Heating control circuit of cooking utensil

Abstract

The invention relates to the technical field of cooking utensils, in particular to a cooking utensil heating control circuit which comprises an oil temperature detection module, an oil smoke detection module, a first switch module and an intelligent control module. The oil temperature detection module collects oil temperature signals, converts the oil temperature signals into oil temperature electric signals and outputs the oil temperature electric signals to the first switch module. When the oil temperature electric signal voltage is larger than a preset threshold value, the first switch module conducts power supply connection between the power supply and the lampblack detection module. After the power supply connection is conducted, the oil smoke detection module collects oil smoke gas parameters in real time and transmits the oil smoke gas parameters to the intelligent control module. And the intelligent control module compares the oil smoke gas parameter with a preset threshold value, generates a heating power adjusting signal and outputs the heating power adjusting signal to the heating assembly. The circuit intelligently activates the oil smoke detection module through an oil temperature signal, invalid power consumption of a sensor is avoided, meanwhile, the heating power is accurately regulated and controlled based on oil smoke pollution parameters, and the problems of detection lag and insufficient harmful substance generation risk control in a traditional single temperature control scheme are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cooking utensils, in particular to a cooking utensil heating control circuit. BACKGROUND

[0002] In the field of modern kitchen appliances, the heating control technology of cooking utensils has been evolving around the needs of safety, efficiency and health. The traditional heating control scheme of cooking utensils (such as induction cookers, electric frying pans, etc.) mainly relies on a single temperature detection method, which monitors the temperature of the pot through thermocouples, thermistors and other sensors. When the oil temperature exceeds the preset threshold, power is cut off or power is adjusted to avoid safety hazards or smoke problems caused by overheating.

[0003] However, single temperature detection cannot fully reflect the risk of harmful substance generation during cooking. Pollutants such as volatile organic compounds (VOCs) and particulate matter (PM2.5 / PM10) generated by oil thermal decomposition and food material burning, their generation starting point and concentration change law are not simply linearly related to oil temperature. For example, VOCs have begun to generate significantly at an oil temperature of 120-150℃, which is earlier than the appearance of visible smoke (corresponding to high concentration of particulate matter). The traditional temperature control system only uses "whether to smoke" (i.e. particulate matter concentration) as the basis for risk judgment, which cannot capture the accumulation of VOCs in the early low oil temperature stage, resulting in chronic health risks being ignored.

[0004] The above content is only used to assist in understanding the technical solutions of the present application and does not represent the acknowledgement of the above content as prior art. SUMMARY

[0005] The main purpose of the present application is to provide a cooking utensil heating control circuit, which aims to solve the technical problem that the traditional heating control scheme of cooking utensils mainly relies on a single temperature detection method, which cannot fully reflect the risk of harmful substance generation during cooking.

[0006] To achieve the above-mentioned purpose, the present application provides a cooking utensil heating control circuit, which comprises an oil temperature detection module, an oil smoke detection module, a first switch module and an intelligent control module. The oil temperature detection module is connected with the first switch module, the first switch module is connected with a power supply and an oil smoke detection module respectively, the oil smoke detection module is connected with the intelligent control module, and the intelligent control module is connected with a cooking utensil heating component. The oil temperature detection module is used for collecting oil temperature signals during cooking and converting the oil temperature signals into corresponding oil temperature electrical signals and outputting the oil temperature electrical signals to the first switch module. The first switch module is used for turning on the power supply connection between the power supply and the oil smoke detection module when the voltage value of the oil temperature electrical signal is greater than a first preset voltage threshold. The oil fume detection module is configured to collect, in real time, an oil fume gas parameter generated during cooking when the power supply connection is turned on. The intelligent control module is configured to compare the oil fume gas parameter collected in real time with a preset oil fume concentration threshold, and generate a heating power adjustment signal according to a comparison result and output the heating power adjustment signal to the cooking appliance heating assembly.

[0007] Optionally, the oil fume gas parameter includes an oil fume particulate matter concentration and a volatile organic matter concentration, and the oil fume detection module includes a particulate matter sensor and a gas sensor, wherein the particulate matter sensor is configured to detect the oil fume particulate matter concentration, and the gas sensor is configured to detect the volatile organic matter concentration. Correspondingly, the intelligent control module includes a first calculation unit, a second calculation unit, and a power adjustment unit, wherein a first end of the first calculation unit is connected with the particulate matter sensor, a second end of the first calculation unit is connected with the power adjustment unit, a first end of the second calculation unit is connected with the gas sensor, and a second end of the second calculation unit is connected with the power adjustment unit. The first calculation unit is configured to calculate a first difference value between the oil fume particulate matter concentration and a preset oil fume particulate matter concentration when the oil fume particulate matter concentration is greater than the preset oil fume particulate matter concentration. The second calculation unit is configured to calculate a second difference value between the volatile organic matter concentration and a preset volatile organic matter concentration when the volatile organic matter concentration is greater than the preset volatile organic matter concentration. The power adjustment unit is configured to generate a heating power adjustment signal based on the first difference value or the second difference value and output the heating power adjustment signal to the cooking appliance heating assembly.

