A boiling detection system and method for a split electric heating appliance

Abstract

This invention provides a boiling detection system and method for split-type electric heating appliances. The method includes: acquiring vibration signals from a vibration sensor; processing the acquired vibration signals; determining the boiling state of the liquid inside the inner tank based on the processed vibration signals to obtain a first determination result; controlling an ultrasonic transmitting module to transmit ultrasonic signals into the inner tank; receiving ultrasonic signals passing through the inner tank from an ultrasonic acquisition module; determining the boiling state of the liquid inside the inner tank based on the transmitted ultrasonic signals and the ultrasonic signals passing through the inner tank to obtain a second determination result; and obtaining a final result based on the first and second determination results. The boiling detection system and method for split-type electric heating appliances provided by this invention can achieve boiling detection by using two detection methods for mutual verification, thus improving the accuracy of the detection.

Description

Technical Field

[0001] This invention relates to the field of boiling detection technology, and in particular to a boiling detection system and method for split-type electric heating appliances. Background Technology

[0002] When electric heating appliances heat internal liquids (water, porridge, etc.), detecting whether the liquid has boiled is a crucial step in determining the next operating state. Existing boiling detection methods generally use temperature sensors. However, for split-type electric heating appliances, since the inner tank is removable, its surface can oxidize and become contaminated during cleaning and relocation. Over time, the bottom of the inner tank may also deform. These factors affect the contact between the temperature sensor and the inner tank. Changes in the contact state can lead to a discrepancy between the measured temperature and the actual temperature inside the tank, resulting in overheating or underheating. This can cause the power to cut off before the liquid boils, or the liquid to boil excessively and overflow, posing a safety hazard, especially when the liquid overflows. Furthermore, the temperature reflected at the bottom of the tank varies depending on the viscosity of the liquid (e.g., when cooking porridge or water), making it difficult to accurately determine whether the liquid has boiled using a temperature sensor. Therefore, designing a boiling detection system and method for split-type electric heating appliances is essential. Summary of the Invention

[0003] The purpose of this invention is to provide a boiling detection system and method for split-type electric heating appliances, which can realize boiling detection by using two detection methods for mutual verification, thereby improving the accuracy of detection.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A boiling detection system for a split-type electric heating appliance includes: an inner liner of the split-type electric heating appliance, characterized in that it further includes a vibration sensor, an ultrasonic transmitting module, an ultrasonic acquiring module, and a processor. The vibration sensor is disposed at the bottom of the inner liner, the ultrasonic transmitting module is disposed on one side of the outer side of the inner liner, and the ultrasonic acquiring module is disposed on the other side. The vibration sensor, the ultrasonic transmitting module, and the ultrasonic acquiring module are all electrically connected to the processor.

[0006] The vibration sensor is used to collect vibration signals from the inner liner and send them to the processor;

[0007] The ultrasonic transmitting module is used to transmit ultrasonic signals into the interior of the inner liner.

[0008] The ultrasonic acquisition module is used to receive ultrasonic signals after they have passed through the inside of the liner.

[0009] The processor is used to process the vibration signal, determine the boiling state of the liquid inside the inner liner based on the processed vibration signal, and verify the determined boiling state of the liquid inside the inner liner based on the emitted ultrasonic signal and the ultrasonic signal after passing through the inner liner.

[0010] The present invention also provides a boiling detection method for split-type electric heating appliances, applied to the above-mentioned boiling detection system for split-type electric heating appliances, comprising the following steps:

[0011] Step 1: Acquire the vibration signal from the vibration sensor;

[0012] Step 2: Process the acquired vibration signal, determine the boiling state of the liquid inside the inner liner based on the processed vibration signal, and obtain the first judgment result;

[0013] Step 3: The processor controls the ultrasonic transmitting module to emit ultrasonic signals into the inner liner, and the ultrasonic acquiring module receives the ultrasonic signals that have passed through the inner liner.

