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 corona pin is arranged in the oil smoke channel and is used for carrying out corona on air and generating ion cloud capable of migrating along with airflow; the driving ring is arranged in the oil smoke channel and is positioned at the downstream of the corona pin; the current detection module is used for detecting current between the corona pin and the driving ring; the first detection ring is arranged in the oil smoke channel and is positioned at the downstream of the driving ring; the second detection ring is arranged in the oil smoke channel and is positioned at the downstream of the first detection ring; the tip of the corona pin, the driving ring, the first detection ring and the second detection ring are coaxially arranged; and the controller is electrically connected with the first detection ring, the second detection ring and the current detection module. The detection device can be used for detecting the airflow velocity, the oil smoke concentration and the humidity in the oil smoke channel, the cost is low, and the problems of installation conflict and signal interference of multiple detection sensors can be solved.

Description

Technical Field

[0001] This invention relates to the field of oil fume purification technology, and in particular to an oil fume extractor and its control method. Background Technology

[0002] As an essential kitchen appliance in every household, the range hood works by using a high-speed rotating impeller in the casing to draw in cooking fumes from the air inlet, filter the fumes using the impeller, and then expel the filtered fumes from the air outlet, thus purifying the kitchen air.

[0003] Traditional range hoods operate with fixed speeds or settings, requiring users to manually select the appropriate setting based on different scenarios such as stir-frying or steaming. However, users typically engage in various cooking activities that affect the amount of smoke generated in the cooking area, such as stir-frying, adding ingredients, or lifting the lid to create a sudden surge of smoke or steam. Traditional range hoods with fixed speeds or settings struggle to adapt to these unexpected situations.

[0004] To address the aforementioned technical issues, Chinese utility model patent ZL201922181387.6 (authorization announcement number CN211290212U) discloses an automatic start-stop integrated oil fume purification machine, including a fume hood, an oil fume purifier, and a fan. It also includes a detection device and a manual switch. The fan has low-power and high-power states. The manual switch controls the fan to initially operate in low-power mode. The detection device detects oil fumes and water vapor in the kitchen air. If oil fumes are detected, a first feedback signal is issued; if only water vapor is detected, a second feedback signal is issued. The controller of the oil fume purifier responds to the first feedback signal by controlling the oil fume purifier to start and the fan to operate in high-power mode. The controller of the oil fume purifier responds to the second feedback signal by controlling the oil fume purifier to stop and the fan to shut down in high-power mode.

[0005] While the aforementioned integrated fume purification system can detect oil fumes and water vapor in the kitchen air using humidity and smoke sensors, the smoke sensor detects smoke concentration based on changes in light flux or scattering when smoke is present. If oil fumes and water vapor are mixed, it cannot distinguish between them, leading to inaccurate scene assessment. Furthermore, in actual use, oil fume conditions are complex, and the real-time correlation between airflow speed and oil fume concentration cannot be obtained during range hood operation, potentially resulting in poor fume extraction or excessive fan noise. Therefore, an additional flow sensor is needed to determine if the current oil fume concentration matches the airflow speed, which is costly and lacks a high level of intelligence. Further improvements to the existing technology are therefore necessary. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a range hood that can simultaneously measure humidity, oil fume concentration and airflow speed to distinguish between water vapor and oil fume in the oil fume channel, in contrast to the above-mentioned prior art.

[0007] 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 realize automatic control of different cooking scenarios and dynamically adjust the fan speed of the range hood.

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

[0009] The casing has an oil fume duct;

[0010] Its features also include:

[0011] A corona needle, located within the fume duct, is used to corona the air, generating an ion cloud that can migrate with the airflow.

[0012] A drive ring is disposed within the fume duct, along the fluid flow path, and is located downstream of the corona needle;

[0013] The current detection module is used to detect the current between the corona needle and the drive ring;

[0014] The first detection ring is located in the fume duct, along the fluid flow path, and is downstream of the drive ring;

[0015] The second detection ring is located within the fume duct, along the fluid flow path, downstream of the first detection ring; the tip of the corona needle, the drive ring, the first detection ring, and the second detection ring are arranged coaxially.

[0016] The controller is electrically connected to the first detection ring, the second detection ring, and the current detection module. The controller is configured to: obtain the airflow velocity and oil fume concentration in the fume channel based on the detection results of the first and second detection rings, and obtain the humidity in the fume channel based on the detection results of the current detection module, thereby distinguishing between water vapor and oil fume in the fume channel.