[0008] Optionally, the intelligent control module further includes a signal adjustment unit. A first end of the signal adjustment unit is connected with the first end of the first calculation unit and the first end of the second calculation unit respectively, and a second end of the signal adjustment unit is connected with the power adjustment unit. The first calculation unit is further configured to output a difference signal corresponding to the first difference value to the signal adjustment unit, and the second calculation unit is further configured to output a difference signal corresponding to the second difference value to the signal adjustment unit. The signal adjustment unit is configured to perform signal transformation on the difference signal through PID adjustment and transmit the transformed difference signal to the power adjustment unit. The power adjustment unit is further configured to generate a heating power adjustment signal according to the transformed difference signal and output the heating power adjustment signal to the cooking appliance heating assembly.

[0009] Optionally, the circuit further comprises a pressure detection module; The pressure detection module is connected with the oil temperature detection module and the intelligent control module. The oil temperature detection module is further configured to output a cooking utensil pressure detection signal to the pressure detection module when the voltage value of the oil temperature electrical signal is less than a second preset voltage threshold. The pressure detection module is configured to determine whether the cooking utensil is in an empty burning state according to a pressure electrical signal of the cooking utensil when the cooking utensil pressure detection signal is received, and output a first heating signal to the intelligent control module if the cooking utensil is in the empty burning state. The intelligent control module is further configured to generate a step power adjustment signal and output the signal to the cooking utensil heating assembly to automatically switch to low-power maintenance after the oil temperature reaches the target preheating temperature when the first heating signal is received.

[0010] Optionally, the pressure detection module is further configured to determine whether the cooking utensil adds food materials according to a pressure electrical signal of the cooking utensil when the cooking utensil pressure detection signal is received, and output a second heating signal to the intelligent control module if the cooking utensil adds food materials. The intelligent control module is further configured to generate a short-time high-power compensation signal and output the signal to the cooking utensil heating assembly to shorten the food material moisture evaporation time when the second heating signal is received.

[0011] Optionally, the first calculation unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, and a first amplifier. The first end of the first resistor is connected with the particulate matter sensor, the second end of the first resistor is connected with the first end of the third resistor and the positive input end of the first amplifier respectively, the second end of the third resistor is connected with the output end of the first amplifier and the signal adjustment unit, the first end of the second resistor is connected with a first reference power supply, the second end of the second resistor is connected with the negative input end of the amplifier and the first end of the fourth resistor, the second end of the fourth resistor is grounded, and the output end of the first amplifier is connected with the signal adjustment unit.

[0012] Optionally, the second calculation unit comprises a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a second amplifier. The first end of the fifth resistor is connected with the gas sensor, the second end of the fifth resistor is connected with the first end of the seventh resistor and the positive input end of the second amplifier respectively, the second end of the seventh resistor is connected with the output end of the second amplifier and the signal conditioning unit, the first end of the sixth resistor is connected with the second reference power supply, the second end of the sixth resistor is connected with the negative input end of the amplifier and the first end of the eighth resistor, the second end of the eighth resistor is grounded, and the output end of the second amplifier is connected with the signal conditioning unit.

[0013] Optionally, the power conditioning unit comprises a ninth resistor, a tenth resistor, an eleventh resistor, a third amplifier and a 555 timer. The first end of the ninth resistor is connected with the signal conditioning unit, the second end of the ninth resistor is connected with the first end of the eleventh resistor, the first end of the tenth resistor and the positive input end of the third amplifier respectively, the negative input end of the third amplifier is grounded, the output end of the third amplifier is connected with the 555 timer, the second end of the eleventh resistor is connected with the third reference power supply, and the second end of the tenth resistor is connected with the output end of the third amplifier.

[0014] Optionally, the oil temperature detection module comprises a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a first capacitor, wherein the twelfth resistor is a thermistor. The first end of the twelfth resistor is connected with the first end of the thirteenth resistor and the first end of the fourteenth resistor, the second end of the thirteenth resistor is connected with the power supply, the second end of the fourteenth resistor is grounded, the first end of the first capacitor is connected with the first end of the fourteenth resistor, the second end of the first capacitor is grounded, and the second end of the twelfth resistor is connected with the first switch module.

[0015] Optionally, the first switch module comprises a comparator, a first switch tube and a fifteenth resistor. The positive input end of the comparator is connected with the second end of the twelfth resistor, the negative input end of the comparator is connected with the fourth reference power supply, the output end of the comparator is connected with the control end of the first switch tube, the input end of the first switch tube is connected with the second end of the fifteenth resistor, the first end of the fifteenth resistor is connected with the power supply, and the output end of the first switch tube is connected with the oil temperature detection module.

