by comprising the following steps:

[0017] S1. Turn on the range hood;

[0018] S2, Air quality sensor self-test;

[0019] S3. Determine if the detection cycle has exceeded the time since the last detection;

[0020] If so, the sensor oil accumulation detection and removal subprocess is triggered;

[0021] If not, monitor the background air quality and proceed to step S4;

[0022] S4. Determine if there is a sudden increase in air pollutant levels;

[0023] If so, then actively initiate ventilation and proceed to step S5;

[0024] If not, check if the range hood is running. If it is running, increase the fan speed. If it is not running, switch to sleep mode.

[0025] S5. Control the air volume of the range hood;

[0026] S6. Determine whether the pollutant concentration change rate dc / dt > R1 is true; R1 is the concentration change rate threshold.

[0027] If so, increase the airflow level and proceed to step S7;

[0028] If not, reduce the fan speed and proceed to step S7.

[0029] S7. Continuously monitor the rate of change of pollutant concentration until dc / dt ≤ R1;

[0030] S8, Return to background air monitoring.

[0031] Further preferably, the sensor oil accumulation detection and removal sub-process includes the following steps:

[0032] S301, Air quality sensor initialization;

[0033] S302. Determine if the range hood is running;

[0034] If so, proceed to step S303;

[0035] If not, then enter hibernation mode;

[0036] S303. Determine whether the detection cycle has exceeded the time since the last detection;

[0037] If so, the range hood will be set to the detection gear and the process will proceed to step S304;

[0038] If not, the range hood will operate at the preset normal setting;

[0039] S304. Real-time monitoring of vibration signals;

[0040] S305. Calculate the current dominant vibration frequency f_v of the sensor;

[0041] S306. Determine whether f_v is within the range of f_n±2hz;

[0042] If so, the cleaning time continues for T_c1, and then proceeds to step S307;

[0043] If not, then switch the range hood to the normal setting;

[0044] S307. Calculate the dominant vibration frequency f_v of the sensor after cleaning;

[0045] S308. Determine whether f_v is no longer within the range of f_n±2hz;

[0046] If so, the cleaning is deemed effective, and the process proceeds to step S310;

[0047] If not, an abnormal alarm is triggered, and the sensor is continuously cleaned for a period of time T_c2, then proceed to step S309.

[0048] S309. Has the alarm been cleared?

[0049] If so, proceed to step S310;

[0050] If not, then report a sensor maintenance request;

[0051] S310, switch the range hood to normal setting.

[0052] Further optimization is made in step S306, where the continuous cleaning time T_c1 ≥ 30s, and in step S308, where the continuous cleaning time T_c2 ≥ 60s.

[0053] Compared with existing designs, the advantages of this invention are as follows: This range hood installs an air quality sensor on a miniature elastic cantilever beam with a specific natural frequency. It utilizes the broadband vibration energy generated by the range hood fan during operation. When the fan's vibration frequency matches the natural frequency of the cantilever beam, resonance is excited, causing the sensor to generate high-frequency micro-amplitude vibrations. This achieves passive mechanical peeling of oil stains from the sensor surface, solving the problems of inaccurate detection and shortened lifespan caused by oil stains in traditional sensors. Furthermore, the inclined airflow channel and the sensor that swings with the cantilever beam can form a vortex-like turbulence generator, transforming simple harmonic vibrations into three-dimensional swirling flow to enhance air mixing and improve detection sensitivity. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the installation structure of a range hood according to an embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram illustrating a usage scenario of the range hood according to an embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of the air quality sensor installation structure according to an embodiment of the present invention;

[0057] Figure 4 This is a schematic diagram of the airflow around the air quality sensor according to an embodiment of the present invention;

[0058] Figure 5 This is a schematic diagram illustrating the principle of improving the detection accuracy of the air quality sensor according to an embodiment of the present invention;

[0059] Figure 6This is a schematic diagram of an air quality detection system according to an embodiment of the present invention;

