An oil product identification method, a healthy diet recommendation method and an extractor hood

Abstract

This invention relates to an oil identification method. The method initializes a database, controls a microwave transceiver for transmission and reception, calculates and detects the characteristic frequency of the oil's smoke generation based on the transceiver's transmitted and received signals, compares this characteristic frequency with the microwave characteristic frequencies of various oils in the database, and then obtains the oil identification result for the current oil. This oil identification method can accurately identify the type of oil. This invention also relates to a healthy eating recommendation method, which identifies the oil used for cooking and obtains the saturated fatty acid (SFA) percentage of the current oil i. i This method then assesses the health risks associated with the diet and generates recommendations for adjusting the types of oil used and the frequency of use within a set period. This healthy eating recommendation method can more effectively control saturated fatty acids in cooking oils. The invention also relates to range hoods that utilize the aforementioned oil identification method and / or healthy eating recommendation method.

Description

Technical Field

[0001] This invention relates to a method for identifying oil, a method for recommending healthy diets, and a range hood. Background Technology

[0002] As people's living standards continue to improve, healthy eating is receiving increasing attention. Range hoods, as a common kitchen appliance, are also beginning to play a role in promoting healthy eating. For example, the Chinese invention patent "Range Hood and Control Method for Range Hood" (CN105222194B, application number 201510703438.0) discloses a method that monitors the weight of oil filtered during cooking. Based on the positive correlation between the weight of filtered oil and the weight of oil used by the user, the method guides users on healthy eating by measuring the relationship between the weight of oil used and the increase in filtered oil during multiple cooking processes. However, this method has certain limitations. The oil cup of the range hood accumulates not only oil but also cooking steam, which can lead to misjudgments if the user frequently uses steaming. Furthermore, monitoring the weight of filtered oil cannot determine the type of oil. Different types of oil have a significant impact on a user's healthy diet, and therefore, relying solely on monitoring the increase in filtered oil cannot provide more reasonable dietary cooking advice.

[0003] To address the issue of oil type identification, Chinese invention patent CN109654560B (application number 201811631002.5), entitled "A Range Hood Capable of Assessing Kitchen Air and Quality Based on the Type of Oil Used," discloses a range hood that identifies oil types through temperature and image processing. However, in actual use, the captured images are significantly affected by ambient light, the color of cooking utensils (often dark), the color of the ingredients, the cooking time, and the addition of oil during cooking—all factors that can affect the accurate identification of oil types. Furthermore, the polycyclic aromatic hydrocarbon (PAH) detection device and the camera used for image acquisition are relatively large and costly. Summary of the Invention

[0004] The first technical problem to be solved by the present invention is to provide an oil identification method that can accurately identify the types of oils, in contrast to the above-mentioned prior art.

[0005] The second technical problem to be solved by the present invention is to provide a healthy dietary recommendation method that can effectively obtain the proportion of saturated fatty acids in cooking oils and give healthier suggestions for the use of cooking oils, in contrast to the above-mentioned prior art.

[0006] The third technical problem to be solved by the present invention is to provide a range hood that applies the aforementioned oil identification method and / or healthy diet recommendation method to the prior art.

[0007] The technical solution adopted by this invention to solve the first technical problem mentioned above is: an oil identification method, characterized by: initializing a database, the database including microwave characteristic frequencies corresponding to different oils; controlling a microwave transceiver to perform transmission and reception in the current oil fume environment; and calculating and detecting the characteristic frequencies of the current oil fume based on the transmitted and received signals of the microwave transceiver. , characteristic frequency Microwave characteristic frequencies of various oil products in the database The comparison and calculation are performed to obtain the current oil type identification result.

[0008] Preferably, the microwave transceiver operates in the 0.1-6 GHz frequency band.

[0009] To achieve more accurate detection of different oil products, avoid humidity interference in the frequency band, and save computing resources and time, the microwave transceiver transmits a swept-frequency continuous wave signal with a frequency range of 0.5-2GHz and a step interval of nMHz, for a total of N frequency points, N=1.5*1024 / n.

[0010] The microwave transceiver transmits signals in the following form: ,in Indicates the first There are several frequency points, i = 1, 2, 3, ..., N; This represents the amplitude value of the transmitted signal. This is the initial phase, which is reset to zero after calibration.