[0017] To apply the pulse voltage, the corona needle is electrically connected to a high-frequency pulse generator.

[0018] To shorten the response time, the drive ring, the first detection ring, and the second detection ring are arranged along the direction of oil fume flow perpendicular to the oil fume channel.

[0019] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: a control method for a range hood as described above, wherein a fan is provided inside the casing, characterized by comprising the following steps:

[0020] Step 1: Control the high-frequency pulse generator to make the corona needle corona the air, thereby generating an ion cloud in the fume channel. The ion cloud migrates towards the first and second detection rings under the action of the airflow in the fume channel.

[0021] The time difference Δt between the peak current captured by the first and second detection loops is collected, and the current values ​​detected by the first and second detection loops are recorded respectively.

[0022] Step 2: Control the high-frequency pulse generator to not work, and detect the current between the corona needle and the drive ring through the current detection module;

[0023] Step 3: Capture the peak current based on the time difference between the first and second detection loops. The airflow velocity in the fume duct is calculated, and the fume concentration in the fume duct is calculated based on the current values ​​detected by the first and second detection rings. Additionally, the current between the corona needle and the drive ring is detected by the current detection module. Calculate the humidity in the fume extraction duct;

[0024] Step 4: Determine the current cooking scenario based on the different values ​​of airflow velocity, oil fume concentration and humidity in the fume duct, and control the fan to perform corresponding actions according to different cooking scenarios.

[0025] Preferably, the airflow velocity in step 3 is... The calculation formula is:

[0026]

[0027] in, The time difference between the first and second detection rings capturing the peak current when there is no airflow in the fume duct; This is the distance between the drive ring and the first detection ring.

[0028] Preferably, the oil fume concentration in step 3 is... The calculation formula is:

[0029]

[0030] in, This is a calibration coefficient, which is related to the dielectric constant of oil fume particles; The current attenuation coefficient is... , This is the current value detected by the first detection ring. This is the current value detected by the second detection ring.

[0031] Preferably, the humidity in step 3 The calculation formula is:

[0032]

[0033] in, This represents the current offset caused by humidity. , This is the reference current when there is no high-voltage pulse, that is, the current value between the corona needle and the drive ring when there is no high-voltage pulse. This is the reference current under dry air conditions.

[0034] Preferably, the specific control logic for determining the current cooking scenario in step 4 is as follows:

[0035] When the airflow velocity > And the concentration of oil fumes > If so, the current cooking scenario is determined to be a stir-fry scenario;

[0036] When humidity And airflow velocity < If so, the current cooking scenario is determined to be a steaming or boiling scenario;

[0037] When the concentration of oil fumes > and humidity satisfy < If so, the current cooking scenario is determined to be a frying scenario;

[0038] in and These are the first set airflow velocity and the second set airflow velocity, respectively. ; and These are the first and second set oil fume concentrations, respectively. ; , and These are the first set humidity, the second set humidity, and the third set humidity, respectively. > > .

[0039] Preferably, the specific control logic for controlling the fan to perform corresponding actions according to different cooking scenarios in step 4 is as follows:

[0040] If the current cooking scenario is stir-frying, increase the operating level of the fan;

[0041] If the cooking scenario is steaming or boiling, adjust the fan speed to medium and dehumidify and exhaust.

[0042] If the current cooking scenario is frying, the fan speed will be controlled in a step-by-step manner.

[0043] Preferably, in step 3 if Less than the first set time difference ,or If the current exceeds the first set current I, then the first and second detection rings are determined to be in an abnormal working state.

[0044] Preferably, after determining that the first detection ring and the second detection ring are in an abnormal working state, the method further includes the following steps: controlling the corona needle to discharge so that the corona needle can perform self-cleaning.

[0045] Preferably, before step 1, the following step is further included: controlling the corona needle to discharge so that the corona needle can perform self-cleaning.