[0060] Figure 7 This is a flowchart illustrating the control method according to an embodiment of the present invention;

[0061] Figure 8 This is a schematic diagram of the sensor oil accumulation detection and removal sub-process in an embodiment of the present invention. Detailed Implementation

[0062] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0063] like Figure 1 and Figure 2 As shown, the range hood in this embodiment includes a housing 7, which comprises an upper housing 71 and a lower housing 72. A range hood fan 8 is installed inside the upper housing 71. A sensor mounting cavity 9 is formed on the left side wall of the lower housing 72, and an air quality sensor 2 is installed inside the sensor mounting cavity 9. Alternatively, the air quality sensor 2 can also be installed on the right side wall of the lower housing 72. The air quality sensor 2 can detect the concentration of pollutants (such as cooking fumes and TVOCs) near the sensor mounting cavity 9.

[0064] like Figure 3 and Figure 4 As shown, the air quality sensor mounting structure of this embodiment includes a housing 1 and an air quality sensor 2 installed inside the housing 1. A detection cavity 6 is formed inside the housing 1. The housing 1 is located inside the sensor mounting cavity 9. An airflow channel 3 is opened on the housing 1 to connect the inside and outside of the housing 1. A cantilever beam 4 is installed inside the housing 1. The cantilever beam 4 has micro-elasticity and is horizontally arranged. The air quality sensor 2 is installed at the end of the cantilever beam 4. The outer diameter of the probe of the air quality sensor 2 is larger than the outer diameter of the cantilever beam 4. The airflow channel 3 is arranged obliquely downward from the inside to the outside, and the diameter of the airflow channel 3 gradually increases from the inside to the outside. The air quality sensor 2 is connected to the outside of the housing 7 through the airflow channel 3.

[0065] like Figure 5 As shown, the working principle of the above-mentioned air quality sensor mounting structure is to install the air quality sensor 2 on a cantilever beam 4 with a specific natural frequency. By utilizing the broadband vibration energy generated by the range hood fan 7 during operation, resonance is excited when the fan vibration frequency matches the natural frequency of the cantilever beam, causing the probe of the air quality sensor 2 to generate high-frequency micro-amplitude vibration (such as amplitude 0.05-0.1mm). This achieves passive mechanical peeling of oil stains from the probe surface of the air quality sensor 2, solving the problems of detection inaccuracy and shortened lifespan caused by oil stains in traditional sensors.

[0066] Even in the normal operating mode of the fan, the cantilever beam 4 will vibrate slightly, which can create an unsteady flow field around the probe, producing a "micro-piston pump" effect. That is, the reciprocating motion of the probe compresses the surrounding air, generating local pressure fluctuations, ΔP=ρ·(2πfA). 2 Where is the air density, f is the vibration frequency, and A is the amplitude, which is equivalent to forming a micro-positive-negative pressure alternating field on the probe surface to assist in driving the gas into the airflow channel 3.

[0067] A protective grille 5 is installed on the side of the outer casing 1. The grille holes on the protective grille 5 form airflow channels 3, and the spacing between adjacent airflow channels 3 is 1-2 mm. A cantilever beam 4 is installed on the inner side wall of the casing opposite to the protective grille 5. The inclination angle α of the airflow channel 3 relative to the horizontal plane is 15°≤α≤60°. The airflow channel 3 adopts the above-mentioned inclined grille hole structure, that is, the outward and downward deflection hole. On the one hand, it can prevent large oil stains from entering. On the other hand, when the airflow is inclined to the outside, it is easier to couple with the vortex generated by vibration. Furthermore, when the airflow is guided to encounter the sensor probe, since the probe size is larger than the cantilever beam size, a Karman vortex street-like phenomenon will be excited near the probe, which will enhance the local turbulence intensity, generate a turbine-induced effect, and further enhance the gas mixing uniformity, thus improving the effectiveness of detection and solving the problem that the air quality of the sampling point of other ordinary gas sensors may not be uniform with the surrounding air.

