Non-contact Anti-overflow detection liquid heater

Abstract

The present application discloses a non-contact anti-overflow detection liquid heater. A PCB measurement board of the liquid heater is provided with a water level measurement region formed by a plurality of first capacitor electrode sheets and an anti-overflow detection region formed by a plurality of second capacitor electrode sheets; the anti-overflow detection region comprises a first sub-anti-overflow detection region and a second sub-anti-overflow detection region which are obtained by means of division by a division groove and are arranged side by side; and an individual second capacitor electrode sheet is divided into two sub-electrode sheets by the division groove, said two sub-electrode sheets being respectively located in two columns of sub-anti-overflow detection regions. The liquid heater of the present invention can achieve water level signal detection and overflow signal detection of multiple different pulping capacities in a non-contact manner, can achieve intelligent making of pulp beverages of different pulping capacities, achieves more reliable detection of a foam type pulp overflow signal generated during pulping, allows for more effective recognition of the overflow signal, and is not prone to the safety risk of overflow of bubble and foam type pulp.

Description

Liquid heater with air-to-air anti-overflow detection

[0001] This application claims priority to the following Chinese patent applications, the entire contents of which are incorporated herein by reference:

[0002] A Chinese patent application with application number 202311436066.0, titled “A Liquid Level Detection Method for a Liquid Heater,” was submitted to the China Patent Office on November 1, 2023;

[0003] A Chinese patent application was submitted to the China Patent Office on February 27, 2024, with application number 202410210628.8 and invention name "A liquid heater with remote anti-overflow detection". Technical Field

[0004] The present application belongs to the technical field of kitchen appliances, and in particular relates to a liquid heater with air-through anti-overflow detection. Background Art

[0005] Liquid heaters or food processors used to make drinks such as soy milk and rice porridge are widely used kitchen appliances. Water level detection and overflow prevention detection are important parts to ensure the safe operation of liquid heaters. Some existing liquid heaters use annular capacitor plates to achieve water level detection and overflow prevention detection, while other existing liquid heaters use PCB boards or PFB soft boards with metal sheets to perform water level detection and overflow prevention detection. However, the installation of capacitor plates in the prior art is relatively complicated and requires a large installation space. In addition, due to the characteristics of bubbles, foam, slurry, etc. that are different from water and their uneven surfaces, the prior art cannot accurately identify the height of the slurry, and cannot guarantee accurate overflow prevention detection. Moreover, the pulping capacity range of the above-mentioned existing liquid heaters is relatively narrow.

[0006] Therefore, how to provide a liquid heater that can accurately identify the height of pulp foam to improve the reliability and intelligence of overflow detection under a large pulping capacity range and make the setting of capacitor plates simpler is an urgent problem that people in this field need to solve.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a liquid heater with air-to-air overflow prevention detection. The liquid heater can realize water level signal detection of multiple different pulping capacities and overflow signal detection corresponding to different pulping capacities through air, and can realize the intelligent production of pulp beverages with different pulping capacities. Moreover, the detection of foam-type pulp overflow signals generated during the pulping process is more reliable, and the overflow signals can be identified more effectively, and there is no safety risk of overflow of bubbles and foam-type pulp.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a liquid heater with air-spaced anti-overflow detection, comprising a glass cup body forming a pulping container, and a PCB detection board mounted on the outer wall of the pulping container for detecting the liquid level height, characterized in that the PCB detection board is provided with a water level detection area for detecting water and an anti-overflow detection area for detecting bubbles and foam, the anti-overflow detection area being located above the water level detection area, the water level detection area being used for water level detection of different pulping capacities, and the anti-overflow detection area being used for detecting different overflow signals corresponding to different pulping capacities, the water level detection area having a plurality of first capacitor electrodes for detecting water level signals, and the anti-overflow detection area having a plurality of second capacitor electrodes for detecting overflow signals, the anti-overflow detection area comprising a first sub-anti-overflow detection area and a second sub-anti-overflow detection area arranged side by side, divided by a dividing groove, each second capacitor electrode being divided by the dividing groove into two sub-electrode pieces located in the first sub-anti-overflow detection area and the second sub-anti-overflow detection area, respectively, and the PCB detection board being further provided with a control chip electrically connected to the first capacitor electrode piece and each sub-electrode piece, respectively.

