Aerosol-generating device

Abstract

The invention discloses an aerosol generating device which comprises a liquid storage unit used for storing liquid capable of generating aerosol; a heating element for heating the liquid; the liquid transfer unit is used for transferring the liquid stored in the liquid storage unit to the heating element; the power supply is used for supplying power to the heating element; the circuit is configured to judge whether the liquid stored in the liquid storage unit is reduced to a threshold value or not after a preset time point after the heating element starts heating; wherein the preset time point is determined according to the moment when the resistance change rate of the heating element is reduced to 1%-30% of the resistance change rate of the heating element when heating is started. After the resistance change rate of the heating element is reduced to 1%-30%, whether dry burning occurs or not in the second half period of smoking each time can be accurately judged, unexpected harmful gas and scorched smell are avoided, damage to the health of a user is prevented, and the smoking experience of the user is improved.

Description

[0001] This divisional application is a divisional application of Chinese patent application No. 202011160206.2, filed on October 27, 2020, entitled "Aerosol Generating Device". Technical Field

[0002] This application relates to the field of smoking accessories technology, and more particularly to an aerosol generating device. Background Technology

[0003] One type of aerosol generating device produces vapor by heating e-liquid for users to inhale. It generally consists of two parts: an atomizer and a battery assembly. The atomizer stores e-liquid and has an atomizing core for heating the e-liquid. The battery assembly supplies power to the atomizing core, causing it to heat up and generate high temperatures, which in turn heat the e-liquid.

[0004] Patent document CN103338665A discloses an electrically operated flotation generation system. Between 0 seconds and 0.2 seconds of each suction, the slope of the temperature curve increases as the liquid storage section becomes vacant. Therefore, the linearity of the temperature rise rate in the "vacant" region between suction X1 and X2 can be used to measure the amount of remaining flotation matrix in the liquid storage section. This allows for faster determination of temperature level changes and helps reduce the risk of flotation properties deteriorating.

[0005] The problem with this method is that the heater temperature rises sharply between 0 seconds and 0.2 seconds of each suction, and this period is very short and the temperature data fluctuates greatly. Therefore, the slope method cannot accurately determine whether the amount of liquid stored has decreased to the threshold during this period. Summary of the Invention

[0006] This application provides an aerosol generating device to solve the problem of accurately identifying dry burning of the aerosol generating device when it is being pumped out.

[0007] This application provides an aerosol generating apparatus, comprising:

[0008] Liquid storage unit for storing liquids that can generate aerosols;

[0009] Heating element for heating the liquid;

[0010] A liquid transfer unit is used to transfer the liquid stored in the liquid storage unit to the heating element;

[0011] A power source for providing power to the heating element;

[0012] The circuit is configured to determine, after a preset time point following the start of heating by the heating element, whether the liquid stored in the liquid storage unit has decreased to a threshold value.

[0013] The preset time point is determined based on the moment when the resistance change rate of the heating element decreases to 1% to 30% of the resistance change rate of the heating element when heating is started.

[0014] The dry burning of aerosol generators mostly occurs in the latter half of each pumping cycle. After the resistance change rate of the heating element decreases to 1% to 30%, it is advantageous to accurately determine whether dry burning has occurred in the latter half of each pumping cycle, thus avoiding the generation of unwanted harmful gases and burnt smells, preventing harm to the user's health, and improving the user's pumping experience. Attached Figure Description

[0015] The realization of the objectives, functional features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. One or more embodiments are illustrated by way of example through the corresponding pictures in the accompanying drawings. These illustrative descriptions do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the figures in the drawings do not constitute a limitation on scale.

