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 device is characterized by further comprising a pair or two pairs of ultrasonic transducers, and each pair of ultrasonic transducers comprises a first ultrasonic transducer arranged on the wall surface of the oil smoke channel and a second ultrasonic transducer arranged on the wall surface, opposite to the first ultrasonic transducer, of the oil smoke channel, the second ultrasonic transducer and the first ultrasonic transducer in each pair of ultrasonic transducers oppositely emit ultrasonic waves with the same resonant frequency; and the controller is electrically connected with the first ultrasonic transducer and the second ultrasonic transducer in each pair of ultrasonic transducers. According to the range hood, the oil smoke concentration and the airflow speed can be detected at the same time without an additional flow sensor, 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] The ultrasonic transducers are one or two pairs, each pair of ultrasonic transducers including a first ultrasonic transducer disposed on a wall surface of the oil fume duct and a second ultrasonic transducer disposed on a wall surface of the oil fume duct opposite to the first ultrasonic transducer, wherein the second ultrasonic transducer and the first ultrasonic transducer in each pair of ultrasonic transducers emit ultrasonic waves having the same resonant frequency relative to each other;

[0012] A controller is electrically connected to the first ultrasonic transducer and the second ultrasonic transducer in each pair of ultrasonic transducers. The controller is configured to obtain the oil fume concentration in the oil fume channel based on the attenuation of the ultrasonic wave in the oil fume channel, and to calculate the difference between the downstream ultrasonic wave propagation time and the upstream ultrasonic wave propagation time based on the ultrasonic wave, thereby obtaining the airflow velocity in the oil fume channel.

[0013] Preferably, the ultrasonic transducer is a pair, and the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers can alternately emit ultrasonic waves of a first frequency f1 and ultrasonic waves of a second frequency f2, where f1>f2.

[0014] Preferably, the angle between the ultrasonic waves emitted by the first ultrasonic transducer and the second ultrasonic transducer and the flow direction of the airflow in the oil fume channel is an acute angle.

[0015] Preferably, there are two pairs of ultrasonic transducers, wherein the first ultrasonic transducer and the corresponding second ultrasonic transducer in one pair of ultrasonic transducers can emit ultrasonic waves of a first frequency f1 relative to each other; the first ultrasonic transducer and the corresponding second ultrasonic transducer in the other pair of ultrasonic transducers can emit ultrasonic waves of a second frequency f2, f1>f2, and the ultrasonic waves of the first frequency f1 and the ultrasonic waves of the second frequency f2 are cross-arranged.

[0016] Preferably, the angle θ between the ultrasonic wave of the first frequency f1 and the flow direction of the airflow in the oil fume channel is an acute angle, and the angle β between the ultrasonic wave of the second frequency f2 and the flow direction of the airflow in the oil fume channel is also an acute angle.

[0017] Preferably, θ and β have the same value.

[0018] In order to further improve the detection accuracy, a temperature and humidity sensor is also provided on the wall of the oil fume duct where the first ultrasonic transducer is located, and the temperature and humidity sensor is arranged adjacent to the first ultrasonic transducer, and / or a temperature and humidity sensor is also provided on the wall of the oil fume duct where the second ultrasonic transducer is located, and the temperature and humidity sensor is arranged adjacent to the second ultrasonic transducer.

[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, a pair or two pairs of ultrasonic transducers are respectively provided in the oil fume passage where the first air guide plate and the second air guide plate are located.

[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 first ultrasonic transducer and the second ultrasonic transducer to operate;

[0023] Step 2: Control the first ultrasonic transducer and the second ultrasonic transducer to transmit ultrasonic waves of a first frequency f1, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer to obtain the oil fume concentration ρ in the oil fume channel; and control the first ultrasonic transducer and the second ultrasonic transducer to transmit ultrasonic waves of a second frequency f2, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer to obtain the airflow velocity v in the oil fume 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] 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:

[0028] Step 1: Control the two first ultrasonic transducers and the two second ultrasonic transducers to operate;

[0029] Step 2: Control the first ultrasonic transducer and the corresponding second ultrasonic transducer in one pair of ultrasonic transducers to both transmit ultrasonic waves of a first frequency f1, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers to obtain the oil fume concentration ρ in the oil fume channel; and control the first ultrasonic transducer and the corresponding second ultrasonic transducer in another pair of ultrasonic transducers to both transmit ultrasonic waves of a second frequency f2, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers to obtain the airflow velocity v in the oil fume channel;

[0030] 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;

[0031] Step 4: Determine the current working scene of the range hood according to the value of the oil smoke concentration ρ;

[0032] 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.

