Induction heating body structure, induction control system and induction control method

Abstract

The invention discloses an induction heating body structure, an induction control system and an induction control method, the induction heating body structure comprises a heating wire, an induction electrode layer and a protective coating which are sequentially arranged in the radial direction, and an insulating sleeve is arranged outside the heating wire. According to the induction heating body structure, the induction control system and the induction control method, the heating assembly integrated with the induction electrode layer is adopted, and induction and response to cigarette insertion and the clean state of the surface of the heating body in the inner core and circumferential heating mode can be met; the mode that an alternating-current impedance signal is injected into a heating body electrode layer is adopted, no other additional sensor is needed, the external state of the smoking set heating body can be sensed at low cost and in a multi-mode angle, the intelligent degree is improved, and the peripheral cost of the smoking set is reduced; the surface cleanliness of the smoking set, the cigarette insertion state and the smoking parameters can be sensed, and low-cost and multifunctional intelligent detection is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat-not-burn cigarettes, and more specifically, to an induction heating body structure, an induction control system and an induction control method. Background Art

[0002] Heated cigarette products are a new type of tobacco product, which are usually composed of heated tobacco devices and tobacco cartridges. They use electric heating methods such as inner core needle type and outer circumferential direction to bake the tobacco cartridges at a temperature of about 300°C to generate atomized aerosol for consumers to inhale.

[0003] With the development of detection technology, heated tobacco devices are rapidly developing in areas such as cartridge status sensing and heating control. For example, photoelectric detection uses the principle of signal emission-reflection trigger detection to detect whether a cartridge is in the cartridge chamber and trigger control actions. Mechanical induction triggering triggers a mechanical switch to enable heating control when the cartridge is inserted into the cartridge chamber.

[0004] In the detection scenario of heated tobacco products, traditional technologies (such as mechanical contact, single optical methods, etc.) have problems such as poor environmental adaptability, single detection dimension, and complex hardware integration. They can easily cause problems such as wear of sensor detection devices, aging and failure of mechanical parts, and contamination and obstruction, resulting in failure of system detection functions and false touches.

[0005] Therefore, there is an urgent need for an induction heating body structure, an induction control system and an induction control method. Summary of the Invention

[0006] The purpose of the present invention is to provide an induction heating body structure, an induction control system and an induction control method to solve the problems in the above-mentioned prior art, and to be able to sense and respond to the insertion of cigarettes and the cleanliness status of the heating body surface based on AC impedance detection technology.

[0007] The present invention provides an induction heating body structure, an induction control system and an induction control method, which include: a heating wire, an induction electrode layer and a protective coating arranged in sequence in a radial direction, and an insulating sleeve is provided on the outside of the heating wire.

[0008] As described above, the induction heating body structure, wherein preferably, the induction heating body structure is applicable to the inner core heating structure and the circumferential heating structure, and the induction heating body structure applicable to the inner core heating structure is provided with the heating wire, the induction electrode layer and the protective coating in sequence from the inside to the outside in the radial direction; the induction heating body structure applicable to the circumferential heating structure is provided with the heating wire, the induction electrode layer and the protective coating in sequence from the outside to the inside in the radial direction.

[0009] In the induction heating body structure as described above, preferably, the induction electrode layer and the protective coating are located on the insulating sleeve, and an airflow sensing hole penetrating along the Al axis is provided in the insulating sleeve.

[0010] The induction heating body structure as described above, wherein, preferably, the induction heating body structure further includes a fixed base, the induction electrode layer is connected to an induction control electrode, and the induction control electrode is led out from the position where the fixed base is located; the heating wire is connected to a heating control electrode, and the heating control electrode is led out from the position where the fixed base is located.

[0011] The present invention also provides an induction control system including the above-mentioned induction heating body structure, the induction control system also including: a microcontroller, an AC signal generator and an impedance acquisition circuit, the AC signal generator is arranged between the microcontroller and the induction electrode layer, and the impedance acquisition circuit is respectively connected to the microcontroller, the induction electrode layer and the heating wire.

[0012] In the induction control system as described above, preferably, the AC signal generator includes a first digital frequency synthesizer and a first operational amplifier unit arranged in sequence, wherein the first digital frequency synthesizer is connected to the microcontroller, and the first operational amplifier unit is connected to the sensing electrode layer;

[0013] The impedance acquisition circuit includes a high-speed AD conversion unit, a second operational amplifier unit, and a first precision sampling resistor, which are arranged in sequence, wherein the high-speed AD conversion unit is connected to the microcontroller, and the first precision sampling resistor is connected to the sensing electrode layer;

[0014] The impedance acquisition circuit further includes a third operational amplifier unit and a second precision sampling resistor which are sequentially arranged, wherein the third operational amplifier unit is connected to the high-speed AD conversion unit, and the second precision sampling resistor is connected to the heating wire.

[0015] The induction control system as described above, wherein preferably, the induction control system further comprises a second digital frequency synthesizer and a switch unit which are arranged in sequence, wherein the second digital frequency synthesizer is connected to the microcontroller, and the switch unit is connected to the heating wire.

[0016] The present invention also provides an induction control method using the above-mentioned induction control system, comprising the following steps:

[0017] Based on the induction control system, an AC impedance parameter characterization model of the induction heating body is constructed;

[0018] Perform initial calibration on the reference state parameter value of the response signal under clean state;

[0019] Performing static testing on the cigarette according to the AC impedance parameter characterization model of the induction heating body to obtain state parameters of the induction electrode layer in a static identification state, so as to identify at least one of the cleanliness level and contact state of the surface of the induction electrode layer;

[0020] During the smoking process, the cigarette is dynamically detected to obtain the state parameters of the sensing electrode layer in the dynamic identification state to determine at least one of the cleanliness of the smoking device surface, the cigarette insertion state and the smoking parameters.

[0021] In the induction control method as described above, preferably, the step of constructing an AC impedance parameter characterization model of an induction heating body based on the induction control system includes:

[0022] Characterize the equivalent circuit of the sensing electrode layer;

[0023] injecting an excitation test signal into the induction heating structure;

[0024] Discretely collect the response signal of the sensing electrode layer;

[0025] Extract the fundamental component of the current in the sensing electrode layer and calculate its characteristics.

