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 range hood is characterized by further comprising a grating arranged in the oil smoke channel in the direction perpendicular to the airflow flowing direction, and the grating is connected with the inner circumferential wall of the oil smoke channel; the light emitting module is arranged on the wall surface of the oil smoke channel, the light emitting module is arranged adjacent to the grating and located at the downstream of the grating, and the light emitting module is used for emitting parallel light beams in the direction perpendicular to the airflow flowing direction; the receiving module is arranged on the wall surface, opposite to the light emitting module, of the oil smoke channel, and the receiving module and the light emitting module are oppositely arranged; and the controller is electrically connected with the receiving module, and the controller is configured to be capable of analyzing the signal received by the receiving module to obtain the oil smoke concentration in the oil smoke channel and the airflow velocity in the oil smoke channel. The range hood can simultaneously detect light intensity attenuation (concentration) and light spot jitter (flow velocity) through a single light source, and an additional flow sensor is not needed.

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 grille is arranged in the oil fume passage in a direction perpendicular to the airflow direction, and the grille is connected to the inner peripheral wall of the oil fume passage;

[0012] a light emitting module, disposed on a wall surface of the oil fume passage, the light emitting module being disposed adjacent to the grille and located downstream of the grille, the light emitting module being configured to emit a parallel light beam perpendicular to a flow direction of the airflow;

[0013] The receiving module is arranged on a wall of the oil smoke passage opposite to the light emitting module, and the receiving module is arranged opposite to the light emitting module;

[0014] The controller is electrically connected to the receiving module, and is configured to analyze the signal received by the receiving module to obtain the oil smoke concentration and the air flow velocity in the oil smoke channel.

[0015] In order to reduce the interference of ambient light, the light beam emitted by the light emitting module is infrared light.

[0016] Preferably, the wavelength of the infrared light is 850 nm.

[0017] Preferably, the divergence angle of the parallel light beam emitted by the light emitting module is less than 10°.

[0018] Preferably, the receiving module is a photoresistor array composed of a plurality of adjacently arranged photoresistors.

[0019] 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.

[0020] Preferably, there are two optical transmission 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 an optical transmission module and a receiving module used in conjunction with the optical transmission module.

[0021] 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:

[0022] Step 1: Control the operation of the optical transmitting module and the receiving module;

[0023] Step 2: Collect the signal received by the receiving module and analyze the signal received by the receiving module to obtain the oil smoke concentration ρ and air flow velocity v in the oil smoke channel;

[0024] 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;

[0025] Step 4: Determine the current working scene of the range hood according to the value of the oil smoke concentration ρ;

[0026] 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.

[0027] Preferably, the calculation formula for the oil smoke concentration ρ in step 2 is:

[0028]

[0029] Where k is the calibration coefficient, k is a constant, V0 is the reference voltage when the photoresistor array is clean, and Vt is the real-time voltage of the photoresistor array.

[0030] The first method for calculating the airflow velocity is: the airflow velocity v in step 2 is calculated as follows:

[0031] according to Calculate the air flow velocity v;

[0032] Where f is the vibration frequency of the grid, S t is the Trauhal number related to the grille shape, and d is the size of the non-hollow hole in the middle of the grille.

[0033] The second method for calculating the airflow velocity is: the airflow velocity v in step 2 is calculated as follows:

[0034] One of the photoresistors in the photoresistor array is referred to as a first photoresistor, and another photoresistor adjacent to the first photoresistor is referred to as a second photoresistor;

[0035] The light intensity signal received by the first photoresistor within the set time is recorded as S1(t), and the light intensity signal received by the second photoresistor within the set time is recorded as S2(t). There is a time delay τ between S2(t) and S1(t);

[0036] 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;

[0037] Calculate the cross-correlation function Where m is a constant;

[0038] Find m 峰值 =argmax R 12 [n];

[0039] Calculating time delay

[0040] but L is the distance between the first photoresistor and the second photoresistor.

[0041] Preferably, the specific control logic of step 4 is:

[0042] When ρ<ρ2, it is determined that the current working scene of the range hood is a low-oil smoke scene;

[0043] When ρ2≤ρ≤ρ3, the current working scene of the range hood is determined to be the medium oil smoke scene;

[0044] When ρ>ρ3, the current working scene of the range hood is determined to be a heavy oil smoke scene;

[0045] 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.