[0011] As an improvement, the propagation of microwaves in the oil fume medium satisfies Maxwell's equations, and the electric field components can be expressed as: in, f is the microwave frequency. U is the microwave propagation constant. The microwave attenuation coefficient is... It is the phase constant;

[0012] The complex permittivity, It is the real part. This represents the imaginary part of the dielectric loss caused by cooking fumes. It reflects the characteristics of oil fumes;

[0013] The microwave transceiver received signal power model is as follows: ,in In frequency point attenuation coefficient , This is the length of the microwave propagation path; For the velocity of electromagnetic waves, c = 3 × 10 8 m / s;

[0014] By power attenuation ratio Reverse reasoning: ;

[0015] Using N frequency points The data is fitted and calculated to obtain the feature frequencies. .

[0016] As an improvement, the least squares method is used to determine the characteristic frequencies. Fitting calculation.

[0017] As an improvement, characteristic frequency The fitting calculation method is as follows:

[0018] For N frequency points Data, establish a system of nonlinear equations: ; The relaxation strength of the current oil-generating fume medium; These are the fitted values;

[0019] Set the loss function as follows: , These are measured values;

[0020] The initialization conditions for iterative calculations are: GHz, ;

[0021] Set the Jacobian matrix: ;

[0022] The parameter update equation is: ;

[0023] The convergence condition is: when the iteration step size is... GHz and End at time;

[0024] The feature frequencies were obtained through fitting calculations. .

[0025] The calculation is simple; the database includes the permissible deviations of characteristic frequencies corresponding to different oil products. ;

[0026] Characteristic frequency Microwave characteristic frequencies of various oil products in the database The comparison calculation method is to calculate Corresponding to each type of oil similarity , ;

[0027] Pick Furthermore, the oil type with the highest data is the oil type identification result for the current oil.

[0028] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: a healthy diet recommendation method, characterized in that: initializing a database, wherein the database includes the percentage of saturated fatty acids corresponding to different oils;

[0029] Identify the type of oil used in cooking and obtain the percentage of saturated fatty acids in oil i. ;

[0030] Within a set period, the health risks of the diet are assessed based on the frequency of different types of oil used in cooking and the saturated fatty acid content of the corresponding oils. Based on the health risk assessment, recommendations are generated to adjust the types of oils used in the diet and the corresponding frequency of use within the set period.

[0031] As an improvement, the health risk of diet is assessed based on the Health Risk Index (HRI).

[0032] ;In the formula, Indicates the first The number of times a certain type of oil is used per week, expressed in times per week. Indicates the first The percentage of saturated fatty acids in various oil products, expressed as a percentage. and These are different weighting coefficients.

[0033] As an improvement, when 0 < HRI ≤ 10, the risk level of the current dietary oil consumption habit is judged to be low risk, and it is recommended to maintain the current oil consumption habit.

[0034] When 10 < HRI ≤ 20, the risk level of the current dietary oil consumption habits is judged to be medium risk, and it is recommended to adjust the oil combination and reduce the use of oils with high SFA values.

[0035] When HRI > 20, the current dietary oil consumption habits are considered high-risk. It is recommended to immediately reduce the use of oils with high SFA values ​​and to seek medical advice.

[0036] To obtain more accurate oil identification results, the aforementioned oil identification method is used to identify the oils used in cooking.

[0037] The technical solution adopted by the present invention to solve the third technical problem mentioned above is as follows: a range hood, comprising a housing with an oil fume channel, characterized in that: a microwave transceiver is provided inside the housing, a controller and a memory are provided inside the housing, and the controller is electrically connected to the microwave transceiver and the memory;

[0038] The database is stored in memory;

[0039] The system stores computer instructions for instructing the controller to perform the aforementioned oil identification method and / or the aforementioned healthy eating recommendation method.

[0040] To reduce direct wave interference, the microwave transceiver includes a microwave transmitter and a microwave receiver, with the transmitting antenna of the microwave transmitter and the receiving antenna of the microwave receiver arranged at a 90° angle.

[0041] Preferably, the offset angle of the transmitting antenna of the microwave transmitter relative to the axis of oil fume flow is α, where 10°≤α≤20°.