[0033] Preferably, the method for obtaining the oil smoke concentration ρ in step 2 is:

[0034]

[0035] Among them, I T and I R are the input voltage and feedback voltage of the first ultrasonic transducer respectively; α is the oil smoke sound absorption coefficient, L is the distance between the first ultrasonic transducer and the second ultrasonic transducer in the horizontal direction, and x is the distance between the first ultrasonic transducer and the second ultrasonic transducer in the vertical direction.

[0036] Preferably, the air flow velocity v in step 2 is obtained by:

[0037] Calculate the difference △t between the ultrasonic propagation time t1 in the downstream direction and the ultrasonic propagation time t2 in the upstream direction;

[0038]

[0039] Wherein, c is the ultrasonic sound velocity when the fan in the range hood is started;

[0040] The air flow velocity v can be calculated based on △t.

[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, and one or two pairs of ultrasonic transducers 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 one or two pairs of ultrasonic transducers 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 C_L in the first oil fume channel, the oil fume concentration C_R in the second oil fume channel, the airflow velocity V_L in the first oil fume channel, and the airflow velocity V_R in the second oil fume channel;

[0055] Step c: Determine the current operating scenario of the corresponding side of the range hood based on the oil fume concentration C_L and the airflow velocity V_L in the first oil fume duct, and set the required flow rate Q_L in the first oil fume duct based on the current operating scenario; and determine the current operating scenario of the corresponding side of the range hood based on the oil fume concentration C_R and the airflow velocity V_R in the second oil fume duct, and set the required flow rate Q_R in the second oil fume duct based on the current operating scenario;

[0056] Step d: Calculate the sum Q_total of Q_L and Q_R, where Q_total corresponds to the total demand flow rate, and determine whether one of the values C_L and C_R is greater than a preset concentration value. If so, increase the opening of the air deflector on the side corresponding to the oil smoke concentration greater than the preset concentration value, and decrease the opening of the air deflector on the other side, and proceed to step e; if not, maintain the current openings of the two air deflectors unchanged, and proceed to step e;

[0057] Step e: determining whether the airflow velocity V_L in the first oil fume duct and the airflow velocity V_R in the second oil fume duct match the total required flow rate Q_total, and changing the fan gear in the range hood accordingly according to different matching results.

[0058] Preferably, the specific control logic in step e is:

[0059] If the total required flow rate Q_total is greater than the exhaust capacity of the air flow velocity V_L in the first oil fume channel and the air flow velocity V_R in the second oil fume channel, the fan gear in the range hood is increased;

[0060] If the total required flow rate Q_total is less than the exhaust capacity of the air flow velocity V_L in the first oil fume channel and the air flow velocity V_R in the second oil fume channel, the fan gear in the range hood is reduced;

[0061] If the total required flow rate Q_total is equal to the exhaust capacity of the airflow velocity V_L in the first oil fume channel and the airflow velocity V_R in the second oil fume channel, the fan gear in the range hood is kept unchanged.

[0062] Preferably, before executing step a, the first air guide plate and the second air guide plate are controlled to have a set opening, and the fan gear position in the range hood is set to a set gear position.