[0068] Furthermore, this embodiment achieves optimized directional airflow guidance structure. In this embodiment, the guide convergence angle θ of the flow channel 3 is 3°≤θ≤15°, where θ is the difference between the inclination angle of the lower wall of the airflow channel 2 relative to the horizontal plane and the inclination angle of the upper wall relative to the horizontal plane. In this embodiment, the inclination angle of the lower wall relative to the horizontal plane is greater than that of the upper wall relative to the horizontal plane. The inclination angle α of the airflow channel refers to the inclination angle of the lower wall of the airflow channel 3 relative to the horizontal plane. By adopting the guide convergence angle θ, the airflow can be guided, and the convergence channel naturally has an airflow acceleration effect, which increases the airflow velocity entering the outer shell 1 and makes it easier to induce vortex flow inside the detection cavity 6.

[0069] The formula for calculating turbulence intensity is as follows:

[0070]

[0071] Where u′, v′, w′ are velocity pulsations. The vibration scheme greatly increases the turbulence intensity due to the superposition of high-frequency disturbances and eddies, while fans generally increase the wind speed in one direction. In order to improve efficiency and reduce noise, they often pursue the reduction of turbulence intensity.

[0072] The resonance principle of sensor contamination level detection:

[0073] The resonance point is used to detect oil accumulation in the sensor. When the dirt accumulates to a certain extent (oil mass accumulation m), the level of dirt accumulation is determined. aOnce the threshold is reached, the designed trigger frequency matches the current dominant vibration frequency, automatically determining whether to enter the probe contamination cleaning process and providing precise cleaning reminders.

[0074] The formula for the natural frequency of a cantilever beam is as follows:

[0075]

[0076] Among them, f n The natural frequency of the cantilever beam is given by E, the elastic modulus of the material is given by I, the moment of inertia of the cross section is given by m, and the probe mass is given by m. a Indicates the mass of oil accumulation, m b L represents the mass of the cantilever beam itself, and L represents the length of the cantilever beam.

[0077] The vibration characteristics of the fan are as follows:

[0078] Actual measured main vibration frequency band of the fan at each speed setting (example of a range hood):

[0079]

[0080] Design guidelines for reference:

[0081] Let f n =For example, 50Hz (the center value of a frequency band that can be achieved by a range hood, but is not commonly found, can be defined as the detection level) is achieved by adjusting L and T (thickness T has the most sensitive effect on frequency, f n ∝T 1.5 );

[0082] Critical conditions for oil stain removal:

[0083] Among them, a c F represents the critical value of probe acceleration at resonance. 粘附 The value represents the adhesion force of the oil stain (measured at 0.1-1 mN), and μ represents the coefficient of friction between the oil stain and the probe surface.

[0084] Maximum acceleration a at resonance max =(2πfn) 2 AQ;

[0085] A: Fan excitation amplitude (input value, obtained from actual measurement);

[0086] Q: Quality Factor (For steel in air, ζ≈0.005, therefore Q≈100);

[0087] Example calculation is as follows:

[0088] When f n =50Hz, A=60μm (detection range), a max=(2πfn) 2 A·Q=(2π×50) 2 ×6×10 -5 ×100≈59m / s 2 (Approximately 6g, or 6 times the acceleration due to gravity), far exceeding the typical oil stain stripping threshold a. c ≈2m / s 2 .

[0089] like Figure 6 As shown, the side airflow passes through the sensor module, and the main control MCU, i.e. the controller, reads the data from the sensor module and controls the motor of the range hood 7 accordingly, controlling its airflow level and other parameters. In addition, it can also control other modules such as lights.

[0090] like Figure 7 As shown, the control method of this range hood includes the following steps:

[0091] S1. Turn on the range hood;

[0092] S2, Air Quality Sensor 2 Self-Test;

[0093] S3. Determine if the detection cycle has exceeded the time since the last detection;

[0094] If so, the sensor oil accumulation detection and removal subprocess is triggered;

[0095] If not, monitor the background air quality and proceed to step S4;

[0096] S4. Determine if there is a sudden increase in air pollutant levels;

[0097] If so, then actively initiate ventilation and proceed to step S5;

[0098] If not, determine whether the range hood 7 is running. If it is running, increase the airflow level of the range hood 7. If it is not running, switch to sleep mode.