[0014] Step 4: The processor determines the boiling state of the liquid inside the inner liner based on the emitted ultrasonic signal and the ultrasonic signal after passing through the inner liner, obtains a second judgment result, and obtains the final result based on the first judgment result and the second judgment result.

[0015] Optionally, in step 2, the acquired vibration signal is processed, specifically as follows:

[0016] The processor performs a low-pass filter on the acquired vibration signal, with a cutoff frequency of 30Hz to filter interference. Then, a low-frequency periodic signal is extracted from the low-pass filtered vibration signal using a cross-correlation operation. The expression for the cross-correlation operation is as follows:

[0017]

[0018] The sampling rate is set to 100Hz, the correlation length is 4 seconds, and the number of samples is 400. The samples are divided into two groups, x and y. x is the original signal with 400 samples, and y is the first half of the data of x with 200 samples. Cross-correlation is performed according to the expression for cross-correlation. Segmented operation is also used, that is, 400 samples are collected for 4 seconds, and cross-correlation is performed once. This process is repeated to obtain the waveform of the correlation coefficient R(m). By detecting the interval between peaks, the frequency of the periodic signal can be determined.

[0019] Optionally, in step 2, the boiling state of the liquid inside the inner liner is determined based on the processed vibration signal, specifically as follows:

[0020] If the frequency of the periodic signal is measured, it is determined that periodic vibration has occurred, and the liquid inside the inner liner is determined to be in a boiling state. Otherwise, the acquisition and processing of vibration signals continue until the frequency of the periodic signal is measured.

[0021] Optionally, in step 3, the processor controls the ultrasonic transmitting module to emit ultrasonic signals into the inner liner, and the ultrasonic acquiring module receives the ultrasonic signals passing through the inner liner. Specifically:

[0022] If the processor determines that the liquid inside the inner liner is boiling, the processor controls the ultrasonic transmitting module to emit a first ultrasonic signal into the inner liner. The first ultrasonic signal passes through the liquid inside the inner liner and becomes a second ultrasonic signal. The ultrasonic acquiring module receives the second ultrasonic signal. The ultrasonic transmitting module and the ultrasonic acquiring module respectively send the first ultrasonic signal and the second ultrasonic signal to the processor.

[0023] Optionally, in step 4, the processor determines the boiling state of the liquid inside the inner liner based on the emitted ultrasonic signal and the ultrasonic signal after passing through the inner liner, obtains a second determination result, and obtains the final result based on the first and second determination results, specifically:

[0024] The processor calculates the return loss based on the first and second ultrasonic signals, and determines the boiling state of the liquid inside the inner liner based on the return loss, obtaining a second judgment result. If the first judgment result is the same as the second judgment result, the liquid inside the inner liner is determined to be in a boiling state; otherwise, it is in a non-boiling state.

[0025] Optionally, the processor calculates the return loss based on the first ultrasonic signal and the second ultrasonic signal, specifically as follows:

[0026] The processor acquires the first power P from the first ultrasonic signal. i And the second power P in the second ultrasonic signal r The return loss is calculated as follows:

[0027]

[0028] Optionally, the boiling state of the liquid inside the inner tank can be determined based on the return loss, specifically:

[0029] If the first ultrasonic signal changes periodically, then after each cycle, delay for a first preset time to obtain multiple echo losses, obtain the maximum, minimum and average values ​​of the multiple echo losses, and determine whether the liquid inside the inner liner is boiling based on the obtained maximum, minimum and average values.

[0030] If the first ultrasonic signal is a constant signal, then every second preset time interval, multiple return losses are acquired, and the maximum, minimum and average values ​​of the multiple return losses are acquired. Based on the acquired maximum, minimum and average values, it is determined whether the liquid inside the inner liner is boiling.

