Range hood and control method thereof

Abstract

The invention relates to a range hood and a control method thereof, and the range hood comprises: a housing having an oil smoke channel; the light emitting module is arranged on the inner wall surface of the oil smoke channel, and the included angle between the emitting direction of the light emitting module and the flowing direction of airflow in the oil smoke channel is an acute angle; the first receiving module is arranged on the downstream of the light emitting module, and the first receiving module is located on the other inner wall surface, opposite to the inner wall surface where the light emitting module is located, of the oil smoke channel; the second receiving module is arranged on the inner wall surface of the oil smoke channel where the light emitting module is located, and is located at the upstream of the light emitting module; and the controller is electrically connected with the first receiving module and the second receiving module. The range hood has the advantages that the range hood realizes detection of the oil smoke concentration and the airflow velocity by sharing the light emitting module and through the single light source, an additional flow sensor is not needed, the cost is low, and the intelligent degree is high.

Description

Technical Field

[0001] The present invention relates to the technical field of oil fume purification, and in particular to a range hood and a control method thereof. Background Art

[0002] As an essential kitchen appliance in every household, the range hood draws in oil smoke from the air inlet through the high-speed rotating impeller in the volute, filters the oil smoke with the impeller, and discharges the filtered oil smoke from the air outlet to complete the kitchen air purification task.

[0003] Range hoods with integrated range hood and stove functions or intelligent activation and air volume adjustment have become increasingly popular in recent years. On the one hand, some range hood and stove combo packages often activate the range hood solely upon turning on the stove, but cannot effectively identify actual changes in oil smoke. Measuring oil smoke concentration requires an additional oil smoke concentration sensor. Products with oil smoke detection functions often use light sensors to detect oil smoke concentration. This simply uses the principle of oil smoke affecting the refractive index of light in the air to determine the amount of oil smoke and then controls the fan speed based on the oil smoke concentration. However, this method is not linked to the current airflow speed of the oil smoke, resulting in a slow response.

[0004] In actual use, oil smoke conditions fluctuate in a complex manner. During range hood operation, it's impossible to determine the real-time correlation between airflow velocity and oil smoke concentration, which can easily lead to poor oil smoke extraction or excessive fan noise. Therefore, an additional flow sensor is required to determine whether the current oil smoke concentration matches the airflow velocity, which is costly and lacks intelligence. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a range hood that can simultaneously detect oil fume concentration and airflow velocity without the need for an additional flow sensor, in response to the above-mentioned prior art.

[0006] The second technical problem to be solved by the present invention is to provide a control method for the above-mentioned range hood, which can accurately adjust the fan speed so that the air flow speed and the oil fume concentration are more closely matched.

[0007] The third technical problem to be solved by the present invention is to provide a control method for the above-mentioned range hood, which can accurately adjust the fan speed according to the cooking conditions of the left and right stoves to improve the oil fume extraction effect.

[0008] The technical solution adopted by the present invention to solve the first technical problem is: a range hood comprising:

[0009] The casing has an oil smoke passage;

[0010] It is characterized by also including:

[0011] A light emitting module is provided on the inner wall surface of the oil fume passage, wherein the angle between the emission direction of the light emitting module and the flow direction of the airflow in the oil fume passage is an acute angle;

[0012] A first receiving module is provided downstream of the light emitting module, and the first receiving module is located on another inner wall surface of the oil smoke passage opposite to the inner wall surface where the light emitting module is located;

[0013] The second receiving module is provided on the inner wall surface of the oil smoke passage where the light transmitting module is located, and is located upstream of the light transmitting module;

[0014] The controller is electrically connected to the first receiving module and the second receiving module. The controller is configured to: analyze the signal received by the first receiving module to obtain the oil fume concentration in the oil fume channel; and analyze the signal received by the first receiving module and the signal received by the second receiving module to obtain the airflow velocity in the oil fume channel.

[0015] In order to achieve oil fume flow regulation of the range hood, an air inlet is opened on the front side of the casing, and a first air guide plate and a second air guide plate are distributed on the left and right behind the air inlet inside the casing. The first air guide plate and the second air guide plate can independently deflect relative to the casing to change the air inlet area of the corresponding position of the air inlet.

[0016] Preferably, there are two light emitting modules, which are respectively arranged in the oil fume duct where the first air guide plate and the second air guide plate are located, and the oil fume duct where the first air guide plate and the second air guide plate are located are also respectively provided with light emitting modules and first receiving modules and second receiving modules used in conjunction with the light emitting modules.