[0099] S5. Control the air volume of the range hood 7;

[0100] S6. Determine whether the pollutant concentration change rate dc / dt > R1 is true; R1 is the concentration change rate threshold.

[0101] If so, increase the airflow level and proceed to step S7;

[0102] If not, reduce the fan speed and proceed to step S7.

[0103] S7. Continuously monitor the rate of change of pollutant concentration until dc / dt ≤ R1;

[0104] S8, Return to background air monitoring.

[0105] like Figure 8 As shown, the sensor oil accumulation detection and removal sub-process of this embodiment includes the following steps:

[0106] S301, Initialize air quality sensor 2;

[0107] S302. Determine whether the range hood 7 is running;

[0108] If so, proceed to step S303;

[0109] If not, then enter hibernation mode;

[0110] S303. Determine whether the detection cycle has exceeded the time since the last detection;

[0111] If so, the range hood 7 will operate at the detection setting and proceed to step S304;

[0112] If not, the range hood 7 will operate at the preset normal setting;

[0113] S304. Real-time monitoring of vibration signals;

[0114] S305. Calculate the current dominant vibration frequency f_v of the sensor;

[0115] S306. Determine whether f_v is within the range of f_n±2hz;

[0116] If so, the cleaning time continues for T_c1, and then proceeds to step S307;

[0117] If not, then the range hood 7 is switched to the normal setting;

[0118] S307. Calculate the dominant vibration frequency f_v of the sensor after cleaning;

[0119] S308. Determine whether f_v is no longer within the range of f_n±2hz;

[0120] If so, the cleaning is deemed effective, and the process proceeds to step S310;

[0121] If not, an abnormal alarm is triggered, and the sensor is continuously cleaned for a period of time T_c2, then proceed to step S309.

[0122] S309. Has the alarm been cleared?

[0123] If so, proceed to step S310;

[0124] If not, then report a sensor maintenance request;

[0125] S310, switch the range hood 7 to normal setting.

[0126] In step S306, the continuous cleaning time T_c1 ≥ 30s, and in step S308, the continuous cleaning time T_c2 ≥ 60s.

[0127] The above control method brings the following technical effects: utilizing waste vibration energy, it is 100% more energy-efficient than traditional electric heating cleaning, achieving energy consumption optimization; the sensor lifespan is extended from 6 months to more than 3 years, resulting in low maintenance costs; furthermore, it predicts the degree of oil accumulation by vibration frequency deviation, achieving intelligent diagnosis; when cleaning is detected, it automatically cleans or extends the cleaning time for enhanced cleaning, achieving adaptive control; the resonant frequency is set at around 50Hz or above to avoid overlapping with the low-frequency (4-8Hz) sensitive frequency of the human body, achieving safety protection.

[0128] In addition, the range hood can be controlled by a voice module, which is equipped with a control module, a voice receiving module, and a voice parsing module. The voice receiving module receives user commands, and the voice parsing module parses the commands. Based on the parsed commands, the controller controls the range hood to perform corresponding operations, thereby realizing intelligent control of the range hood and improving the user experience.

Claims

1. An air quality sensor mounting structure, comprising a housing (1) and an air quality sensor (2) mounted inside the housing (1), wherein the housing (1) has an airflow channel (3) connecting the interior and exterior of the housing (1), characterized in that: The outer shell (1) forms a detection cavity (6), and a cantilever beam (4) is installed inside the detection cavity (6). The air quality sensor (2) is installed at the end of the cantilever beam (4). The airflow channel (3) is arranged obliquely downward from the inside to the outside, and the diameter of the airflow channel (3) gradually increases from the inside to the outside.