[0042] In order to effectively ensure the resonant propagation of microwaves and better obtain the characteristic frequency of microwave absorption by the oil fume medium generated based on different oil products during the microwave resonant propagation process, a resonator is provided in the oil fume channel. The resonator is provided with a resonant cavity that runs through the direction of oil fume flow. The microwave transmitter is located at the upstream end of the resonant cavity, and the microwave receiver is located at the downstream end of the resonant cavity.

[0043] In order to correct the temperature drift of the node constant caused by temperature in a timely manner, a temperature sensor for detecting temperature is also provided at the upstream end of the resonant cavity, and the temperature sensor is electrically connected to the controller.

[0044] Preferably, the ports at both ends of the resonant cavity are arranged in a horn shape.

[0045] Compared with existing technologies, the advantages of this invention are as follows: The oil identification method of this invention is based on the fact that when microwaves propagate in the oil fume medium of different oils, they utilize the differences in the molecular structure of different oils and their different absorption characteristics of microwaves. By observing the differences in microwave energy absorption curves, the microwave transceiver can obtain different and specific characteristic frequencies for different oils. Thus based on characteristic frequencies It can accurately identify the type of oil. Compared with the image processing methods used in the prior art, the oil identification method in this invention is less affected by environmental interference, requires less computation, and uses a small microwave transceiver that is easy to install and has a low cost.

[0046] The healthy diet recommendation method in this invention is based on the effective identification of oil types, which facilitates the statistical analysis of the number of times different oils are used in cooking and the corresponding proportion of saturated fatty acids in the oils. This allows for the assessment of the health risks of the diet and provides oil adjustment suggestions to reduce the total amount of saturated fatty acids in the cooking process to a healthy range, thus benefiting the user's dietary health.

[0047] The range hood of this invention utilizes the aforementioned oil identification method and / or healthy eating recommendation method. Based on the ability to accurately identify oil types, it facilitates the development of extended functions based on oil information, making the range hood more intelligent. It can provide healthy eating suggestions based on oil usage, offering reasonable recommendations for different oil types to ensure the user's dietary health. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the internal structure of the oil fume channel of the range hood in an embodiment of the present invention.

[0049] Figure 2 This is a flowchart of the oil identification method in an embodiment of the present invention.

[0050] Figure 3 This is a flowchart of a healthy diet recommendation method in an embodiment of the present invention. Detailed Implementation

[0051] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0052] The oil identification method in this embodiment can be applied to any scenario that requires oil information identification. When performing this oil identification method, the oil needs to be heated to a smoke state, so it is particularly suitable for use in range hoods.

[0053] When a dielectric material is subjected to an external electric field, it needs time to polarize. This is not a problem for electrostatic fields, as there is always enough time for polarization to fully develop. However, under an alternating electric field, if the frequency is too high, the change in polarization direction will not keep up with the change in the electric field direction, and the corresponding polarization intensity will decrease. In the macroscopic dielectric relaxation spectrum, the dielectric constant decreases with increasing frequency, while the conductivity increases. This dependence of the dielectric constant and conductivity on the electric field frequency is called dielectric relaxation. Different dielectric relaxation mechanisms appear in different frequency ranges. That is, dielectric relaxation is like a "memory delay of matter." When an electric field acts on a material, such as an oil droplet or water molecule, the charges inside the material attempt to "queue up" and move in the direction of the electric field. However, this "queueing up" action takes time. Water molecules, with their small diameter, can achieve an instantaneous response; oil droplets, with their large diameter, have a delayed response.

[0054] The molecular structures of different oils vary due to differences in parameters such as fatty acid chain length and saturation, resulting in varying polarization relaxation times. Differences: For example, olive oil, which is mainly composed of monounsaturated fatty acids, has less resistance to molecular motion → Smaller molecular structures indicate higher frequency; for example, lard, which is mainly composed of saturated fatty acids, has a tightly packed molecular structure. Large droplet size → low characteristic frequency. Understanding this characteristic of different conductive media allows for the differentiation of oil droplet types through broadband loss spectrum analysis, thereby enabling oil identification.