[0017] The technical solution adopted by the present invention to solve the second technical problem is: a control method of the range hood as described above, characterized by comprising the following steps:

[0018] Step 1: Control the optical transmitting module, the first receiving module and the second receiving module to operate;

[0019] Step 2: collecting signals received by the first receiving module and the second receiving module, and analyzing the signals received by the first receiving module and the second receiving module to obtain the oil smoke concentration ρ and the air flow velocity v in the oil smoke channel;

[0020] Step 3: Determine whether the oil smoke concentration ρ is greater than the first oil smoke concentration threshold ρ1. If so, control the fan in the range hood to operate at the set gear and proceed to step 4; if not, proceed to step 2;

[0021] Step 4: Determine the current working scene of the range hood according to the value of the oil smoke concentration ρ;

[0022] Step 5: Set the airflow velocity threshold according to different working scenarios of the range hood, and adjust the fan gear in the range hood accordingly based on the comparison result of the airflow velocity v with the airflow velocity threshold set in the corresponding working scenario, and proceed to step 2.

[0023] Preferably, the calculation formula for the oil smoke concentration ρ in step 2 is:

[0024] ρ=k×I_S

[0025] Wherein, k is the calibration coefficient, k is a constant, and I_S is the forward scattered light intensity received by the first receiving module.

[0026] Preferably, the air flow velocity v in step 2 is obtained by:

[0027] The forward scattered light intensity signal received by the first receiving module within the set time is recorded as S1(t), and the backward scattered light intensity signal received by the second receiving module within the set time is recorded as S2(t). There is a time delay τ between S2(t) and S1(t);

[0028] At a fixed frequency f s S1(t) and S2(t) are sampled respectively to obtain a first sequence S1[n] and a second sequence S2[n], where n is a discrete time index, n=0, 1, ...N-1;

[0029] Calculate the cross-correlation function Where m is a constant;

[0030] Find m 峰值 =argmax R 12 [n];

[0031] Calculating time delay

[0032] but L1 is the horizontal distance between the first receiving module and the light emitting module, L2 is the distance between the second receiving module and the light emitting module, and θ is the angle between the emission direction of the light emitting module and the flow direction of the airflow in the oil fume channel.

[0033] Preferably, the specific control logic of step 4 is:

[0034] When ρ<ρ2, it is determined that the current working scene of the range hood is a low-oil smoke scene;

[0035] When ρ2≤ρ≤ρ3, the current working scene of the range hood is determined to be the medium oil smoke scene;

[0036] When ρ>ρ3, the current working scene of the range hood is determined to be a heavy oil smoke scene;

[0037] Wherein, ρ2 is the second oil fume concentration threshold, ρ3 is the third oil fume concentration threshold, ρ2 and ρ3 are both constants, and ρ1<ρ2<ρ3.

[0038] Preferably, the specific control logic in step 5 is:

[0039] When v<Va, the fan gear in the range hood is increased;

[0040] When Va≤v≤Vb, the fan position in the range hood remains unchanged;

[0041] When v>Vb, the fan gear in the range hood is reduced;

[0042] Among them, Va is the minimum airflow velocity threshold value when the range hood does not emit smoke in the current working scenario, and Vb is the maximum airflow velocity threshold value when the range hood does not emit smoke in the current working scenario. Va and Vb are both constants.

[0043] The technical solution adopted by the present invention to solve the third technical problem is: a control method for the range hood as described above, characterized in that: the oil fume passage where the first air guide plate is located is recorded as the first oil fume passage, the optical transmission module, the first receiving module, and the second receiving module in the first oil fume passage are recorded as the first detection module; the oil fume passage where the second air guide plate is located is recorded as the second oil fume passage, and the optical transmission module, the first receiving module, and the second receiving module in the second oil fume passage are recorded as the second detection module;

[0044] The control method comprises the following steps:

[0045] Step a, controlling the first detection module and the second detection module to work respectively;

[0046] Step b, obtaining the oil fume concentration P1 in the first oil fume channel, the oil fume concentration P2 in the second oil fume channel, the airflow velocity V1 in the first oil fume channel, and the airflow velocity V2 in the second oil fume channel;