[0046] Compared with existing technologies, the advantages of this invention are as follows: By corona-electrode the air through a corona needle in the fume extraction channel, an ion cloud that migrates with the airflow is generated, allowing the airflow velocity to be calculated using the ion migration time difference. Furthermore, the current attenuation caused by the adsorption of ions by fume particles during migration allows the fume concentration to be calculated using the current attenuation coefficient. Additionally, the ionization efficiency can be altered by water molecules, allowing the humidity in the fume extraction channel to be calculated using the current value between the corona needle and the drive ring when there is no high-voltage pulse. Therefore, a single detection device can be used to detect the airflow velocity, fume concentration, and humidity in the fume extraction channel, resulting in low cost and resolving the problems of conflicting installations and signal interference between multiple sensors. This range hood can accurately identify different cooking scenarios and adjust the fan speed accordingly, improving the user experience. Attached Figure Description

[0047] Figure 1 This is a schematic diagram illustrating the use of the range hood according to an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram illustrating the operation of the corona needle, driving ring, first detection ring, and second detection ring in an embodiment of the present invention. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0050] like Figure 1 As shown, the range hood in this embodiment includes a housing 1 and a fan (not shown in the figure). The housing 1 has an oil fume duct 10, and the fan is located inside the oil fume duct 10. The fan uses existing technology and will not be described in detail here. A stove a is provided below the range hood.

[0051] like Figure 2As shown, the range hood in this embodiment also includes a corona needle 2, a drive ring 3, a current detection module, a first detection ring 4, a second detection ring 5, and a controller. The corona needle 2, drive ring 3, first detection ring 4, and second detection ring 5 are all located within the fume duct 10. The corona needle 2 is used to corona-electrode the air, generating an ion cloud that can migrate with the airflow. Along the fluid flow path, the drive ring 3 is located downstream of the corona needle 2; the first detection ring 4 is located downstream of the drive ring 3; and the second detection ring 5 is located downstream of the first detection ring 4. The tip of the corona needle 2, the drive ring 3, the first detection ring 4, and the second detection ring 5 are coaxially arranged (error ≤ 0.1mm) to ensure the symmetry of the electric field along the ion migration path (because the coaxial layout allows the ion cloud to diffuse along the central axis, avoiding time difference (Δt) measurement errors caused by electric field distortion). In this embodiment, the installation method of the corona needle 2, drive ring 3, first detection ring 4, and second detection ring 5 adopts existing technology. Figure 2 As shown, in this embodiment, the corona needle 2 can be made of tungsten steel, and the drive ring 3, the first detection ring 4 and the second detection ring 5 are all made of stainless steel wire rings, and the diameters of the drive ring 3, the first detection ring 4 and the second detection ring 5 gradually increase.

[0052] The current detection module is used to detect the current between the corona needle 2 and the drive ring 3; the controller is electrically connected to the first detection ring 4, the second detection ring 5 and the current detection module. The controller is configured to: obtain the airflow velocity and oil fume concentration in the fume channel 10 according to the detection results of the first detection ring 4 and the second detection ring 5, and obtain the humidity in the fume channel 10 according to the detection results of the current detection module, thereby distinguishing the water vapor and oil fume conditions in the fume channel 10.

[0053] In this embodiment, the corona needle 2 is electrically connected to a high-frequency pulse generator (not shown in the figure). The high-frequency pulse generator is used to apply a pulse voltage to the corona needle 2. Because the ion cloud rises naturally and is in the same direction as the exhaust airflow of the range hood, in order to shorten the response time, and because gravity can prevent the accumulation of oil on the electrode surface, and with high-pressure self-cleaning, maintenance is not required, the drive ring 3, the first detection ring 4, and the second detection ring 5 are arranged along the direction of oil fume flow perpendicular to the oil fume channel 10.

[0054] This embodiment also relates to a control method for the range hood described above, which includes the following steps:

[0055] Step 1: Control the high-frequency pulse generator to make the corona needle corona the air, thereby generating an ion cloud in the fume channel. The ion cloud migrates towards the first and second detection rings under the action of the airflow in the fume channel.

[0056] The time difference Δt between the peak current captured by the first and second detection loops is collected, and the current values ​​detected by the first and second detection loops are recorded respectively.

[0057] Before step 1, the following steps are also included: controlling the corona needle to discharge so that the corona needle can perform self-cleaning;

[0058] Step 2: Control the high-frequency pulse generator to not work, and detect the current between the corona needle and the drive ring through the current detection module;

[0059] Step 3: Capture the peak current based on the time difference between the first and second detection loops. The airflow velocity in the fume duct is calculated, and the fume concentration in the fume duct is calculated based on the current values ​​detected by the first and second detection rings. Additionally, the current between the corona needle and the drive ring is detected by the current detection module. Calculate the humidity in the fume extraction duct;

[0060] In this embodiment, the airflow velocity The calculation formula is:

[0061]

[0062] in, The time difference between the first and second detection rings capturing the peak current when there is no airflow in the fume duct; The distance between the drive ring and the first detection ring;