[0031] Optionally, the determination of whether the liquid inside the inner liner is boiling can be based on the obtained maximum, minimum, and average values, specifically:

[0032] If the difference between the maximum and minimum values ​​of the obtained return loss is greater than 0.1 times the average value, it is determined that the liquid inside the inner tank is boiling; otherwise, it is determined that the liquid inside the inner tank is not boiling.

[0033] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: The boiling detection system and method for split-type electric heating appliances provided by the present invention includes: acquiring vibration signals from a vibration sensor; processing the acquired vibration signals; determining the boiling state of the liquid inside the inner tank based on the processed vibration signals to obtain a first determination result; controlling an ultrasonic transmitting module to transmit ultrasonic signals into the inner tank; receiving ultrasonic signals passing through the inner tank from an ultrasonic acquiring module; determining the boiling state of the liquid inside the inner tank based on the transmitted ultrasonic signals and the ultrasonic signals passing through the inner tank to obtain a second determination result; and obtaining a final result based on the first determination result and the second determination result. By detecting the boiling state through vibration signals and verifying the first detection result through ultrasonic signals, the accuracy of the detection is improved. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of the split-type electric heating appliance boiling detection system according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the boiling detection method for split-type electric heating appliances according to an embodiment of the present invention;

[0037] Figure 3 The waveform of the vibration signal;

[0038] Figure 4 This is a waveform diagram of the vibration signal after low-pass filtering.

[0039] Figure 5 The waveform of the correlation coefficient R(m) is shown. Detailed Implementation

[0040] The purpose of this invention is to provide a boiling detection system and method for split-type electric heating appliances, which can realize boiling detection by using two detection methods for mutual verification, thereby improving the accuracy of detection.

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] like Figure 1 As shown, the boiling detection system for a split-type electric heating appliance provided in this embodiment of the invention includes: an inner liner of the split-type electric heating appliance, a vibration sensor, an ultrasonic transmitting module, an ultrasonic acquiring module, and a processor. The vibration sensor is disposed at the bottom of the inner liner, the ultrasonic transmitting module is disposed on one side of the outer side of the inner liner, and the ultrasonic acquiring module is disposed on the other side. The vibration sensor, the ultrasonic transmitting module, and the ultrasonic acquiring module are all electrically connected to the processor.

[0043] The vibration sensor is used to collect vibration signals from the inner liner and send them to the processor;

[0044] The ultrasonic transmitting module is used to transmit ultrasonic signals into the interior of the inner liner.

[0045] The ultrasonic acquisition module is used to receive ultrasonic signals after they have passed through the inside of the liner.

[0046] The processor is used to process the vibration signal, determine the boiling state of the liquid inside the inner liner based on the processed vibration signal, and verify the determined boiling state of the liquid inside the inner liner based on the emitted ultrasonic signal and the ultrasonic signal after passing through the inner liner.

[0047] like Figure 2 As shown, the present invention also provides a boiling detection method for split-type electric heating appliances, applied to the above-mentioned boiling detection system for split-type electric heating appliances, comprising the following steps:

[0048] Step 1: Acquire the vibration signal from the vibration sensor;

[0049] Step 2: Process the acquired vibration signal, determine the boiling state of the liquid inside the inner liner based on the processed vibration signal, and obtain the first judgment result;

[0050] Step 3: The processor controls the ultrasonic transmitting module to emit ultrasonic signals into the inner liner, and the ultrasonic acquiring module receives the ultrasonic signals that have passed through the inner liner.

[0051] Step 4: The processor determines the boiling state of the liquid inside the inner liner based on the emitted ultrasonic signal and the ultrasonic signal after passing through the inner liner, obtains a second judgment result, and obtains the final result based on the first judgment result and the second judgment result.