[0047] Step c, determining whether the maximum value of P1 and P2 is greater than the set value P, if so, proceeding to step c; if not, maintaining the fan gear position of the range hood unchanged and proceeding to step b;

[0048] Step d: Determine whether V1 is within [V0-k, V0+k] and whether V2 is within [V0-k, V0+k], where V0 is the target flow rate of oil smoke, k is the preset flow rate, and V0-k>0. If so, keep the current positions of the first and second air deflectors unchanged; if not, proceed to step e;

[0049] Step e: adjusting the positions of the first air guide plate and the second air guide plate, and adjusting the fan gear position of the range hood, and detecting the adjusted airflow velocity V1′ in the first oil fume duct and the adjusted airflow velocity V2′ in the second oil fume duct;

[0050] Step f: Determine whether V1′ is greater than V0, and whether the absolute value of the difference between V1′ and V2′ is less than q times V0, where q∈(0,1). If so, maintain the current state and proceed to step b. If not, close the first air guide plate or the second air guide plate, adjust the fan gear in the range hood to the highest gear, and proceed to step b.

[0051] Preferably, in step e, adjusting the positions of the first air deflector and the second air deflector is specifically as follows:

[0052] Adjust the opening of the first air guide plate to α, and the calculation formula of α is: α=α0+Δα*(P1-P2) / P;

[0053] Adjust the opening of the second air guide plate to β. The calculation formula of β is: β = β0 - Δβ * (P1 - P2) / P;

[0054] Wherein, α0 is the initial opening of the first air guide plate, Δα is the opening adjustment coefficient of the first air guide plate; β0 is the initial opening of the second air guide plate, Δβ is the opening adjustment coefficient of the second air guide plate.

[0055] Preferably, in step e, a PID algorithm is used to adjust the fan gear position of the range hood.

[0056] Compared with existing technologies, the present invention has the following advantages: It utilizes the airflow within the fume duct to scatter the light emitted by the optical transmitter module, and the optical signal is received by the first and second receiver modules. This allows the positive correlation between the intensity of the forward scattered light and the concentration to be used to determine the fume concentration within the fume duct. Furthermore, the time delay between the reception of the first and second receiver modules is calculated using a cross-correlation function, which is then used to calculate the airflow velocity. This method eliminates interference from airflow disturbances on the light scattering signal, improving the stability of concentration measurement. Therefore, the range hood uses a shared optical transmitter module and a single light source to detect both fume concentration and airflow velocity, eliminating the need for additional flow sensors. This reduces costs and provides a high level of intelligence. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 Schematic diagram of the installation of the optical transmitting module, the first receiving module and the second receiving module in the first embodiment of the present invention;

[0058] Figure 2 This is a flow chart of a control method for a range hood in Embodiment 1 of the present invention;

[0059] Figure 3 This is a schematic diagram of the range hood in use according to the second embodiment of the present invention;

[0060] Figure 4 It is a side view of the range hood in the second embodiment of the present invention. DETAILED DESCRIPTION

[0061] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0062] Example 1:

[0063] The range hood in this embodiment includes a casing 100, a smoke shield b and a fan (not shown in the figure). An air inlet 10 is opened on the front side of the casing 100. The smoke shield b is restrained on the front side of the casing 100 in a rotatable manner to open or close the air inlet 10. The fan is arranged in the casing 100, and the casing 100 has an oil fume channel a.

[0064] like Figure 1 As shown, the range hood further includes a light emitting module 1, a first receiving module 2, a second receiving module 3, and a controller. The light emitting module 1 is positioned on the inner wall of the oil fume duct a, with the angle θ between the emission direction of the light emitting module 1 and the airflow direction within the oil fume duct a being acute. The first receiving module 2 is positioned downstream of the light emitting module 1 and located on the inner wall of the oil fume duct a opposite to the inner wall of the oil fume duct a where the light emitting module 1 is positioned. The second receiving module 3 is positioned on the inner wall of the oil fume duct a where the light emitting module 1 is positioned, and upstream of the light emitting module 1. The controller is electrically connected to the first receiving module 2 and the second receiving module 3 and is configured to analyze the signals received by the first receiving module 2 to determine the oil fume concentration within the oil fume duct a and to analyze the signals received by the first receiving module 2 and the second receiving module 3 to determine the airflow velocity within the oil fume duct a. The controller is also electrically connected to the fan to automatically control its operation.