[0046] Preferably, the specific control logic in step 5 is:

[0047] When v<Va, the fan gear in the range hood is increased;

[0048] When Va≤v≤Vb, the fan position in the range hood remains unchanged;

[0049] When v>Vb, the fan gear in the range hood is reduced;

[0050] 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.

[0051] The technical solution adopted by the present invention to solve the third technical problem is as follows: the oil fume passage where the first air guide plate is located is referred to as the first oil fume passage, the optical transmitting module and the receiving module in the first oil fume passage are referred to as the first detection module, the oil fume passage where the second air guide plate is located is referred to as the second oil fume passage, and the optical transmitting module and the receiving module in the second oil fume passage are referred to as the second detection module;

[0052] The control method comprises the following steps:

[0053] Step a, controlling the first detection module and the second detection module to work respectively;

[0054] Step b, obtaining the oil fume concentration CL in the first oil fume channel, the oil fume concentration CR in the second oil fume channel, the airflow velocity VL in the first oil fume channel, and the airflow velocity VR in the second oil fume channel;

[0055] Step c: Determine whether the maximum value of CL and CR is greater than the set value P. If so, proceed to step c; if not, maintain the fan gear position of the range hood unchanged and proceed to step b.

[0056] Step d: Determine whether the absolute value of the difference between VL and Vt is less than q times Vt, or whether the absolute value of the difference between VR and Vt is less than q times Vt, where Vt is the set target oil fume flow rate and q∈(0,1). If so, keep the current positions of the first and second air deflectors unchanged; if not, proceed to step e.

[0057] 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 VL′ in the first oil fume duct and the adjusted airflow velocity VR′ in the second oil fume duct;

[0058] Step f: Determine whether VL′ is greater than Vt, and VR′ is less than or equal to r times Vt, where r∈(0,1). If so, lock the first air guide plate or the second air guide plate in position 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.

[0059] Preferably, in step e, adjusting the positions of the first air deflector and the second air deflector is specifically as follows:

[0060] Adjust the opening of the first air guide plate to α, and the calculation formula of α is: α=α0+Δα*(CL-CR) / 10;

[0061] Adjust the opening of the second air guide plate to β. The calculation formula of β is: β = β0 - Δβ * (CL - CR) / 10;

[0062] 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.

[0063] Preferably, in step e, a PID algorithm is used to adjust the fan gear position of the range hood.

[0064] Compared with existing technologies, the present invention has the following advantages: by placing a grille perpendicular to the airflow direction in the oil fume duct, when airflow occurs in the duct, the grille is stimulated by the airflow to periodically vibrate. Furthermore, by arranging the optical transmitter and receiver modules in opposite positions, the vibration of the fluid passing through the grille changes the optical path, causing the light intensity and light spot position received by the receiver module to fluctuate. This allows for simultaneous detection of light intensity attenuation (concentration) and light spot jitter (flow rate) using a single light source. Therefore, this range hood does not require an additional flow sensor, is low-cost, and highly intelligent. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is a schematic diagram of the installation of the optical transmitting module and the receiving module in Example 1 of the present invention (there is no airflow in the oil fume duct);

[0066] Figure 2 This is a schematic diagram of the installation of the optical transmitting module and the receiving module in the first embodiment of the present invention (there is airflow in the oil fume duct);

[0067] Figure 3 This is a flow chart of a control method for a range hood in Embodiment 1 of the present invention;

[0068] Figure 4 This is a schematic diagram of the range hood in use according to the second embodiment of the present invention;

[0069] Figure 5 It is a side view of the range hood in the second embodiment of the present invention. DETAILED DESCRIPTION

[0070] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0071] Example 1:

[0072] 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.

[0073] like Figure 1 and Figure 2As shown, the range hood also includes a grille 1, a light emitting module 2, a receiving module 3 and a controller. The grille 1 is arranged in the oil fume channel a perpendicular to the direction of airflow, and the grille 1 is connected to the inner peripheral wall of the oil fume channel a; the light emitting module 2 is arranged on the wall of the oil fume channel a, the light emitting module 2 is arranged adjacent to the grille 1, and is located downstream of the grille 1. The light emitting module 2 is used to emit parallel light beams perpendicular to the direction of airflow; the receiving module 3 is arranged on the wall of the oil fume channel a opposite to the light emitting module 2, and the receiving module 3 is arranged opposite to the light emitting module 2; the controller is electrically connected to the receiving module 3, and the controller is configured to: analyze the signal received by the receiving module 3 to obtain the oil fume concentration in the oil fume channel a and the airflow velocity in the oil fume channel a.