[0016] The application provides a cooking utensil heating control circuit, which comprises an oil temperature detection module, an oil fume detection module, a first switch module and an intelligent control module; wherein the oil temperature detection module is connected with the first switch module, the first switch module is connected with a power supply and the oil fume detection module respectively, the oil fume detection module is connected with the intelligent control module, and the intelligent control module is connected with a cooking utensil heating assembly; the oil temperature detection module is used for collecting an oil temperature signal in a cooking process and converting the oil temperature signal into a corresponding oil temperature electrical signal output to the first switch module; the first switch module is used for turning on a power supply connection between the power supply and the oil fume detection module when a voltage value of the oil temperature electrical signal is greater than a first preset voltage threshold; the oil fume detection module is used for collecting an oil fume gas parameter generated in the cooking process in real time when the power supply connection is turned on; and the intelligent control module is used for comparing the oil fume gas parameter collected in real time with a preset oil fume concentration threshold and generating a heating power adjustment signal output to the cooking utensil heating assembly according to a comparison result. The scheme intelligently activates the oil fume detection module through the oil temperature signal, avoids invalid power consumption of the sensor, accurately regulates and controls the heating power based on the oil fume pollution parameter, and effectively solves the problems of detection lag, unreasonable energy consumption and insufficient risk control of harmful substance generation in the traditional single temperature control scheme. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a structural schematic diagram of an embodiment of the cooking utensil heating control circuit of the application; Figure 2 FIG. 2 is a structural schematic diagram of another embodiment of the cooking utensil heating control circuit of the application; Figure 3 FIG. 3 is a structural schematic diagram of another embodiment of the cooking utensil heating control circuit of the application; Figure 4 FIG. 4 is a circuit principle diagram of the first calculation unit and the second calculation unit of the embodiment of the cooking utensil heating control circuit of the application; Figure 5 FIG. 5 is a circuit principle diagram of the power adjustment unit of the embodiment of the cooking utensil heating control circuit of the application.

[0018] Figure 6 FIG. 6 is a circuit principle diagram of the oil temperature detection module and the first switch module of the embodiment of the cooking utensil heating control circuit of the application.

[0019] BRIEF DESCRIPTION OF DRAWINGS

[0020] The implementation, functional features and advantages of the application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0021] It should be understood that the specific embodiments described herein are merely illustrative of the present application and do not limit the present application.

[0022] With reference to Figures 1 to 6 , the present application proposes a cooking utensil heating control circuit, which comprises an oil temperature detection module 10, an oil fume detection module 30, a first switching module 20 and an intelligent control module 40. Wherein, the oil temperature detection module 10 is connected with the first switching module 20, the first switching module 20 is connected with a power supply V1 and the oil fume detection module 30 respectively, the oil fume detection module 30 is connected with the intelligent control module 40, and the intelligent control module 40 is connected with a cooking utensil heating assembly. The oil temperature detection module 10 is used for collecting oil temperature signals in a cooking process and converting the oil temperature signals into corresponding oil temperature electrical signals and outputting the oil temperature electrical signals to the first switching module 20. The first switching module 20 is used for turning on a power supply connection between the power supply V1 and the oil fume detection module 30 when a voltage value of the oil temperature electrical signals is greater than a first preset voltage threshold. The oil fume detection module 30 is used for collecting oil fume gas parameters generated in the cooking process in real time when the power supply connection is turned on. The intelligent control module 40 is used for comparing the real-time collected oil fume gas parameters with a preset oil fume concentration threshold and generating a heating power adjustment signal according to a comparison result and outputting the heating power adjustment signal to the cooking utensil heating assembly.

[0023] It should be noted that the oil temperature detection module 10 collects oil temperature signals in a cooking process in real time and converts temperature physical quantities into electrical signals, such as voltage or current signals, which can be recognized by a circuit, and outputs the electrical signals to the first switching module 20 as a condition for triggering the oil fume detection module 30 to work. Specifically, the temperature sensor can be used to perceive oil temperature changes, such as thermocouples, thermistors and infrared temperature measuring elements. The oil temperature is converted into corresponding voltage signals by using temperature-electrical signal characteristics of the sensor, such as Seebeck effect of thermocouples and resistance-temperature change characteristics of thermistors, for example, a millivolt-level voltage output by a thermocouple linearly increases with the oil temperature. The oil temperature electrical signals are positive correlation analog voltage signals, such as 0-5V, corresponding to oil temperatures of 0-250℃, which directly affect the turn-on logic of the first switching module 20.

[0024] In an embodiment of the present application, with reference to Figure 6 , the oil temperature detection module 10 can comprise a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14 and a first capacitor C1, wherein the twelfth resistor R12 is a thermistor. The first end of the twelfth resistor R12 is connected with the first end of the thirteenth resistor R13 and the first end of the fourteenth resistor R14, the second end of the thirteenth resistor R13 is connected with a power supply V1, the second end of the fourteenth resistor R14 is grounded, the first end of the first capacitor C1 is connected with the first end of the fourteenth resistor R14, the second end of the first capacitor C1 is grounded, and the second end of the twelfth resistor R12 is connected with the first switch module 20.

[0025] It should be noted that the twelfth resistor R12 can perceive the oil temperature change and convert it into a resistance value change, through the nonlinear change of resistance value with temperature, and a voltage signal output to the first switch module 20 by a voltage division circuit composed of the thirteenth resistor R13 and the fourteenth resistor R14. The first capacitor C1 is used to filter high-frequency noise in the voltage of the voltage division node, so as to avoid the instantaneous fluctuation of the oil temperature signal from causing the first switch module 20 to be triggered by mistake.

