A liquid heater with air-proof detection and spill prevention

Abstract

This invention relates to kitchen appliances, specifically a liquid heater with a non-contact overflow detection system. The PCB detection board mounted on the side wall of the glass container has multiple capacitor plates, including multiple first capacitor plates and multiple second capacitor plates. Different first capacitor plates are used for water level detection at different pulping capacities, while the second capacitor plates detect bubbles and foam for overflow prevention. Different second capacitor plates are used to detect different overflow prevention signals corresponding to different pulping capacities. The sensing area of ​​a single second capacitor plate is larger than that of a single first capacitor plate. This liquid heater can remotely detect water levels and overflow prevention signals at multiple pulping capacities, enabling intelligent production of slurry beverages with different pulping capacities. Furthermore, it provides more reliable detection of foamy overflow signals generated during pulping, more effectively identifying overflow prevention signals and reducing the safety risks associated with the overflow of bubble- or foamy slurries.

Description

Technical Field

[0001] This invention relates to kitchen appliances, and in particular to a liquid heater with a non-discharge detection and spill prevention function. Background Technology

[0002] Existing technology CN97225228.2 discloses a liquid level sensor that can detect the milk level without contact. This solution specifically emphasizes that this liquid level sensor is applicable to all non-metallic containers requiring non-contact liquid level control, as conductive metal containers can interfere with the sensor's sensing, affecting the actual liquid level detection. Meanwhile, existing technology CN200920291175.7 discloses an easy-to-clean soymilk maker. This soymilk maker is equipped with capacitive plates that can detect changes in liquid state. These capacitive plates are either circular metal sheets or multiple plates surrounding the maker head or cup body. They utilize capacitive sensing to achieve anti-overflow, anti-dry-burning, and water level detection. Compared to previous soymilk makers, since there is no need to drill holes in the maker head to install anti-overflow electrodes, it not only reduces the risk of water entering the maker head but also improves the ease of cleaning. However, the capacitor plates on this soymilk maker need to be installed around the machine head or cup body, which takes up a lot of space and is relatively complicated to install.

[0003] To further simplify non-contact capacitive liquid level detection devices, existing technology discloses a capacitive stepless water level detection device, comprising a capacitive slider formed by several equidistantly arranged capacitive sensors. The capacitive slider is connected to a chip via induction lines, and the chip is connected to a central processing unit (CPU) via signal lines. The CPU is connected to a water level display. During operation, under the control of the chip, the data detected by the capacitive sensors is transmitted to the CPU. The CPU processes the received data and then sends it to the water level display to show the current water level. This structure is simple and can achieve stepless water level detection. Furthermore, this detection method is unaffected by water temperature, effectively avoiding the problem of inaccurate water level detection caused by parasitic characteristics resulting from changes in the detection environment and other factors, such as water temperature. The inventors have found that while this solution has high accuracy in detecting water signals, it is less accurate for detecting non-liquid substances such as bubbles, foam, or slurry. Firstly, due to the slightly lower conductivity of these substances, the capacitive sensors detect only small changes in capacitance, making it difficult for the chip to distinguish between a liquid level signal and parasitic capacitance. On the other hand, when liquids produce bubbles, foam, or slurry, especially slurry foam, a thick slurry layer forms above the liquid surface. Furthermore, the presence of foam within this slurry layer obstructs contact between the slurry and the cup wall, creating a gap that affects the capacitance value sensed by the capacitive sensor. Moreover, the surface of the slurry layer is uneven; generally, the slurry is higher in the center of the cup and lower where it contacts the wall, and even the height of the slurry in contact with different parts of the cup wall can vary. This means the capacitive sensor may be unable to detect a specific capacitance value or may detect a very low value. Consequently, the chip cannot identify the exact location of the liquid level, potentially leading to a spillage safety risk. Therefore, this solution is generally suitable for water level signal detection in applications such as health-preserving kettles.

[0004] Meanwhile, existing technology CN201610753199.4 also discloses an anti-overflow method and a food processor. This food processor has a signal PCB board with metal plates of the same size evenly spaced on it. As the volume of liquid in the cup gradually increases, the capacitance formed by the metal plates and the liquid in the cup increases, thereby enabling the detection of both the water level signal and the anti-overflow signal by sensing the liquid level using the metal plates. However, the anti-overflow detection position in this solution is a fixed position at the highest point on the PCB board. In actual use, the metal plate below the anti-overflow detection position can identify the water level signal, but due to the characteristics of the slurry foam, this fixed anti-overflow detection position is greatly affected by external parasitic capacitance and cannot accurately identify the anti-overflow signal. Furthermore, because the surface of the foam is not smooth, the fixed anti-overflow detection position may cause a large deviation between the detected anti-overflow position and the actual foam position, posing a safety risk of spillage.

[0005] Furthermore, existing technology CN201921962352.X discloses a capacitive continuous liquid level detection structure and its electric kettle. This liquid level detection structure has two parallel-arranged sensing electrode plates and also discloses detecting the water level height by duty cycle. In this solution, the outer surface of the electric kettle has an arc-shaped structure. Therefore, a flexible PFB board needs to be attached to the outer wall of the kettle by adhesive. Since there are two sensing electrode plates on the PFB board, as the water level rises, the arc-shaped sensing electrode plates on the outer wall of the kettle will become visible. The sensing part near the actual water level can also sense the change in capacitance value. However, there will be a significant deviation between the water level calculated based on the duty cycle and the actual water level, reducing the accuracy of detection. Fortunately, for electric kettles, the water level detection deviation is not serious and will not pose a safety risk. However, the inventors have discovered that this solution is only suitable for detecting the water level in electric kettles and cannot detect overflow signals. This is because the conductivity of bubbles and foam is reduced, which decreases the sensitivity of the sensing electrode to detect bubbles and foam. Furthermore, the unevenness of the bubble and foam surface will further increase the detection error of the curved PFB flexible board. Therefore, this solution is not suitable for detecting overflow signals and is prone to posing a safety risk of pulp overflow. Summary of the Invention

[0006] The objective of this invention is to provide a liquid heater with air-to-air overflow detection. This liquid heater can detect water level signals for multiple different pulping capacities in an air-to-air manner, and can detect different overflow signals corresponding to different pulping capacities. This enables intelligent production of slurry beverages with different pulping capacities. Moreover, the detection of foamy slurry overflow signals generated during the pulping process is more reliable, and the overflow signal can be more effectively identified, reducing the safety risks of overflow of bubble or foamy slurry.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a liquid heater for air-to-air spill detection, the liquid heater comprising a glass cup forming a slurry container and a PCB detection board installed on the outer side wall of the glass cup for detecting liquid level height, characterized in that: the PCB detection board is provided with a plurality of spaced capacitor plates, the capacitor plates comprising a plurality of first capacitor plates and a plurality of second capacitor plates located above the first capacitor plates, different first capacitor plates being used for water level signal detection of different slurry capacities, and different second capacitor plates being used for different spill prevention signal detection of bubbles and foam, wherein the sensing area of ​​a single second capacitor plate is larger than the sensing area of ​​a single first capacitor plate.