[0016] Figure 1 This is a schematic diagram of the aerosol generating device provided in the embodiments of this application;

[0017] Figure 2 This is a schematic diagram of the resistance detection circuit in the aerosol generating device provided in the embodiments of this application;

[0018] Figure 3 This is a schematic diagram of another resistance detection circuit in the aerosol generating device provided in the embodiments of this application;

[0019] Figure 4 This is a schematic diagram of the control process of the aerosol generation device provided in the embodiments of this application;

[0020] Figure 5 This is a schematic diagram of the control process of the aerosol generation device provided in the embodiments of this application;

[0021] Figure 6 This is another schematic diagram of the control process of the aerosol generation device provided in the embodiments of this application;

[0022] Figure 7 This is another schematic diagram of the control process of the aerosol generation device provided in the embodiments of this application. Detailed Implementation

[0023] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application. To facilitate understanding of this application, a more detailed description is provided below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "upper," "lower," "left," "right," "inner," "outer," and similar expressions used in this specification are for illustrative purposes only.

[0024] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0025] Figure 1 This is a schematic diagram of the aerosol generating device provided in the embodiments of this application.

[0026] like Figure 1 As shown, the aerosol generating device includes a nozzle 11, a liquid storage unit 12, a liquid transfer unit 13, a heating element 14, a circuit 15, a power supply 16, and a sensor 17.

[0027] The nozzle 11 is used for users to inhale the aerosol generated by heating.

[0028] The liquid storage unit 12 is used to store a liquid capable of generating aerosols. The liquid may be a tobacco-containing substance including volatile tobacco flavor components, or it may be a liquid including non-tobacco substances. For example, the liquid may include water, solvents, ethanol, plant extracts, flavorings, fragrances, or vitamin mixtures. Flavorings may include, but are not limited to, menthol, peppermint oil, spearmint oil, and various fruit flavorings. Fragrances may include ingredients capable of providing the user with a variety of flavors or aromas. Vitamin mixtures may be substances containing at least one of vitamins A, B, C, and E, but are not limited to. Additionally, the liquid may include aerosol-forming agents such as glycerin and propylene glycol.

[0029] The liquid transfer unit 13 can transfer the liquid stored in the liquid storage unit 12 to the heating element 14. For example, the liquid transfer unit 13 can be made of cotton fiber, ceramic fiber, glass fiber, etc., but is not limited to these.

[0030] Heating element 14 is a component used to heat the liquid transferred through liquid transfer unit 13. For example, heating element 14 can be a metal wire, metal plate, ceramic heater, etc., but is not limited to these. Alternatively, heating element 14 can be made of a conductive heating wire such as nickel-chromium wire, and can be arranged in a structure wound around liquid transfer unit 13. Heating element 14 can be heated by an electric current supply, and transfers heat to the liquid in contact with heating element 14 to heat the liquid, thereby generating an aerosol. In this example, heating element 14 is made of a material with a temperature coefficient of resistance characteristic, such as stainless steel 316, titanium, nickel, nickel-chromium alloy, etc.

[0031] Circuit 15 controls the overall operation of the aerosol generating device. Specifically, circuit 15 controls not only the operation of the power supply 16 and the heating element 14, but also the operation of other components within the aerosol generating device. Furthermore, circuit 15 can determine whether the aerosol generating device is operational by checking the status of its components.

[0032] Circuit 15 includes at least one processor. The processor may include a logic gate array, or may include a combination of a general-purpose microprocessor and a memory storing a program executable in the microprocessor. Furthermore, those skilled in the art will understand that circuit 15 may include another type of hardware.

[0033] Power source 16 provides electricity for operating the aerosol generating apparatus. For example, power source 16 can provide electricity to heat heating element 14 and can provide the electricity required to operate circuit 15. In addition, power source 16 can provide the electricity required to operate sensors, motors, etc. provided in the aerosol generating apparatus.

[0034] The power source 16 can be, but is not limited to, a lithium iron phosphate (LiFePO4) battery. For example, the power source 16 can be a lithium cobalt oxide (LiCoO2) battery or a lithium titanate battery. The power source 16 can be a rechargeable battery or a disposable battery.

[0035] Sensor 17 is used to detect the user's suction action and generate a corresponding electrical signal, so that circuit 15 controls the operation of power supply 16, heating element 14, etc. according to the electrical signal. Sensor 17 can be a common pressure sensor, differential pressure sensor, airflow sensor, etc.