[0026] The first switch module 20 is a power supply control switch of the oil smoke detection module 30, and whether the circuit between the power supply V1 and the oil smoke detection module 30 is turned on or not is determined according to the voltage value of the oil temperature electric signal, so as to realize the on-demand activation of the oil smoke detection module 30 and avoid invalid power consumption. A first preset voltage threshold is preset, such as a voltage value corresponding to an oil temperature of 120 DEG C, that is, a critical temperature at which grease begins to significantly generate VOCs. When the voltage of the oil temperature electric signal is greater than the first preset voltage threshold, the module is turned on to supply power to the oil smoke detection module 30, otherwise, the module is turned off to stop power supply. The first switch module 20 can adopt semiconductor switching elements such as bipolar transistors (BJT) and field effect tubes (MOSFET), or electromechanical switches such as relays, and the switching state is controlled after the threshold value is determined by the voltage comparator A4 (such as LM393).

[0027] In an embodiment of the present application, referring to Figure 6 , the first switch module 20 comprises a comparator A4, a first switch tube Q1 and a fifteenth resistor R15. The positive input end of the comparator A4 is connected with the second end of the twelfth resistor R12, the reverse input end of the comparator A4 is connected with a fourth reference power supply Vref4, the output end of the comparator A4 is connected with the control end of the first switch tube Q1, the input end of the first switch tube Q1 is connected with the second end of the fifteenth resistor R15, the first end of the fifteenth resistor R15 is connected with a power supply V1, and the output end of the first switch tube Q1 is connected with the oil temperature detection module 10.

[0028] It should be noted that the comparator A4 realizes real-time comparison of the oil temperature electrical signal and the preset voltage threshold, and outputs a switch control signal (high / low level). The positive input end receives the oil temperature electrical signal output by the oil temperature detection module 10 from the second end of the twelfth resistor R12, i.e., the voltage of the voltage division node, which reflects the real-time oil temperature. The negative input end is connected to the fourth reference voltage Vref4, i.e., the reference voltage corresponding to the first preset voltage threshold, such as 2.5V, which is provided by a power supply voltage division or a precision voltage reference chip. The output end outputs a control signal according to the voltage relationship between the two ends. When the positive input voltage is greater than the negative input voltage (preset threshold), a high level (such as 5V) is output. Conversely, a low level (such as 0V) is output. The comparator A4 converts the analog voltage signal into a digital logic signal (high / low level) to directly drive the conduction or cutoff of the first switch tube Q1. The first switch tube Q1, such as a triode or MOSFET, serves as an execution element to realize circuit on-off control between the power supply V1 and the oil fume detection module 30 according to the control signal output by the comparator A4. The fifteenth resistor R15 limits the current flowing into the control end of the first switch tube Q1, protects the switch tube from excessive current impact, and ensures the stability of the output signal of the comparator A4.

[0029] The oil fume detection module 30 collects the oil fume gas parameters generated during the cooking process in real time after the first switch module 20 is powered on, identifies the oil fume pollution degree, and outputs to the intelligent control module 40 as the basis for power adjustment. The intelligent control module 40 receives the real-time data of the oil fume detection module 30, compares it with the preset oil fume concentration safety threshold, generates a heating power adjustment signal, drives the adjustment power of the cooking appliance, and realizes oil fume concentration feedback temperature control, wherein the heating components are, for example, electromagnetic oven coils, heating wires, and gas proportional valves. The intelligent control module 40 presets the oil fume concentration threshold, such as VOCs concentration 0.2ppm and PM2.5 concentration 50μg / m³, which represents the critical value of health risk. When it exceeds, power adjustment is triggered; according to the comparison result, an analog signal (such as 0-10V voltage) or a digital signal (such as PWM pulse width modulation signal) is output to control the power of the heating components. For example, the power is reduced by 10%-20% when the oil fume exceeds the standard.

[0030] Specifically, referring to Figure 2 , the oil fume gas parameters include oil fume particulate matter concentration and volatile organic matter concentration, and the oil fume detection module 30 includes a particulate matter sensor 301 and a gas sensor 302, wherein the particulate matter sensor 301 is used to detect the oil fume particulate matter concentration, and the gas sensor 302 is used to detect the volatile organic matter concentration. Correspondingly, the intelligent control module 40 comprises a first calculation unit 401, a second calculation unit 402, and a power adjustment unit 403, wherein a first end of the first calculation unit 401 is connected with the particulate matter sensor 301, a second end of the first calculation unit 401 is connected with the power adjustment unit 403, a first end of the second calculation unit 402 is connected with the gas sensor 302, and a second end of the second calculation unit 402 is connected with the power adjustment unit 403; The first calculation unit 401 is configured to calculate a first difference between the oil fume particulate matter concentration and a preset oil fume particulate matter concentration when the oil fume particulate matter concentration is greater than the preset oil fume particulate matter concentration. The second calculation unit 402 is configured to calculate a second difference between the volatile organic matter concentration and a preset volatile organic matter concentration when the volatile organic matter concentration is greater than the preset volatile organic matter concentration. The power adjustment unit 403 is configured to generate a heating power adjustment signal based on the first difference or the second difference and output the heating power adjustment signal to the cooking utensil heating assembly.