[0065] like Figure 2 As shown, this embodiment also discloses a control method for the range hood, which includes the following steps:

[0066] Step 1: Control the optical transmitting module, the first receiving module and the second receiving module to operate;

[0067] The control method further includes determining whether the intelligent mode is turned on before executing step 1. If the intelligent mode is turned on, step 1 is executed; otherwise, the manual operation mode of the range hood is executed.

[0068] Step 2: collecting signals received by the first receiving module and the second receiving module, and analyzing the signals received by the first receiving module and the second receiving module to obtain the oil smoke concentration ρ and the air flow velocity v in the oil smoke channel;

[0069] The calculation formula of the oil smoke concentration ρ in this embodiment is:

[0070] ρ=k×I_S

[0071] Wherein, k is the calibration coefficient, k is a constant, and I_S is the forward scattered light intensity received by the first receiving module;

[0072] The principle of the above fume concentration is based on Mie scattering theory. The forward scattered light intensity is positively correlated with the concentration. Therefore, the calibration coefficient k can be determined through experiments, that is, the fume concentration can be obtained according to the above calculation formula.

[0073] In this embodiment, the air flow velocity v is obtained as follows:

[0074] The forward scattered light intensity signal received by the first receiving module within the set time is recorded as S1(t), and the backward scattered light intensity signal received by the second receiving module within the set time is recorded as S2(t). There is a time delay τ between S2(t) and S1(t);

[0075] At a fixed frequency f s S1(t) and S2(t) are sampled respectively to obtain a first sequence S1[n] and a second sequence S2[n], where n is a discrete time index, n=0, 1, ...N-1;

[0076] Calculate the cross-correlation function Where m is a constant;

[0077] Find m 峰值 =argmaxR 12 [m];

[0078] Calculating time delay

[0079] but L1 is the horizontal distance between the first receiving module and the light emitting module, L2 is the distance between the second receiving module and the light emitting module, and θ is the angle between the emission direction of the light emitting module and the flow direction of the airflow in the oil smoke channel;

[0080] In this embodiment, the cross-correlation function, which is well-established in engineering, can be used to obtain the time delay between the first receiving module and the second receiving module, and then calculate the airflow velocity.

[0081] Step 3: Determine whether the oil smoke concentration ρ is greater than the first oil smoke concentration threshold ρ1. If so, control the fan in the range hood to operate at the set gear and proceed to step 4; if not, proceed to step 2;

[0082] Step 4: Determine the current working scene of the range hood according to the value of the oil smoke concentration ρ;

[0083] The specific control logic of step 4 is:

[0084] When ρ<ρ2, it is determined that the current working scene of the range hood is a low-oil smoke scene;

[0085] When ρ2≤ρ≤ρ3, the current working scene of the range hood is determined to be the medium oil smoke scene;

[0086] When ρ>ρ3, the current working scene of the range hood is determined to be a heavy oil smoke scene;

[0087] Wherein, ρ2 is the second oil fume concentration threshold, ρ3 is the third oil fume concentration threshold, ρ2 and ρ3 are both constants, and ρ1<ρ2<ρ3; in this embodiment, the small oil fume scene, medium oil fume scene, and large oil fume scene are all relative to the oil fume concentration. For example, it is well known to those skilled in the art that frying is a large oil fume scene, and the oil fume scene corresponding to steaming is smaller than that corresponding to frying; the specific values of ρ1, ρ2, and ρ3 in this embodiment can be determined based on experiments or experience;

[0088] Step 5: Set airflow velocity thresholds according to different working scenarios of the range hood, and adjust the fan gear of the range hood accordingly based on the comparison result of the airflow velocity v with the airflow velocity threshold set for the corresponding working scenario, and then proceed to step 2;

[0089] The specific control logic in step 5 is:

[0090] When v<Va, the fan gear in the range hood is increased;

[0091] When Va≤v≤Vb, the fan position in the range hood remains unchanged;

[0092] When v>Vb, the fan gear in the range hood is reduced;

[0093] Where Va is the minimum airflow velocity threshold for the range hood to avoid smoke leakage in the current operating scenario, and Vb is the maximum airflow velocity threshold for the range hood to avoid smoke leakage in the current operating scenario. Both Va and Vb are constants. The specific values of Va and Vb in this embodiment can be determined based on experimentation or experience. The higher the fan gear position, the faster the fan speed.