[0052] The principle of using vibration signals for boiling detection is as follows: When water is heated to a certain temperature (not the boiling point), bubbles will also be produced in the water. However, these bubbles are not steam produced by water vaporization, but rather air that was originally dissolved in the water. As the temperature increases, the solubility of gas in water decreases, causing some of the air that was originally dissolved in the liquid to escape from the liquid after heating, resulting in the turbulence of the liquid and thus generating periodic vibrations. Steam bubbles are not only produced when water boils. When water reaches a certain temperature, steam bubbles will be produced, but these bubbles are smaller and more numerous. The hissing sound we hear when boiling water is heated to a certain temperature is produced by a large number of small bubbles. The hissing sound is also a kind of vibration, but with a relatively high frequency. When water boils, it primarily produces significant turbulence. This turbulence generates vibrations at low frequencies, generally below 10Hz, which is lower than the 20Hz lower limit of human hearing. Therefore, boiling water actually feels relatively quiet. As we can see, water produces vibrations over a wide frequency range during heating. Since we are only concerned with low-frequency periodic vibrations around 10Hz, necessary signal processing is required. Figure 3 The display shows the pot vibration signal obtained from the sound (vibration) sensor when water boils. The low-frequency vibration we are interested in is completely submerged in a large amount of noise. To detect whether there is a low-frequency periodic signal in the signal, low-pass filtering and cross-correlation calculation are required. Since we are interested in the signal around 10Hz, the cutoff frequency of the low-pass filter is selected as 30Hz. This ensures that the useful signal can pass through while filtering out interference such as power supply at 50Hz. Figure 4 This is the signal waveform after low-pass filtering.

[0053] In step 2, the acquired vibration signal is processed, specifically as follows:

[0054] The processor performs a low-pass filter on the acquired vibration signal, with a cutoff frequency of 30Hz to filter interference. Then, a low-frequency periodic signal is extracted from the low-pass filtered vibration signal using a cross-correlation operation. The expression for the cross-correlation operation is as follows:

[0055]

[0056] With a sampling rate of 100Hz, a correlation length of 4 seconds, and 400 samples, if we use the above formula for conventional calculations, taking x = y, it's equivalent to performing autocorrelation, which requires approximately 80,000 multiplication-addition operations. To reduce the computational load, the samples are divided into two groups: x and y. x is the original signal with 400 samples, and y is the first half of the data from x with 200 samples. Cross-correlation is then performed according to the expression for cross-correlation. This way, the result can be obtained in half the time of the preceding autocorrelation operation, without experiencing output attenuation, which is beneficial for subsequent judgment. Furthermore, a segmented operation is used: 400 samples are acquired over 4 seconds, and a cross-correlation operation is performed once, and so on, resulting in the waveform of the correlation coefficient R(m) as shown below. Figure 5 As shown, the frequency of a periodic signal can be determined by detecting the interval between peaks.

[0057] In step 2, the boiling state of the liquid inside the inner tank is determined based on the processed vibration signal, specifically as follows:

[0058] When the liquid is not boiling, the inner liner is relatively stable and there is no obvious periodic vibration. If the frequency of the periodic signal is measured, it is determined that periodic vibration has occurred and the liquid inside the inner liner is boiling. Otherwise, the vibration signal is collected and processed until the frequency of the periodic signal is measured.

[0059] In step 3, the processor controls the ultrasonic transmitting module to emit ultrasonic signals into the inner liner, and the ultrasonic acquiring module receives the ultrasonic signals that have passed through the inner liner. Specifically:

[0060] If the processor determines that the liquid inside the inner liner is boiling, the processor controls the ultrasonic transmitting module to emit a first ultrasonic signal into the inner liner. The first ultrasonic signal passes through the liquid inside the inner liner and becomes a second ultrasonic signal. The ultrasonic acquiring module receives the second ultrasonic signal. The ultrasonic transmitting module and the ultrasonic acquiring module respectively send the first ultrasonic signal and the second ultrasonic signal to the processor.