[0031] It should be noted that the particulate matter sensor 301 monitors the concentration of oil fume particulate matter (such as PM2.5 and PM10) generated during the cooking process in real time, reflecting the content of solid or liquid aerosol generated by high-temperature decomposition of oil or burning of food materials. The particulate matter sensor 301 can adopt an optical scattering principle, such as an infrared LED plus a photodiode, to calculate the concentration by detecting the scattering intensity of light by particulate matter; or a capacitive sensor, which indirectly measures the concentration by the amount of change in capacitance caused by the deposition of particulate matter, and outputs an analog voltage signal or a digital signal, which is directly input to the first calculation unit 401 of the intelligent control module 40. The gas sensor 302 monitors the concentration of volatile organic pollutants (such as propylene aldehyde, benzopyrene, formaldehyde, and other VOCs) generated during the cooking process in real time, reflecting the degree of thermal oxidation of oil or deterioration of food materials. Specifically, the gas sensor 302 can use a metal oxide semiconductor (MOS) sensor (such as MQ-7 and MQ-135): the surface adsorption of gas molecules causes a change in electrical conductivity, and the resistance change is inversely proportional to the VOCs concentration; or an electrochemical sensor: a weak current is generated by the oxidation-reduction reaction of gas on the electrode, and the current size is proportional to the concentration; the output signal is also an analog voltage signal or a digital signal, which is input to the second calculation unit 402 of the intelligent control module 40.

[0032] The first calculation unit 401 starts to calculate when the oil smoke particle concentration is greater than a preset oil smoke particle concentration threshold, such as 50 μg / m³, which represents a health risk threshold, to determine whether the particle sensor 301 data is over the threshold in real time. If it is over the threshold, a first difference between the real-time concentration and the preset threshold is calculated to quantify the degree of particle pollution. The first difference is transmitted to the power adjustment unit 403 as one of the basis for reducing the heating power. The greater the difference, the greater the power adjustment range. Similarly, the second calculation unit 402 starts to calculate when the volatile organic compound concentration is greater than a preset volatile organic compound concentration threshold, such as 0.1 ppm, which represents a critical value at which fat begins to deteriorate significantly. The gas sensor 302 data is determined in real time to see if it is over the threshold. If it is over the threshold, a second difference between the real-time concentration and the preset threshold is calculated to quantify the degree of VOCs pollution. The second difference is transmitted to the power adjustment unit 403 to determine the power adjustment strategy together with the particle difference. VOCs over the threshold can be given priority because it is more directly harmful.

[0033] The power adjustment unit 403 receives the first difference of the first calculation unit 401 and the second difference of the second calculation unit 402, which can trigger power adjustment separately or jointly. If only the particle is over the threshold, the power is reduced by the first difference; if only the VOCs is over the threshold, the power is reduced by the second difference; if both are over the threshold, the larger difference is taken as the adjustment range, or a weighted algorithm is used, such as a higher weight for VOCs because of the higher risk of carcinogenesis; a heating power adjustment signal, such as a PWM duty cycle signal or a 0-10V analog voltage signal, is generated to drive the heating component to adjust the power.

[0034] Further, the intelligent control module 40 further comprises a signal adjustment unit 50; A first end of the signal adjustment unit 50 is connected to a first end of the first calculation unit 401 and a first end of the second calculation unit 402, respectively, and a second end of the signal adjustment unit 50 is connected to the power adjustment unit 403; The first calculation unit 401 is further configured to output a differential signal corresponding to the first difference to the signal adjustment unit 50, and the second calculation unit 402 is further configured to output a differential signal corresponding to the second difference to the signal adjustment unit 50; The signal adjustment unit 50 is configured to perform signal transformation on the differential signal by PID adjustment and transmit the transformed differential signal to the power adjustment unit 403; The power adjustment unit 403 is further configured to generate a heating power adjustment signal according to the transformed differential signal and output the signal to the cooking appliance heating component.

[0035] The signal conditioning unit 50 is a bridge connecting the first calculation unit 401 and the second calculation unit 402 with the power conditioning unit 403, and its core function is to optimize the detected pollution difference signal, realize signal dynamic transformation through the PID (proportion-integral-derivative) adjustment algorithm, ensure the stability, accuracy and anti-interference of the power adjustment, and avoid oscillation or adjustment lag caused by direct open-loop control.

[0036] In an embodiment, referring to Figure 4 , the first calculation unit 401 comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a first amplifier A1. The first end of the first resistor R1 is connected with the particulate matter sensor 301, the second end of the first resistor R1 is connected with the first end of the third resistor R3 and the positive input end of the first amplifier A1 respectively, the second end of the third resistor R3 is connected with the output end of the first amplifier A1 and the signal conditioning unit 50, the first end of the second resistor R2 is connected with the first reference power Vref1, the second end of the second resistor R2 is connected with the negative input end of the amplifier and the first end of the fourth resistor R4, the second end of the fourth resistor R4 is grounded, and the output end of the first amplifier A1 is connected with the signal conditioning unit 50.