[0026] The method for representing the equivalent circuit of the sensing electrode layer includes:

[0027] When the heating element is not working, the sensing electrode layer is equivalent to a pure resistor. , which is related to the surface capacitance In parallel, it can be characterized as:

[0028]

[0029] Among them, the impedance modulus is:

[0030] The phase angle is represented by the following formula: ,

[0031] The step of injecting an excitation test signal into the induction heating structure comprises:

[0032] When the induction heating element is not working, the microcontroller is used to trigger the first digital frequency synthesizer to output an AC signal with a fixed amplitude. , where the amplitude voltage ,frequency , , , input the AC signal to the electrode input end of the sensing electrode layer,

[0033] The discrete acquisition of the response signal of the sensing electrode layer includes:

[0034] Perform current-to-voltage conversion on the phase-shifted signal:

[0035] Current injected into the sensing electrode layer Converted into sampling voltage through the first precision sampling resistor , injection current Can be characterized as:

[0036]

[0037] in, The phase angle that the current phase leads the voltage is expressed as,

[0038] Sampling voltage Can be characterized as:

[0039] ;

[0040] Sampling voltage Perform signal amplification and ADC discrete acquisition: the sampling voltage is amplified by the second operational amplifier unit Perform signal amplification: the amplified voltage signal is: , where 100 represents the gain of the second operational amplifier unit; the original voltage is synchronously collected in a discrete manner through the high-speed AD conversion unit And the amplified voltage signal , get the digital sequence , characterized by:

[0041]

[0042] Among them, the high-speed AD conversion unit includes 24-bit ADS1256, sampling rate , sampling period , number of sampling points , n=0,1,2,…N-1,N=1024, n[n] is Gaussian white noise with mean 0 and variance ,

[0043] The extraction and characteristic calculation of the current fundamental component of the sensing electrode layer includes:

[0044] Derivation of the modulus |Z|: For the five signal cycles collected, N=1024 point signals, solve the frequency domain complex sequence X(k):

[0045]

[0046] Determine the fundamental frequency point based on the frequency domain complex sequence , extract the real part of the frequency point and the imaginary part ,available and phase

[0047]

[0048]

[0049]

[0050] in, express Peak value;

[0051] According to Ohm's law, the impedance modulus |Z| of the sensing electrode layer is calculated using the following formula:

[0052]

[0053] Derived phase angle ,include:

[0054] The voltage signal phase and the current signal phase are calculated using the following formula:

[0055] Voltage signal phase

[0056] Current signal phase

[0057] in, , Represents the complex sequence of the fundamental wave (f=50kHZ) component ,in:

[0058]

[0059] Real part :

[0060] Imaginary part :

[0061] Real part :

[0062] Imaginary part :

[0063] Then the phase angle Can be characterized as:

[0064] ,

[0065] Calculate conductance and resistance:

[0066]

[0067] ,

[0068] The initial calibration of the reference state parameter value of the response signal in the clean state includes:

[0069] In the absence of smoking, cigarette insertion, and electrode cleaning, the acquisition parameters are: continuous 30s acquisition and calculation of the impedance modulus of the induction electrode layer of the induction heating structure | Phase shift angle , conductivity and resistors .

[0070] In the above-mentioned induction control method, preferably, the static detection of the cigarette is performed based on the AC impedance parameter characterization model of the induction heating body to obtain the state parameters of the induction electrode layer in the static identification state to identify at least one of the cleanliness level and contact state of the surface of the induction electrode layer, including:

[0071] Calculating the signal modulus, resistance, conductance, and capacitance of the sensing electrode layer in a static identification state according to the AC impedance parameter characterization model of the induction heating body, wherein the static identification state represents a powered-on, non-heating state;

[0072] Calculate the characteristic offset of the state parameter of the sensing electrode layer under the actual measurement state;

[0073] According to the characteristic offset of the state parameter of the sensing electrode layer under the actual measurement state, the cleanliness and contact state of the surface side of the sensing electrode layer are identified, specifically including:

[0074] If |G| / |G0|>2.0 and |Z| / Z0<0.65 for 5 consecutive times, it is judged as severe conductive pollution, and the heating power is immediately cut off and an alarm is issued;

[0075] If |G| / |G0|∈[1.5,2.0] and |Z| / Z0<0.80 for 4 consecutive times, it is judged as light conductive pollution and the user is prompted to clean the electrode;

[0076] If 6 times in a row <0.8 and |Z| / Z0>1.10, it is judged as organic pollution and the heating power is automatically reduced by 10%;

[0077] If the 50ms low-frequency detection is triggered 10 times in a row, the total detection time is 500ms, and the no-load benchmark parameter is collected, it is determined to be in a clean state, with no stains on the electrode surface and no cigarette inserted;

[0078] If detected three times in a row >1.6 and |Z| / Z0<0.85, it is determined to be a cigarette insertion, and the cigarette insertion has the highest priority. Once triggered, the heating system initialization process is immediately activated.

[0079] During the smoking process, the cigarette is dynamically detected to obtain the state parameters of the sensing electrode layer in the dynamic identification state to determine at least one of the cleanliness of the smoking device surface, the cigarette insertion state, and the smoking parameters, including:

[0080] Under dynamic working conditions, the real-time impedance deviation of the sensing electrode layer is calculated;

[0081] Restore the real-time surface temperature of the sensing electrode layer according to the real-time impedance deviation of the sensing electrode layer;

[0082] According to the real-time impedance deviation of the sensing electrode layer and the real-time surface temperature, the triggering and termination events of the puffing action are determined;

[0083] According to the real-time impedance deviation of the sensing electrode layer, the real-time surface temperature and the rate of change of the real-time surface temperature, the triggering and termination events of the puffing action, the duration of the puffing action and the flow rate are calculated.