2. The air quality sensor mounting structure according to claim 1, characterized in that: The protective grille (5) is installed on the side of the outer shell (1), and the airflow channel (3) is formed on the protective grille (5). The cantilever beam (4) is installed on the inner side wall of the shell opposite to the protective grille (5).

3. The air quality sensor mounting structure according to claim 2, characterized in that: The cantilever beam (4) is set horizontally, and the outer diameter of the probe of the air quality sensor (2) is larger than the outer diameter of the cantilever beam (4).

4. The air quality sensor mounting structure according to claim 1, characterized in that: The inclination angle α of the airflow channel (3) relative to the horizontal plane is 15°≤α≤60°, and the guide convergence angle θ of the airflow channel (3) is 3°≤θ≤15°.

5. The air quality sensor mounting structure according to claim 1, characterized in that: The spacing between adjacent airflow channels (3) is 1-2 mm.

6. A range hood, comprising a housing (7), wherein a range hood fan (8) is installed inside the housing (7), and an air quality sensor (2) as described in any one of claims 1 to 5 is installed on the housing (7), wherein the air quality sensor (2) is connected to the outside of the housing (7) through the airflow channel (3).

7. The range hood according to claim 6, characterized in that: The housing (7) includes an upper housing (71) and a lower housing (72). The fume extractor (8) is installed inside the upper housing (71). A sensor mounting cavity (9) is opened on the left or right side wall of the lower housing (72). The outer shell (1) of the air quality sensor mounting structure is located in the sensor mounting cavity (9).

8. A control method for a range hood, characterized in that: The range hood according to claim 6 or 7 uses this control method, which includes the following steps: S1. Turn on the range hood; S2, Air quality sensor (2) self-test; S3. Determine if the detection cycle has been exceeded since the last detection; If so, the sensor oil accumulation detection and removal subprocess is triggered; If not, monitor the background air quality and proceed to step S4; S4. Determine if there is a sudden increase in air pollutant levels; If so, then actively initiate ventilation and proceed to step S5; If not, determine whether the range hood (8) is running. If it is running, increase the air volume of the range hood (8). If it is not running, switch to sleep mode. S5. Control the air volume of the range hood (8); S6. Determine whether the pollutant concentration change rate dc / dt > R1 is true; R1 is the concentration change rate threshold. If so, increase the airflow level and proceed to step S7; If not, reduce the fan speed and proceed to step S7. S7. Continuously monitor the rate of change of pollutant concentration until dc / dt ≤ R1; S8, Return to background air monitoring.

9. The control method for a range hood according to claim 8, characterized in that... The sensor-based oil accumulation detection and removal sub-process includes the following steps: S301, Initialization of air quality sensor (2); S302. Determine whether the range hood (8) is running; If so, proceed to step S303; If not, then enter hibernation mode; S303. Determine whether the detection cycle has exceeded the time since the last detection; If so, the fume extractor (8) will operate at the detection setting and proceed to step S304; If not, the fume extractor (8) will operate at the preset normal setting; S304. Real-time monitoring of vibration signals; S305. Calculate the current dominant vibration frequency f_v of the sensor; S306. Determine whether f_v is within the range of f_n±2hz; If so, the cleaning time continues for T_c1, and then proceeds to step S307; If not, the range hood (8) is switched to the normal setting; S307. Calculate the dominant vibration frequency f_v of the sensor after cleaning; S308. Determine whether f_v is no longer within the range of f_n±2hz; If so, the cleaning is deemed effective, and the process proceeds to step S310; If not, an abnormal alarm is triggered, and the sensor is continuously cleaned for a period of time T_c2, then proceed to step S309. S309. Has the alarm been cleared? If so, proceed to step S310; If not, then report a sensor maintenance request; S310, switch the range hood (8) to the normal setting.

10. The control method for a range hood according to claim 9, characterized in that: In step S306, the continuous cleaning time T_c1 ≥ 30s, and in step S308, the continuous cleaning time T_c2 ≥ 60s.

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