[0008] Furthermore, the PCB detection board is also provided with a dividing groove for dividing the second capacitor electrode, and a single second capacitor electrode is divided into two sub-electrodes by the dividing groove. Under the same overflow prevention height, the sensing areas of the two corresponding sub-electrodes are not equal.

[0009] Furthermore, the dividing groove is a straight dividing groove that is inclined relative to the PCB inspection board;

[0010] Alternatively, the dividing groove may be a curved dividing groove.

[0011] Furthermore, the PCB detection board includes a strip-shaped substrate, a control chip, and an output terminal. The first capacitor electrode and the second capacitor electrode are located on the front surface of the substrate facing the glass body. Multiple first capacitor electrodes form a water level detection area on the substrate, and multiple second capacitor electrodes form an anti-overflow detection area on the substrate. The anti-overflow detection area is located above the water level detection area. The control chip and the output terminal are disposed on the rear surface of the substrate.

[0012] Furthermore, both the control chip and the output terminal are located below the water level detection area;

[0013] Alternatively, during the water level detection process, the control chip sequentially and cyclically detects the capacitance value of each first capacitor electrode at a set time, and at any given moment, only one first capacitor electrode is energized for detection, while the other first capacitor electrodes are grounded.

[0014] Alternatively, during the overflow detection process, the control chip sequentially and cyclically detects the capacitance value of each second capacitor electrode at a set time, and at any given moment, only one second capacitor electrode is energized for detection, while the remaining second capacitor electrodes are grounded.

[0015] Furthermore, the PCB testing board is also covered with a mesh shielding layer, which includes a first shielding layer and a second shielding layer respectively attached to the two sides of the PCB testing board, and the second shielding layer surrounds the outside of the capacitor electrode along the edge of the PCB testing board.

[0016] Furthermore, the mesh shielding layer is grounded;

[0017] Alternatively, the lower side opening of the second shielding layer;

[0018] Alternatively, the mesh shielding layer may be a copper-clad mesh.

[0019] Furthermore, a heating device for heating the pulping container is provided at the bottom of the glass cup body, and a motor is provided in the mounting cavity below the glass cup body. The rotating shaft driven by the motor passes through the bottom of the glass cup body and extends into the pulping container, and a crushing device is connected to the end of the rotating shaft. The PCB detection board is installed between the glass cup body and the handle, and a main control device is also provided in the mounting cavity below the glass cup body. The main control device is electrically connected to the motor, the heating device and the PCB detection board respectively.

[0020] Furthermore, the multiple capacitor electrodes are arranged at equal intervals;

[0021] Alternatively, the number of the second capacitor plates is greater than the number of the first capacitor plates;

[0022] Alternatively, the detection height of a single second capacitor electrode shall not be less than twice the detection height of a single first capacitor electrode;

[0023] Alternatively, the detection height of a single first capacitor electrode is 3mm to 6mm;

[0024] Alternatively, the detection height of a single second capacitor electrode can be 8mm to 12mm.

[0025] Furthermore, different pulping capacities correspond to different pulping processes;

[0026] Furthermore, different pulping capacities have corresponding overflow prevention signal detection;

[0027] Alternatively, the detection plate determines the pulping capacity based on the water level signal detected by the first capacitor electrode, determines the corresponding second capacitor electrode based on the correspondence between different pulping capacities and overflow prevention signal detection, and uses the second capacitor electrode as the initial overflow prevention detection position.

[0028] In existing technologies, the detection of water level and overflow signals using capacitive electrodes also utilizes the principle of touch sensing. When the capacitor electrode is near the liquid, it generates a capacitance value. The control chip indirectly determines the water level and overflow signals based on the fluctuations in this capacitance value. Through continuous research, the inventors have discovered that the capacitance value sensed by the capacitor electrode for liquid signals exhibits a wide range of variation. When the capacitor electrode is close to the liquid, the capacitance value fluctuates significantly, while at greater distances, the fluctuation is smaller. Furthermore, the magnitude of the capacitance fluctuation is also related to the liquid's form and conductivity. When the liquid is pure and highly conductive, the sensed capacitance value fluctuates significantly, enabling accurate liquid level detection. However, when the liquid is in a bubble or foamy state, the conductivity decreases, resulting in relatively smaller capacitance value fluctuations. It is precisely because the capacitance value fluctuates less when the liquid is in a bubble or foamy state that the control chip cannot determine whether it is a liquid level signal. Furthermore, the capacitance changes generated by the capacitor electrode are also affected by environmental factors, easily forming parasitic capacitance. This parasitic capacitance can cause the capacitor electrode to sense capacitance fluctuations, potentially leading to misjudgments by the control chip. For example, when a hand approaches the capacitor electrode, capacitance fluctuations occur. In this case, the control chip cannot distinguish between interference capacitance and the actual liquid level capacitance. Similarly, water droplets on the outer wall of the slurry container can also cause the capacitor electrode to sense capacitance fluctuations, resulting in misjudgments by the control chip. Additionally, although existing capacitor electrodes can detect both water level and overflow signals, for slurries formed by bubbles or foam, the uneven surface of the foam makes it difficult for existing fixed-position overflow capacitor electrodes to accurately identify the actual foam height, easily leading to slurry overflow.