[0084] Calculating the real-time impedance deviation of the sensing electrode layer in the dynamic working state includes:

[0085] Calculate theoretical impedance: Based on the programmable heating curve , the theoretical resistance of the sensing electrode layer is determined to be:

[0086]

[0087] in, represents the measured resistance at the reference temperature, Indicates the reference temperature;

[0088] Calibrate the resistance baseline of the sensing electrode layer when there is no airflow: Detect the resistance of the heated sensing electrode layer in the programmed heating curve mode At this time, the deviation between the resistance baseline and the theoretical resistance value is ;

[0089] During the puffing process, the real-time impedance deviation of the sensing electrode layer is calculated: the sensing electrode layer is stimulated by a signal with a sampling frequency of 50 kHz, and the measured resistance of the sensing electrode layer is calculated according to the formula The real-time impedance deviation of the sensing electrode layer is calculated using the following formula:

[0090] ,

[0091] The method of restoring the real-time surface temperature of the sensing electrode layer according to the real-time impedance deviation of the sensing electrode layer includes:

[0092] The measured temperature of the sensing electrode layer is calculated using the following formula:

[0093] ,

[0094] The determining of the triggering and termination events of the puffing action based on the real-time impedance deviation of the sensing electrode layer and the real-time surface temperature includes:

[0095] Identify the trigger of the suction event: At this moment, if the following conditions are met at the same time, it is considered a suction trigger event:

[0096]

[0097] ,

[0098] in, represents the sensitivity threshold, Indicates the rate of change threshold;

[0099] Determine the suction termination event: At this moment, if the following conditions are met at the same time, it is determined that the puffing is finished:

[0100]

[0101] ,

[0102] Calculating the duration and flow rate of the puff action based on the real-time impedance deviation of the sensing electrode layer, the real-time surface temperature, the rate of change of the real-time surface temperature, and the triggering and termination events of the puff action includes:

[0103] According to the trigger and termination events of the suction action, the duration of a single suction is determined as Second;

[0104] Calculate the flow rate based on the real-time impedance deviation of the sensing electrode layer and the real-time surface temperature:

[0105] The thermal balance relationship of the sensing electrode layer is determined by the following formula:

[0106]

[0107] The conductive heat input power of the induction heating structure is calculated by the following formula: ,in, is the conduction thermal resistance, Indicates programmed temperature, is the temperature of the heated body surface, which is approximately a constant;

[0108] The convection heat loss power is calculated using the following formula:

[0109] Convection heat loss power: ,

[0110] Where h represents the convective heat transfer coefficient, which is related to the air flow velocity v. The empirical formula is , k and m are calibration coefficients, laminar flow m≈0.5, turbulent flow ≈1, Indicates the effective heat dissipation area of the electrode wire, , Indicates the ambient temperature;

[0111] Calculate the flow rate based on the convection heat loss power: Since in steady state: , combined with , we can get:

[0112]

[0113] Ignore the second-order small quantity , after simplification, we can get :

[0114]

[0115] Combined with laminar flow fitting formula as well as The slope k of , then we have the following relationship:

[0116]

[0117] Where m represents the convective heat transfer coefficient, ,

[0118] When the flow velocities are known to be 1 m / s, 2 m / s, 3 m / s, 4 m / s and 5 m / s, record the corresponding and slope maximum | |, the fitting relationship between flow rate and slope can be obtained:

[0119] .

[0120] The present invention provides an induction heating body structure, an induction control system and an induction control method. A heating component with an integrated induction electrode layer is used to meet the requirements of sensing and responding to cigarette insertion and the cleanliness of the heating body surface under inner core and circumferential heating modes. An AC impedance signal is injected into the heating body electrode layer without any other additional sensors, which can realize low-cost, multi-modal perception of the external state of the smoking device heating body, improve the degree of intelligence, and reduce the cost of smoking device peripherals. It can realize the perception of the cleanliness of the smoking device surface, the cigarette insertion state and the puffing parameters, and realize low-cost, multi-functional intelligent detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0121] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described below with reference to the accompanying drawings, in which:

[0122] Figure 1 This is a schematic diagram of the assembly structure of the induction heating body structure corresponding to the inner core heating structure provided by the present invention;

[0123] Figure 2 An exploded view of the induction heating body structure corresponding to the inner core heating structure provided by the present invention;

[0124] Figure 3 This is a schematic diagram of the assembly structure of the induction heating body structure corresponding to the circumferential heating structure provided by the present invention;

[0125] Figure 4 An exploded view of the induction heating body structure corresponding to the circumferential heating structure provided by the present invention;

[0126] Figure 5 Structural block diagram of the induction heating control system provided by the present invention

[0127] Figure 6 A flow chart of the induction heating control method provided by the present invention;

[0128] Figure 7 This is a logic diagram of the induction heating control method provided by the present invention.

[0129] Explanation of the accompanying drawings: 1-heating wire, 2-insulating sleeve, 3-sensing electrode layer, 4-protective coating, 5-airflow sensing hole, 6-fixed base, 7-heating control electrode, 8-sensing control electrode, 9-microcontroller, 10-first digital frequency synthesizer, 11-first operational amplifier unit, 12-high-speed AD conversion unit, 13-second operational amplifier unit, 14-first precision sampling resistor, 15-third operational amplifier unit, 16-second precision sampling resistor, 17-second digital frequency synthesizer, 18-switch unit. DETAILED DESCRIPTION

[0130] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the present disclosure, its application, or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions, and numerical values set forth in these embodiments should be interpreted as being merely exemplary and not as limiting.

[0131] The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are simply used to distinguish different parts. Terms such as "include" or "comprising" mean that the elements preceding the term include the elements listed after the term, and do not exclude the possibility of also including other elements. Terms such as "upper," "lower," and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0132] In the present disclosure, when a specific component is described as being located between a first component and a second component, there may or may not be an intervening component between the specific component and the first component or the second component. When a specific component is described as being connected to another component, the specific component may be directly connected to the other component without an intervening component, or may not be directly connected to the other component but have an intervening component.

[0133] All terms (including technical or scientific terms) used in this disclosure have the same meaning as those understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined herein.

[0134] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0135] AC impedance testing technology applies a sinusoidal AC signal of a specific frequency to the object being measured, collects the voltage and current responses, and calculates parameters such as the impedance modulus and phase angle to analyze changes in the electrical properties (resistance R, capacitance C, and inductance L) of the material or system. This technology offers the advantages of non-contact, multi-parameter coupled sensing, and can sensitively capture subtle changes in the surface condition of the object being measured (such as the dielectric constant of the contacting object, the conductivity of contaminants, and the integrity of the interface).