[0063] Compared with existing technologies, the present invention has the following advantages: by installing one or two pairs of ultrasonic transducers in the oil fume duct, and using one pair of ultrasonic transducers to alternately emit ultrasonic waves of two different frequencies, or using two pairs of ultrasonic transducers to emit ultrasonic waves of two different frequencies, the present invention also provides advantages. Low-frequency ultrasonic waves have relatively long wavelengths and are less susceptible to interference from oil. This allows the difference between the downstream and upstream ultrasonic propagation times to be calculated based on the ultrasonic waves, thereby determining the airflow velocity within the oil fume duct. Furthermore, high-frequency ultrasonic waves are easily interfered with by oil fume, enabling concentration detection within the oil fume duct. Therefore, the present range hood can simultaneously detect oil fume concentration and airflow velocity without requiring an additional flow sensor, resulting in low cost and a high level of intelligence. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is a schematic diagram of the installation of a pair of ultrasonic transducers in Example 1 of the present invention (with airflow in the oil fume channel);

[0065] Figure 2 This is a flow chart of a control method for a range hood in Embodiment 1 of the present invention;

[0066] Figure 3 This is a schematic diagram of the installation of two pairs of ultrasonic transducers in the second embodiment of the present invention (with airflow in the oil fume duct);

[0067] Figure 4 This is a schematic diagram of the use status of the range hood in the third embodiment of the present invention;

[0068] Figure 5 This is a side view of the range hood in embodiment 3 of the present invention. DETAILED DESCRIPTION

[0069] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0070] Example 1:

[0071] 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.

[0072] like Figure 1As shown, the range hood also includes a pair of ultrasonic transducers and a controller, the pair of ultrasonic transducers including a first ultrasonic transducer 1 provided on the wall of the oil fume duct a and a second ultrasonic transducer 2 provided on the wall of the oil fume duct a opposite to the first ultrasonic transducer 1, the second ultrasonic transducer 2 and the first ultrasonic transducer 1 in the pair of ultrasonic transducers relatively emit ultrasonic waves with the same resonant frequency; the controller is electrically connected to the first ultrasonic transducer 1 and the second ultrasonic transducer 2 in the pair of ultrasonic transducers, and the controller is configured to: obtain the oil fume concentration in the oil fume duct a according to the attenuation of the ultrasonic wave in the oil fume duct a, and calculate the difference between the downstream ultrasonic wave propagation time and the upstream ultrasonic wave propagation time according to the ultrasonic wave, thereby obtaining the airflow velocity in the oil fume duct a.

[0073] In this embodiment, the first ultrasonic transducer 1 and the second ultrasonic transducer 2 in the pair of ultrasonic transducers can alternately emit ultrasonic waves of a first frequency f1 and an ultrasonic wave of a second frequency f2, where f1>f2. This alternating emission method is used in a time-sharing manner, and the angle between the ultrasonic waves emitted by the first ultrasonic transducer 1 and the second ultrasonic transducer 2 and the direction of the airflow in the oil fume duct a is an acute angle. In this embodiment, the first frequency f1 is 120Khz, and the second frequency f2 is 40Khz. By emitting two frequencies of ultrasonic waves through the same ultrasonic transducer, the efficiency of this method is reduced, but the cost is lower, and this solution can be used when the accuracy requirements are not high.

[0074] A temperature and humidity sensor 3 is also provided on the wall of the oil fume duct a where the first ultrasonic transducer 1 is located, and the temperature and humidity sensor 3 is arranged adjacent to the first ultrasonic transducer 1, and / or a temperature and humidity sensor 3 is also provided on the wall of the oil fume duct a where the second ultrasonic transducer 2 is located, and the temperature and humidity sensor 3 is arranged adjacent to the second ultrasonic transducer 2.

[0075] like Figure 2 As shown, this embodiment also discloses a control method for the range hood, which includes the following steps:

[0076] Step 1: Control the first ultrasonic transducer and the second ultrasonic transducer to operate;

[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: Control the first ultrasonic transducer and the second ultrasonic transducer to transmit ultrasonic waves of a first frequency f1, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer to obtain the oil fume concentration ρ in the oil fume channel; and control the first ultrasonic transducer and the second ultrasonic transducer to transmit ultrasonic waves of a second frequency f2, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer to obtain the airflow velocity v in the oil fume channel;

[0079] In this embodiment 2, the method for obtaining the oil smoke concentration ρ is:

[0080]

[0081] Among them, I T and I R are the input voltage and feedback voltage of the first ultrasonic transducer respectively; α is the oil smoke sound absorption coefficient, L is the distance between the first ultrasonic transducer and the second ultrasonic transducer in the horizontal direction, and x is the distance between the first ultrasonic transducer and the second ultrasonic transducer in the vertical direction;