[0029] For the liquid heater of this invention, the PCB detection board is provided with a water level detection area and an overflow prevention detection area, each consisting of multiple first capacitor plates and multiple second capacitor plates arranged at intervals. This allows for the detection of water levels for various pulping capacities, as well as the detection of different overflow prevention signals corresponding to different pulping capacities. Compared to existing overflow prevention detection positions with only one fixed position, the liquid heater of this invention enables more intelligent production of slurry beverages, with higher pulping efficiency. While ensuring the production of beverages for one to multiple people, it also solves the problems of failure, excessively long overflow prevention time, and pulp foam adhesion to the wall that are common with existing technologies that only have one fixed overflow prevention detection position. Furthermore, this invention uses different overflow prevention signal detection for different pulping capacities, which not only ensures that the pulp does not overflow, but also improves the space utilization of the pulping container, optimizing pulping efficiency and avoiding problems such as excessively long pulping time or poor pulverization.

[0030] In the pulping process, when the pulp is agitated or heated, bubbles and foam rise to the surface. The capacitance values ​​of the capacitor plates sensing these bubbles and foam fluctuate only slightly, making it difficult for the control chip to accurately distinguish between parasitic capacitance and an actual overflow prevention signal. However, with the liquid heater of this invention, because the detection height of a single second capacitor plate is greater than that of a single first capacitor plate, the second capacitor plate has a larger sensing area during actual detection, enabling it to obtain a larger fluctuation capacitance value and achieve more accurate overflow prevention signal detection. This effectively prevents the overflow of bubbles and foam during pulping. Therefore, compared to existing technologies, using the liquid heater of this invention for overflow prevention signal detection is more reliable and reduces the safety risk of pulp overflow. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings:

[0032] Figure 1 This is a schematic diagram of the structure of a liquid heater according to a first embodiment of the present invention;

[0033] Figure 2 for Figure 1 Schematic diagram of the front surface structure of the PCB inspection board;

[0034] Figure 3 for Figure 1 A schematic diagram of the rear surface structure of a PCB inspection board;

[0035] Figure 4 for Figure 1 Topology block diagram of the PCB inspection board;

[0036] Figure 5 This is a schematic diagram of the structure of a second embodiment of the PCB testing board of the present invention. Detailed Implementation

[0037] Example 1:

[0038] like Figure 1 , Figure 2 , Figure 3 , Figure 4The diagram shows a schematic of a liquid heater according to the present invention. This liquid heater is a food processing machine for making soy milk beverages, comprising a glass cup 1 forming a slurry container 10 and a lid 2 fitted onto the glass cup 1. A heating device 4 for heating the slurry container 10 is provided at the bottom of the glass cup 1, and a motor 3 is installed in the mounting cavity 20 below the glass cup 1. A rotating shaft driven by the motor 3 passes through the bottom of the glass cup 1 and extends into the slurry container 10, with a pulverizing device (not shown) connected to the end of the rotating shaft. A PCB detection board 5 for liquid level detection is installed on the outer side wall of the glass cup 1, between the glass cup 1 and the handle (not shown). A main control device (not shown) is also provided in the mounting cavity 20 below the glass cup 1, and the main control device is electrically connected to the motor 3, the heating device 4, and the PCB detection board 5.

[0039] The PCB testing board 5 includes a strip-shaped substrate 51, capacitor plates mounted on the substrate, a control chip 52, and an output terminal 53. The capacitor plates are electrically connected to the control chip 52, and the control chip 52 is connected to the main control device through the output terminal 53. The capacitor plates include a plurality of first capacitor plates 54a and a plurality of second capacitor plates 54b arranged at intervals. The plurality of first capacitor plates 54a form a water level detection area 55a (a dashed frame below the W plane) on the substrate 51, and the plurality of second capacitor plates 54b... An overflow detection area 55b (a dashed box above the W plane) is formed on the substrate 51. The overflow detection area 55b is located above the water level detection area 55a. Different first capacitor plates 54a correspond to different pulping capacity liquid levels on the water level detection area 55a, and different second capacitor plates 54b correspond to different overflow detection positions on the overflow detection area 55b. Each pulping capacity liquid level on the water level detection area 55a has a corresponding overflow detection position on the overflow detection area 55b. Furthermore, multiple first capacitor plates 54a and multiple second capacitor plates 54b are electrically connected to the control chip 52 one by one through printed circuits (not shown in the figure) on the substrate 51. Along the height direction of the substrate 51, the detection height of a single first capacitor plate 54a is smaller than the detection height of a single second capacitor plate 54b.

[0040] In this embodiment, the first capacitor electrode 54a and the second capacitor electrode 54b are both attached to the front surface of the substrate 51 facing the glass body 1, while the control chip 52 and the output terminal 53 are disposed on the rear surface of the substrate 51, and both the control chip 52 and the output terminal 53 are located below the water level detection area 55. Simultaneously, a mesh shielding layer is also attached to the substrate 51. The mesh shielding layer is grounded and includes a first shielding layer 57a attached to the rear surface of the substrate 51 and a second shielding layer 57b attached to the front surface of the substrate 51. The second shielding layer 57b surrounds the water level detection area 55a and the overflow detection area 55b along the edge of the substrate 51, and has a lower opening 571. In this embodiment, the mesh shielding layer is a copper-clad mesh, used to shield the capacitor electrodes from the inductive interference of external parasitic capacitance. In this embodiment, the printed circuit is attached to the rear surface of the substrate 51, and the input terminal passes through the substrate 51 and is electrically connected to each capacitor electrode. The output terminal of the printed circuit runs along the outer periphery of the mesh shielding layer. The output terminal of the printed circuit can pass through the lower opening of the second shielding layer 57b and be electrically connected to the control chip 52.

[0041] Furthermore, in this embodiment, a dividing groove 58 is provided on the overflow detection area 55b of the substrate 51. The dividing groove 58 divides the overflow detection area 55b into a first sub-overflow detection area tri1 and a second sub-overflow detection area tri2 arranged side by side. Each second capacitor electrode 54b is divided into two sub-electrodes located in the two columns of sub-overflow detection areas, and each sub-electrode in the two columns of sub-overflow detection areas is electrically connected to the control chip 52 one by one through printed circuits. At the same liquid level below the highest point of the overflow detection area 55b, the sensing area of ​​the first sub-overflow detection area tri1 is not equal to the sensing area of ​​the second sub-overflow detection area tri2. In this embodiment, the dividing groove 58 divides the overflow detection area 55b into two triangular sub-overflow detection areas with equal areas at an angle along the diagonal of the overflow detection area 55b.