[0036] An air inlet is provided near the sensor 17 in the aerosol generating device. When the aerosol generating device is drawn in, the airflow enters through the air inlet, flows through the sensor 17, power supply 16, circuit 15, heating element 14, etc., and then flows out through the nozzle 11. The dashed arrow in the figure roughly shows the airflow path.

[0037] It should be noted that, Figure 1Only components relevant to this embodiment are shown. Those skilled in the art will understand that the aerosol generating apparatus may also include, in addition to... Figure 1 Other common components besides those shown.

[0038] Figure 2 This is a schematic diagram of a resistance detection circuit provided in an embodiment of this application.

[0039] like Figure 2 As shown, Ri is the heating element 14, and R1 is the sampling resistor. The heating element 14 and the sampling resistor R1 are connected in series between the power supply 16 (shown as VBAT in the figure) and the push-pull output port IO of the processor. The processor's first voltage sampling port ADC1 is connected to one end of the sampling resistor R1, and the processor's second voltage sampling port ADC2 is connected to the other end of the sampling resistor R1. Compared with the prior art, the switching transistor and its associated resistor (with a large resistance value) connected in series with the sampling resistor R1 are omitted.

[0040] When it is necessary to detect the resistance of heating element 14, the push-pull output port IO outputs a low level, and then the processor obtains the voltage V through the first voltage sampling port ADC1. ADC1 The voltage V is obtained through the second voltage sampling port ADC2. ADC2 The resistance of heating element 14 can then be obtained using the following formula:

[0041] Ri=(V BAT -V ADC2 )×R1 / (V ADC2 -V ADC1 )

[0042] Figure 3 This is a schematic diagram of another resistance detection circuit provided in an embodiment of this application.

[0043] like Figure 3 As shown, circuit 15 includes a switching transistor Q8, a heating element 14 (connected to terminals D+ and D- in the figure), and a sampling resistor R4, all connected in series between the positive and negative terminals of power supply 16 (shown as VBAT in the figure). U1 is a sensor 17. The control terminal of switching transistor Q8 is connected to the processor's control port OUT_CTR, which controls the switching transistor Q8 to turn on or off. The processor's first voltage sampling port AT-DET is located between switching transistor Q8 and heating element 14, and the processor's second voltage sampling port OUT1-ADC is located between heating element 14 and sampling resistor R4. Compared with the prior art, the switching transistor and its associated resistor (with a large resistance value) connected in series with sampling resistor R1 are also omitted; instead, the main circuit is used to detect the resistance value.

[0044] Specifically, when sensor 17 detects suction, the processor controls switch Q8 to turn on via control port OUT_CTR, and then the processor obtains voltage V through the first voltage sampling port AT-DET. AT-DET The voltage V is obtained through the second voltage sampling port OUT1-ADC. OUT1-ADC The resistance of heating element 14 can then be obtained using the following formula:

[0045] Ri = V AT-DET ×R4 / V OUT1-ADC -R4

[0046] based on Figures 2-3 The resistance detection circuit, circuit 15, is configured to determine whether the liquid stored in the liquid storage unit 12 has decreased to a threshold value after a preset time point after the heating element 14 starts heating.

[0047] The preset time point is determined based on the moment when the resistance change rate of the heating element 14 decreases to 1% to 30% of the resistance change rate of the heating element 14 when heating is started.

[0048] In this example, after the resistance change rate of the heating element decreases to 1%–30%, it is determined whether the liquid stored in the liquid storage unit 12 has decreased to the threshold value. This avoids the problem of inaccurate judgment caused by large fluctuations in the initial temperature (or real-time resistance) data. Preferably, the judgment can be made after the resistance change rate of the heating element decreases to 5%–30%; more preferably, the judgment can be made after the resistance change rate of the heating element decreases to 5%–25%; even more preferably, the judgment can be made after the resistance change rate of the heating element decreases to 5%–20%; even more preferably, the judgment can be made after the resistance change rate of the heating element decreases to 10%–20%.