[0136] Changes in the surface condition of the heating element (e.g., cigarette insertion, tar residue) directly alter its equivalent RC parallel circuit parameters—the difference between the cigarette's dielectric constant (ε=2-4) and that of a clean surface—resulting in changes in capacitance C. Organic or conductive contamination, on the other hand, causes characteristic shifts in dielectric loss or resistance R, respectively. AC impedance detection technology, through broadband signal excitation and multi-dimensional feature extraction (|Z|, θ combined with capacitance ΔC and temperature response k), accurately identifies contact status and contamination type. Furthermore, by leveraging material functionality (the heating element also serves as a detection electrode), it reduces hardware cost and structural complexity, making it a core technology for addressing the challenges of surface condition detection under complex operating conditions.

[0137] In view of this, the present invention designs an induction heating body structure based on AC impedance detection technology, and constructs an induction control system and a corresponding induction control method on this basis.

[0138] like Figures 1-4 As shown, the induction heating body structure provided in this embodiment includes: a heating wire 1, an induction electrode layer 3 and a protective coating 4 arranged in sequence in the radial direction, and an insulating sleeve 2 is provided outside the heating wire 1.

[0139] Specifically, the material of the heating wire 1 is nickel-chromium alloy wire (Cr20Ni80), and the diameter is designed to be 0.15 mm-0.25 mm, for example, 0.2 mm.

[0140] The insulating sleeve 2 is made of ceramics such as 95% alumina or zirconia, with a thickness of 0.12mm-0.16mm, for example 0.14mm. It has a temperature resistance of up to 1400°C, an insulation resistance greater than 10¹²Ω·cm, and a breakdown voltage of approximately 15kV / mm.

[0141] The sensing electrode layer 3 is made of a copper-nickel alloy film (e.g., CuNi44). The copper-nickel alloy has excellent electrical conductivity and can maintain relatively stable electrical properties at temperatures around 800°C. It is also much cheaper than a platinum-rhodium alloy film. The film thickness is 70 μm to 90 μm, for example, 80 μm, to meet impedance detection requirements and form a good bond with other layer materials.

[0142] Protective coating 4 is made of a silicon carbide-aluminum oxide composite coating (SiC-Al2O3). Silicon carbide has excellent thermal conductivity and thermal shock resistance, while aluminum oxide improves the coating's hardness and chemical stability. The composite coating has a thickness of 70-90 μm, for example, 80 μm, effectively protecting the internal structure.

[0143] Among them, the induction heating body structure is suitable for the inner core heating structure and the circumferential heating structure, such as Figure 1 and Figure 2 As shown, the induction heating body structure suitable for the inner core heating structure is provided with the heating wire 1, the induction electrode layer 3 and the protective coating 4 in sequence from the inside to the outside in the radial direction; Figure 3 and Figure 4 As shown, the induction heating body structure suitable for the circumferential heating structure is provided with the heating wire 1, the induction electrode layer 3 and the protective coating 4 in sequence from the outside to the inside in the radial direction.

[0144] The induction heating body suitable for the inner core heating structure is a slender cylindrical structure with a diameter of 1 mm and a length of 17 mm. It adopts a layered structure, which includes a heating wire 1, an insulating sleeve 2, an induction electrode layer 3 and a protective coating 4 from the inside to the outside.

[0145] The induction heating body structure suitable for the circumferential heating structure is cylindrical, with a diameter of 8 mm and a length of 17 mm. It adopts a layered structure, which includes a protective coating 4, an induction electrode layer 3, a heating wire 1 and an insulating sleeve 2 from the inside to the outside.

[0146] Further, if Figures 1-4 As shown, the sensing electrode layer 3 and the protective coating 4 are located on the insulating sleeve 2 ; an airflow sensing hole 5 is provided in the insulating sleeve 2 and passes through along the axial direction.

[0147] Through the airflow sensing hole 5, airflow suction can be quickly sensed.

[0148] Furthermore, the induction heating body structure also includes a fixed base 6, the induction electrode layer 3 is connected to an induction control electrode 8, and the induction control electrode 8 is led out from the position where the fixed base 6 is located; the heating wire 1 is connected to a heating control electrode 7, and the heating control electrode 7 is led out from the position where the fixed base 6 is located.

[0149] The induction control electrode 8 and the heating control electrode 7 can be used for power supply and signal excitation.

[0150] like Figure 5 As shown, this embodiment also provides an induction control system including the above-mentioned induction heating body structure, and the induction control system further includes: a microcontroller 9, an AC signal generator and an impedance acquisition circuit, wherein the AC signal generator is arranged between the microcontroller 9 and the induction electrode layer 3, and the impedance acquisition circuit is connected to the microcontroller, the induction electrode layer 3 and the heating wire 1 respectively.

[0151] The microcontroller (MCU) 9 integrates a digital signal processing (DSP) module, which performs impedance spectroscopy analysis, multi-sensor data fusion (such as capacitance, temperature, and spectral signals), and status determination algorithms. After device initialization or cleaning, 20 sets of cleaning status data are continuously collected to calculate the baseline impedance signature.

[0152] Specifically, the AC signal generator includes a first digital frequency synthesizer 10 and a first operational amplifier unit 11 arranged in sequence, wherein the first digital frequency synthesizer 10 is connected to the microcontroller 9, and the first operational amplifier unit 11 is connected to the sensing electrode layer 3;

[0153] The impedance acquisition circuit includes a high-speed AD conversion unit 12, a second operational amplifier unit 13, and a first precision sampling resistor 14, which are arranged in sequence. The high-speed AD conversion unit 12 is connected to the microcontroller 9, and the first precision sampling resistor 14 is connected to the sensing electrode layer 3.

[0154] The impedance acquisition circuit further includes a third operational amplifier unit 15 and a second precision sampling resistor 16 which are sequentially arranged, wherein the third operational amplifier unit 15 is connected to the high-speed AD conversion unit 12 , and the second precision sampling resistor 16 is connected to the heating wire 1 .

[0155] Among them, the model of the first digital frequency synthesizer 10 is: AD9833, the model of the first operational amplifier unit 11 is: AD8130, the resistance of the first precision sampling resistor 14 is: 100Ω, ±0.1% accuracy, the resistance of the second precision sampling resistor 16 is: 1Ω, ±0.1% accuracy, the model of the second operational amplifier unit 13 is: INA128, and the model of the high-speed AD conversion unit 12 is: 24-bit ADS1256.