[0037] It should be noted that the first resistor R1 connects the output end of the particulate matter sensor 301 with the positive input end of the first amplifier A1, matches the sensor output impedance and limits the input current, and ensures the stable input of the sensor signal to the amplification circuit. The second resistor R2 and the fourth resistor R4 convert the first reference power Vref1 into the threshold voltage of the negative input end of the amplifier through the voltage division principle, wherein the first reference power Vref1 presets the reference voltage corresponding to the preset oil smoke particulate matter concentration, such as 2.5V corresponding to the preset threshold 50μg / m³. The third resistor R3 and the first resistor R1 constitute a feedback loop of the differential amplification circuit, determine the voltage amplification multiple of the amplifier, and amplify the difference between the sensor signal and the threshold to a range suitable for subsequent processing. The first amplifier A1, i.e. the differential operational amplifier, realizes the differential amplification of the real-time signal of the particulate matter sensor 301 and the preset threshold, and outputs a voltage signal proportional to the difference between the real-time concentration and the preset threshold, i.e. the first difference electrical signal representation.

[0038] Similarly, the second calculation unit 402 comprises a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a second amplifier A2. The first end of the fifth resistor R5 is connected with the gas sensor 302, the second end of the fifth resistor R5 is connected with the first end of the seventh resistor R7 and the positive input end of the second amplifier A2 respectively, the second end of the seventh resistor R7 is connected with the output end of the second amplifier A2 and the signal conditioning unit 50, the first end of the sixth resistor R6 is connected with the second reference power supply Vref2, the second end of the sixth resistor R6 is connected with the negative input end of the amplifier and the first end of the eighth resistor R8, the second end of the eighth resistor R8 is grounded, and the output end of the second amplifier A2 is connected with the signal conditioning unit 50. Since the second calculation unit 402 is similar in structure to the first calculation unit 401, no more description is made here.

[0039] In an embodiment, referring to Figure 5 , the power conditioning unit 403 comprises a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a third amplifier A3 and a 555 timer. The first end of the ninth resistor R9 is connected with the signal conditioning unit 50, the second end of the ninth resistor R9 is connected with the first end of the eleventh resistor R11, the first end of the tenth resistor R10 and the positive input end of the third amplifier A3 respectively, the negative input end of the third amplifier A3 is grounded, the output end of the third amplifier A3 is connected with the 555 timer, the second end of the eleventh resistor R11 is connected with the third reference power supply Vref3, and the second end of the tenth resistor R10 is connected with the output end of the third amplifier A3.

[0040] It should be noted that the ninth resistor R9 is used to limit the current flowing from the output end of the signal conditioning unit 50 to the power conditioning unit 403, to protect the signal conditioning unit 50 from excessive load, and to match the impedance of the signal conditioning unit 50 and the subsequent circuit, to ensure that the analog conditioning signal is stably transmitted to the positive input end of the third amplifier A3. The eleventh resistor R11 and the third reference power supply Vref3 constitute a voltage dividing branch, to provide a reference bias voltage for the positive input end of the third amplifier A3, or as a reference threshold for the comparator A4. The tenth resistor R10 and the third amplifier A3 constitute a voltage series negative feedback loop, to determine the voltage amplification of the amplifier, to amplify the input conditioning signal to a voltage range suitable for driving the 555 timer. The third amplifier A3 is a non-inverting operational amplifier, to amplify and buffer the output signal of the signal conditioning unit 50, to improve the driving capability and adjust the voltage amplitude, to provide a stable control voltage for the 555 timer. The 555 timer is a PWM signal generator, to generate a pulse width modulation (PWM) signal according to the voltage signal output by the third amplifier A3, to adjust the average power of the heating component by changing the duty cycle of the output pulse.

[0041] Further, with reference to Figure 3 , the circuit further comprises a pressure detection module 60; The pressure detection module 60 is connected with the oil temperature detection module 10 and the intelligent control module 40; The oil temperature detection module 10 is further configured to output a cooking utensil pressure detection signal to the pressure detection module 60 when the voltage value of the oil temperature electrical signal is less than a second preset voltage threshold; The pressure detection module 60 is configured to determine whether the cooking utensil is in an empty burning state according to a pressure electrical signal of the cooking utensil when the cooking utensil pressure detection signal is received, and output a first heating signal to the intelligent control module 40 if the cooking utensil is in the empty burning state; The intelligent control module 40 is further configured to generate a step power adjustment signal and output the signal to the cooking utensil heating assembly to automatically switch to low-power maintenance after the oil temperature reaches the target preheating temperature when the first heating signal is received.