[0055] like Figure 2 As shown, the oil identification method in this embodiment involves initializing a database, which includes microwave characteristic frequencies corresponding to different oils. This data can be obtained through testing in research and development experiments. The microwave transceiver 2 is then controlled to transmit and receive signals in the current oil fume environment. Based on the transmitted and received signals from the microwave transceiver 2, the characteristic frequencies of the current oil fume are calculated and detected. , characteristic frequency Microwave characteristic frequencies of various oil products in the database The comparison and calculation are performed to obtain the current oil type identification result.

[0056] Microwave transceiver 2 operates in the 0.1-6 GHz frequency band. The polarization relaxation time of the oil droplet. The corresponding characteristic frequency is approximately 0.1-2 ns. It falls exactly within the 0.5-2GHz range, and the dielectric loss of oil droplets in this frequency band is... The dominant frequency (>90%) and negligible water vapor influence (<5%) avoid humidity interference in the frequency band and eliminate the need for high-frequency scanning, saving computational resources and time. Therefore, in this embodiment, the microwave transceiver 2 transmits a swept-frequency continuous wave signal with a frequency range of 0.5-2 GHz and a step interval of n MHz, resulting in a total of N frequency points, where N = 1.5 * 10²⁴ / n. The step interval is determined based on specific operating conditions; in this embodiment, a step interval of 50 MHz is set, resulting in 31 frequency points.

[0057] The form of the signal transmitted by microwave transceiver 2 is as follows: ,in Indicates the first There are several frequency points, i = 1, 2, 3, ..., N; The amplitude value of the transmitted signal, in this embodiment Fixed at 10Vpp; This is the initial phase, which is reset to zero after calibration.

[0058] The propagation of microwaves in the oil fume medium follows Maxwell's equations, and the electric field components can be expressed as: in, f is the microwave frequency. U is the microwave propagation constant. The microwave attenuation coefficient is... is the phase constant.

[0059] The complex permittivity, It is the real part. This represents the imaginary part of the dielectric loss caused by cooking fumes. It reflects the characteristics of oil fumes.

[0060] The attenuation of the received signal power of microwave receiver 22 is caused by the dielectric loss of the oil droplets. The received signal power model of microwave transceiver 2 is as follows: ,in In frequency point attenuation coefficient , This is the length of the microwave propagation path; For the velocity of electromagnetic waves, c = 3 × 10 8 m / s.

[0061] By power attenuation ratio Reverse reasoning: Using N frequency points The data is fitted and calculated to obtain the feature frequencies. .

[0062] In this embodiment, the least squares method is used to determine the characteristic frequencies. Fitting calculation. Characteristic frequencies. The fitting calculation method is as follows.

[0063] For N frequency points Data, establish a system of nonlinear equations: ; The relaxation strength of the current oil-generating fume medium; These are the fitted values.

[0064] Set the loss function as follows: , These are measured values.

[0065] The initialization conditions for iterative calculations are: GHz, .

[0066] Set the Jacobian matrix: .

[0067] The parameter update equation is: .

[0068] The convergence condition is: when the iteration step size is... GHz and The process will end at that time.

[0069] The feature frequencies were obtained through fitting calculations. .

[0070] When performing oil product identification, the characteristic frequencies calculated for the current oil product are... Microwave characteristic frequencies corresponding to each oil product in the database Similarity calculations are performed to determine the specific type of oil product.

[0071] To enable similarity calculation, the database also includes allowable deviations in the characteristic frequencies corresponding to different oil products. .

[0072] In this embodiment, the database stores the following data information.

[0073] Oil categories Microwave characteristic frequency Allowable deviation olive oil 0.82 0.03 rapeseed oil 1.05 0.03 lard 1.78 0.03 Coconut oil 2.31 0.03

[0074] Characteristic frequency Microwave characteristic frequencies of various oil products in the database The comparison calculation method is to calculate Corresponding to each type of oil similarity , .Pick Furthermore, the oil type with the highest data is the oil type identification result for the current oil.

[0075] During actual measurement, the calculated =1.052GHz, when performing matching calculations with data corresponding to rapeseed oil, =0.938, thus identifying the current oil category as rapeseed oil.