[0074] In this embodiment, the light beam emitted by the light emitting module 2 is infrared light with a wavelength of 850 nm, and the divergence angle of the parallel light beam emitted by the light emitting module 2 is less than 10°. In addition, the receiving module 3 is a photoresistor array composed of multiple adjacent photoresistors.

[0075] like Figure 3 As shown, this embodiment also discloses a control method for the range hood, which includes the following steps:

[0076] Step 1: Control the operation of the optical transmitting module and the receiving module;

[0077] 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.

[0078] Step 2: Collect the signal received by the receiving module and analyze the signal received by the receiving module to obtain the oil smoke concentration ρ and air flow velocity v in the oil smoke channel;

[0079] The calculation formula of the oil smoke concentration ρ in this embodiment is:

[0080]

[0081] Where k is the calibration coefficient, k is a constant, V0 is the reference voltage when the photoresistor array is clean, and Vt is the real-time voltage of the photoresistor array;

[0082] The principle of the above oil smoke concentration is to use the light intensity attenuation model, that is, when light passes through the oily airflow, it is absorbed and weakened, and when it reaches the receiving end (such as the photoresistor) when it is relatively clean, the voltage concentration output by the photoresistor group is The calibration coefficient k can be determined through experiments, that is, the fume concentration can be obtained according to the above calculation formula;

[0083] In this embodiment, there are two methods for calculating the air flow velocity:

[0084] Solution 1: Using the spot jitter frequency method, that is, when the airflow passes through the grille, periodic vortex shedding will be generated due to the Karman vortex street effect, causing the grille to vibrate. In this way, single light source transmitting and receiving modules can be arranged in opposite directions, and the vibration of the fluid passing through the middle grille can be used to change the light path. Then, the light intensity attenuation (concentration) and spot jitter (flow velocity) can be simultaneously detected by a single light source.

[0085] The air flow velocity v is calculated as:

[0086] according to Calculate the air flow velocity v;

[0087] Where f is the vibration frequency of the grid, S t is the Trauhal number related to the grille shape, d is the size of the non-hollow hole in the middle of the grille;

[0088] Because different grilles will make S t The value of fluctuates, so it can be measured in advance by experiment. In this embodiment, S t =0.21; In addition, there are multiple circular holes (i.e., hollow holes) evenly distributed on the grille, so the size of the non-hollow hole in the middle of the grille can be obtained by measurement. In this embodiment, d=2mm;

[0089] Solution 2: Using the double photoresistor signal delay cross-correlation verification method;

[0090] The air flow velocity v is calculated as:

[0091] One of the photoresistors in the photoresistor array is recorded as a first photoresistor, and another photoresistor adjacent to the first photoresistor is recorded as a second photoresistor;

[0092] The light intensity signal received by the first photoresistor within the set time is recorded as S1(t), and the light intensity signal received by the second photoresistor within the set time is recorded as S2(t). There is a time delay τ between S2(t) and S1(t);

[0093] 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;

[0094] Calculate the cross-correlation function Where m is a constant;

[0095] Find m 峰值 =argmax R 12 [n];

[0096] Calculating time delay

[0097] but L is the distance between the first photoresistor and the second photoresistor;

[0098] In this embodiment, the cross-correlation function, which is well-established in engineering, can be used to obtain the time delay between the first photoresistor and the second photoresistor, and then calculate the airflow velocity.

[0099] 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;

[0100] Step 4: Determine the current working scene of the range hood according to the value of the oil smoke concentration ρ;

[0101] The specific control logic of step 4 is:

[0102] When ρ<ρ2, it is determined that the current working scene of the range hood is a low-oil smoke scene;

[0103] When ρ2≤ρ≤ρ3, the current working scene of the range hood is determined to be the medium oil smoke scene;

[0104] When ρ>ρ3, the current working scene of the range hood is determined to be a heavy oil smoke scene;

[0105] 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;

[0106] 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.