[0049] In one example, the preset time point is after 600ms (including 600ms); preferably, the preset time point is after 800ms (including 800ms); more preferably, the preset time point is after 1000ms (including 1000ms).

[0050] In one example, circuit 15 is configured to determine whether the liquid stored in liquid storage unit 12 has decreased to a threshold value based on the magnitude of the resistance change rate of heating element 14 and a preset resistance change rate.

[0051] Specifically, if the resistance change rate of the heating element 14 is greater than the preset resistance change rate, it is determined that the liquid stored in the liquid storage unit 12 has been reduced to the threshold value.

[0052] Furthermore, the circuit 15 is configured to determine whether the liquid stored in the liquid storage unit 12 has decreased to a threshold value based on the number of times the resistance change rate of the heating element 14 continuously exceeds a preset resistance change rate.

[0053] Specifically, if the resistance change rate of the heating element 14 exceeds the preset resistance change rate for more than a first preset number of times, it is determined that the liquid stored in the liquid storage unit 12 has been reduced to the threshold value.

[0054] In this example, circuit 15 is configured to store the real-time resistance value of heating element 14 in a preset buffer and calculate the rate of change of resistance of heating element 14:

[0055] K j =(R N+j -R 0+j ) / R 0+j , where K j denoted as the resistance change rate of heating element 14, N is the length of the preset buffer zone, and j is a natural number.

[0056] For example: Suppose N=5, when j=0, K0=(R5-R0) / R0; when j=1, K1=(R6-R1) / R1; when j=2, K2=(R7-R2) / R2; when j=3, K3=(R8-R3) / R3; and so on.

[0057] In this example, typically there is liquid in the first half of each suction, but no liquid in the second half (e.g., insufficient liquid supply), which causes the resistance change rate of the heating element 14 to exceed the preset resistance change rate more than the first preset number of times.

[0058] In one example, circuit 15 is configured to determine whether the liquid stored in liquid storage unit 12 has decreased to the threshold based on the real-time resistance of heating element 14 and the magnitude of the over-temperature threshold.

[0059] In this example, circuit 15 is configured as follows:

[0060] If the real-time resistance of the heating element 14 exceeds the over-temperature threshold, the power output to the heating element 14 is reduced in order to maintain the temperature of the heating element 14 at the preset temperature, or to maintain the real-time resistance of the heating element 14 at the resistance value corresponding to the preset temperature.

[0061] If the power output to the heating element 14 is reduced to the preset power and the temperature of the heating element 14 is still not maintained at the preset temperature, or the real-time resistance of the heating element 14 is still not maintained at the resistance value corresponding to the preset temperature, then it is determined that the liquid stored in the liquid storage unit 12 has decreased to the threshold value.

[0062] The over-temperature threshold is the resistance value corresponding to the maximum atomization temperature that the aerosol generating device can accept during suction. The over-temperature threshold can be a default threshold or a dynamic threshold, determined according to the different materials of the heating element 14. The preset temperature is the atomization temperature that the aerosol generating device is expected to maintain during suction to achieve the best atomization effect.

[0063] If the heating element 14 fails to maintain its temperature at the preset temperature or fails to maintain its real-time resistance at the value corresponding to the preset temperature, it means that during the period when the power output to the heating element 14 is reduced to the preset power, the real-time resistance or temperature of the heating element 14 continues to rise; specifically, the real-time resistance of the heating element 14 exceeds the value corresponding to the preset temperature or the temperature of the heating element 14 exceeds the preset temperature.

[0064] In this example, continuous suction usually causes the temperature of the heating element 14 to be too high. Even if the liquid supply is normal, it will still fail to maintain the temperature of the heating element 14 at the preset temperature, or fail to maintain the real-time resistance of the heating element 14 at the resistance value corresponding to the preset temperature.