[0076] When this oil identification method is applied to range hoods, it can control the display of oil information on the range hood's information screen, or use the oil information to provide users with information on the current oil medium, cooking precautions, and recommended recipes for the current oil, thereby enhancing the user-friendliness and intelligence of the range hood application.

[0077] The oil identification method in this invention is based on the fact that different oils have different molecular structures and absorption characteristics when microwaves propagate in the oil fume medium. By observing the differences in microwave energy absorption curves, the microwave transceiver 2 can acquire different and specific characteristic frequencies for different oils. Thus based on characteristic frequencies It can accurately identify the type of oil. Compared with the image processing method used in the prior art, the oil identification method in this invention is less affected by environmental interference, requires less computation, and uses a small microwave transceiver 2 that is easy to install and has a low cost.

[0078] like Figure 3As shown, this invention also relates to a healthy diet recommendation method comprising the following steps: initializing a database, the database including the saturated fatty acid percentages corresponding to different oils; identifying the oils used for cooking; and obtaining the saturated fatty acid percentage (SFA) corresponding to the current oil i. i Within a set period, the health risks of the diet are assessed based on the frequency of different cooking oils used and the corresponding saturated fatty acid content of those oils. Based on the health risk assessment, recommendations are generated to adjust the types of oils used in the diet and the corresponding frequency of use within the set period. The set period can be determined specifically as needed, such as one week or one month.

[0079] The identification of cooking oil can be based on existing oil identification methods, or the aforementioned oil identification methods can be used, which provide more accurate results.

[0080] High cholesterol is a major chronic disease affecting many middle-aged and elderly people, and "oil" plays a significant role in this. Excessive intake of foods high in saturated fat increases the risk of cardiovascular disease. Saturated fatty acids (SFAs) are mainly derived from animal fats such as lard, tallow, and mutton fat, as well as some vegetable oils, such as palm oil and coconut oil. However, coconut oil is a medium-chain saturated fatty acid. Not all saturated fatty acids are harmful to the human body. For example, the medium-chain fatty acids in coconut oil have the property of increasing metabolic rate and promoting fat burning.

[0081] Monounsaturated fatty acids, such as olive oil, camellia oil, peanut oil, and rapeseed oil, play a crucial role in the health field due to their unique chemical structure and biological activity. Take oleic acid in olive oil as an example: this fatty acid can not only effectively lower low-density lipoprotein cholesterol (LDL-C), the so-called "bad cholesterol," reducing its deposition on blood vessel walls and thus lowering the risk of atherosclerosis and cardiovascular disease, but it can also increase the level of high-density lipoprotein cholesterol (HDL-C), the "good cholesterol," further strengthening the defenses of cardiovascular health.

[0082] Polyunsaturated fatty acids (PUFAs) can be further classified into n-3 (Omega-3) and n-6 ​​(Omega-6) series based on the position of the first double bond. Both types of fatty acids are essential for the human body, but they need to be maintained in an appropriate ratio in the diet. ① n-3 series (Omega-3): Possesses numerous health benefits, including anti-inflammatory properties, reduced cardiovascular disease risk, and improved brain and retinal function. Common sources: flaxseed oil, perilla oil, sea buckthorn oil, fish oil (such as oil from deep-sea fish like salmon, mackerel, and herring), walnuts, quinoa, chia seeds, etc. ② n-6 series (Omega-6): While also an essential fatty acid, excessive intake can lead to an imbalance in the ratio with n-3 series fatty acids, potentially causing problems such as inflammation. Common sources: peanut oil, soybean oil, corn oil, sunflower seed oil, sesame oil, and other affordable vegetable oils.

[0083] Based on this, in this embodiment, the health risk of the diet is assessed according to the Health Risk Index (HRI) based on the oil identification results. In the Health Risk Index (HRI) formula, Indicates the first The number of times a certain type of oil is used per week, expressed in times per week. Indicates the first The percentage of saturated fatty acids in each type of oil, expressed in percent. and These are weighted coefficients, based on the WHO's prioritization of intake frequency and oil quality. Since intake habits vary across regions, adjustments can be made according to the product and the region of use. and It can be stored in a database, and the program can automatically select based on user-defined parameters. In this embodiment, the settings are... and The initial value is , .