[0107] The specific control logic in step 5 is:

[0108] When v<Va, the fan gear in the range hood is increased;

[0109] When Va≤v≤Vb, the fan position in the range hood remains unchanged;

[0110] When v>Vb, the fan gear in the range hood is reduced;

[0111] 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.

[0112] In this embodiment, the grille is installed perpendicular to the airflow direction (i.e., the airflow passes through the grille holes from bottom to top to maximize the generation of vortex disturbances to the grille and provide an excitation source). When there is no airflow in the oil smoke channel, the light spot received by the receiving module is a stable circular light spot, such as Figure 1 As shown in the figure; when there is airflow in the oil smoke channel, the grille will vibrate periodically due to the airflow excitation, causing the light intensity and spot position received by the receiving module to fluctuate up and down, as shown in the figure. Figure 2 As shown; therefore, the vibration of the fluid when passing through the grid can be used to change the light path, and then the light intensity attenuation (concentration) and light spot jitter (flow rate) can be simultaneously detected by a single light source.

[0113] Example 2:

[0114] Different from the first embodiment, Figure 4 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 5 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.

[0115] 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 .

[0116] like Figure 4As 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 distributed on the left and right, in this embodiment, the oil fume channel where the first air guide plate 11 and the second air guide plate 12 are located is further provided with a light emitting module 2 and a receiving module 3 used in conjunction with the light emitting module 2.

[0117] In this embodiment, the optical transmitting module 2 is disposed close to the front side of the housing 100 , and the receiving module 3 is disposed close to the rear side of the housing 100 .

[0118] The oil fume passage where the first air deflector 11 is located is referred to as the first oil fume passage, and the optical transmitter module 2 and receiver module 3 within the first oil fume passage are referred to as the first detection module. The oil fume passage where the second air deflector 12 is located is referred to as the second oil fume passage, and the optical transmitter module 2 and receiver module 3 within the second oil fume passage are referred to as the second detection module. The detection processes of the first and second detection modules are independent, and the detection principles are the same.

[0119] This embodiment also discloses a control method for the range hood, which includes the following steps:

[0120] Step a, controlling the first detection module and the second detection module to work respectively;

[0121] Step b, obtaining the oil fume concentration CL in the first oil fume channel, the oil fume concentration CR in the second oil fume channel, the airflow velocity VL in the first oil fume channel, and the airflow velocity VR in the second oil fume channel;

[0122] Step c: Determine whether the maximum value of CL and CR is greater than the set value P. If so, proceed to step c; if not, maintain the fan gear position of the range hood unchanged and proceed to step b.

[0123] The specific value of P is determined based on experiments or experience; in this embodiment, P = 0.5 mg / m3;

[0124] Step d: Determine whether the absolute value of the difference between VL and Vt is less than q times Vt, or whether the absolute value of the difference between VR and Vt is less than q times Vt, where Vt is the set target oil fume flow rate and q∈(0,1). If so, keep the current positions of the first and second air deflectors unchanged; if not, proceed to step e.

[0125] The specific values ​​of Vt and q are determined based on experiments or experience; in this embodiment, q=0.2;

[0126] 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 VL′ in the first oil fume duct and the adjusted airflow velocity VR′ in the second oil fume duct;

[0127] In this embodiment, the positions of the first air deflector and the second air deflector are adjusted as follows:

[0128] Adjust the opening of the first air guide plate to α, and the calculation formula of α is: α=α0+Δα*(CL-CR) / 10;

[0129] Adjust the opening of the second air guide plate to β. The calculation formula of β is: β = β0 - Δβ * (CL - CR) / 10;

[0130] 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;

[0131] In this embodiment, a PID algorithm is used to adjust the fan gear position of the range hood. In this embodiment, the fan gear position is adjusted based on the relationship between the oil fume concentration CL in the first oil fume channel and the oil fume concentration CR in the second oil fume channel. The PID algorithm can make the maximum value of CL and CR less than the set value P.

[0132] Step f: Determine whether VL' is greater than Vt, and VR' is less than or equal to r times Vt, where r∈(0,1). If so, lock the first or second air deflector in its position and proceed to step b. If not, close the first or second air deflector, adjust the range hood fan to its highest setting, and proceed to step b. The specific value of r is determined based on experimentation or experience; in this embodiment, r = 0.3.

[0133] 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.