[0042] In existing technologies, capacitive electrodes for detecting water levels and overflow signals also utilize the principle of touch sensing. When the capacitor electrode is near the liquid, it generates a capacitance value. The control chip indirectly determines the water level and overflow signals based on the fluctuations in this capacitance value. Through continuous research, the inventors have discovered that the capacitance value sensed by the capacitor electrode for liquid signals exhibits a wide range of variation. When the capacitor electrode is close to the liquid, the capacitance value fluctuates significantly, while at greater distances, the fluctuation is smaller. Furthermore, the magnitude of the capacitance fluctuation is also related to the liquid's form and conductivity. When the liquid is pure and highly conductive, the sensed capacitance value fluctuates significantly, enabling accurate liquid level detection. However, when the liquid is in a bubble or foamy state, the conductivity decreases, resulting in relatively smaller fluctuations in the sensed capacitance value. It is precisely because the liquid is in a bubble or foamy state that the small fluctuations in the sensed capacitance value prevent the control chip from determining whether it is a liquid level signal. Furthermore, the capacitance changes generated by the capacitor electrode are also affected by environmental factors, easily forming parasitic capacitance. This parasitic capacitance can cause the capacitor electrode to sense small capacitance fluctuations, potentially leading to misjudgments by the control chip. For example, when a hand approaches the capacitor electrode, capacitance fluctuations occur. In this case, the control chip cannot distinguish between interference capacitance and the actual liquid level capacitance. Similarly, water droplets on the outer wall of the slurry container can also cause the capacitor electrode to sense capacitance fluctuations, resulting in misjudgments by the control chip. Additionally, although existing capacitor electrodes can detect both water level and overflow signals, for slurries formed by bubbles or foam, the uneven surface of the foam makes it difficult for existing fixed-position overflow capacitor electrodes to accurately identify the actual foam height, easily leading to slurry overflow.

[0043] In the food processing machine of this embodiment, the PCB detection board is provided with a water level detection area and an overflow prevention detection area, each consisting of multiple first capacitor plates and multiple second capacitor plates arranged at intervals. This allows for the detection of water levels for various pulping capacities, as well as the detection of different overflow prevention signals corresponding to different pulping capacities. Compared to existing overflow prevention detection positions with only one fixed position, the food processing machine of this embodiment can achieve more intelligent production of pulped beverages with higher pulping efficiency. While ensuring the production of beverages for one to multiple people, it also solves the problems of failure, excessively long overflow prevention time, and pulp residue sticking to the wall that are common with existing technologies that only have one fixed overflow prevention detection position. Furthermore, this embodiment uses different overflow prevention detection positions for different pulping capacities, which not only ensures that pulp overflow does not occur, but also improves the space utilization of the pulping container, optimizes pulping efficiency, and avoids problems such as excessively long pulping time or poor pulverization.

[0044] The first capacitor in the water level detection area detects the pulping water level for the corresponding pulping capacity, while the second capacitor in the overflow prevention detection area detects the overflow height reached by the pulp for the corresponding pulping capacity during the pulping process. When the second capacitor detects that the pulp for the current pulping capacity has reached the preset overflow prevention detection position, the control chip transmits a signal to the main control device. The main control device then performs corresponding operations according to the program settings, such as stopping the motor or stopping the heating to wait for overflow prevention. However, during the pulping process, when the pulp is agitated or heated, bubbles and foam rise to the surface. The capacitance value of the capacitor sensing bubbles and foam fluctuates only slightly, making it difficult for the control chip to accurately distinguish between parasitic capacitance and the actual overflow prevention signal. For the food processing machine of this invention, since the detection height of a single second capacitor electrode is greater than that of a single first capacitor electrode, the second capacitor electrode has a larger sensing area during actual detection, enabling it to obtain a larger fluctuation capacitance value and achieve more accurate overflow signal detection. Compared with existing technologies, it can detect overflow signals such as rising bubbles and foam, effectively solving the problem that existing single-type capacitor electrodes can only accurately detect water levels but cannot effectively detect overflow signals. This greatly reduces the safety risk of overflow of slurry such as bubbles and foam during the application of existing capacitive overflow detection technology.

[0045] Since the non-contact PCB testing board is attached to the outside of the glass, and considering that the non-contact PCB testing board detects and judges the liquid level signal by detecting changes in capacitance value, during user use, factors such as water flow and user contact with the mounting structure of the PCB testing board can cause changes in the capacitance value of the capacitor plates on the PCB testing board, leading to risks such as abnormal liquid level detection and overflow during the pulping process. In this embodiment, the three-sided copper-clad shielding of the water level detection area and the overflow prevention detection area on the substrate of the PCB testing board, as well as the mesh copper-clad shielding on the rear surface of the substrate, can minimize the influence of external induction interference on the capacitor plates, effectively solving the problem of abnormal capacitance value fluctuations caused by condensation on the side of the assembled PCB testing board or user touch, thus ensuring the reliability of the detection.

[0046] It should be noted that the pulping container in this embodiment is cylindrical. The PCB detection board can be used for both water level and overflow detection. The PCB detection board's substrate is a rigid board, and its vertical arrangement on the outer wall of the pulping container effectively prevents the curved structure of the container from causing the capacitors to sense non-required capacitance values. In this embodiment, the minimum pulping capacity is not lower than the lower limit of the lowest first capacitor to ensure that at least one capacitor detects the water level. The maximum pulping capacity is not higher than the lower limit of the lowest second capacitor or is located between the highest first capacitor and the lowest second capacitor to ensure at least one inter-electrode capacitance difference detection point. Similarly, the minimum overflow detection point is not lower than the lowest second capacitor to ensure that the second capacitor can sense the overflow signal, while the maximum overflow detection point corresponding to the maximum pulping capacity should be lower than the lower limit of the highest second capacitor so that the highest second capacitor can serve as the final auxiliary overflow safety detection.

[0047] In this embodiment, the first capacitor plates on the water level detection area are arranged at equal intervals, and the detection height h of the water level detection area is actually the maximum pulping capacity V. H With minimum pulping capacity V L The heights between them are related as follows: Where r is the radius of the pulping container, n is the number of first capacitor plates, Δh is the spacing between adjacent first capacitor plates, and h n This refers to the detection height of a single first capacitor electrode. Therefore, for the first capacitor electrode in this embodiment, In this embodiment, the water level detection area is provided with n first capacitor plates, that is, the water level detection area has n different pulping capacities.