[0042] It should be noted that the pressure detection module 60 is used to assist in determining whether the cooking utensil is in an empty burning state, i.e., no pot is placed on the heating assembly or there is no food in the pot, and cooperates with the oil temperature detection module 10 to avoid safety hazards or energy waste caused by empty burning through step power adjustment. When the voltage value of the oil temperature electrical signal output by the oil temperature detection module 10 is less than the second preset voltage threshold, such as less than 100℃ corresponding to the oil temperature, the preset threshold voltage 1V, which represents the low-temperature preheating stage, indicates that the current is in the initial heating stage or the temperature is not up to standard, and there may be an empty burning risk. When empty burning, the temperature rises quickly and is easy to overheat. The oil temperature detection module 10 sends a cooking utensil pressure detection signal, such as a high-level signal "1", to the pressure detection module 60, indicating that it is necessary to detect whether the current is in an empty burning state. The pressure sensor collects the pressure of the cooking utensil on the heating assembly in real time and converts it into a pressure electrical signal, such as a pressure signal <0.5V when empty and ≥1V when loaded. If the pressure detection signal is received and the pressure electrical signal is less than the empty burning determination threshold, such as 0.8V, which represents no pot or light load, it is determined to be in an empty burning state, and a first heating signal is output to the intelligent control module 40; if the pressure electrical signal is greater than or equal to the threshold, the empty burning process is skipped and the normal heating logic is run.

[0043] The stepwise power adjustment of the intelligent control module 40, when receiving the first heating signal, first heats at low power to avoid the temperature from rising sharply due to the high power during the empty burning, and the high temperature is easy to damage the heating assembly during the empty burning; the second stage: when the oil temperature detection module 10 feeds back that the oil temperature reaches the target preheating temperature, automatically switches to low power maintenance to prevent continuous high temperature during the empty burning, and at the same time maintains the hot standby state, and can quickly heat up if the pot is placed; generate a stepwise PWM signal, such as a first stage duty ratio of 40%, and a second stage duty ratio of 20%, drive the heating assembly to adjust the power according to the stage, and avoid the temperature fluctuation caused by the direct power-off of the traditional empty burning protection.

[0044] Further, the pressure detection module 60 is further configured to, when receiving the cooking utensil pressure detection signal, determine whether the cooking utensil adds food according to the pressure electrical signal of the cooking utensil, and output a second heating signal to the intelligent control module 40 if the cooking utensil adds food; The intelligent control module 40 is further configured to, when receiving the second heating signal, generate a short-time high-power compensation signal and output the signal to the cooking utensil heating assembly to shorten the evaporation time of the moisture of the food.

[0045] It should be noted that the second heating signal is a trigger signal output by the pressure detection module 60 to the intelligent control module 40 after identifying that the cooking utensil adds food, which can be a digital level signal, such as a high level “1” or a specific coded signal, for indicating that the food has been added and the short-time high-power compensation needs to be started to quickly recover the oil temperature.

[0046] It should be noted that in this document, the terms “comprising”, “including”, or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles, or systems that include a series of elements not only include those elements, but also include other elements not explicitly listed, or further include elements inherent to such processes, methods, articles, or systems. Without more limitations, the element defined by the statement “comprising a” does not exclude the presence of additional identical elements in the process, method, article, or system including the element.

[0047] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings of the present application, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A cooking appliance heating control circuit, characterized by, The circuit comprises an oil temperature detection module, an oil fume detection module, a first switch module and an intelligent control module; The oil temperature detection module is connected with the first switch module, the first switch module is connected with a power supply and the oil fume detection module respectively, the oil fume detection module is connected with the intelligent control module, and the intelligent control module is connected with a heating assembly of a cooking appliance. The oil temperature detection module is configured to collect an oil temperature signal in a cooking process and convert the oil temperature signal into a corresponding oil temperature electrical signal and output the oil temperature electrical signal to the first switch module. The first switch module is configured to turn on a power supply connection between the power supply and the oil fume detection module when a voltage value of the oil temperature electrical signal is greater than a first preset voltage threshold. The oil fume detection module is configured to collect an oil fume gas parameter generated in the cooking process in real time when the power supply connection is turned on. The intelligent control module is configured to compare the oil fume gas parameter collected in real time with a preset oil fume concentration threshold and generate a heating power adjustment signal according to a comparison result and output the heating power adjustment signal to the heating assembly of the cooking appliance.

2. The cooking appliance heating control circuit of claim 1, wherein, The oil fume gas parameter comprises an oil fume particulate matter concentration and a volatile organic matter concentration, the oil fume detection module comprises a particulate matter sensor and a gas sensor, the particulate matter sensor is configured to detect the oil fume particulate matter concentration, and the gas sensor is configured to detect the volatile organic matter concentration. Correspondingly, the intelligent control module comprises a first calculation unit, a second calculation unit and a power adjustment unit, a first end of the first calculation unit is connected with the particulate matter sensor, a second end of the first calculation unit is connected with the power adjustment unit, a first end of the second calculation unit is connected with the gas sensor, and a second end of the second calculation unit is connected with the power adjustment unit. The first calculation unit is configured to calculate a first difference value between the oil fume particulate matter concentration and a preset oil fume particulate matter concentration when the oil fume particulate matter concentration is greater than the preset oil fume particulate matter concentration. The second calculation unit is configured to calculate a second difference value between the volatile organic matter concentration and a preset volatile organic matter concentration when the volatile organic matter concentration is greater than the preset volatile organic matter concentration. The power adjustment unit is configured to generate a heating power adjustment signal according to the first difference value or the second difference value and output the heating power adjustment signal to the heating assembly of the cooking appliance.