[0010] In one embodiment, the sensing area of ​​each second capacitor electrode is larger than the sensing area of ​​each first capacitor electrode.

[0011] In one embodiment, the dividing groove is a straight dividing groove arranged obliquely relative to the PCB detection board;

[0012] Alternatively, the dividing groove is a curved dividing groove;

[0013] Alternatively, the first sub-overflow prevention detection area and the second sub-overflow prevention detection area have the same size;

[0014] Alternatively, for a height below the top of the overflow prevention detection zone, the sensing area of ​​the first sub-overflow prevention detection zone below the height is not equal to the sensing area of ​​the second sub-overflow prevention detection zone below the height.

[0015] In one embodiment, the first capacitor electrode and the second capacitor electrode are arranged on the front surface of the PCB detection board, and a grid shielding layer is also provided on the PCB detection board. The grid shielding layer includes a first shielding layer attached to the rear surface of the PCB detection board and a second shielding layer attached to the front surface of the PCB detection board, and the second shielding layer is enclosed along the edge of the PCB detection board to the outside of the first capacitor electrode and the second capacitor electrode.

[0016] In one embodiment, the mesh shielding layer is grounded; or the lower side of the second shielding layer is open; or the mesh shielding layer is a copper-clad mesh.

[0017] In one embodiment, the control chip is used to cyclically detect the capacitance value of each first capacitor electrode at a set time interval during the water level detection process, and at any time, only one first capacitor electrode is powered on for detection, and the remaining first capacitor electrodes are set to ground;

[0018] Alternatively, the control chip is used to cyclically detect the capacitance value of each second capacitor electrode at a set time interval in the water level detection process, and at any time, only one second capacitor electrode is powered on for detection, and the other second capacitor electrodes are set to be grounded;

[0019] Alternatively, the number of the second capacitor electrodes is greater than the number of the first capacitor electrodes;

[0020] Alternatively, the detection height of a single second capacitor electrode is not less than twice the detection height of a single first capacitor electrode;

[0021] Alternatively, the detection height of a single first capacitor electrode is 3 mm to 6 mm;

[0022] Alternatively, the detection height of a single second capacitor electrode is 8 mm to 12 mm.

[0023] In one embodiment, during the anti-overflow detection process of the PCB detection board, the control chip obtains the cumulative value ΔC of the capacitance value increment detected by each sub-electrode in the first sub-anti-overflow detection area. tri1 and the cumulative value ΔC of the capacitance increment detected by each sub-electrode in the second sub-overflow prevention detection area tri2 , and according to ΔC tri1 and ΔC tri2 The ratio of determines the current height of the foam.

[0024] In one embodiment, the control chip presets an area ratio K0 of the first sub-overflow detection zone and the second sub-overflow detection zone below the same height. During the overflow detection process, the control chip calculates the incremental ratio K of the capacitance values ​​of the first sub-overflow detection zone and the second sub-overflow detection zone. The control chip determines the current height of the foam based on the relationship between K and K0.

[0025] Alternatively, the control chip is preset with a total height H of the anti-overflow detection area. During the anti-overflow detection process, the control chip calculates the incremental ratio K of the capacitance values ​​of the first sub-anti-overflow detection area and the second sub-anti-overflow detection area, and the control chip determines the current height of the foam based on the ratio of K to H.

[0026] In one embodiment, the control chip is used to correct the calculated K value according to different liquid heaters. η is the correction coefficient.

[0027] In one embodiment, the plurality of first capacitor electrodes are arranged from bottom to top in the order of L1 to Ln The marks are arranged at intervals. In the water level detection, the capacitance difference between two adjacent first capacitor electrodes is ΔC Ln-L(n-1) , when ΔC Ln-L(n-1) When it is the maximum value, the control chip confirms that the amount of water currently added to the pulping container is the first capacitor electrode L n The corresponding water level, n is the number of first capacitor electrodes.

[0028] In one embodiment, after the control chip confirms the first capacitor electrode L corresponding to the current water level, the PCB detection board is also used to recheck the water level. During the water level recheck, the control chip determines whether the first capacitor electrode L is greater than a preset fluctuation threshold based on the capacitance fluctuation sensed by each first capacitor electrode.