[0061] In step 4, the processor determines the boiling state of the liquid inside the inner liner based on the emitted ultrasonic signal and the ultrasonic signal after passing through the inner liner, obtaining a second determination result. Based on the first and second determination results, the final result is obtained, specifically:

[0062] The processor calculates the return loss based on the first and second ultrasonic signals, and determines the boiling state of the liquid inside the inner liner based on the return loss, obtaining a second judgment result. If the first judgment result is the same as the second judgment result, the liquid inside the inner liner is determined to be in a boiling state; otherwise, it is in a non-boiling state.

[0063] The processor calculates the return loss based on the first and second ultrasonic signals, specifically as follows:

[0064] The processor acquires the first power P from the first ultrasonic signal. i And the second power P in the second ultrasonic signal r The return loss is calculated as follows:

[0065]

[0066] The boiling state of the liquid inside the inner tank is determined based on the return loss, specifically as follows:

[0067] If the first ultrasonic signal changes periodically, a first preset time is delayed after each cycle. The first preset time is set according to the change cycle of the first ultrasonic signal. Multiple echo losses are obtained, and the maximum, minimum and average values ​​of the multiple echo losses are obtained. Based on the obtained maximum, minimum and average values, it is determined whether the liquid inside the inner liner is boiling.

[0068] If the first ultrasonic signal is a constant signal, then every second preset time interval (which can be set to 1.5 seconds), multiple echo losses are acquired, and the maximum, minimum and average values ​​of the multiple echo losses are acquired. Based on the acquired maximum, minimum and average values, it is determined whether the liquid inside the inner liner is boiling.

[0069] The determination of whether the liquid inside the inner liner is boiling is based on the obtained maximum, minimum, and average values.

[0070] If the difference between the maximum and minimum values ​​of the obtained return loss is greater than 0.1 times the average value, it is determined that the liquid inside the inner tank is boiling; otherwise, it is determined that the liquid inside the inner tank is not boiling.

[0071] The present invention provides a boiling detection system and method for split-type electric heating appliances. The method includes acquiring vibration signals from a vibration sensor, processing the acquired vibration signals, determining the boiling state of the liquid inside the inner tank based on the processed vibration signals to obtain a first determination result, controlling an ultrasonic transmitting module to transmit ultrasonic signals into the inner tank, receiving ultrasonic signals passing through the inner tank via an ultrasonic acquisition module, determining the boiling state of the liquid inside the inner tank based on the transmitted ultrasonic signals and the ultrasonic signals passing through the inner tank to obtain a second determination result, and obtaining a final result based on the first and second determination results. By detecting the boiling state through vibration signals and verifying the first detection result through ultrasonic signals, the accuracy of the detection is improved.

[0072] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention.