[0134] 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 grille (1) is arranged in the oil smoke passage (a) perpendicular to the direction of air flow, and the grille (1) is connected to the inner peripheral wall of the oil smoke passage (a); A light emitting module (2) is provided on the wall surface of the oil smoke passage (a), the light emitting module (2) being provided adjacent to the grille (1) and located downstream of the grille (1), the light emitting module (2) being used to emit a parallel light beam perpendicular to the flow direction of the airflow; The receiving module (3) is arranged on a wall surface of the oil smoke passage (a) opposite to the light emitting module (2), and the receiving module (3) is arranged opposite to the light emitting module (2); The controller is electrically connected to the receiving module (3), and is configured to analyze the signal received by the receiving module (3) to obtain the oil smoke concentration in the oil smoke channel (a) and the air flow velocity in the oil smoke channel (a).

2. The range hood according to claim 1, characterized in that: The light beam emitted by the light emitting module (2) is infrared light.

3. The range hood according to claim 2, characterized in that: The wavelength of the infrared light is 850 nm.

4. The range hood according to claim 2, characterized in that: The divergence angle of the parallel light beam emitted by the light emitting module (2) is less than 10°.

5. The range hood according to any one of claims 1 to 4, characterized in that: The receiving module (3) is a photoresistor array composed of a plurality of adjacently arranged photoresistors.

6. The range hood according to claim 5, 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).

7. The range hood according to claim 6, characterized in that: There are two light emitting modules (2), 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 (a) where the first air guide plate (11) and the second air guide plate (12) are located is also respectively provided with a light emitting module (2) and a receiving module (3) used in conjunction with the light emitting module (2).

8. A range hood control method according to claim 5, characterized in that The steps include: Step 1: Control the operation of the optical transmitting module and the receiving module; Step 2: Collect the signal received by the receiving module and analyze the signal received by the receiving module to obtain the oil smoke concentration ρ and 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.

9. The control method according to claim 8, characterized in that: The calculation formula of the oil smoke concentration ρ in step 2 is: Where k is the calibration coefficient, k is a constant, V0 is the reference voltage when the photoresistor array is clean, and Vt is the real-time voltage of the photoresistor array.

10. The control method according to claim 8, characterized in that: The calculation method of the air flow velocity v in step 2 is: according to Calculate the air flow velocity v; Where f is the vibration frequency of the grid, S t is the Trauhal number related to the grille shape, and d is the size of the non-hollow hole in the middle of the grille.

11. The control method according to claim 8, wherein: The calculation method of the air flow velocity v in step 2 is: One of the photoresistors in the photoresistor array is referred to as a first photoresistor, and another photoresistor adjacent to the first photoresistor is referred to as a second photoresistor; The light intensity signal received by the first photoresistor within the set time is recorded as S1(t), and the light intensity signal received by the second photoresistor 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 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; Calculate the cross-correlation function Where m is a constant; Find m 峰值 =argmax R 12 [m]; Calculating time delay but L is the distance between the first photoresistor and the second photoresistor.

12. The control method according to any one of claims 8 to 11, 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.

13. The control method according to any one of claims 8 to 11, characterized in that: 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.

14. A range hood control method according to claim 7, 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 transmitting module and the receiving 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 transmitting module and the receiving 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 CL in the first oil fume channel, the oil fume concentration CR in the second oil fume channel, the airflow velocity VL in the first oil fume channel, and the airflow velocity VR in the second oil fume channel; Step c: Determine whether the maximum value of CL and CR is greater than the set value P. If so, proceed to step c; if not, maintain the fan gear position of the range hood unchanged and proceed to step b. Step d: Determine whether the absolute value of the difference between VL and Vt is less than q times Vt, or whether the absolute value of the difference between VR and Vt is less than q times Vt, where Vt is the set target oil fume flow rate and q∈(0,1). 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 VL′ in the first oil fume duct and the adjusted airflow velocity VR′ in the second oil fume duct; Step f: Determine whether VL′ is greater than Vt, and VR′ is less than or equal to r times Vt, where r∈(0,1). If so, lock the first air guide plate or the second air guide plate in position 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.

15. The control method according to claim 14, 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*(CL-CR) / 10; Adjust the opening of the second air guide plate to β. The calculation formula of β is: β = β0 - Δβ * (CL - CR) / 10; 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.

16. The control method according to claim 14, wherein: In the step e, a PID algorithm is used to adjust the fan gear position of the range hood.

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