[0094] In this embodiment, when at least one of the first receiving module and the second receiving module receives abnormal data, the self-cleaning program is triggered, and the receiving module with abnormal receiving data needs to be cleaned. The cleaning mechanism used for cleaning can adopt existing technology and will not be elaborated here.

[0095] Example 2:

[0096] Different from the first embodiment, Figure 3 As shown, the housing 100 in this embodiment is further provided with a first air guide plate 11 and a second air guide plate 12, one on the left and one on the right, behind the air inlet 10. The first air guide plate 11 and the second air guide plate 12 can independently deflect relative to the housing 1 to change the air inlet area at the corresponding position of the air inlet 10. The housing 1 is provided with a first driving mechanism (not shown in the figure) that can drive the deflection of the first air guide plate 11 and a second driving mechanism (not shown in the figure) that can drive the deflection of the second air guide plate 12. The above-mentioned first driving mechanism and second driving mechanism are both based on existing technologies and will not be further described here. Figure 4 As shown, the first air guide plate 11 and the second air guide plate 12 in this embodiment can be independently arranged behind the air inlet 10 in a manner that their bottom edges can be deflected around a straight line extending left and right as a rotation axis. The first air guide plate 11 and the second air guide plate 12 can be individually driven by various driving mechanisms to deflect forward to reduce the air inlet area of the corresponding position of the air inlet 10, or can be driven by various driving mechanisms to deflect backward to increase the air inlet area of the corresponding position of the air inlet 10.

[0097] The controller is also electrically connected to the first drive mechanism and the second drive mechanism to automatically control the movements of the first air guide plate 11 and the second air guide plate 12 .

[0098] like Figure 3 As shown, two stoves are arranged on the left and right below the range hood. In order to dynamically adjust the working state of the range hood according to the cooking conditions of the two stoves, in this embodiment, the oil fume duct where the first air guide plate 11 and the second air guide plate 12 are located is also provided with a light emitting module 1 and a first receiving module 2 and a second receiving module 3 used in conjunction with the light emitting module 1. The oil fume duct where the first air guide plate 11 is located is recorded as the first oil fume duct, and the light emitting module, the first receiving module and the second receiving module in the first oil fume duct are recorded as the first detection module. The oil fume duct where the second air guide plate 12 is located is recorded as the second oil fume duct, and the light emitting module, the first receiving module and the second receiving module in the second oil fume duct are recorded as the second detection module. The detection processes of the above-mentioned first detection module and the second detection module are independent, and the detection principles are the same.

[0099] This embodiment also discloses a control method for the range hood, which includes the following steps:

[0100] Step a, controlling the first detection module and the second detection module to work respectively;

[0101] Step b, obtaining the oil fume concentration P1 in the first oil fume channel, the oil fume concentration P2 in the second oil fume channel, the airflow velocity V1 in the first oil fume channel, and the airflow velocity V2 in the second oil fume channel;

[0102] The above-mentioned method for detecting the oil smoke concentration and air flow velocity is the same as that in the first embodiment, and will not be further described here;

[0103] Step c, determining whether the maximum value of P1 and P2 is greater than the set value P, if so, proceeding to step c; if not, maintaining the fan gear position of the range hood unchanged and proceeding to step b;

[0104] Step d: Determine whether V1 is within [V0-k, V0+k] and whether V2 is within [V0-k, V0+k], where V0 is the target flow rate of oil smoke, k is the preset flow rate, and V0-k>0. If so, keep the current positions of the first and second air deflectors unchanged; if not, proceed to step e;

[0105] The specific values of V0 and k are determined based on experiments or experience, and k is the tolerance allowed for the target flow rate of oil smoke;

[0106] Step e: adjusting the positions of the first air guide plate and the second air guide plate, and adjusting the fan gear position of the range hood, and detecting the adjusted airflow velocity V1′ in the first oil fume duct and the adjusted airflow velocity V2′ in the second oil fume duct;

[0107] In this embodiment, the positions of the first air deflector and the second air deflector are adjusted as follows:

[0108] Adjust the opening of the first air guide plate to α, and the calculation formula of α is: α=α0+Δα*(P1-P2) / P;

[0109] Adjust the opening of the second air guide plate to β. The calculation formula of β is: β = β0 - Δβ * (P1 - P2) / P;

[0110] Wherein, α0 is the initial opening of the first air guide plate, Δα is the opening adjustment coefficient of the first air guide plate; β0 is the initial opening of the second air guide plate, Δβ is the opening adjustment coefficient of the second air guide plate;

[0111] In this embodiment, a PID algorithm is used to adjust the fan position of the range hood. In this embodiment, the fan position is adjusted based on the relationship between the oil fume concentration P1 in the first oil fume passage and the oil fume concentration P2 in the second oil fume passage. The PID algorithm can make the maximum value of P1 and P2 less than the set value P.