[0065] In one example, circuit 15 is configured as follows:

[0066] Before the preset time point, obtain the initial resistance value and M real-time resistance values ​​of the heating element 14;

[0067] Calculate the difference between each real-time resistance value and the initial resistance value;

[0068] Compare the M differences with the M preset differences one by one;

[0069] If the number of times the difference exceeds the preset difference is greater than the second preset number, it is determined that the liquid in the liquid storage unit 12 has been reduced to the threshold.

[0070] In this example, the difference typically exceeds a second preset number of times because the liquid storage unit 12 has no liquid or very little liquid. Therefore, N different values ​​are set for identification. The N preset differences are empirical values ​​or test values, for example, obtained by integrating test data from a large number of tests. N is a positive integer, generally between 8 and 16, preferably between 8 and 14, and even more preferably between 8 and 12. The detection interval for the N real-time resistance values ​​is between 40ms and 100ms, preferably between 40ms and 80ms.

[0071] In one example, circuit 15 is configured as follows:

[0072] Before a preset time point, obtain the real-time resistance value of the heating element;

[0073] The real-time resistance value of the heating element is compared with a preset maximum threshold.

[0074] If the real-time resistance of the heating element is greater than the preset maximum threshold, it is determined that the liquid stored in the liquid storage unit has decreased to the threshold.

[0075] In this example, if the liquid storage unit 12 has no liquid or very little liquid, the liquid level in the liquid storage unit 12 can be determined by comparing the real-time resistance of the heating element 14 with a preset maximum threshold. Generally, the preset maximum threshold is greater than the over-temperature threshold.

[0076] It should be noted that in the above example, if the liquid in the liquid storage unit 12 has decreased to a threshold, the power output to the heating element 14 will be stopped. This avoids the generation of unwanted harmful gases and burnt smells, prevents harm to the user's health, and improves the user's suction experience.

[0077] Figure 4 This is a schematic diagram of the control process of the aerosol generation device provided in an embodiment of this application. The control process is illustrated with a specific example and specifically includes:

[0078] Step S21: Start the aerosol generating device;

[0079] Step S22: Obtain the initial resistance value and 10 real-time resistance values ​​of the heating element 14; for example: initial resistance value R0, real-time resistance values ​​R1 to R10;

[0080] Step S23: Calculate the difference between each real-time resistance value and the initial resistance value; for example: R1-R0 (denoted as D1), R2-R0 (denoted as D2)...R10-R0 (denoted as D10), thus obtaining 10 differences;

[0081] Step S24: Compare the 10 differences with the 10 preset differences one by one; assuming that the 10 preset differences are d1, d2...d10, then compare the size of D1 with d1, the size of D2 with d2...D10 with d10.

[0082] Step S25: Determine whether the number of times the difference exceeds the preset difference exceeds 4 times;

[0083] Step S26: If the difference exceeds the preset difference more than 4 times consecutively, stop outputting power to the heating element 14 (step S32); otherwise, obtain the real-time resistance value of the heating element 14 again 800ms after the aerosol generating device is started.

[0084] Step S27: Calculate the resistance change rate of heating element 14 based on the real-time resistance value of heating element 14 obtained again.

[0085] Step S28: Determine whether the number of times the resistance change rate exceeds the preset resistance change rate exceeds 4 consecutive times; if the number of times the resistance change rate exceeds the preset resistance change rate exceeds 4 consecutive times, stop the power output to the heating element 14 (step S32); otherwise, continue the comparison and judgment.

[0086] Step S29: Based on the real-time resistance value of the heating element 14 obtained again, determine whether the real-time resistance value of the heating element 14 exceeds the over-temperature threshold.

[0087] Step S30: If the real-time resistance of the heating element 14 exceeds the over-temperature threshold, reduce the power output of the heating element 14; otherwise, continue the comparison and judgment.

[0088] Step S31: Determine whether the preset temperature has been successfully maintained; if the preset temperature has not been successfully maintained, reduce the power output of the heating element 14; otherwise, continue the comparison and determination.

[0089] It should be noted that in the above control process, it is feasible to implement only steps S26 to S32 after the aerosol generating device is started, and it is also feasible to implement steps S22 to S25 after the aerosol generating device is restarted.