[0029] In one embodiment, different second capacitor electrodes correspond to different anti-overflow detection positions, and different anti-overflow detection positions correspond to different pulping procedures.

[0030] In one embodiment, the first capacitor electrodes are arranged equidistantly in the water level detection area, and the detection height of each first capacitor electrode is Among them, V L is the minimum pulping capacity of the pulping container, V H is the maximum pulping capacity, and at least a portion of the pulping container located between the minimum pulping capacity and the maximum pulping capacity is a cylindrical structure, r is the radius of the cylindrical structure, n is the number of first capacitor electrodes, and Δh is the spacing between adjacent first capacitor electrodes.

[0031] In one embodiment, the second capacitor electrodes are arranged equidistantly in the anti-overflow detection area, and the detection height of each second capacitor electrode is Among them, H m is the height from the lowest end of the water level detection area to the highest end of the overflow prevention detection area, N is the number of overflow prevention detection positions corresponding to different pulping capacities, and Δh is the spacing between adjacent second capacitor electrodes, which is equal to the spacing between adjacent first capacitor electrodes, wherein, N and n are integers.

[0032] In the prior art, the capacitor electrode detects water level and overflow signals by utilizing the principle of air-space induction. When the capacitor electrode is close to the liquid, a capacitance value is sensed, and the control chip indirectly determines the water level signal and overflow signal based on the fluctuation of the capacitance value. The inventor has found through continuous research that the capacitance value of the capacitor electrode sensing the liquid signal has a large range of variation. When the capacitor electrode is close to the liquid, the capacitance value fluctuates greatly, while when it is farther away, the capacitance value fluctuates less. At the same time, the capacitance value fluctuation generated by the capacitor electrode is also related to the liquid form and conductivity. When the liquid is pure liquid and has strong conductivity, the capacitance value fluctuates greatly, which can achieve accurate detection of the liquid level. When the liquid is in the form of bubbles or foam, the capacitance value fluctuates relatively little due to the reduced conductivity. It is precisely because when the liquid is in the form of bubbles or foam, the capacitance value sensed by the capacitor electrode fluctuates less, and the control chip cannot determine whether it is a liquid level signal. Moreover, the capacitance change produced by the capacitor electrode will also be affected by environmental factors, which can easily form parasitic capacitance, and parasitic capacitance will also cause the capacitor electrode to sense smaller capacitance fluctuations, and the control chip may also misjudge. For example, when a person's hand is close to the capacitor electrode, capacitance fluctuations will also occur. At this time, the control chip cannot distinguish whether it is an interference capacitance value or an actual liquid level capacitance value, or water droplets on the outer wall of the slurry container will also cause the capacitor electrode to sense capacitance fluctuations, and the control chip may misjudge. In addition, although the existing capacitor electrode can be used to detect both water level signals and overflow signals, for slurries formed by bubbles, foam, etc., due to the uneven surface of the slurry, the existing fixed anti-overflow capacitor electrode is not accurate in identifying the actual slurry height, and slurry overflow is more likely to occur.

[0033] For the liquid heater of the present invention, a water level detection area and an anti-overflow detection area are provided on the PCB detection board, which are respectively arranged by a plurality of first capacitor electrodes and a plurality of second capacitor electrodes. This can realize the water level detection of a variety of different pulping capacities in the air, and can also realize the detection of different overflow signals corresponding to a variety of different pulping capacities in the air. Compared with the existing anti-overflow detection position with only one fixed position, the liquid heater of the present invention can realize more intelligent production of pulp beverages and higher pulping efficiency. While ensuring the production of one or more servings of beverages, it can also solve the problems of the existing technology that only one fixed anti-overflow detection position is prone to failure, excessive anti-overflow time, and pulp foam sticking to the wall. In addition, the present invention uses different pulping capacities to correspond to different anti-overflow detection positions, which not only ensures that the problem of pulp overflow will not occur, but also has a higher space utilization rate of the pulping container, can achieve the optimization of pulping efficiency, and avoid the problems of excessive pulping time or poor crushing.