[0112] Step f: Determine whether V1′ is greater than V0, and whether the absolute value of the difference between V1′ and V2′ is less than q times V0, where q∈(0,1). If so, maintain the current state and proceed to step b. If not, close the first or second air deflector, adjust the range hood fan speed to the highest setting, and proceed to step b. The specific value of q is determined based on experimentation or experience; in this embodiment, q = 0.2.

[0113] In this embodiment, the oil fume concentration in the first oil fume channel, the oil fume concentration in the second oil fume channel, the air flow rate in the first oil fume channel and the air flow rate in the second oil fume channel are detected, and the first air guide plate and the second air guide plate are adjusted accordingly according to the detected oil fume concentration and air flow rate of the two oil fume channels. This enables the method to accurately adjust the fan speed according to the cooking conditions of the left and right stoves to improve the oil fume absorption effect and enhance the user experience.

[0114] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A range hood comprising: The housing (100) has an oil smoke passage (a); It is characterized by also including: A light emitting module (1) is arranged on the inner wall surface of the oil smoke channel (a), and the angle between the emission direction of the light emitting module (1) and the flow direction of the airflow in the oil smoke channel (a) is an acute angle; A first receiving module (2) is provided downstream of the light emitting module (1), and the first receiving module (2) is located on another inner wall surface of the oil smoke passage (a) opposite to the inner wall surface where the light emitting module (1) is located; A second receiving module (3) is provided on the inner wall surface of the oil smoke channel (a) where the light transmitting module (1) is located, and is located upstream of the light transmitting module (1); A controller is electrically connected to the first receiving module (2) and the second receiving module (3), and is configured to: analyze the signal received by the first receiving module (2) to obtain the oil smoke concentration in the oil smoke channel (a); and also analyze the signal received by the first receiving module (2) and the signal received by the second receiving module (3) to obtain the air flow velocity in the oil smoke channel (a).

2. The range hood according to claim 1, characterized in that: An air inlet (10) is provided on the front side of the housing (100), and a first air guide plate (11) and a second air guide plate (12) are further provided inside the housing (100), one on the left and one on the right, behind the air inlet (10). The first air guide plate (11) and the second air guide plate (12) can independently deflect relative to the housing (100) to change the air inlet area at the corresponding position of the air inlet (10).

3. The range hood according to claim 2, characterized in that: There are two light emitting modules (1), which are respectively arranged in the oil fume passage (a) where the first air guide plate (11) and the second air guide plate (12) are located. The oil fume passage where the first air guide plate (11) and the second air guide plate (12) are located is also provided with a light emitting module (1) and a first receiving module (2) and a second receiving module (3) used in conjunction with the light emitting module (1).

4. A range hood control method according to claim 1, characterized in that The steps include: Step 1: Control the optical transmitting module, the first receiving module and the second receiving module to operate; Step 2: collecting signals received by the first receiving module and the second receiving module, and analyzing the signals received by the first receiving module and the second receiving module to obtain the oil smoke concentration ρ and the air flow velocity v in the oil smoke channel; Step 3: Determine whether the oil smoke concentration ρ is greater than the first oil smoke concentration threshold ρ1. If so, control the fan in the range hood to operate at the set gear and proceed to step 4; if not, proceed to step 2; Step 4: Determine the current working scene of the range hood according to the value of the oil smoke concentration ρ; Step 5: Set the airflow velocity threshold according to different working scenarios of the range hood, and adjust the fan gear in the range hood accordingly based on the comparison result of the airflow velocity v with the airflow velocity threshold set in the corresponding working scenario, and proceed to step 2.

5. The control method according to claim 4, characterized in that: The calculation formula of the oil smoke concentration ρ in step 2 is: ρ=k×I_S Wherein, k is the calibration coefficient, k is a constant, and I_S is the forward scattered light intensity received by the first receiving module.