[0156] The working principle of the AC signal generator is as follows: a sinusoidal excitation signal with a frequency of 50 kHz is generated by a first digital frequency synthesizer 10 of model AD9833, amplified to 5 Vpp by a first operational amplifier unit 11 of model AD8130, and applied to the electrode end of the induction electrode layer 3 of the induction heating body structure.

[0157] The impedance acquisition circuit works as follows: the current signal is converted into a voltage signal through a first precision sampling resistor 14 (100Ω, ±0.1% accuracy). After differential amplification by a second operational amplifier unit 13 (INA128), the signal is input into a high-speed AD conversion unit 12 (24-bit ADS1256) to synchronously acquire the voltage signal V(t) and the current signal I(t).

[0158] Furthermore, the induction control system further includes a second digital frequency synthesizer 17 and a switch unit 18 which are arranged in sequence, wherein the second digital frequency synthesizer 17 is connected to the microcontroller 9 , and the switch unit 18 is connected to the heating wire 1 .

[0159] The second digital frequency synthesizer 17 is of model AD9833 and is used to generate an electrical signal of a certain frequency; the switch unit 18 is used to control the switching of a large current.

[0160] like Figure 6 and Figure 7 As shown, the induction control method provided in this embodiment includes the following steps during actual execution:

[0161] Step S1: Based on the induction control system, an AC impedance parameter characterization model of an induction heating body is constructed.

[0162] In one embodiment of the induction control method of the present invention, step S1 may specifically include:

[0163] Step S11: characterize the equivalent circuit of the sensing electrode layer.

[0164] Specifically, when the heating element is not working, the sensing electrode layer is equivalent to a pure resistor. , which is related to the surface capacitance In parallel, it can be characterized as:

[0165]

[0166] Among them, the impedance modulus is: ,

[0167] The phase angle is represented by the following formula: .

[0168] Step S12: injecting an excitation test signal into the induction heating structure.

[0169] Specifically, when the induction heating element is not working, the microcontroller is used to trigger the first digital frequency synthesizer to output an AC signal with a fixed amplitude. , where the amplitude voltage ,frequency , , , inputting the AC signal to the electrode input end of the sensing electrode layer.

[0170] Step S13: Discretely collect the response signal of the sensing electrode layer.

[0171] In one embodiment of the induction control method of the present invention, step S13 may specifically include:

[0172] Step S131: performing current-to-voltage conversion on the phase-shifted signal:

[0173] Current injected into the sensing electrode layer Through the first precision sampling resistor ( ) is converted to a sampling voltage , injection current Can be characterized as:

[0174]

[0175] in, The phase angle that the current phase leads the voltage is expressed as,

[0176] Sampling voltage Can be characterized as:

[0177] .

[0178] Step S132: Perform current-voltage conversion on the phase-shift signal to sample the voltage. Perform signal amplification and ADC discrete acquisition: the sampling voltage is amplified by the second operational amplifier unit Perform signal amplification: the amplified voltage signal is: , where 100 represents the gain of the second operational amplifier unit; the original voltage is synchronously collected in a discrete manner through the high-speed AD conversion unit And the amplified voltage signal , get the digital sequence , characterized by:

[0179]

[0180] Among them, the high-speed AD conversion unit includes 24-bit ADS1256, sampling rate , sampling period , number of sampling points , 200 points per signal cycle, ensuring full cycle sampling, n=0,1,2,…N-1,N=1024, n[n] is Gaussian white noise with mean 0 and variance .

[0181] Step S14: extracting and calculating the characteristics of the fundamental component of the current of the sensing electrode layer.

[0182] In one embodiment of the induction control method of the present invention, step S14 may specifically include:

[0183] Step S141, module value |Z| derivation: for the five signal cycles collected, N=1024 point signals, solve the frequency domain complex sequence X(k):

[0184] .

[0185] Step S142: Determine the fundamental frequency point according to the frequency domain complex sequence , extract the real part of the frequency point and the imaginary part ,available and phase

[0186]

[0187]

[0188]

[0189] in, express peak value.

[0190] Step S143: Calculate the impedance modulus |Z| of the sensing electrode layer according to Ohm's law using the following formula:

[0191]

[0192] Step S144: Derivation of phase angle ,include:

[0193] The voltage signal phase and the current signal phase are calculated using the following formula:

[0194] Voltage signal phase

[0195] Current signal phase

[0196] in, , Represents the complex sequence of the fundamental wave (f=50kHZ) component ,in:

[0197]

[0198] Real part :

[0199] Imaginary part :

[0200] Real part :

[0201] Imaginary part :

[0202] Then the phase angle Can be characterized as:

[0203] .

[0204] Step S145: Calculate conductance and resistance:

[0205]

[0206] .

[0207] Step S2: Initially calibrate the reference state parameter value of the response signal in the clean state.

[0208] Specifically, under the condition of no smoking, no cigarette inserted and clean electrodes, the acquisition parameters are: continuous 30s acquisition and calculation of the impedance modulus of the induction electrode layer of the induction heating body structure | Phase shift angle , conductivity and resistors .

[0209] Step S3: statically inspect the cigarette according to the AC impedance parameter characterization model of the induction heating body to obtain state parameters of the induction electrode layer in a static identification state, so as to identify at least one of the cleanliness level and contact state of the surface of the induction electrode layer.

[0210] In one embodiment of the induction control method of the present invention, step S3 may specifically include:

[0211] Step S31 : calculating the signal modulus, resistance, conductance, and capacitance of the sensing electrode layer in a static identification state according to the AC impedance parameter characterization model of the induction heating body, wherein the static identification state represents a powered-on, non-heating state.

[0212] Step S32: Calculate the characteristic offset of the state parameter of the sensing electrode layer under the actual measurement state.

[0213] Step S33 : identifying the cleanliness and contact state of the surface side of the sensing electrode layer according to the characteristic offset of the state parameter of the sensing electrode layer under the actual measurement state.

[0214] Table 1 Identification table of the surface cleanliness and contact status of the sensing electrode layer

[0215]

[0216] Specifically, as shown in Table 1, if |G| / |G0|>2.0 and |Z| / Z0<0.65 for five consecutive times, it is determined to be severe conductive pollution. At this time, the heating power is immediately cut off and an alarm is issued. The user can use a cleaning brush to clean the surface.