[0063] The above This inherent delay can be determined through calibration experiments. This airflow velocity calculation method separates the velocity signal using the time-difference method, avoiding interference from the mechanical structure of traditional anemometers and improving resolution to [specific value missing]. This is more in line with the accuracy of capturing airflow inside the range hood;

[0064] In this embodiment, the oil fume concentration The calculation formula is:

[0065]

[0066] in, This is a calibration coefficient, which is related to the dielectric constant of oil fume particles; The current attenuation coefficient is... , This is the current value detected by the first detection ring. The current value detected by the second detection ring;

[0067] The above It was also determined through calibration experiments that ions collide with and adsorb onto oil fume particles during migration, leading to a decrease in the number of ions. Therefore, the current of the second detection ring... It must be less than The current attenuation coefficient α is positively correlated with the oil fume concentration, therefore the above formula is obtained through... Correcting the nonlinear adsorption effect to achieve the desired concentration It exhibits an approximately linear relationship with α; this method for calculating oil fume concentration utilizes ion adsorption effect and spatial difference detection, eliminating the need for optical sensors and avoiding the problem of oil smudge obstruction.

[0068] In this embodiment, humidity The calculation formula is:

[0069]

[0070] in, This represents the current offset caused by humidity. , This is the reference current when there is no high-voltage pulse, that is, the current value between the corona needle and the drive ring when there is no high-voltage pulse. The reference current under dry air; as described above. These are the factory calibration values;

[0071] The relationship between ionization efficiency and humidity: Water molecules in the air lower the air breakdown voltage, resulting in a decrease in ionization current at the same voltage. The current-humidity relationship increases with increasing humidity (RH); experiments have confirmed that the current-humidity relationship conforms to the characteristics of a power function, with the exponent... To fit the optimal value; using As a benchmark, the influence of temperature on ionization efficiency is eliminated; in the absence of high-voltage pulses, a constant low voltage, typically +100V DC, is applied to the corona needle, with the drive ring grounded. The process flows from the corona needle to the air medium and then to the drive ring, creating a small ionization current. This humidity calculation method integrates humidity detection into the baseline characteristics of the ionization module, eliminating the need for a separate humidity sensor and reducing system complexity.

[0072] In this embodiment, if Less than the first set time difference ,or If the current exceeds the first set current I, the first and second detection rings are determined to be in an abnormal working state. After determining that the first and second detection rings are in an abnormal working state, the following steps are also included: controlling the corona needle to discharge so that the corona needle can perform self-cleaning and trigger an alarm. The specific values ​​of I and can be determined based on experiments or experience. In this embodiment... I = 2mA;

[0073] Step 4: Determine the current cooking scenario based on the different values ​​of airflow velocity, oil fume concentration and humidity in the fume duct, and control the fan to perform corresponding actions according to different cooking scenarios;

[0074] The specific control logic for determining the current cooking scenario is as follows:

[0075] When the airflow velocity > And the concentration of oil fumes > If so, the current cooking scenario is determined to be a stir-fry scenario;

[0076] When humidity And airflow velocity < If so, the current cooking scenario is determined to be a steaming or boiling scenario;

[0077] When the concentration of oil fumes > and humidity satisfy < If so, the current cooking scenario is determined to be a frying scenario;

[0078] in and These are the first set airflow velocity and the second set airflow velocity, respectively. ; and These are the first and second set oil fume concentrations, respectively. ; , and These are the first set humidity, the second set humidity, and the third set humidity, respectively. > > ;

[0079] , , , and The specific value can be determined based on experiments or experience. In this embodiment... =5m / s, =2m / s, =30mg / m³, =25mg / m³, , , ;

[0080] The specific control logic for controlling the fan to perform corresponding actions based on different cooking scenarios is as follows:

[0081] If the current cooking scenario is stir-frying, increase the operating level of the fan;

[0082] If the cooking scenario is steaming or boiling, adjust the fan speed to medium and dehumidify and exhaust.

[0083] If the current cooking scenario is frying, the fan speed will be controlled in a step-by-step manner.