6. The control method according to claim 4, characterized in that: The air flow velocity v in step 2 is obtained as follows: The forward scattered light intensity signal received by the first receiving module within the set time is recorded as S1(t), and the backward scattered light intensity signal received by the second receiving module within the set time is recorded as S2(t). There is a time delay τ between S2(t) and S1(t); At a fixed frequency f s Sampling S1(t) and S2(t) respectively to obtain a first sequence S1[n] and a second sequence S2[n], where n is a discrete time index and m=0, 1, ...N-1; Calculate the cross-correlation function Where n is a constant; Find m 峰值 =arg max R 12 [n]; Calculating time delay but L1 is the horizontal distance between the first receiving module and the light emitting module, L2 is the distance between the second receiving module and the light emitting module, and θ is the angle between the emission direction of the light emitting module and the flow direction of the airflow in the oil fume channel.

7. The control method according to claim 5, characterized in that: The specific control logic of step 4 is: When ρ<ρ2, it is determined that the current working scene of the range hood is a low-oil smoke scene; When ρ2≤ρ≤ρ3, the current working scene of the range hood is determined to be the medium oil smoke scene; When ρ>ρ3, the current working scene of the range hood is determined to be a heavy oil smoke scene; Wherein, ρ2 is the second oil fume concentration threshold, ρ3 is the third oil fume concentration threshold, ρ2 and ρ3 are both constants, and ρ1<ρ2<ρ3.

8. The control method according to claim 6, wherein: The specific control logic in step 5 is: When v<Va, the fan gear in the range hood is increased; When Va≤v≤Vb, the fan position in the range hood remains unchanged; When v>Vb, the fan gear in the range hood is reduced; Among them, Va is the minimum airflow velocity threshold value when the range hood does not emit smoke in the current working scenario, and Vb is the maximum airflow velocity threshold value when the range hood does not emit smoke in the current working scenario. Va and Vb are both constants.

9. A range hood control method according to claim 3, characterized in that: The oil fume channel where the first air guide plate is located is referred to as the first oil fume channel, the optical transmitter module, the first receiver module, and the second receiver module in the first oil fume channel are referred to as the first detection module, the oil fume channel where the second air guide plate is located is referred to as the second oil fume channel, and the optical transmitter module, the first receiver module, and the second receiver module in the second oil fume channel are referred to as the second detection module; The control method comprises the following steps: Step a, controlling the first detection module and the second detection module to work respectively; Step b, obtaining the oil fume concentration P1 in the first oil fume channel, the oil fume concentration P2 in the second oil fume channel, the airflow velocity V1 in the first oil fume channel, and the airflow velocity V2 in the second oil fume channel; Step c, determining whether the maximum value of P1 and P2 is greater than the set value P, if so, proceeding to step c; if not, maintaining the fan gear position of the range hood unchanged and proceeding to step b; Step d: Determine whether V1 is within [V0-k, V0+k] and whether V2 is within [V0-k, V0+k], where V0 is the target flow rate of oil smoke, k is the preset flow rate, and V0-k>0. If so, keep the current positions of the first and second air deflectors unchanged; if not, proceed to step e; Step e: adjusting the positions of the first air guide plate and the second air guide plate, and adjusting the fan gear position of the range hood, and detecting the adjusted airflow velocity V1′ in the first oil fume duct and the adjusted airflow velocity V2′ in the second oil fume duct; Step f: Determine whether V1′ is greater than V0, and whether the absolute value of the difference between V1′ and V2′ is less than q times V0, where q∈(0,1). If so, maintain the current state and proceed to step b. If not, close the first air guide plate or the second air guide plate, adjust the fan gear in the range hood to the highest gear, and proceed to step b.

10. The control method according to claim 9, characterized in that: The specific steps of adjusting the positions of the first air deflector and the second air deflector in step e are as follows: Adjust the opening of the first air guide plate to α, and the calculation formula of α is: α=α0+Δα*(P1-P2) / P; Adjust the opening of the second air guide plate to β. The calculation formula of β is: β = β0 - Δβ * (P1 - P2) / P; Wherein, α0 is the initial opening of the first air guide plate, Δα is the opening adjustment coefficient of the first air guide plate; β0 is the initial opening of the second air guide plate, Δβ is the opening adjustment coefficient of the second air guide plate.

11. The control method according to claim 9, characterized in that: In the step e, a PID algorithm is used to adjust the fan gear position of the range hood.

Images