[0217] If |G| / |G0|∈[1.5,2.0] and |Z| / Z0<0.80 for four consecutive times, it is determined to be light conductive contamination, and the user is prompted to clean the electrode. For example, the prompt method may be a flashing yellow LED light.

[0218] If 6 times in a row If the value is less than 0.8 and |Z| / Z0>1.10, it is judged as organic pollution and the heating power is automatically reduced by 10% to compensate for the decrease in thermal efficiency caused by the stains;

[0219] If the 50ms low-frequency detection is triggered 10 times in a row, the total detection time is 500ms, and the no-load benchmark parameter is collected, it is determined to be in a clean state, with no stains on the electrode surface and no cigarette inserted;

[0220] If detected three times in a row >1.6 and |Z| / Z0<0.85, it is determined as cigarette insertion, and cigarette insertion has the highest priority. Once triggered, the heating system initialization process is immediately activated.

[0221] Step S4: During the smoking process, the cigarette is dynamically detected to obtain the state parameters of the sensing electrode layer in the dynamic identification state to determine at least one of the cleanliness of the smoking device surface, the cigarette insertion state, and the smoking parameters.

[0222] In one embodiment of the induction control method of the present invention, step S4 may specifically include:

[0223] Step S41 : Under a dynamic working state, calculating the real-time impedance deviation of the sensing electrode layer.

[0224] In the present invention, the calculation principle of the real-time deviation of the impedance of the sensing electrode layer is as follows: the impedance of the electrode wire (metal) is detected. varies with temperature T, where Indicates the resistance temperature coefficient of the electrode wire. When the suction airflow passes through, the airflow takes away the heat of the electrode wire and the heating wire, resulting in the actual temperature of the heating body surface Lower than the current programmed temperature The faster the airflow velocity, the more heat is taken away, and the greater the rate and amplitude of decrease in the resistance of the electrode wire. In one embodiment of the induction control method of the present invention, the step S41 may specifically include:

[0225] Step S411, calculate theoretical impedance: according to the program-controlled heating curve , the theoretical resistance of the sensing electrode layer is determined to be:

[0226]

[0227] in, represents the measured resistance at a reference temperature (e.g. room temperature), Indicates the reference temperature.

[0228] Step S412: Calibrate the resistance baseline of the sensing electrode layer when there is no airflow: Detect the resistance of the heated sensing electrode layer in the programmable heating curve mode. At this time, the deviation between the resistance baseline and the theoretical resistance value is .

[0229] Step S413: During the puffing process, calculate the real-time impedance deviation of the sensing electrode layer: stimulate the sensing electrode layer with a signal with a sampling frequency of 50 kHz, and calculate the measured resistance of the sensing electrode layer according to the formula The real-time impedance deviation of the sensing electrode layer is calculated using the following formula:

[0230] .

[0231] Step S42 : Restore the real-time surface temperature of the sensing electrode layer according to the real-time impedance deviation of the sensing electrode layer.

[0232] Specifically, the measured temperature of the sensing electrode layer is calculated using the following formula:

[0233] .

[0234] Step S43: Determine the triggering and termination events of the puffing action based on the real-time impedance deviation and the real-time surface temperature of the sensing electrode layer.

[0235] In one embodiment of the induction control method of the present invention, step S43 may specifically include:

[0236] Step S431, determine the triggering of the suction event: At this moment, if the following conditions are met at the same time, it is considered a suction trigger event:

[0237]

[0238] ,

[0239] in, Indicates the sensitivity threshold, for example, 3%-5%, Indicates the rate of change threshold, which is 20mΩ / ms.

[0240] Step S432, determine the suction termination event: At this moment, if the following conditions are met at the same time, it is determined that the puffing is finished:

[0241]

[0242] .

[0243] Step S44: Calculate the duration and flow rate of the puffing action based on the real-time impedance deviation of the sensing electrode layer, the real-time surface temperature, the rate of change of the real-time surface temperature, and the triggering and termination events of the puffing action.

[0244] In one embodiment of the induction control method of the present invention, step S44 may specifically include:

[0245] Step S441: Determine the duration of a single puff based on the trigger and termination events of the puff action. Second.

[0246] Step S442: Calculate the flow rate based on the real-time impedance deviation of the sensing electrode layer and the real-time surface temperature:

[0247] In the present invention, the calculation principle of flow rate is: when the suction airflow passes through, the convection heat transfer between the surface of the sensing electrode layer and the airflow is enhanced, resulting in the heat dissipation power Increase, the induction heating structure maintains the temperature of the induction electrode layer approximately equal to , the heat dissipation change caused by the airflow will be reflected by the slight fluctuation of the resistance of the sensing electrode layer, and the heat dissipation changes smoothly. In one embodiment of the induction control method of the present invention, the step S442 may specifically include:

[0248] Step S4421: Determine the thermal balance relationship of the sensing electrode layer using the following formula:

[0249]

[0250] Step S4422: Calculate the conduction heat input power of the induction heating structure using the following formula: ,in, is the conduction thermal resistance, Indicates programmed temperature, is the temperature of the heated body surface, which is approximately a constant.

[0251] Step S4423: Calculate the convection heat loss power using the following formula:

[0252] Convection heat loss power: ,

[0253] Where h represents the convective heat transfer coefficient, which is related to the air flow velocity v. The empirical formula is , k and m are calibration coefficients, laminar flow m≈0.5, turbulent flow ≈1, Indicates the effective heat dissipation area of the electrode wire, , Indicates the ambient temperature.

[0254] Calculate the flow rate based on the convection heat loss power: Since in steady state: , combined with , we can get:

[0255]

[0256] Ignore the second-order small quantity , after simplification, we can get :

[0257]

[0258] Combined with laminar flow fitting formula as well as The slope k of , then we have the following relationship:

[0259]

[0260] Where m represents the convective heat transfer coefficient, ,

[0261] When the flow velocities are known to be 1 m / s, 2 m / s, 3 m / s, 4 m / s and 5 m / s, record the corresponding and slope maximum | |, the fitting relationship between flow rate and slope can be obtained:

[0262] .

[0263] It should be noted that the present invention does not specifically limit the execution order of step S3 and step S4.