[0090] like Figure 5 As shown, curve K1 represents the heating element 14 when it is dry-burning after the aerosol generating device is started and before it is drawn in (e.g., as shown in A in the figure), and curve K2 represents the heating element 14 when it is not dry-burning after the aerosol generating device is started and before it is drawn in. The vertical axis in the figure represents the resistance (mΩ) of the heating element 14, and the horizontal axis represents the number of resistance measurements. It should be noted that, for ease of explanation, the variation curves between K1 and K2 are not shown; please refer to curves K1 and K2 for further understanding.

[0091] Within the first 800ms, by acquiring the initial resistance value and 10 real-time resistance values ​​of the heating element 14, the difference between each real-time resistance value and the initial resistance value is calculated. The 10 differences are compared one by one with 10 preset differences. It is determined whether the number of times the difference exceeds the preset difference consecutively exceeds 4 times, so that the heating element 14 can be identified as dry burning.

[0092] It should be noted that within the first 800ms, due to the very short duration and large temperature fluctuations, the slope method or resistance change rate method cannot accurately determine whether the amount of liquid in the storage section has decreased to the threshold, which can easily lead to misjudgment and affect the user's suction experience. This example reduces or avoids misjudgment by comparing multiple differences one-to-one.

[0093] like Figure 6 As shown, curve K3 is the curve when the heating element 14 is dry-burned when the aerosol generating device is evacuated, and curve K4 is the curve when the heating element 14 is not dry-burned when the aerosol generating device is evacuated (no dry-burning occurred after the aerosol generating device was started and before it was evacuated).

[0094] After 800ms, the real-time resistance value of heating element 14 is acquired again, and the rate of change of resistance of heating element 14 is calculated. It is determined whether the number of times the rate of change of resistance exceeds the preset rate of change of resistance exceeds four consecutive times, thus identifying whether heating element 14 has undergone dry burning. As shown in Figure B, after this node, the slope of curve K3 increases significantly, thus confirming that heating element 14 underwent dry burning when the aerosol generating device was being drawn in.

[0095] It should be noted that the above regarding Figure 6 The method of judgment described is not suitable for the entire aspiration phase, for example... Figure 5 The situation is illustrated below. Because the resistance data fluctuates significantly from the start of heating element 14 until a certain time point (e.g., time point T1 in the figure), the above-described judgment method can easily lead to misjudgment, thus affecting the user's suction experience. The time point can be determined based on when the resistance change rate of heating element 14 decreases to 1% to 30% of the resistance change rate of heating element 14 at the start of heating. Taking time point T1 as an example, calculations show that time T1 is when the resistance change rate of curve K3 decreases to 1% of the resistance change rate of heating element 14 at the start of heating. Based on the horizontal axis, sampling start time, and sampling interval, T1 can be estimated to be 800ms. Therefore, using the above-described judgment method after 800ms can reduce or avoid misjudgment.

[0096] like Figure 7 As shown, curve K5 is the curve when the heating element 14 is dry-burned when the aerosol generating device is evacuated, and curve K6 is the curve when the heating element 14 is not dry-burned when the aerosol generating device is evacuated.

[0097] After 800ms, the real-time resistance value of heating element 14 can be obtained again and compared with the over-temperature threshold. If the real-time resistance value of heating element 14 exceeds the over-temperature threshold, the power output to heating element 14 is reduced. If the temperature of heating element 14 is successfully maintained at the preset temperature, it can be determined that heating element 14 did not dry-burn when the aerosol generating device was being drawn in. As shown in Figure D, at this node, the real-time resistance value of heating element 14 exceeds the over-temperature threshold. After reducing the power output to heating element 14, the temperature of heating element 14 is successfully maintained at the preset temperature.

[0098] As shown in Figure C, at this node, the real-time resistance of heating element 14 exceeds the over-temperature threshold. Even after reducing the power output to heating element 14, the temperature of heating element 14 was not successfully maintained at the preset temperature, and the resistance of heating element 14 continued to rise. Therefore, it can be determined that heating element 14 is dry-burning when the aerosol generating device is being drawn in.