[0082] Since the Beer-Lambert law reveals the relationship between the degree of absorption and the concentration of the absorbent, the modified Beer-Lambert law can be used to obtain the calculation formula for the oil smoke concentration ρ. The above-mentioned α can be obtained through experimental calibration. In this embodiment, 120kHz continuous pulses (duty cycle 10%) are transmitted, and the receiving end measures the signal amplitude attenuation and dynamically compensates for the influence of temperature and humidity (for every 10% increase in humidity, α is corrected by a certain value, such as +1.2%). The output concentration level is, for example, 0-10mg / m 3 (The measuring range can be modified according to the actual machine);

[0083] In this embodiment 2, the air flow velocity v is obtained as follows:

[0084] Calculate the difference △t between the ultrasonic propagation time t1 in the downstream direction and the ultrasonic propagation time t2 in the upstream direction;

[0085]

[0086] Wherein, c is the ultrasonic sound velocity when the fan in the range hood is started;

[0087] The air flow velocity v can be calculated based on △t;

[0088] The principle of obtaining the above-mentioned airflow velocity and oil fume concentration is as follows: the second frequency f2 (40Khz) has a relatively long wavelength compared to the first frequency f1 (120Khz) of the ultrasonic wave, so it is not easily interfered with by the oil. When the sound propagates in the medium, the first frequency f1 (120Khz) of the ultrasonic wave has a relatively shorter wavelength and is more easily affected by parameters such as the medium concentration. Therefore, the propagation time difference of the bidirectional sound wave in the downstream / reverse flow of the oil fume gas is measured. Combined with the fact that high-frequency ultrasonic waves are easily interfered with by oil fume, the synchronous detection of airflow velocity and concentration is achieved.

[0089] 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;

[0090] Step 4: Determine the current working scene of the range hood according to the value of the oil smoke concentration ρ;

[0091] The specific control logic of step 4 is:

[0092] When ρ<ρ2, it is determined that the current working scene of the range hood is a low-oil smoke scene;

[0093] When ρ2≤ρ≤ρ3, the current working scene of the range hood is determined to be the medium oil smoke scene;

[0094] When ρ>ρ3, the current working scene of the range hood is determined to be a heavy oil smoke scene;

[0095] 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;

[0096] 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.

[0097] The specific control logic in step 5 is:

[0098] When v<Va, the fan gear in the range hood is increased;

[0099] When Va≤v≤Vb, the fan position in the range hood remains unchanged;

[0100] When v>Vb, the fan gear in the range hood is reduced;

[0101] 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.

[0102] Example 2:

[0103] like Figure 3 As shown, different from the first embodiment, the ultrasonic transducers in this embodiment are two pairs, wherein the first ultrasonic transducer 1 and the corresponding second ultrasonic transducer 2 in one pair of ultrasonic transducers relatively emit ultrasonic waves of a first frequency f1; the first ultrasonic transducer 1 and the corresponding second ultrasonic transducer 2 in the other pair of ultrasonic transducers can emit ultrasonic waves of a second frequency f2, f1>f2, and the ultrasonic waves of the first frequency f1 and the second frequency f2 are cross-arranged.

[0104] The angle θ between the ultrasonic wave of the first frequency f1 and the airflow direction in the oil fume channel a is an acute angle, and the angle β between the ultrasonic wave of the second frequency f2 and the airflow direction in the oil fume channel a is also an acute angle. θ and β have the same value.