[0264] Furthermore, in some embodiments of the present invention, the induction control method further includes step S5, outputting the induction state of the heating body and the response control parameters.

[0265] The induction heating body structure, induction control system and induction control method provided by the embodiments of the present invention adopt a heating component with an integrated induction electrode layer, which can meet the requirements of sensing and responding to cigarette insertion and the cleanliness status of the heating body surface under the inner core and circumferential heating mode; adopting the method of injecting AC impedance signal into the heating body electrode layer without other additional sensors, it can realize low-cost, multi-modal angle perception of the external state of the heating body of the smoking device, improve the degree of intelligence, and reduce the cost of smoking device peripherals; it can realize the perception of the cleanliness of the smoking device surface, the cigarette insertion status and the puffing parameters, and realize low-cost, multi-functional intelligent detection.

[0266] Thus far, various embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0267] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. An induction heating structure, characterized in that: include: A heating wire, an induction electrode layer and a protective coating are arranged in sequence in a radial direction, and an insulating sleeve is arranged outside the heating wire.

2. The induction heating structure according to claim 1, characterized in that: The induction heating body structure is applicable to the inner core heating structure and the circumferential heating structure. The induction heating body structure applicable to the inner core heating structure is provided with the heating wire, the induction electrode layer and the protective coating in order from the inside to the outside in the radial direction; The induction heating body structure suitable for the circumferential heating structure is provided with the heating wire, the induction electrode layer and the protective coating in sequence from the outside to the inside in the radial direction.

3. The induction heating structure according to claim 1, characterized in that: The sensing electrode layer and the protective coating are located on the insulating sleeve, and an airflow sensing hole penetrating along the axial direction is provided in the insulating sleeve.

4. The induction heating structure according to claim 3, characterized in that: The induction heating body structure also includes a fixed base, the induction electrode layer is connected to an induction control electrode, and the induction control electrode is led out from the position of the fixed base; the heating wire is connected to a heating control electrode, and the heating control electrode is led out from the position of the fixed base.

5. An induction control system comprising the induction heating structure according to any one of claims 1 to 4, characterized in that: The induction control system further includes: a microcontroller, an AC signal generator and an impedance acquisition circuit. The AC signal generator is arranged between the microcontroller and the sensing electrode layer, and the impedance acquisition circuit is connected to the microcontroller, the sensing electrode layer and the heating wire respectively.

6. The induction control system according to claim 5, characterized in that: The AC signal generator includes a first digital frequency synthesizer and a first operational amplifier unit arranged in sequence, wherein the first digital frequency synthesizer is connected to the microcontroller, and the first operational amplifier unit is connected to the sensing electrode layer; The impedance acquisition circuit includes a high-speed AD conversion unit, a second operational amplifier unit, and a first precision sampling resistor, which are arranged in sequence, wherein the high-speed AD conversion unit is connected to the microcontroller, and the first precision sampling resistor is connected to the sensing electrode layer; The impedance acquisition circuit further includes a third operational amplifier unit and a second precision sampling resistor which are sequentially arranged, wherein the third operational amplifier unit is connected to the high-speed AD conversion unit, and the second precision sampling resistor is connected to the heating wire.

7. The induction control system according to claim 6, characterized in that: The induction control system further includes a second digital frequency synthesizer and a switch unit which are sequentially arranged, wherein the second digital frequency synthesizer is connected to the microcontroller, and the switch unit is connected to the heating wire.

8. An induction control method using the induction control system according to any one of claims 5 to 7, characterized in that: include: Based on the induction control system, an AC impedance parameter characterization model of the induction heating body is constructed; Perform initial calibration on the reference state parameter value of the response signal under clean state; Performing static testing on the cigarette according to the AC impedance parameter characterization model of the induction heating body to obtain state parameters of the induction electrode layer in a static identification state, so as to identify at least one of the cleanliness level and contact state of the surface of the induction electrode layer; During the smoking process, the cigarette is dynamically detected to obtain the state parameters of the sensing electrode layer in the dynamic identification state to determine at least one of the cleanliness of the smoking device surface, the cigarette insertion state and the smoking parameters.

9. The induction control method according to claim 8, characterized in that: The method of constructing an AC impedance parameter characterization model of an induction heating body based on the induction control system includes: Characterize the equivalent circuit of the sensing electrode layer; injecting an excitation test signal into the induction heating structure; Discretely collect the response signal of the sensing electrode layer; Extract the fundamental component of the current in the sensing electrode layer and calculate its characteristics. The method for representing the equivalent circuit of the sensing electrode layer includes: When the heating element is not working, the sensing electrode layer is equivalent to a pure resistor. , which is related to the surface capacitance In parallel, it can be characterized as: ， Among them, the impedance modulus is: , The phase angle is represented by the following formula: , The step of injecting an excitation test signal into the induction heating structure comprises: When the induction heating element is not working, the microcontroller is used to trigger the first digital frequency synthesizer to output an AC signal with a fixed amplitude. , where the amplitude voltage ,frequency , , , input the AC signal to the electrode input end of the sensing electrode layer, The discrete acquisition of the response signal of the sensing electrode layer includes: Perform current-to-voltage conversion on the phase-shifted signal: Current injected into the sensing electrode layer Converted into sampling voltage through the first precision sampling resistor , injection current Can be characterized as: ， in, The phase angle that the current phase leads the voltage is expressed as, Sampling voltage Can be characterized as: ； Sampling voltage Perform signal amplification and ADC discrete acquisition: the sampling voltage is amplified by the second operational amplifier unit Perform signal amplification: the amplified voltage signal is: , where 100 represents the gain of the second operational amplifier unit; the original voltage is synchronously collected in a discrete manner through the high-speed AD conversion unit And the amplified voltage signal , get the digital sequence , characterized by: ， Among them, the high-speed AD conversion unit includes 24-bit ADS1256, sampling rate , sampling period , number of sampling points , n=0,1,2,…N-1,N=1024, n[n] is Gaussian white noise with mean 0 and variance , The extraction and characteristic calculation of the current fundamental component of the sensing electrode layer includes: Derivation of the modulus |Z|: For the five signal cycles collected, N=1024 point signals, solve the frequency domain complex sequence X(k): ， Determine the fundamental frequency point based on the frequency domain complex sequence , extract the real part of the frequency point and the imaginary part ,available and phase , ， ， ， in, express Peak value; According to Ohm's law, the impedance modulus |Z| of the sensing electrode layer is calculated using the following formula: ， Derived phase angle ,include: The voltage signal phase and the current signal phase are calculated using the following formula: Voltage signal phase , Current signal phase , in, , Represents the complex sequence of the fundamental wave (f=50kHZ) component ,in: ， Real part : , Imaginary part : , Real part : , Imaginary part : , Then the phase angle Can be characterized as: ， Calculate conductance and resistance: ， ， The initial calibration of the reference state parameter value of the response signal in the clean state includes: In the absence of smoking, cigarette insertion, and electrode cleaning, the acquisition parameters are: continuous 30s acquisition and calculation of the impedance modulus of the induction electrode layer of the induction heating structure | Phase shift angle , conductivity and resistors .