[0034] Among them, the anti-overflow detection area of ​​the PCB detection board of the liquid heater of the present invention is also provided with a dividing groove arranged obliquely relative to the PCB detection board. The anti-overflow detection area is divided by the dividing groove into a first sub-anti-overflow detection area and a second sub-anti-overflow detection area arranged side by side, and the single second capacitor electrode is divided by the dividing groove into two sub-electrodes respectively located in two columns of sub-anti-overflow detection areas. The first capacitor electrode and each sub-electrode are respectively electrically connected to the control chip on the PCB detection board. At the same anti-overflow height below the top of the highest second capacitor electrode, the sensing area of ​​the first sub-anti-overflow detection area is not equal to the sensing area of ​​the second sub-anti-overflow detection area. That is to say, in this embodiment, the dividing groove divides the anti-overflow detection area into two triangular detection areas of the same size and inverted shape, and, except for the topmost point, the sensing area of ​​the first sub-anti-overflow detection area at any other height is not equal to the sensing area of ​​the second sub-anti-overflow detection area.

[0035] The liquid heater with remote anti-overflow detection of the present invention has a water level detection function for detecting the amount of water added to the pulping container before pulping and an anti-overflow detection function for detecting the height of the pulp during pulping. During the anti-overflow detection process, the control chip on the PCB detection board obtains the cumulative value ΔC of the capacitance value increment detected by each sub-electrode in the first sub-anti-overflow detection area. tri1 and the cumulative value ΔC of the capacitance increment detected by each sub-electrode in the second sub-overflow prevention detection area tri2 , and according to ΔC tri1 and ΔC tri2 The current overflow prevention height is determined by the ratio of the capacitance detected by the two sub-overflow detection zones. Because the foam on the slurry surface is uneven during the pulping process, by comparing the cumulative capacitance values ​​detected by the two sub-overflow detection zones, an overflow signal closer to the actual overflow prevention detection position can be obtained, effectively preventing the overflow of slurry such as bubbles and foam during the pulping process. Therefore, compared to the existing technology, the overflow signal detection using the liquid heater of the present invention is more reliable and less likely to pose a safety risk of slurry overflow. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only embodiments of the present invention. Those skilled in the art can also derive other drawings based on the provided drawings without inventive effort.

[0037] The present invention will be further described below in conjunction with the accompanying drawings:

[0038] FIG1 is a schematic structural diagram of a liquid heater according to a first embodiment of the present invention;

[0039] FIG2 is a schematic diagram of the front surface structure of the PCB detection board in FIG1;

[0040] FIG3 is a schematic diagram of the rear surface structure of the PCB detection board in FIG1 ;

[0041] FIG4 is a topological circuit block diagram of the PCB detection board in FIG1 ;

[0042] FIG5 is a schematic structural diagram of a second embodiment of a PCB detection board according to the present invention. DETAILED DESCRIPTION

[0043] Prior art CN97225228.2 discloses a liquid level sensor component that can detect the position of the milk liquid level without contacting the milk. The solution particularly emphasizes that this liquid level sensor is suitable for all other non-metallic containers that require contactless (air-based) liquid level control, because conductive metal containers will interfere with the sensing of the liquid level sensor, affecting the detection effect of the actual liquid level. At the same time, prior art CN200920291175.7 also discloses an easy-to-clean soymilk machine, which is provided with a capacitor plate that can detect changes in the liquid state. The capacitor plate is a circular metal sheet, or multiple capacitor plates arranged around the machine head or cup body, and uses the capacitive sensing effect to achieve overflow prevention, dry burning prevention and water level detection. Compared with previous soymilk machines, since there is no need to drill holes in the lower cover of the machine head to install anti-overflow electrodes, it can not only reduce the hidden dangers of water entering the machine head, but also improve the convenience of cleaning the soymilk machine. However, the capacitor plates provided on the soymilk machine need to be arranged around the machine head or the cup body, the capacitor plates occupy a large space, and the installation is relatively complicated.