Claims

1. A method for detecting boiling in a split-type electric heating appliance, characterized in that, The method is applied to a boiling detection system for a split-type electric heating appliance. The detection system includes an inner liner of the split-type electric heating appliance. It is characterized in that it further includes a vibration sensor, an ultrasonic emission module, an ultrasonic acquisition module, and a processor. The vibration sensor is disposed at the bottom of the inner liner, the ultrasonic emission module is disposed on one side of the outer side of the inner liner, and the ultrasonic acquisition module is disposed on the other side. The vibration sensor, the ultrasonic emission module, and the ultrasonic acquisition module are all electrically connected to the processor. The vibration sensor is used to collect vibration signals from the inner liner and send them to the processor; The ultrasonic transmitting module is used to transmit ultrasonic signals into the interior of the inner liner. The ultrasonic acquisition module is used to receive ultrasonic signals after they have passed through the inside of the liner. The processor is used to process the vibration signal, determine the boiling state of the liquid inside the inner liner based on the processed vibration signal, and verify the determined boiling state of the liquid inside the inner liner based on the emitted ultrasonic signal and the ultrasonic signal after passing through the inner liner. The detection method includes the following steps: Step 1: Acquire the vibration signal from the vibration sensor; Step 2: Process the acquired vibration signal, determine the boiling state of the liquid inside the inner liner based on the processed vibration signal, and obtain the first judgment result; Step 3: The processor controls the ultrasonic transmitting module to emit ultrasonic signals into the inner liner, and the ultrasonic acquiring module receives the ultrasonic signals that have passed through the inner liner. Step 4: The processor determines the boiling state of the liquid inside the inner liner based on the emitted ultrasonic signal and the ultrasonic signal after passing through the inner liner, obtains the second judgment result, and obtains the final result based on the first judgment result and the second judgment result. In step 2, the processing of the acquired vibration signal specifically includes: The processor performs a low-pass filter on the acquired vibration signal, with a cutoff frequency of 30Hz to filter interference. Then, a low-frequency periodic signal is extracted from the low-pass filtered vibration signal using a cross-correlation operation. The expression for the cross-correlation operation is as follows: ； The sampling rate was set to 100Hz, the correlation length to 4 seconds, and the number of samples to 400. The samples were divided into two groups, x and y. x represents the original signal with 400 samples, and y represents the first half of the data from x with 200 samples. Cross-correlation was performed according to the expression for cross-correlation, using a segmented approach: 400 samples were collected over 4 seconds for one cross-correlation operation, and this process was repeated to obtain the correlation coefficient. The frequency of a periodic signal can be determined by detecting the time interval between peaks in the waveform. The determination of the boiling state of the liquid inside the inner liner based on the processed vibration signal is specifically as follows: If the frequency of the periodic signal is measured, it is determined that periodic vibration has occurred, and the liquid inside the inner liner is determined to be in a boiling state. Otherwise, the acquisition and processing of vibration signals continue until the frequency of the periodic signal is measured. Step 4 specifically includes: the processor calculates the return loss based on the first ultrasonic signal and the second ultrasonic signal, and determines the boiling state of the liquid inside the inner liner based on the return loss, and obtains a second judgment result. If the first judgment result is the same as the second judgment result, it is determined that the liquid inside the inner liner is in a boiling state; otherwise, it is in a non-boiling state. The processor calculates the return loss based on the first ultrasonic signal and the second ultrasonic signal, specifically by: the processor acquiring the first power in the first ultrasonic signal. and the second power in the second ultrasonic signal The return loss is calculated as follows: ； The method of determining the boiling state of the liquid inside the inner tank based on return loss is as follows: If the first ultrasonic signal changes periodically, then after each cycle, delay for a first preset time to obtain multiple echo losses, obtain the maximum, minimum and average values ​​of the multiple echo losses, and determine whether the liquid inside the inner liner is boiling based on the obtained maximum, minimum and average values. If the first ultrasonic signal is a constant signal, then every second preset time interval, multiple echo losses are acquired, and the maximum, minimum and average values ​​of the multiple echo losses are acquired. Based on the acquired maximum, minimum and average values, it is determined whether the liquid inside the inner liner is boiling. The determination of whether the liquid inside the inner liner is boiling is based on the obtained maximum, minimum and average values. Specifically, if the difference between the maximum and minimum values ​​of the obtained return loss is greater than 0.1 times the average value, then the liquid inside the inner liner is determined to be boiling; otherwise, the liquid inside the inner liner is determined not to be boiling.

2. The boiling detection method for split-type electric heating appliances according to claim 1, characterized in that, In step 3, the processor controls the ultrasonic transmitting module to emit ultrasonic signals into the inner liner, and the ultrasonic acquiring module receives the ultrasonic signals that have passed through the inner liner. Specifically: If the processor determines that the liquid inside the inner liner is boiling, the processor controls the ultrasonic transmitting module to emit a first ultrasonic signal into the inner liner. The first ultrasonic signal passes through the liquid inside the inner liner and becomes a second ultrasonic signal. The ultrasonic acquiring module receives the second ultrasonic signal. The ultrasonic transmitting module and the ultrasonic acquiring module respectively send the first ultrasonic signal and the second ultrasonic signal to the processor.

Images