[0084] The calculated Health Risk Index (HRI) can parameterize the risk level of dietary oil habits, thus making it easier to provide healthy oil-based dietary recommendations.

[0085] based on The data calculations can directly provide users with some healthy cooking oil dietary plans for their reference. For example, the following two plans, A and B, can be provided.

[0086] Option A: Common Edible Oil Classifications and Recommendations

[0087] Oil type Saturated fatty acids (SFA) Monounsaturated fatty acids (MUFA) Polyunsaturated fatty acids (PUFAs) Recommended usage frequency (times / week) Applicable cooking methods olive oil 14% 73% 11% ≤5 Cold dishes, low-temperature frying rapeseed oil 7% 63% 28% ≤7 General Peanut oil 17% 46% 32% ≤3 High-temperature frying Camellia oil 10% 78% 12% ≤5 Alternative to lard lard 40% 48% 12% ≤1 Traditional baking (limited quantity) Coconut oil 92% 6% 2% ≤0.5 (≤2 times per month) Special flavor requirements

[0088] Option B: Example of a health rotation plan.

[0089] Week Recommended oil combination HRI control objectives Scientific basis Week 1 Rapeseed oil (4 times) + olive oil (3 times) HRI=6.8 Monounsaturated fatty acids (MUFAs) account for more than 60%, which is in line with cardiovascular protection. Week 2 Peanut oil (2 times) + Camellia oil (5 times) HRI=7.4 Balanced Omega-6 / Omega-3 ratio (peanut oil 5:1, camellia oil 10:1) Week 3 Olive oil (5 times) + coconut oil (1 time) HRI=13.2 Limit coconut oil usage (SFA < 10% of total fat). Week 4 Rapeseed oil (7 times) HRI=4.9 Choose the lowest SFA grade oil when using a single type of oil.

[0090] Based on the oil products used by the user The data calculation can first assess the risk level of dietary oil habits, and then adjust the oil consumption plan according to the specific risk level of dietary oil habits.

[0091] Specifically, when 0 < HRI ≤ 10, the risk level of the current dietary oil consumption habit is judged as low risk, and it is recommended to maintain the current oil consumption habit; when 10 < HRI ≤ 20, the risk level of the current dietary oil consumption habit is judged as medium risk, and it is recommended to adjust the oil combination and reduce the use of oils with high SFA values; when HRI > 20, the risk level of the current dietary oil consumption habit is judged as high risk, and it is recommended to immediately reduce the use of oils with high SFA values ​​and seek medical consultation.

[0092] For example: A user used lard twice this week (SFA=40%), coconut oil once (SFA=92%), and rapeseed oil three times (SFA=7%). The corresponding calculated HRI is:

[0093]

[0094] The HRI is 4.156, indicating a low-risk level for the current dietary oil consumption habits. It is recommended that the user maintain their current oil consumption habits. However, given the frequent use of lard, the risk associated with lard should be considered. If the proportion is relatively high, it is advisable to suggest that users replace lard with camellia oil, or adjust the use of olive oil to 4 times / week to reduce the risk. Percentage.

[0095] The healthy diet recommendation method in this invention is based on the effective identification of oil types, which facilitates the statistical analysis of the number of times different oils are used in cooking and the corresponding proportion of saturated fatty acids in the oils. This allows for the assessment of the health risks of the diet and provides oil adjustment suggestions to reduce the total amount of saturated fatty acids in the cooking process to a healthy range, thus benefiting the user's dietary health.

[0096] like Figure 1 As shown, the present invention also relates to a range hood, including a housing 1 with an oil fume channel 11, a microwave transceiver 2 disposed inside the housing 1, a controller and a memory disposed inside the housing 1, and the controller being electrically connected to the microwave transceiver 2 and the memory.

[0097] The database is stored in memory, and its configuration corresponds to the specific method used by the range hood. Computer instructions are also stored, which instruct the controller to execute the aforementioned oil identification method and / or the aforementioned healthy eating recommendation method.