[0105] This embodiment also discloses a control method for the range hood, which includes the following steps:

[0106] Step 1: Control the two first ultrasonic transducers and the two second ultrasonic transducers to operate;

[0107] Step 2: Control the first ultrasonic transducer and the corresponding second ultrasonic transducer in one pair of ultrasonic transducers to both transmit ultrasonic waves of a first frequency f1, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers to obtain the oil fume concentration ρ in the oil fume channel; and control the first ultrasonic transducer and the corresponding second ultrasonic transducer in another pair of ultrasonic transducers to both transmit ultrasonic waves of a second frequency f2, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers to obtain the airflow velocity v in the oil fume channel;

[0108] 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;

[0109] Step 4: Determine the current working scene of the range hood according to the value of the oil smoke concentration ρ;

[0110] The specific control logic of step 4 is:

[0111] When ρ<ρ2, it is determined that the current working scene of the range hood is a low-oil smoke scene;

[0112] When ρ2≤ρ≤ρ3, the current working scene of the range hood is determined to be the medium oil smoke scene;

[0113] When ρ>ρ3, the current working scene of the range hood is determined to be a heavy oil smoke scene;

[0114] 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;

[0115] 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.

[0116] The specific control logic in step 5 is:

[0117] When v<Va, the fan gear in the range hood is increased;

[0118] When Va≤v≤Vb, the fan position in the range hood remains unchanged;

[0119] When v>Vb, the fan gear in the range hood is reduced;

[0120] 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.

[0121] Example 3:

[0122] 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.

[0123] 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 .

[0124] like Figure 4 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 distributed on the left and right, in this embodiment, a pair or two pairs of ultrasonic transducers are respectively provided in the oil fume channel where the first air guide plate 11 and the second air guide plate 12 are located.

[0125] The oil fume passage where the first air guide plate is located is referred to as the first oil fume passage, and the pair or two pairs of ultrasonic transducers 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 pair or two pairs of ultrasonic transducers in the second oil fume passage are referred to as the second detection module.

[0126] This embodiment also discloses a control method for the range hood, which includes the following steps:

[0127] Step a, controlling the first detection module and the second detection module to work respectively;

[0128] Step b, obtaining the oil fume concentration C_L in the first oil fume channel, the oil fume concentration C_R in the second oil fume channel, the airflow velocity V_L in the first oil fume channel, and the airflow velocity V_R in the second oil fume channel;

[0129] Step c: Determine the current operating scenario of the corresponding side of the range hood based on the oil fume concentration C_L and the airflow velocity V_L in the first oil fume duct, and set the required flow rate Q_L in the first oil fume duct based on the current operating scenario; and determine the current operating scenario of the corresponding side of the range hood based on the oil fume concentration C_R and the airflow velocity V_R in the second oil fume duct, and set the required flow rate Q_R in the second oil fume duct based on the current operating scenario;

[0130] In this embodiment, the required flow rates for different working scenarios can be confirmed based on experiments or experience, and will not be elaborated here. The range of oil fume concentration values, air flow velocity value ranges, and required flow rates for different working scenarios are first confirmed through experience, so the working scenarios (stir-frying, frying, steaming, or idle, etc.) can be matched by looking up a table.

[0131] Step d: Calculate the sum Q_total of Q_L and Q_R, where Q_total corresponds to the total demand flow rate, and determine whether one of the values C_L and C_R is greater than a preset concentration value. If so, increase the opening of the air deflector on the side corresponding to the oil smoke concentration greater than the preset concentration value, and decrease the opening of the air deflector on the other side, and proceed to step e; if not, maintain the current openings of the two air deflectors unchanged, and proceed to step e;

[0132] Step e: determining whether the airflow velocity V_L in the first oil fume duct and the airflow velocity V_R in the second oil fume duct match the total required flow rate Q_total, and changing the fan gear of the range hood accordingly according to different matching results;

[0133] If the total required flow rate Q_total is greater than the exhaust capacity of the air flow velocity V_L in the first oil fume channel and the air flow velocity V_R in the second oil fume channel, the fan gear in the range hood is increased;

[0134] If the total required flow rate Q_total is less than the exhaust capacity of the air flow velocity V_L in the first oil fume channel and the air flow velocity V_R in the second oil fume channel, the fan gear in the range hood is reduced;

[0135] If the total required flow rate Q_total is equal to the exhaust capacity of the airflow velocity V_L in the first oil fume channel and the airflow velocity V_R in the second oil fume channel, the fan gear in the range hood is kept unchanged.

[0136] The smoke exhaust capacity corresponding to the air flow velocity in this embodiment can be obtained based on the existing technology, so the comparison between the total required flow rate and the smoke exhaust capacity in this embodiment can also be achieved.