[0048] Furthermore, in this embodiment, the second capacitor plates on the overflow detection area are also arranged at equal intervals of Δh, wherein the distance between the highest first capacitor plate and the lowest second capacitor plate is also Δh. Simultaneously, in this embodiment, for n different pulping capacities, the overflow detection area has corresponding overflow detection positions, where the number of overflow detection positions is set to N. Additionally, to increase the safety of overflow detection, an extra second capacitor plate is added to the substrate as an overflow detection electrode. Therefore, the number of second capacitor plates in the overflow detection area is N+1, with the first N second capacitor plates corresponding to N overflow detection positions, and the N overflow detection positions corresponding to n different pulping capacities. H is set. m This refers to the detection height of the PCB inspection board, which is the sum of the heights of the water level detection area and the overflow prevention detection area. The height of the overflow prevention detection area satisfies H = Hoverflow. m -h=(N+1)h N +NΔh,h NThe detection height of a single second capacitor electrode, i.e. And N and n satisfy: Both N and n are integers.

[0049] The detection height h of a typical single first capacitor electrode n The detection height h of a single second capacitor electrode is selected to be 3mm to 6mm. N The detection height is generally not less than twice that of a single first capacitor electrode, and is generally selected to be 8mm to 12mm. In this embodiment, the first capacitor electrode is preferably selected to be 4mm to 5mm, and the second capacitor electrode is preferably selected to be 10mm.

[0050] It should be noted that the capacitor electrode at the highest point of the overflow detection zone is used to assist in the detection of dangerous overflow signals. This effectively prevents the overflow safety risk caused by the failure of the maximum overflow detection setting corresponding to the maximum pulping capacity, serving as the last line of defense against pulp overflow. Therefore, in this embodiment, a third capacitor electrode can also be separately installed on the substrate above the overflow detection zone as an auxiliary indicator for detecting dangerous overflow signals. In this case, the number of second capacitor electrodes corresponding to the water level detection zone is the same as the number of overflow detection settings, both being N, and the detection height of a single second capacitor electrode meets the following requirements:

[0051] like Figure 4 The diagram shows the circuit layout topology of the PCB testing board in this embodiment. The non-contact PCB testing board includes a control section and an electrode section (capacitor plates). The electrode section is configured with multiple capacitor plates, each connected to a control MCU (control chip). The components of the control section are placed on the opposite side of the substrate from the capacitor plates. An interface module (output terminal) is located at the bottom of the control section, and the terminals of the interface module are surface-mount. The control MCU is located on the upper part of the interface section. A reset circuit module, a power supply circuit module, an output circuit module, and a programming port are respectively configured on both sides of the control MCU. The control MCU has a rewritable memory module, and the control program can be repeatedly updated to the memory module through the programming port, enabling program updates. In this embodiment, the reliability of the control system is ensured through the PCB testing board topology design. At the same time, the interface location is designed to minimize the installation space, improving reliability while reducing the cost of the PCB testing board. In addition, separating the capacitor plates from other components helps improve anti-interference capabilities and ensure reliability.

[0052] For the PCB detection board in this embodiment, different detection and control methods are used for different pulping stages. Specifically, in the beverage making process, the PCB detection board of this embodiment has a water level detection stage for detecting user-added water or automatic water intake, and an anti-overflow detection stage for detecting spillage during the pulping process.

[0053] Water Level Detection: The control chip on the PCB detection board starts to detect the capacitance value on the first capacitor electrode in real time to determine whether the user has placed materials to the preset water level. During real-time detection, at any given moment, only one of the multiple first capacitor electrodes is in sensing mode, while the others are grounded. This ensures that only one capacitor generates a capacitance value in each cycle, thus avoiding the influence of other capacitor electrodes. The PCB detection board detects the capacitance value changes of each capacitor electrode sequentially from bottom to top. When a significant change in the capacitance value of a segment electrode is detected, it is determined that material has been placed. When the capacitance value of the capacitor electrode above a certain segment electrode does not change, the control chip confirms that the current liquid level is at the water level position corresponding to that capacitor electrode. When no significant change in the capacitance value of a segment electrode is detected, it is determined that the user has placed materials and then power is restored. The chip then detects the change in the capacitance difference between the segment electrodes. When a significant change in the capacitance difference between two adjacent segment electrodes is detected, the control chip determines that the current liquid level is at the position of that segment electrode.

[0054] like Figure 2 The PCB testing board shown uses a control chip that sequentially and cyclically detects the capacitance value of the first capacitor electrode in each segment at a set time frequency t0. The control chip calculates the capacitance difference ΔC between the electrodes based on the capacitance values ​​of each segment's electrodes. Ln-Ln-1 The location of the maximum capacitance difference is the current water level.

[0055] For example, at time point T1-n*t0 (where n is the number of the first capacitor plates), the control chip detects a significant change in L1. As the detection time approaches T1, the capacitance difference between segmented first capacitor plates L2 and L1 continuously increases, while the capacitance differences of other segmented electrodes remain essentially unchanged. Therefore, the control chip confirms that the capacitance difference ΔC between segmented first capacitor plates L2 and L1 is significant. L2-L1 At its maximum, the control chip confirms that the current water level is on the first capacitor electrode L2.

[0056] Existing non-contact water level detection methods primarily rely on changes in the capacitance of individual capacitor plates. However, because these plates are discontinuous, significant temperature differences exist between them, and the capacitance is greatly affected by slurry and ambient temperatures. This leads to frequent misjudgments and increases the probability of detection failure. This embodiment addresses this by using a control chip to dynamically track and detect the capacitance difference between adjacent segments of the first capacitor plate, determining the maximum difference as the current water level position. This effectively solves the problem of misjudgment. Similarly, this water level detection method can also be applied to overflow signal detection; however, due to the foamy characteristics of the slurry, its effectiveness is slightly reduced.