[0098] To effectively ensure microwave resonant propagation and better obtain the characteristic frequencies of microwave absorption by oil fume media generated from different oil products during microwave resonant propagation, a resonator 3 is provided in the oil fume channel 11. In this embodiment, the resonator 3 is tubular, and a resonant cavity 31 extending along the oil fume flow direction is provided inside the resonator 3. The microwave transmitter 21 is located at the upstream end of the resonant cavity 31, and the microwave receiver 22 is located at the downstream end of the resonant cavity 31. The resonant cavity 31 is a metal cavity used to continuously oscillate a high-frequency electromagnetic field within it. The cross-section of the resonant cavity 31 is most commonly rectangular or circular. In this embodiment, the inner wall of the annular resonant cavity 31 is coated with an easy-to-clean, oil-resistant coating such as Teflon. The resonator 3 can be made of a thin-walled outer shell of a highly conductive metal such as copper, or a plastic outer shell with copper plating on the inner wall. Furthermore, the ports at both ends of the resonant cavity 31 are arranged in a horn shape. The front horn port guides the flow to collect and accelerate the airflow into the detection area, while the rear horn port suppresses turbulence caused by separation due to sudden expansion of the cross-section.

[0099] The microwave transceiver 2 includes a microwave transmitter 21 and a microwave receiver 22, which are embedded in the inner wall of the resonant cavity 31, or etched using a copper-plated PCB. To reduce direct wave interference, the transmitting antenna of the microwave transmitter 21 and the receiving antenna of the microwave receiver 22 are arranged orthogonally at 90°. The offset angle of the transmitting antenna of the microwave transmitter 21 relative to the oil fume flow axis is α, where 10°≤α≤20°. In this embodiment, the offset angle of the transmitting antenna of the microwave transmitter 21 relative to the oil fume flow axis is 15°, thus enabling the microwave transceiver 2 to operate in a frequency band covering 0.1-6GHz.

[0100] In addition, in order to correct the temperature drift of the node constant caused by temperature in a timely manner, a temperature sensor 4 for detecting temperature is provided at the upstream end of the resonant cavity 31. The temperature sensor 4 is connected to the controller electrical signal.

[0101] The range hood of this invention utilizes the aforementioned oil identification method and / or healthy eating recommendation method. Based on the ability to accurately identify oil types, it facilitates the development of extended functions based on oil information, making the range hood more intelligent. It can provide healthy eating suggestions based on oil usage, offering reasonable recommendations for different oil types to ensure the user's dietary health.

[0102] The specification and claims of this invention use terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," to describe various exemplary structural parts and elements of the invention. However, these terms are used herein merely for ease of explanation and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this invention can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

Claims

1. A method for identifying oil products, characterized in that: Initialize the database, which includes microwave characteristic frequencies corresponding to different oil products; control the microwave transceiver (2) to perform transmission and reception in the current oil fume environment, and calculate and detect the characteristic frequencies of the current oil fume based on the transmitted and received signals of the microwave transceiver (2). , characteristic frequency Microwave characteristic frequencies of various oil products in the database The comparison and calculation are performed to obtain the current oil type identification result.

2. The oil identification method according to claim 1, characterized in that: The microwave transceiver (2) operates in the 0.1-6 GHz frequency band.

3. The oil identification method according to claim 2, characterized in that: The microwave transceiver (2) transmits a swept-frequency continuous wave signal with a frequency range of 0.5-2GHz and a step interval of nMHz. There are a total of N frequency points, N=1.5*1024 / n. The microwave transceiver (2) transmits signals in the following form: ,in Indicates the first There are several frequency points, i = 1, 2, 3, ..., N; This represents the amplitude value of the transmitted signal. This is the initial phase, which is reset to zero after calibration.

4. The oil identification method according to claim 3, characterized in that: The propagation of microwaves in the oil fume medium follows Maxwell's equations, and the electric field components can be expressed as: in, f is the microwave frequency. U is the microwave propagation constant. The microwave attenuation coefficient is... It is the phase constant; The complex permittivity is... It is the real part. This represents the imaginary part of the dielectric loss caused by cooking fumes. It reflects the characteristics of oil fumes; The received signal power model of microwave transceiver (2) is as follows: ,in In frequency point attenuation coefficient , This is the length of the microwave propagation path; For the velocity of electromagnetic waves, c = 3 × 10⁻⁶ 8 m / s; By power attenuation ratio Reverse reasoning: ; Using N frequency points The data is fitted and calculated to obtain the feature frequencies. .