[0044] In order to further simplify the contactless (spaced) capacitance liquid level detection device, the prior art discloses a capacitive water level stepless detection device, comprising a capacitive slider formed by a number of equally spaced capacitance sensors, and the capacitive slider is connected to a chip via an induction line, and the chip is connected to a central processing unit via a signal line, and the central processing unit is connected to a water level display. During operation, under the control of the chip, the data detected by the capacitance sensor is transmitted to the central processing unit, and the central processing unit processes the received data and then delivers it to the water level display to display the current water level. This structure is simple and can achieve stepless detection of the water level. Moreover, this detection method is not affected by water temperature and can effectively avoid the parasitic characteristics caused by changes in the detection environment and other factors such as water temperature, which leads to the problem of inaccurate water level detection. The inventors have found that for this scheme, although the signal induction detection for water has higher accuracy, for the detection of water or other liquid substances in non-liquid shape, such as slurry substances such as bubbles, foam, and slurry, on the one hand, due to the slightly poor conductivity of the above-mentioned substances, the capacitance sensor senses a smaller change in capacitance value, and the chip cannot distinguish whether it is a liquid level signal or a parasitic capacitance. On the other hand, when the liquid produces bubbles, foam, slurry, especially slurry foam, there will be a thicker slurry layer above the liquid surface. Moreover, due to the presence of foam in the slurry layer, the slurry will be blocked from contacting the cup wall, resulting in a gap between the slurry and the cup wall, affecting the capacitance value sensed by the capacitive sensor. Moreover, the surface of the slurry layer is not flat. Generally, the slurry in the center of the cup body is higher, while the slurry in contact with the cup wall is lower. Even the height of the slurry in contact with different positions of the cup wall is different. The capacitive sensor may not be able to sense the specific capacitance value or the sensed capacitance value may be small. Therefore, the chip cannot identify the specific position of the liquid level, which is prone to overflow safety risks. Therefore, this solution is generally suitable for water level signal detection of health pots, etc.

[0045] At the same time, the prior art CN201610753199.4 also discloses an anti-overflow method and a food processor, wherein a PCB board is installed on the food processor, and metal sheets of the same size are equidistantly arranged on the PCB board. When the volume of the liquid level in the cup body gradually increases, the capacitance formed by the metal sheet and the liquid in the cup body will increase, thereby realizing the detection of the liquid level by using the metal sheet to detect the water level signal and the overflow signal. However, the anti-overflow detection position of this scheme is the highest fixed position located on the PCB board. During actual use, the metal sheet below the anti-overflow detection position can recognize the water level signal. However, based on the characteristics of slurry foam and slurry, the fixed anti-overflow detection position is greatly affected by external parasitic capacitance and cannot accurately identify the overflow signal of the slurry. At the same time, since the surface of the slurry is not flat, the fixed anti-overflow detection position may cause the detected anti-overflow position to deviate greatly from the actual slurry position, posing a safety risk of overflow.

[0046] In addition, the prior art CN201921962352.X also discloses a capacitive continuous liquid level detection structure and an electric kettle thereof, wherein the liquid level detection structure has two parallel-arranged sensing electrode sheets, and also discloses detecting the height of the water level by a duty cycle. In this scheme, the outer surface of the electric kettle body is an arc-shaped structure, so it is necessary to use a soft PFB board to be installed on the outer wall of the kettle body by gluing. Since there are two sensing electrode sheets on the PFB soft board, when the water level rises, the sensing electrode sheets arranged in an arc on the outer wall of the kettle body will show a change in capacitance value. The sensing part near the actual water level can also sense the change in capacitance value, and the water level calculated according to the duty cycle will have a significant deviation from the actual water level, which reduces the accuracy of the detection. Fortunately, for the electric kettle, the water level detection deviation is not serious and will not cause a safety risk. However, the inventors have found that this solution can only be used for water level detection in electric kettles, but cannot detect overflow signals, because the conductivity of bubbles and foam is reduced, and the sensitivity of the sensing electrode to bubbles and foam is reduced. Moreover, the unevenness of the surface of bubbles and foam will further increase the error of the arc-shaped PFB soft board detection. Based on this, this solution is not suitable for overflow signal detection and is prone to the safety risk of pulping overflow.

[0047] The following describes embodiments of the present application with reference to the accompanying drawings. The embodiments described below do not limit the invention as set forth in the claims. Furthermore, the entire contents of the configurations represented by the embodiments described below are not intended to be limiting as solutions to the invention as set forth in the claims.