[0057] In this embodiment, the detection of the water level signal also includes other detection methods, such as detection based on the fluctuation of the capacitance value sensed by a single first capacitor electrode. Within a set time period, the control chip continues to sequentially and cyclically detect the capacitance value of each segment of the first capacitor electrode, and at any given time, only one capacitor electrode is energized for detection, while the other capacitor electrodes are grounded. When the fluctuation of the capacitance value sensed by a certain first capacitor electrode exceeds a preset fluctuation threshold of the control chip, the control chip determines that the water level has reached the pulping water level corresponding to that first capacitor electrode; otherwise, the detection of each segment of the capacitor electrode continues cyclically.

[0058] For the PCB testing board in this embodiment, both of the above-mentioned water level signal detection methods are compatible. After either method obtains the current water level signal, the control chip will feed the signal back to the main control device. The main control device will determine the corresponding slurry preparation program based on the corresponding water level signal to realize subsequent slurry production. Of course, for the above methods, after one detection method obtains the water level signal, the other detection method can also perform a re-inspection. Through dual water level signal detection, the water level signal detection can be more accurate and the influence of external parasitic capacitance can be prevented. For example, when the control chip confirms that the current water level corresponds to the first capacitor plate L, during the water level re-inspection, the control chip judges whether the value greater than the preset fluctuation threshold is the first capacitor plate L based on the capacitance value fluctuation sensed by a single first capacitor plate. If it is determined to be the first capacitor plate L, the detection is confirmed to be accurate. If it is determined not to be the first capacitor plate L, the control chip will again perform cyclic detection based on the capacitance difference between two adjacent first capacitor plates until the current water level signal is finally confirmed.

[0059] After the water level detection stage is completed, the slurry production process begins. At the same time, during the slurry production process, the PCB test board also needs to undergo the overflow detection stage to detect the overflow signal.

[0060] Overflow detection: In this embodiment, the overflow detection area includes multiple second capacitor plates, and the overflow detection area is provided with a dividing groove arranged along the diagonal of a rectangle. The dividing groove divides the overflow detection area into two triangular sub-overflow detection areas. At the same liquid level, the sensing areas corresponding to the two sub-overflow detection areas are different.

[0061] like Figure 2 As shown, the overflow detection area is divided into two triangular sub-overflow detection areas, tri1 and tri2, by a dividing groove. The tip of tri1 faces upwards, and the tip of tri2 faces downwards. Tri1 and tri2 are each configured as multiple segmented sub-electrodes. Similarly, when overflow signal detection is performed at a certain moment, the control chip sequentially detects the capacitance value of each sub-electrode in the left and right triangular areas at a set time frequency t0. Furthermore, the incremental capacitance values ​​sensed by each sub-electrode in tri1 and tri2 are accumulated to obtain ΔC. tri1 With ΔC tri2 The control chip then calculates the ratio of the cumulative increments of the capacitance values ​​on both sides, and the control chip uses this ratio to... Determine the current overflow warning signal height.

[0062] Meanwhile, during the pulping process, the foam height on the pulp surface is not uniform, with some areas being higher and others lower. Therefore, during the overflow detection process, the capacitance values ​​sensed by each sub-electrode of tri1 and tri2 exhibit abrupt changes. Furthermore, different liquid heating structures result in variations in the installation of the PCB test board relative to the pulping container. Based on this, the ratio... The corresponding corrections need to be made, namely (η is a correction factor; liquid heaters with different structural forms have corresponding correction factors).

[0063] Meanwhile, the control chip also presets a value K0, which is the height ratio of the left and right sub-overflow detection zones at the same overflow prevention height. When K approaches or equals K0, the control chip confirms the current overflow prevention height reached by the foam and then feeds the overflow prevention signal back to the main control device to implement corresponding program operations, such as stopping the motor or stopping the heating, thereby effectively preventing the safety risk of foam overflow. Of course, in this embodiment, the control chip can also preset the total height H of the overflow detection zones. During the overflow detection process, the control chip calculates the incremental ratio of the capacitance values ​​of the first sub-overflow detection zone and the second sub-overflow detection zone. The control chip determines the current overflow prevention height based on the ratio of K to H. Of course, different liquid heaters have different correction factors η.

[0064] Existing non-contact liquid level detection methods primarily rely on the capacitance change of a single electrode for overflow level detection. However, during pulping, a thick layer of pulp foam forms above the liquid surface. Furthermore, the presence of foam within this layer obstructs contact between the pulp foam and the container wall, creating a gap that affects the capacitance value sensed by a single electrode. Moreover, the surface of the pulp foam layer is not smooth; the pulp foam in the central area of ​​the pulping container is not at the same height as the foam on the container wall, and even the height of the foam varies at different locations on the container wall. A single electrode can only sense a specific value, and this specific value may not necessarily reflect the current pulp foam height. For example, when there are large air bubbles in the middle layer of the pulp, both the pulp below and above the bubbles will be sensed by a single electrode. However, a single electrode can only sense one maximum capacitance value. Therefore, a single electrode cannot transmit the presence of pulp above the bubbles to the control chip, causing the control chip to fail to recognize the overflow prevention signal. Simultaneously, the capacitance value sensed by a single electrode is also affected by pulp temperature and ambient temperature, making it impossible to accurately detect the overflow position and resulting in large detection deviations. Therefore, during pulping, overflow prevention is prone to misjudgment, leading to overflow failure and pulp overflow. The inventors discovered through research that by using multiple capacitor electrodes in segmented configurations, each electrode senses the capacitance value of its respective segment. Furthermore, the ratio of the capacitance increments of two triangles can be roughly equivalent to the ratio of the areas covered by pulp foam in the two triangles. Based on this principle, the detected overflow level can be closer to the set overflow level, thereby significantly reducing the probability of pulp overflow and improving the safety risk of overflow prevention.

[0065] The above-described anti-overflow detection method allows the anti-overflow detection position detected by the PCB inspection board to be closer to the actual anti-overflow position, effectively preventing slurry overflow. Of course, in this embodiment, a single second capacitor electrode is actually formed by the sub-electrode corresponding to the first sub-overflow detection area and the sub-electrode corresponding to the second anti-overflow detection area. Therefore, a water level detection method can also be used, where the capacitance value sensed by the two sub-electrodes is accumulated to determine the capacitance value of the corresponding second capacitor electrode. The control chip then determines the current anti-overflow detection position based on whether the capacitance difference between two adjacent second capacitor electrodes is the maximum. It should be noted that only one of these two anti-overflow signal detection methods can be selected; both cannot be applied simultaneously. In this embodiment, comparing the accumulated capacitance values ​​sensed by the left and right triangles to determine the anti-overflow detection position is more accurate and closer to the actual anti-overflow position reached by the slurry. This solution is also the preferred solution in this embodiment.