[0137] In addition, before executing step a, the first air guide plate and the second air guide plate are controlled to have a set opening, and the fan gear position of the range hood is set to a set gear position. In this embodiment, the set opening is 50% and the set gear position is medium.

[0138] 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: The ultrasonic transducers are one or two pairs, each pair of ultrasonic transducers comprising a first ultrasonic transducer (1) disposed on a wall surface of an oil fume passage (a) and a second ultrasonic transducer (2) disposed on a wall surface of the oil fume passage (a) opposite to the first ultrasonic transducer (1), wherein the second ultrasonic transducer (2) and the first ultrasonic transducer (1) in each pair of ultrasonic transducers emit ultrasonic waves having the same resonant frequency relative to each other; A controller is electrically connected to the first ultrasonic transducer (1) and the second ultrasonic transducer (2) in each pair of ultrasonic transducers. The controller is configured to obtain the oil smoke concentration in the oil smoke channel (a) based on the attenuation of the ultrasonic wave in the oil smoke channel (a), and to calculate the difference between the downstream ultrasonic wave propagation time and the upstream ultrasonic wave propagation time based on the ultrasonic wave, thereby obtaining the air flow velocity in the oil smoke channel (a).

2. The range hood according to claim 1, characterized in that: The ultrasonic transducers are a pair, wherein the first ultrasonic transducer (1) and the second ultrasonic transducer (2) in the pair of ultrasonic transducers can alternately emit ultrasonic waves of a first frequency f1 and ultrasonic waves of a second frequency f2, where f1>f2.

3. The range hood according to claim 2, characterized in that: The angle between the ultrasonic waves emitted relatively by the first ultrasonic transducer (1) and the second ultrasonic transducer (2) and the flow direction of the airflow in the oil smoke channel (a) is an acute angle.

4. The range hood according to claim 1, wherein: The ultrasonic transducers are in two pairs, wherein the first ultrasonic transducer (1) and the corresponding second ultrasonic transducer (2) in one pair of ultrasonic transducers can emit ultrasonic waves of a first frequency f1 relative to each other; and the first ultrasonic transducer (1) and the corresponding second ultrasonic transducer (2) in the other pair of ultrasonic transducers can emit ultrasonic waves of a second frequency f2, f1>f2, and the ultrasonic waves of the first frequency f1 and the ultrasonic waves of the second frequency f2 are arranged crosswise.

5. The range hood according to claim 4, characterized in that: The angle θ between the ultrasonic wave of the first frequency f1 and the flow direction of the airflow in the oil fume channel (a) is an acute angle, and the angle β between the ultrasonic wave of the second frequency f2 and the flow direction of the airflow in the oil fume channel (a) is also an acute angle.

6. The range hood according to claim 5, characterized in that: The values of θ and β are the same.

7. The range hood according to any one of claims 1 to 6, characterized in that: A temperature and humidity sensor (3) is further provided on the wall surface of the oil fume duct (a) where the first ultrasonic transducer (1) is located, and the temperature and humidity sensor (3) is arranged adjacent to the first ultrasonic transducer (1); and / or a temperature and humidity sensor (3) is further provided on the wall surface of the oil fume duct (a) where the second ultrasonic transducer (2) is located, and the temperature and humidity sensor (3) is arranged adjacent to the second ultrasonic transducer (2).

8. The range hood according to any one of claims 1 to 7, 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).

9. The range hood according to claim 8, characterized in that: A pair or two pairs of ultrasonic transducers are respectively provided in the oil fume passage (a) where the first air guide plate (11) and the second air guide plate (12) are located.

10. A range hood control method as claimed in claim 2 or 3, characterized in that The steps include: Step 1: Control the first ultrasonic transducer and the second ultrasonic transducer to operate; Step 2: Control the first ultrasonic transducer and the second ultrasonic transducer to transmit ultrasonic waves of a first frequency f1, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer to obtain the oil fume concentration ρ in the oil fume channel; and control the first ultrasonic transducer and the second ultrasonic transducer to transmit ultrasonic waves of a second frequency f2, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer to obtain the airflow velocity v in the oil fume 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.