10. The induction control method according to claim 8, characterized in that: The method of performing static detection on a cigarette according to the AC impedance parameter characterization model of the induction heating body to obtain state parameters of the induction electrode layer in a static identification state to identify at least one of the cleanliness level and contact state of the surface of the induction electrode layer includes: Calculating the signal modulus, resistance, conductance, and capacitance of the sensing electrode layer in a static identification state according to the AC impedance parameter characterization model of the induction heating body, wherein the static identification state represents a powered-on, non-heating state; Calculate the characteristic offset of the state parameter of the sensing electrode layer under the actual measurement state; According to the characteristic offset of the state parameter of the sensing electrode layer under the actual measurement state, the cleanliness and contact state of the surface side of the sensing electrode layer are identified, specifically including: If |G| / |G0| > 2.0 and |Z| / Z0 < 0.65 for 5 consecutive times, it is judged as severe conductive pollution, and the heating power is immediately cut off and an alarm is issued; If |G| / |G0|∈[1.5,2.0] and |Z| / Z0<0.80 for 4 consecutive times, it is judged as light conductive pollution and the user is prompted to clean the electrode; If 6 times in a row <0.8 and |Z| / Z0>1.10, it is judged as organic pollution and the heating power is automatically reduced by 10%; If the 50ms low-frequency detection is triggered 10 times in a row, the total detection time is 500ms, and the no-load benchmark parameter is collected, it is determined to be in a clean state, with no stains on the electrode surface and no cigarette inserted; If detected three times in a row >1.6 and |Z| / Z0<0.85, it is determined to be a cigarette insertion, and the cigarette insertion has the highest priority. Once triggered, the heating system initialization process is immediately activated. During the smoking process, the cigarette is dynamically detected to obtain the state parameters of the sensing electrode layer in the dynamic identification state to determine at least one of the cleanliness of the smoking device surface, the cigarette insertion state, and the smoking parameters, including: Under dynamic working conditions, the real-time impedance deviation of the sensing electrode layer is calculated; Restore the real-time surface temperature of the sensing electrode layer according to the real-time impedance deviation of the sensing electrode layer; According to the real-time impedance deviation of the sensing electrode layer and the real-time surface temperature, the triggering and termination events of the puffing action are determined; According to the real-time impedance deviation of the sensing electrode layer, the real-time surface temperature, the rate of change of the real-time surface temperature, the triggering and termination events of the puffing action, the puffing action duration and flow rate are calculated. Calculating the real-time impedance deviation of the sensing electrode layer in the dynamic working state includes: Calculate theoretical impedance: Based on the programmable heating curve , the theoretical resistance of the sensing electrode layer is determined to be: ， in, represents the measured resistance at the reference temperature, Indicates the reference temperature; Calibrate the resistance baseline of the sensing electrode layer when there is no airflow: Detect the resistance of the heated sensing electrode layer in the programmed heating curve mode At this time, the deviation between the resistance baseline and the theoretical resistance value is ; During the puffing process, the real-time impedance deviation of the sensing electrode layer is calculated: the sensing electrode layer is stimulated by a signal with a sampling frequency of 50 kHz, and the measured resistance of the sensing electrode layer is calculated according to the formula The real-time impedance deviation of the sensing electrode layer is calculated using the following formula: ， The method of restoring the real-time surface temperature of the sensing electrode layer according to the real-time impedance deviation of the sensing electrode layer includes: The measured temperature of the sensing electrode layer is calculated using the following formula: ， The determining of the triggering and termination events of the puffing action based on the real-time impedance deviation of the sensing electrode layer and the real-time surface temperature includes: Identify the trigger of the suction event: At this moment, if the following conditions are met at the same time, it is considered a suction trigger event: ， ， in, represents the sensitivity threshold, Indicates the rate of change threshold; Determine the suction termination event: At this moment, if the following conditions are met at the same time, it is determined that the puffing is finished: ， ， Calculating the duration and flow rate of the puff action based on the real-time impedance deviation of the sensing electrode layer, the real-time surface temperature and the rate of change of the real-time surface temperature, and the triggering and termination events of the puff action includes: According to the trigger and termination events of the suction action, the duration of a single suction is determined as Second; Calculate the flow rate based on the real-time impedance deviation of the sensing electrode layer and the real-time surface temperature: The thermal balance relationship of the sensing electrode layer is determined by the following formula: ， The conductive heat input power of the induction heating structure is calculated by the following formula: ,in, represents the conduction thermal resistance, Indicates programmed temperature, is the temperature of the heated body surface, which is approximately a constant; The convection heat loss power is calculated using the following formula: Convection heat loss power: , Among them, h represents the convective heat transfer coefficient, which is related to the air flow velocity v. The empirical formula is , k and m are calibration coefficients, laminar flow m≈0.5, turbulent flow ≈1, Indicates the effective heat dissipation area of the electrode wire, , Indicates the ambient temperature; Calculate the flow rate based on the convection heat loss power: Since in steady state: , combined with , we can get: ， Ignore the second-order small quantity , after simplification, we can get : ， Combined with laminar flow fitting formula as well as The slope k of , then we have the following relationship: ， Where m represents the convective heat transfer coefficient, , When the flow velocities are known to be 1 m / s, 2 m / s, 3 m / s, 4 m / s and 5 m / s, record the corresponding and slope maximum | |, the fitting relationship between flow rate and slope can be obtained: 。

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