[0048] Embodiment 1: As shown in Figures 1, 2, 3 and 4, it is a schematic structural diagram of a liquid heater of the present invention. The liquid heater is a food processing machine for making soy milk beverages, comprising a glass cup body 1 forming a pulping container 10 and a cup cover 2 mounted on the glass cup body 1. A heating device 4 for heating the pulping container 10 is provided at the bottom of the glass cup body 1, and a motor 3 is provided in the mounting cavity 20 below the glass cup body 1. A rotating shaft driven by the motor 3 passes through the bottom of the glass cup body 1 and extends into the pulping container 10, and a crushing device is connected to the end of the rotating shaft. A PCB detection board 5 for liquid level detection is installed on the outer side of the side wall of the glass cup body 1. The PCB detection board 5 is installed between the glass cup body 1 and the handle, and a main control device (not shown in the figure) is also provided in the mounting cavity 20 below the glass cup body 1. The main control device is electrically connected to the motor 3, the heating device 4 and the PCB detection board 5 respectively.

[0049] The PCB detection board 5 includes a strip-shaped substrate 51, a capacitor electrode mounted on the substrate, a control chip 52, and an output terminal 53. The capacitor electrode is electrically connected to the control chip 52, and the control chip 52 is connected to the main control device via the output terminal 53. The capacitor electrode includes a plurality of first capacitor electrodes 54a and a plurality of second capacitor electrodes 54b arranged at intervals. The plurality of first capacitor electrodes 54a form a water level detection area 55a (dashed box below the W plane) on the substrate 51, and the plurality of second capacitor electrodes 54b form an anti-overflow detection area 55b (dashed box above the W plane) on the substrate 51. The anti-overflow detection area 55b is located above the water level detection area 55a. Among them, different first capacitor electrodes 54a correspond to different pulping capacity water levels in the water level detection area 55a, and different second capacitor electrodes 54b correspond to different anti-overflow detection positions in the anti-overflow detection area 55b. Moreover, for each pulping capacity water level in the water level detection area 55a, there is a corresponding second capacitor electrode 54b in the anti-overflow detection area 55b to detect the anti-overflow detection position. In addition, the multiple first capacitor electrodes 54a and the multiple second capacitor electrodes 54b are electrically connected to the control chip 52 one by one via printed circuits (not shown) on the substrate 51. Along the height direction of the substrate 51, the detection height of a single first capacitor electrode 54a is smaller than the detection height of a single second capacitor electrode 54b.

[0050] 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, that is, the surface of the substrate 51 facing the glass cup body 1, while the control chip 52 and the output terminal 53 are arranged on the rear surface of the substrate 51, and the control chip 52 and the output terminal 53 are both located below the water level detection area 55. At the same time, a grid shielding layer is also attached to the substrate 51, and the grid shielding layer is grounded. The grid shielding layer 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 is enclosed along the edge of the substrate 51 to the outside of the water level detection area 55a and the anti-overflow detection area 55b, and the lower side of the second shielding layer 57b is open 571. In this embodiment, the grid shielding layer is a copper-clad grid used to shield the inductive interference of external parasitic capacitance on the capacitor electrode. In this embodiment, the printed circuit is attached to the rear surface of the substrate 51, and the input end passes through the substrate 51 and is electrically connected to each capacitor electrode. The output end of the printed circuit is routed along the outer edge of the grid shielding layer, wherein the output end 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.

[0051] Furthermore, in this embodiment, a dividing groove 58 is provided on the overflow detection area 55b of the substrate 51, and 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-electrode plates located in two columns of sub-overflow detection areas, and each sub-electrode plate in the two columns of sub-overflow detection areas is electrically connected to the control chip 52 one by one via printed circuits. Specifically, 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 is tilted along the diagonal of the overflow detection area 55b to divide the overflow detection area 55b into two triangular sub-overflow detection areas of equal area. However, except for the topmost point, the sensing area of ​​the first sub-overflow detection area at any other height is not equal to the sensing area of ​​the second sub-overflow detection area.