11. A control method for a range hood according to any one of claims 4 to 6, characterized in that The steps include: Step 1: Control the two first ultrasonic transducers and the two second ultrasonic transducers to operate; Step 2: Control the first ultrasonic transducer and the corresponding second ultrasonic transducer in one pair of ultrasonic transducers to both transmit ultrasonic waves of a first frequency f1, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers to obtain the oil fume concentration ρ in the oil fume channel; and control the first ultrasonic transducer and the corresponding second ultrasonic transducer in another pair of ultrasonic transducers to both transmit ultrasonic waves of a second frequency f2, collect signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers, and analyze the signals received by the first ultrasonic transducer and the second ultrasonic transducer in the pair of ultrasonic transducers to obtain the airflow velocity v in the oil fume 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.

12. The control method according to claim 10 or 11, characterized in that: The method for obtaining the oil smoke concentration ρ in step 2 is: Among them, I T and I R are the input voltage and feedback voltage of the first ultrasonic transducer respectively; α is the oil smoke sound absorption coefficient, L is the distance between the first ultrasonic transducer and the second ultrasonic transducer in the horizontal direction, and x is the distance between the first ultrasonic transducer and the second ultrasonic transducer in the vertical direction.

13. The control method according to claim 12, characterized in that: The air flow velocity v in step 2 is obtained as follows: Calculate the difference △t between the ultrasonic propagation time t1 in the downstream direction and the ultrasonic propagation time t2 in the upstream direction; Wherein, c is the ultrasonic sound velocity when the fan in the range hood is started; The air flow velocity v can be calculated based on △t.

14. The control method according to claim 10 or 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.

15. The control method according to claim 10 or 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.

16. A range hood control method according to claim 9, characterized in that: The oil fume passage where the first air guide plate is located is referred to as the first oil fume passage, and the pair or two pairs of ultrasonic transducers 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 pair or two pairs of ultrasonic transducers in the second oil fume passage 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 C_L in the first oil fume channel, the oil fume concentration C_R in the second oil fume channel, the airflow velocity V_L in the first oil fume channel, and the airflow velocity V_R in the second oil fume channel; Step c: Determine the current operating scenario of the corresponding side of the range hood based on the oil fume concentration C_L and the airflow velocity V_L in the first oil fume duct, and set the required flow rate Q_L in the first oil fume duct based on the current operating scenario; and determine the current operating scenario of the corresponding side of the range hood based on the oil fume concentration C_R and the airflow velocity V_R in the second oil fume duct, and set the required flow rate Q_R in the second oil fume duct based on the current operating scenario; Step d: Calculate the sum Q_total of Q_L and Q_R, where Q_total corresponds to the total demand flow rate, and determine whether one of the values C_L and C_R is greater than a preset concentration value. If so, increase the opening of the air deflector on the side corresponding to the oil smoke concentration greater than the preset concentration value, and decrease the opening of the air deflector on the other side, and proceed to step e; if not, maintain the current openings of the two air deflectors unchanged, and proceed to step e; Step e: determining whether the airflow velocity V_L in the first oil fume duct and the airflow velocity V_R in the second oil fume duct match the total required flow rate Q_total, and changing the fan gear in the range hood accordingly according to different matching results.

17. The control method according to claim 16, characterized in that: The specific control logic in step e is: If the total required flow rate Q_total is greater than the exhaust capacity of the air flow velocity V_L in the first oil fume channel and the air flow velocity V_R in the second oil fume channel, the fan gear in the range hood is increased; If the total required flow rate Q_total is less than the exhaust capacity of the air flow velocity V_L in the first oil fume channel and the air flow velocity V_R in the second oil fume channel, the fan gear in the range hood is reduced; If the total required flow rate Q_total is equal to the exhaust capacity of the airflow velocity V_L in the first oil fume channel and the airflow velocity V_R in the second oil fume channel, the fan gear in the range hood is kept unchanged.

18. The control method according to claim 16, wherein: Before executing step a, the first air guide plate and the second air guide plate are controlled to have a set opening, and the fan gear position in the range hood is set to a set gear position.

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