5. The oil identification method according to claim 4, characterized in that: Characteristic frequencies are obtained using the least squares method. Fitting calculation.

6. The oil identification method according to claim 5, characterized in that: Characteristic frequency The fitting calculation method is as follows: For N frequency points Data, establish a system of nonlinear equations: ; The relaxation strength of the current oil-generating fume medium; These are the fitted values; Set the loss function as follows: , These are measured values; The initialization conditions for iterative calculations are: GHz, ; Set the Jacobian matrix: ; The parameter update equation is: ; The convergence condition is: when the iteration step size is... GHz and End at time; The feature frequencies were obtained through fitting calculations. .

7. The oil identification method according to any one of claims 1-6, characterized in that: The database includes the permissible deviations of characteristic frequencies for different oil products. ; Characteristic frequency Microwave characteristic frequencies of various oil products in the database The comparison calculation method is to calculate Corresponding to each type of oil similarity , ; Pick Furthermore, the oil type with the highest data is the oil type identification result for the current oil.

8. A method for recommending healthy eating habits, characterized in that: Initialize the database, which includes the percentage of saturated fatty acids for different oil products; Identify the type of oil used in cooking and obtain the percentage of saturated fatty acids (SFA) in the current oil i. i ; Within a set period, the health risks of the diet are assessed based on the frequency of different types of oil used in cooking and the saturated fatty acid content of the corresponding oils. Based on the health risk assessment, recommendations are generated to adjust the types of oils used in the diet and the corresponding frequency of use within the set period.

9. The method for recommending healthy eating habits according to claim 8, characterized in that: Assess the health risks of diet based on the Health Risk Index (HRI); ;In the formula, Indicates the first The number of times a certain type of oil is used per week, expressed in times per week. Indicates the first The percentage of saturated fatty acids in various oil products, expressed as a percentage. and These are different weighting coefficients.

10. The method for recommending healthy eating habits according to claim 9, characterized in that: When 0 < HRI ≤ 10, the risk level of the current dietary oil consumption habit is judged to be low risk, and it is recommended to maintain the current oil consumption habit. When 10 < HRI ≤ 20, the risk level of the current dietary oil consumption habits is judged to be medium risk, and it is recommended to adjust the oil combination and reduce the use of oils with high SFA values. When HRI > 20, the current dietary oil consumption habits are considered high-risk. It is recommended to immediately reduce the use of oils with high SFA values ​​and to seek medical advice.

11. The method for recommending healthy eating habits according to claim 8, characterized in that: The oil identification method according to any one of claims 1 to 7 is used to identify the oil used for cooking.

12. A range hood, comprising a housing (1) having an oil fume duct (11), characterized in that: The housing (1) is equipped with a microwave transceiver (2), and the housing (1) is equipped with a controller and a memory. The controller is electrically connected to the microwave transceiver (2) and the memory. The database is stored in memory; The storage contains computer instructions for causing the controller to perform the oil identification method according to any one of claims 1 to 7, and / or to perform the healthy diet recommendation method according to any one of claims 8 to 11.

13. The range hood according to claim 12, characterized in that: The microwave transceiver (2) includes a microwave transmitter (21) and a microwave receiver (22), wherein the transmitting antenna of the microwave transmitter (21) and the receiving antenna of the microwave receiver (22) are arranged at 90° orthogonal.

14. The range hood according to claim 13, characterized in that: The offset angle of the transmitting antenna of the microwave transmitter (21) relative to the oil fume flow axis is α, 10°≤α≤20°.

15. The range hood according to claim 13, characterized in that: The fume duct (11) is provided with a resonator (3), and the resonator (3) is provided with a resonant cavity (31) that runs through the direction of fume flow. The microwave transmitter (21) is located at the upstream end of the resonant cavity (31), and the microwave receiver (22) is located at the downstream end of the resonant cavity (31).

16. The range hood according to claim 15, characterized in that: The upstream end of the resonant cavity (31) is also provided with a temperature sensor (4) for detecting temperature, and the temperature sensor (4) is electrically connected to the controller.

17. The range hood according to claim 15, characterized in that: The ports at both ends of the resonant cavity (31) are arranged in a horn shape.

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