[0052] In the prior art, the capacitor electrode detects water level and overflow signals by utilizing the principle of air-space induction. When the capacitor electrode is close to the liquid, a capacitance value is sensed, and the control chip indirectly determines the water level signal and overflow signal based on the fluctuation of the capacitance value. The inventors have found through continuous research that the capacitance value of the capacitor electrode sensing the liquid signal has a large range of variation. When the capacitor electrode is close to the liquid, the capacitance value fluctuates greatly, while when it is farther away, the capacitance value fluctuates less. At the same time, the fluctuation of the capacitance value generated by the capacitor electrode is also related to the liquid form and conductivity. When the liquid is pure liquid and has strong conductivity, the fluctuation of the capacitance value sensed is large, which can achieve accurate detection of the liquid level. When the liquid is in the form of bubbles or foam, the capacitance value sensed is relatively small due to the reduced conductivity. It is precisely because when the liquid is in the form of bubbles or foam, the capacitance value sensed by the capacitor electrode fluctuates less, and the control chip cannot determine whether it is a liquid level signal. Moreover, the capacitance change produced by the capacitor electrode will also be affected by environmental factors, which can easily form parasitic capacitance, and parasitic capacitance will also cause the capacitor electrode to sense smaller capacitance fluctuations, and the control chip may also misjudge. For example, when a person's hand is close to the capacitor electrode, capacitance fluctuations will also occur. At this time, the control chip cannot distinguish whether it is an interference capacitance value or an actual liquid level capacitance value. For another example, water droplets on the outer wall of the pulping container will also cause the capacitor electrode to sense the fluctuation of capacitance value, and the control chip may misjudge. In addition, although the existing capacitor electrode can be used to detect both water level signals and overflow signals, for slurries formed by bubbles, foam, etc., due to the uneven surface of the slurry, the existing fixed anti-overflow capacitor electrode is not accurate in identifying the actual slurry height, and it is more likely to cause slurry overflow.

[0053] For the food processing machine of this embodiment, a water level detection area and an overflow prevention detection area are provided on the PCB detection board, which are respectively arranged in an interval of multiple first capacitor electrodes and multiple second capacitor electrodes. This can realize water level detection of various different pulping capacities, and can also realize detection of different overflow signals corresponding to various different pulping capacities. Compared with the existing overflow prevention detection position with only one fixed position, the food processing machine of this embodiment can realize more intelligent production of slurry beverages and higher pulping efficiency. While ensuring the production of one or more servings of beverages, it can also solve the problems of the existing technology with only one fixed overflow prevention detection position, which is prone to failure, excessive overflow prevention time, and pulp foam sticking to the wall. In addition, this embodiment uses different overflow prevention detection positions corresponding to different pulping capacities, which not only ensures that the problem of slurry overflow does not occur, but also improves the space utilization rate of the pulping container, can achieve optimization of pulping efficiency, and avoid problems such as excessive pulping time or poor crushing. In this application, the water level signal refers to the surface of the water in the pulping container, and the overflow signal refers to the surface of the pulp foam or foam in the pulping container.

[0054] Among them, the first capacitor electrode in the water level detection area is used to detect the pulping water level under the corresponding pulping capacity, while the second capacitor electrode in the anti-overflow detection area is used to detect the height of the slurry under the corresponding pulping capacity during the pulping process. When the second capacitor electrode detects that the slurry of the current pulping capacity has reached the preset anti-overflow detection position, the control chip will transmit the signal to the main control device, and the main control device will perform corresponding operations according to the program settings, such as stopping the motor and stopping the heating. However, during the pulping process, when the slurry is whipped or heated, bubbles, foam and other substances will rise on the surface of the slurry. The capacitance value of the capacitor electrode sensing bubbles and foam fluctuates slightly, and the control chip cannot accurately distinguish whether it is parasitic capacitance or actual overflow signal. For the food processing machine of this embodiment, since the detection height of a single second capacitor electrode is greater than the detection height of a single first capacitor electrode (that is, the sensing area of ​​a single second capacitor electrode is greater than the sensing area of ​​a single first capacitor electrode), the second capacitor electrode has a larger sensing area during actual detection, and can obtain a larger fluctuating capacitance value, thereby achieving more accurate overflow signal detection. Compared with the prior art, it can detect overflow signals such as rising bubbles and foam, effectively solving the problem that the existing single type of capacitor electrode can only detect the water level more accurately but cannot effectively detect the overflow signal, and greatly reducing the safety risk of overflow of slurries such as bubbles and foam during the application of the existing capacitive overflow prevention detection technology. It can be understood that the "detection height" of the capacitor electrode in this application refers to the detection range in the height direction. For a single capacitor electrode, the larger its size in the height direction, the larger the detection height of the capacitor electrode.