[0066] Furthermore, it should be noted that in this embodiment, the dividing groove divides the overflow detection area into triangles, resulting in unequal sensing areas for the two sub-overflow detection areas at the same liquid level. It is precisely because of this unequal sensing area that different overflow heights can be determined based on different ratios. Therefore, in this embodiment, the dividing groove is not limited to dividing the overflow detection area into two equal triangles; it could also be divided into two equal trapezoids. Similarly, the dividing groove is not limited to a straight dividing groove inclined relative to the substrate; it could also be a curved dividing groove, for example, dividing the overflow detection area according to a Tai Chi curve, thus dividing the overflow detection area into a Tai Chi shape.

[0067] It should also be noted that during water level detection, the control chip sequentially and cyclically detects the capacitance value of each first capacitor electrode at a set time interval. At any given moment, only one first capacitor electrode is energized for detection, while the others are grounded. Alternatively, during overflow detection, the control chip sequentially and cyclically detects the capacitance value of each second capacitor electrode at a set time interval. Again, at any given moment, only one second capacitor electrode is energized for detection, while the others are grounded. This effectively avoids confusion in capacitance value detection and the influence of external parasitic capacitance on the actual detection signal.

[0068] It should also be noted that, for this embodiment, the pulping container generally requires that at least the mounting area of ​​the PCB detection board be made of a non-conductive material. For example, a pulping container enclosed entirely in glass or plastic, a pulping container formed by combining a through-glass cup and a heating plate, or a pulping container formed by combining a metal cup and a non-metallic transparent window, with the PCB detection board mounted on the transparent window. In general, this is to avoid the conductive pulping container interfering with the detection of the capacitor plates on the PCB detection board, affecting the actual detected capacitance value. Furthermore, in this embodiment, the water level detection area is generally configured to detect only the water level signal and not the overflow prevention signal, while the overflow prevention detection area is generally configured to detect only the overflow prevention signal and not the water level signal. Of course, in this embodiment, the lower few second capacitor plates of the overflow detection zone can also be used to detect water level signals, while the upper few second capacitor plates of the overflow detection zone are used to detect overflow signals. That is, the maximum pulping capacity of the pulping container is higher than the lower few second capacitor plates of the overflow detection zone, but will not exceed the highest second capacitor plate, thus realizing ultra-high water level pulping in the pulping container. Similarly, based on the same principle, the upper few first capacitor plates of the water level detection zone can also be used for overflow detection at ultra-low water levels. As long as the control chip is programmed accordingly, this can be achieved.

[0069] It should be noted that, for the liquid heater of the present invention, different first capacitor plates are used for water level detection of different pulping capacities, and different second capacitor plates are used for detecting different anti-overflow signals corresponding to different pulping capacities. For example, first capacitor plate A corresponds to detecting water level of 300ml pulping capacity, first capacitor plate B corresponds to detecting water level of 400ml pulping capacity, first capacitor plate C corresponds to detecting water level of 600ml pulping capacity, and first capacitor plate D corresponds to detecting water level of 900ml pulping capacity. Here, 300ml to 600ml is one pulping capacity range, and 600ml to 900ml is another pulping capacity range. Each second capacitor electrode can be used to detect the overflow height for a specific pulping capacity, or it can be used to detect the overflow height for a pulping capacity range. For example, the overflow height can be detected by the second capacitor electrode A and the second capacitor electrode B respectively when making 300ml and 600ml pulp. Of course, the same overflow height can also be set when making 300ml and 600ml pulp, and the same second capacitor electrode can be used for detection. Of course, during the pulping process, when the second capacitor electrode corresponding to a certain pulping capacity fails to detect the overflow signal, the adjacent second capacitor electrode located above it can be used as a new overflow detection position for overflow detection. This can effectively avoid the problem of overflow when some second capacitor electrodes fail to detect the signal due to malfunction or other reasons. In other words, during the pulping process, the detection plate will first determine the pulping capacity based on the water level signal detected by the first capacitor electrode. Based on the correspondence between different pulping capacities and overflow signal detection, the corresponding second capacitor electrode will be determined, and this second capacitor electrode will be used as the first overflow detection position. When this second capacitor electrode fails or fails to detect the signal, another second capacitor electrode above it will be used as the second overflow detection position for overflow detection. This effectively solves the problem that existing food processing machines only have one fixed overflow detection position, which can easily lead to overflow when the detection fails.

[0070] Meanwhile, because the slurry foam is uneven during the pulping process, it is difficult to guarantee that the foam rises to the height of a specific second capacitor electrode. For this invention, multiple second capacitor electrodes can also form an anti-overflow detection zone. When foam at a certain pulping capacity or in a certain pulping zone is detected by a second capacitor electrode within this anti-overflow detection zone, the main controller performs corresponding anti-overflow control operations. For example, second capacitor electrodes A and B form an anti-overflow detection zone W. When making 600ml of slurry beverage or 300ml-600ml of slurry beverage, when the second capacitor electrode within this anti-overflow detection zone senses an anti-overflow signal, it is considered that the anti-overflow height has been reached. The main controller then controls the heating device to stop heating or controls the stirring device to stop stirring to prevent the slurry from overflowing.

[0071] It should be noted that the structural changes and parameter selections described in this embodiment can also be applied to other embodiments of the present invention.

[0072] Example 2:

[0073] like Figure 5 The diagram shown is a structural schematic of a PCB detection board according to a second embodiment of the present invention. This embodiment differs from the first embodiment in that: the PCB detection board in this embodiment has no dividing grooves, and each second capacitor electrode 54b on the overflow detection area 55b is a complete capacitor electrode. Similar to the first embodiment, the water level detection area 55a in this embodiment is formed by multiple first capacitor electrodes 54a arranged at equal intervals, and the overflow detection area 55b is formed by multiple second capacitor electrodes 54b arranged at equal intervals. Furthermore, the detection height of a single second capacitor electrode 54b is greater than the detection height of a single first capacitor electrode 54a.