[0099] It should be noted that while preferred embodiments of this application are provided in the specification and accompanying drawings, this application can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of this application; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this application. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this application's specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An aerosol generating device, characterized in that, include: Liquid storage unit for storing liquids that can generate aerosols; Heating element for heating the liquid; A liquid transfer unit is used to transfer the liquid stored in the liquid storage unit to the heating element; A power source for providing power to the heating element; The circuit is configured to determine, after a preset time point following the start of heating by the heating element, whether the liquid stored in the liquid storage unit has decreased to the threshold value based on the real-time resistance of the heating element and the magnitude of the over-temperature threshold.

2. The aerosol generating apparatus according to claim 1, characterized in that, The preset time point is determined based on the moment when the resistance change rate of the heating element decreases to 1% to 30% of the resistance change rate of the heating element when heating is started.

3. The aerosol generating apparatus according to claim 1, characterized in that, The preset time point is after 600ms; preferably, the preset time point is after 800ms; more preferably, the preset time point is after 1000ms.

4. The aerosol generating apparatus according to claim 1, characterized in that, The circuit is configured as follows: If the real-time resistance of the heating element exceeds the over-temperature threshold, the power output to the heating element is reduced in order to maintain the temperature of the heating element at the preset temperature or maintain the real-time resistance of the heating element at the resistance value corresponding to the preset temperature. If the power output to the heating element is reduced to a preset power and the temperature of the heating element is still not maintained at the preset temperature or the real-time resistance of the heating element is still not maintained at the resistance value corresponding to the preset temperature, then it is determined that the liquid stored in the liquid storage unit has decreased to the threshold value.

5. The aerosol generating apparatus according to claim 4, characterized in that, The circuit is configured such that if the power output to the heating element is reduced to a preset power, and the temperature of the heating element has been successfully maintained at a preset temperature or the real-time resistance of the heating element has been successfully maintained at the resistance value corresponding to the preset temperature, then the circuit continues to determine whether the liquid stored in the liquid storage unit has been reduced to the threshold value based on the real-time resistance value of the heating element and the magnitude of the over-temperature threshold.

6. The aerosol generating apparatus according to claim 1, characterized in that, The circuit is configured to stop outputting power to the heating element if the liquid stored in the liquid storage unit has decreased to a threshold value.

7. The aerosol generating apparatus according to claim 1, characterized in that, The circuit is configured as follows: Before a preset time point, obtain the initial resistance value and M real-time resistance values ​​of the heating element; Calculate the difference between each real-time resistance value and the initial resistance value; Compare the M differences with the M preset differences one by one; If the number of times the difference exceeds the preset difference is greater than the preset number, it is determined that the liquid stored in the liquid storage unit has been reduced to the threshold.

8. The aerosol generating apparatus according to claim 1, characterized in that, The circuit is configured as follows: Before a preset time point, obtain the real-time resistance value of the heating element; The real-time resistance value of the heating element is compared with a preset maximum threshold. If the real-time resistance of the heating element is greater than the preset maximum threshold, it is determined that the liquid stored in the liquid storage unit has decreased to the threshold.

9. The aerosol generating apparatus according to claim 1, wherein the circuit comprises a processor and a sampling resistor; The processor has a first voltage sampling port, a second voltage sampling port, and a push-pull output port; The heating element and the sampling resistor are connected in series between the positive terminal of the power supply and the push-pull output port; the two ends of the sampling resistor are respectively connected to the first voltage sampling port and the second voltage sampling port.

10. The aerosol generating device according to claim 1, wherein the circuit includes a processor, a switching transistor, a heating element, and a sampling resistor connected in series between the positive and negative terminals of the power supply; The processor has a first voltage sampling port, a second voltage sampling port, and a control port; The control port is connected to the control terminal of the switching transistor to control the switching transistor to turn on or off. The first voltage sampling port is located between the switching transistor and the heating element, and the second voltage sampling port is located between the heating element and the sampling resistor.

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