[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A range hood, comprising: The casing (1) has an oil fume duct (10); Its features also include: A corona needle (2) is placed in the fume channel (10) to corona the air and generate an ion cloud that can migrate with the airflow. A drive ring (3) is located in the fume channel (10) along the fluid flow path, downstream of the corona needle (2); A current detection module is used to detect the current between the corona needle (2) and the drive ring (3); The first detection ring (4) is located in the fume channel (10) along the fluid flow path, and the first detection ring (4) is located downstream of the drive ring (3); The second detection ring (5) is located in the fume channel (10) along the fluid flow path, and is downstream of the first detection ring (4); the tip of the corona needle (2), the drive ring (3), the first detection ring (4) and the second detection ring (5) are arranged coaxially. The controller is electrically connected to the first detection ring (4), the second detection ring (5) and the current detection module. The controller is configured to: obtain the airflow velocity and oil fume concentration in the oil fume channel (10) based on the detection results of the first detection ring (4) and the second detection ring (5), and obtain the humidity in the oil fume channel (10) based on the detection results of the current detection module, thereby distinguishing the water vapor and oil fume conditions in the oil fume channel (10).

2. The range hood according to claim 1, characterized in that: The corona needle (2) is electrically connected to a high-frequency pulse generator.

3. The range hood according to claim 1 or 2, characterized in that: The drive ring (3), the first detection ring (4), and the second detection ring (5) are arranged along the direction of oil fume flow perpendicular to the oil fume channel (10).

4. A control method for a range hood as described in claim 2 or 3, wherein a fan is provided inside the casing, characterized in that... Includes the following steps: Step 1: Control the high-frequency pulse generator to make the corona needle corona the air, thereby generating an ion cloud in the fume channel. The ion cloud migrates towards the first and second detection rings under the action of the airflow in the fume channel. The time difference Δt between the peak current captured by the first and second detection loops is collected, and the current values ​​detected by the first and second detection loops are recorded respectively. Step 2: Control the high-frequency pulse generator to not work, and detect the current between the corona needle and the drive ring through the current detection module; Step 3: Capture the peak current based on the time difference between the first and second detection loops. The airflow velocity in the fume duct is calculated, and the fume concentration in the fume duct is calculated based on the current values ​​detected by the first and second detection rings. Additionally, the current between the corona needle and the drive ring is detected by the current detection module. Calculate the humidity in the fume extraction duct; Step 4: Determine the current cooking scenario based on the different values ​​of airflow velocity, oil fume concentration and humidity in the fume duct, and control the fan to perform corresponding actions according to different cooking scenarios.

5. The control method according to claim 4, characterized in that: airflow velocity in step 3 The calculation formula is: in, The time difference between the first and second detection rings capturing the peak current when there is no airflow in the fume duct; This is the distance between the drive ring and the first detection ring.

6. The control method according to claim 4, characterized in that: In step 3, the oil fume concentration The calculation formula is: in, This is a calibration coefficient, which is related to the dielectric constant of oil fume particles; The current attenuation coefficient is... , This is the current value detected by the first detection ring. This is the current value detected by the second detection ring.

7. The control method according to claim 4, characterized in that: Humidity in step 3 The calculation formula is: in, This represents the current offset caused by humidity. , This is the reference current when there is no high-voltage pulse, that is, the current value between the corona needle and the drive ring when there is no high-voltage pulse. This is the reference current under dry air conditions.

8. The control method according to any one of claims 4 to 7, characterized in that: The specific control logic for determining the current cooking scenario in step 4 is as follows: When the airflow velocity > And the concentration of oil fumes > If so, the current cooking scenario is determined to be a stir-fry scenario; When humidity And airflow velocity < If so, the current cooking scenario is determined to be a steaming or boiling scenario; When the concentration of oil fumes > and humidity satisfy < If so, the current cooking scenario is determined to be a frying scenario; in and These are the first set airflow velocity and the second set airflow velocity, respectively. ; and These are the first and second set oil fume concentrations, respectively. ; , and These are the first set humidity, the second set humidity, and the third set humidity, respectively. > > .

9. The control method according to claim 8, characterized in that: The specific control logic for controlling the fan to perform corresponding actions according to different cooking scenarios in step 4 is as follows: If the current cooking scenario is stir-frying, increase the operating level of the fan; If the cooking scenario is steaming or boiling, adjust the fan speed to medium and dehumidify and exhaust. If the current cooking scenario is frying, the fan speed will be controlled in a step-by-step manner.

10. The control method according to claim 4, characterized in that: If in step 3 Less than the first set time difference ,or If the current exceeds the first set current I, then the first and second detection rings are determined to be in an abnormal working state.

11. The control method according to claim 10, characterized in that: After determining that the first and second detection rings are in an abnormal working state, the following steps are also included: controlling the corona needle to discharge so that the corona needle can perform self-cleaning.

12. The control method according to claim 4, characterized in that: Before step 1, the following steps are also included: controlling the corona needle to discharge so that the corona needle can perform self-cleaning.

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