[0074] In this embodiment, the pulping process of the food processing machine also includes a water level detection stage and an overflow prevention detection stage. In the water level detection stage, the control chip still calculates the capacitance difference ΔC between the electrodes based on the capacitance values ​​of each segment electrode. Ln-Ln-1The maximum capacitance difference is identified as the current water level. The main control device determines the corresponding pulping program based on the water level signal fed back by the control chip. Different water levels correspond to different pulping processes, resulting in different overflow detection positions for different water levels. This ensures efficient and complete production of the pulp beverage. Simultaneously, multiple overflow detection positions ensure the safety of pulping and effectively prevent overflow. During the overflow detection phase, the control chip determines the current overflow detection position based on the maximum capacitance difference between two adjacent second capacitor plates. Then, it performs corresponding program operations based on the relationship between the current overflow detection position and the program-set overflow detection position. This ensures both the detection of the overflow signal and the prevention of overflow safety risks during pulping. Similar to Embodiment 1, this embodiment, due to the significantly greater detection height of the second capacitor plate than the first capacitor plate, can sense a larger capacitance value for slurry bubbles and foam, thereby achieving more accurate overflow signal detection and preventing misjudgment or failure to recognize overflow signals, thus avoiding safety risks.

[0075] It should be noted that, for this implementation, the water level detection stage and the overflow prevention detection stage can also be determined by the control chip based on the capacitance fluctuation of a single capacitor electrode, as needed.

[0076] Furthermore, it should be noted that the liquid heater of the present invention is not limited to the food processing machine with an integrated motor and cup body disclosed in the embodiments of the present invention. It can also be a soy milk maker with a top-mounted motor, a blender with a separate cup body and base, and a hand-washable food processing machine that can automatically discharge and clean itself. Moreover, the liquid heater of the present invention can also be applied to heating appliances that can perform boiling operations, rice paste making, etc., such as health pots and health cookers.

[0077] Those skilled in the art will understand that this invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of this invention will be included within the scope of the claims.

Claims

1. A liquid heater for leak detection and spill prevention, the liquid heater comprising a glass cup forming a slurry container and a PCB detection board mounted on the outer side wall of the glass cup for detecting liquid level, characterized in that: The PCB detection board is provided with multiple spaced capacitor plates, each capacitor plate including multiple first capacitor plates and multiple second capacitor plates located above the first capacitor plates. Different first capacitor plates are used for water level signal detection of different pulping capacities, and different second capacitor plates are used for different anti-overflow signal detection of bubbles and foam. Different pulping capacities have corresponding anti-overflow signal detection. The sensing area of ​​a single second capacitor plate is larger than the sensing area of ​​a single first capacitor plate.

2. The liquid heater with air-tight detection and spill prevention according to claim 1, characterized in that: The PCB detection board is also provided with a dividing groove for dividing the second capacitor electrode, and a single second capacitor electrode is divided into two sub-electrodes by the dividing groove. Under the same overflow prevention height, the sensing areas of the two corresponding sub-electrodes are not equal.

3. The liquid heater with air-locked detection and spill prevention according to claim 2, characterized in that: The dividing groove is a straight dividing groove that is inclined relative to the PCB inspection board; Alternatively, the dividing groove may be a curved dividing groove.

4. The liquid heater with air-locked detection and spill prevention according to claim 1, characterized in that: The PCB testing board includes a strip-shaped substrate, a control chip, and output terminals. The first capacitor electrode and the second capacitor electrode are located on the front surface of the substrate facing the glass body. Multiple first capacitor electrodes form a water level detection area on the substrate, and multiple second capacitor electrodes form an anti-overflow detection area on the substrate. The anti-overflow detection area is located above the water level detection area. The control chip and output terminals are disposed on the rear surface of the substrate.

5. The liquid heater with air-tight detection and spill prevention according to claim 4, characterized in that: The control chip and output terminals are both located below the water level detection area; Alternatively, during the water level detection process, the control chip sequentially and cyclically detects the capacitance value of each first capacitor electrode at a set time, and at any given moment, only one first capacitor electrode is energized for detection, while the other first capacitor electrodes are grounded. Alternatively, during the overflow detection process, the control chip sequentially and cyclically detects the capacitance value of each second capacitor electrode at a set time, and at any given moment, only one second capacitor electrode is energized for detection, while the remaining second capacitor electrodes are grounded.

6. The liquid heater with air-locked detection and spill prevention according to claim 1, characterized in that: The PCB testing board is also covered with a mesh shielding layer, which includes a first shielding layer and a second shielding layer respectively attached to the two sides of the PCB testing board, and the second shielding layer surrounds the outside of the capacitor electrode along the edge of the PCB testing board.

7. The liquid heater with air-tight detection and spill prevention according to claim 6, characterized in that: The mesh shielding layer is grounded; Alternatively, the lower side opening of the second shielding layer; Alternatively, the mesh shielding layer may be a copper-clad mesh.

8. The liquid heater with air-tight detection and spill prevention according to claim 1, characterized in that: The bottom of the glass cup is equipped with a heating device for heating the pulping container, and a motor is installed in the mounting cavity below the glass cup. The rotating shaft driven by the motor passes through the bottom of the glass cup and extends into the pulping container, and a crushing device is connected to the end of the rotating shaft. The PCB detection board is installed between the glass cup and the handle, and a main control device is also installed in the mounting cavity below the glass cup. The main control device is electrically connected to the motor, the heating device and the PCB detection board respectively.

9. The liquid heater with air-locked detection and spill prevention according to claim 1, characterized in that: Multiple capacitor electrodes are arranged at equal intervals; Alternatively, the number of the second capacitor plates is greater than the number of the first capacitor plates; Alternatively, the detection height of a single second capacitor electrode shall not be less than twice the detection height of a single first capacitor electrode; Alternatively, the detection height of a single first capacitor electrode is 3mm to 6mm; Alternatively, the detection height of a single second capacitor electrode can be 8mm to 12mm.

10. The liquid heater with air-tight detection and spill prevention according to claim 1, characterized in that: The detection plate determines the pulping capacity based on the water level signal detected by the first capacitor plate, and determines the corresponding second capacitor plate based on the correspondence between different pulping capacities and overflow prevention signal detection, and uses the second capacitor plate as the first overflow prevention detection position.

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