3. The cooking appliance heating control circuit of claim 2, wherein, The intelligent control module further comprises a signal adjustment unit. A first end of the signal adjustment unit is connected with the first end of the first calculation unit and the first end of the second calculation unit respectively, and a second end of the signal adjustment unit is connected with the power adjustment unit. The first calculation unit is further configured to output a difference signal corresponding to the first difference value to the signal adjustment unit, and the second calculation unit is further configured to output a difference signal corresponding to the second difference value to the signal adjustment unit. The signal adjustment unit is configured to perform signal transformation on the difference signal through PID adjustment and transmit the transformed difference signal to the power adjustment unit. The power adjusting unit is further configured to generate a heating power adjusting signal according to the transformed differential signal and output the heating power adjusting signal to the cooking appliance heating assembly.

4. The cooking appliance heating control circuit of claim 1, wherein, The circuit further comprises a pressure detection module; The pressure detection module is connected with the oil temperature detection module and the intelligent control module; The oil temperature detection module is further configured to output a cooking appliance pressure detection signal to the pressure detection module when the voltage value of the oil temperature electric signal is less than a second preset voltage threshold value; The pressure detection module is configured to determine whether the cooking appliance is in an empty burning state according to a pressure electric signal of the cooking appliance when the cooking appliance pressure detection signal is received, and output a first heating signal to the intelligent control module if the cooking appliance is in the empty burning state. The intelligent control module is further configured to generate a step power adjusting signal and output the step power adjusting signal to the cooking appliance heating assembly to automatically switch the oil temperature to low-power maintenance after the target preheating temperature is reached when the first heating signal is received.

5. The cooking appliance heating control circuit of claim 4, wherein, The pressure detection module is further configured to determine whether the cooking appliance adds food materials according to a pressure electric signal of the cooking appliance when the cooking appliance pressure detection signal is received, and output a second heating signal to the intelligent control module if the cooking appliance adds food materials. The intelligent control module is further configured to generate a short-time high-power compensation signal and output the short-time high-power compensation signal to the cooking appliance heating assembly to shorten the evaporation time of the moisture of the food materials when the second heating signal is received.

6. The cooking appliance heating control circuit of claim 3, wherein, The first calculation unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, and a first amplifier; The first end of the first resistor is connected with the particulate matter sensor, the second end of the first resistor is connected with the first end of the third resistor and the positive input end of the first amplifier respectively, the second end of the third resistor is connected with the output end of the first amplifier and the signal adjusting unit, the first end of the second resistor is connected with a first reference power supply, the second end of the second resistor is connected with the negative input end of the amplifier and the first end of the fourth resistor, the second end of the fourth resistor is grounded, and the output end of the first amplifier is connected with the signal adjusting unit.

7. The cooking appliance heating control circuit of claim 3, wherein, The second calculation unit comprises a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a second amplifier; The first end of the fifth resistor is connected with the gas sensor, the second end of the fifth resistor is connected with the first end of the seventh resistor and the positive input end of the second amplifier respectively, the second end of the seventh resistor is connected with the output end of the second amplifier and the signal adjusting unit, the first end of the sixth resistor is connected with a second reference power supply, the second end of the sixth resistor is connected with the negative input end of the amplifier and the first end of the eighth resistor, the second end of the eighth resistor is grounded, and the output end of the second amplifier is connected with the signal adjusting unit.

8. The cooking appliance heating control circuit of claim 3, wherein, The power adjusting unit comprises a ninth resistor, a tenth resistor, an eleventh resistor, a third amplifier, and a 555 timer; The first end of the ninth resistor is connected with the signal adjusting unit, the second end of the ninth resistor is connected with the first end of the eleventh resistor, the first end of the tenth resistor and the positive input end of the third amplifier respectively, the reverse input end of the third amplifier is grounded, the output end of the third amplifier is connected with the 555 timer, the second end of the eleventh resistor is connected with the third reference power supply, and the second end of the tenth resistor is connected with the output end of the third amplifier.

9. The cooking appliance heating control circuit of claim 1, wherein, The oil temperature detection module comprises a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a first capacitor, wherein the twelfth resistor is a thermistor. The first end of the twelfth resistor is connected with the first end of the thirteenth resistor and the first end of the fourteenth resistor, the second end of the thirteenth resistor is connected with a power supply, the second end of the fourteenth resistor is grounded, the first end of the first capacitor is connected with the first end of the fourteenth resistor, the second end of the first capacitor is grounded, and the second end of the twelfth resistor is connected with the first switch module.

10. The cooking appliance heating control circuit of claim 9, wherein, The first switch module comprises a comparator, a first switch tube and a fifteenth resistor. The positive input end of the comparator is connected with the second end of the twelfth resistor, the reverse input end of the comparator is connected with a fourth reference power supply, the output end of the comparator is connected with the control end of the first switch tube, the input end of the first switch tube is connected with the second end of the fifteenth resistor, the first end of the fifteenth resistor is connected with a power supply, and the output end of the first switch tube is connected with the oil temperature detection module.

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