[0055] Since the non-contact (air-gated) PCB detection board is attached to the outside of the glass, and considering that the non-contact (air-gated) PCB detection board detects and judges the liquid level signal by detecting the change in capacitance value, there will be water flow during the user's use, the user touches the installation structure position of the PCB detection board, etc., which will cause the capacitance value of the capacitor electrode on the PCB detection board to change, leading to abnormal liquid level detection, overflow in the pulping process, and other risks. In this embodiment, the three-sided copper shielding of the water level detection area and the anti-overflow detection area on the substrate of the PCB detection board and the grid copper shielding on the rear surface of the substrate can eliminate the influence of external inductive interference on the capacitor electrode to the greatest extent, effectively solve the abnormal capacitance value fluctuation caused by the presence of condensed water on the side of the PCB detection board after assembly or the user's touch, resulting in abnormal detection results, and ensure detection reliability.

[0056] It should be noted that the pulping container in this embodiment is in the shape of a straight barrel, and the PCB detection board can be used for detecting both water level signals and overflow signals, and the substrate of the PCB detection board is a hard board. The PCB detection board is arranged vertically on the outer wall of the pulping container, which can effectively prevent the arc structure of the pulping container from causing the capacitor electrode to sense non-required capacitance values. In this embodiment, the minimum pulping capacity water level is not lower than the lower limit of the lowest first capacitor electrode, so as to ensure that at least one capacitor electrode detects the water level signal. The maximum pulping capacity water level is not higher than the lower limit of the lowest second capacitor electrode. Similarly, the minimum anti-overflow detection position is not lower than the lowest second capacitor electrode, so that the second capacitor electrode can sense the overflow signal, and the maximum anti-overflow detection position corresponding to the maximum pulping capacity water level should be lower than the lower limit of the highest second capacitor electrode, so that the highest second capacitor electrode can serve as the last auxiliary anti-overflow safety detection.

[0057] In this embodiment, the first capacitor electrodes 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 Corresponding water level and minimum pulping capacity V L The height difference between the corresponding water levels has the following relationship: Where r is the radius of the pulping container, n is the number of first capacitor electrodes, Δh is the spacing between adjacent first capacitor electrodes, and h n is the detection height of a single first capacitor electrode. It can be seen that for the first capacitor electrode of this embodiment, In this embodiment, n first capacitor electrodes are provided in the water level detection area, that is, the water level detection area has n different pulping capacities.

[0058] Moreover, in this embodiment, the second capacitor electrodes on the anti-overflow detection area are also arranged at equal intervals of Δh, wherein the spacing between the highest first capacitor electrode and the lowest second capacitor electrode is also Δh. At the same time, in this embodiment, for n different pulping capacities, the anti-overflow detection area has corresponding anti-overflow detection positions, wherein the anti-overflow detection positions are set to N. At the same time, in order to increase the safety of anti-overflow detection, a second capacitor electrode needs to be added to the substrate to be used as an anti-overflow detection position. Based on this, the number of second capacitor electrodes in the anti-overflow detection area is N+1, and the first N second capacitor electrodes correspond to N anti-overflow detection positions, and the N anti-overflow detection positions correspond to n different pulping capacities. Set H m is the detection height of the PCB detection board, that is, the sum of the heights of the water level detection area and the overflow prevention detection area. Among them, the height of the overflow prevention detection area satisfies H=H m -h=(N+1)h N +NΔh,h N is the detection height of a single second capacitor electrode, that is, And N and n satisfy: Both N and n are integers.

[0059] Generally, the detection height h of a single first capacitor electrode is n The detection height h of a single second capacitor electrode is selected to be 3mm to 6mm. N Generally, it is not less than 2 times the detection height of a single first capacitor electrode, which is generally selected to be 8mm to 12mm. In this embodiment, h is preferably n 4mm~5mm, h N is 10mm.

[0060] It should be noted that the capacitor electrode at the highest point of the overflow prevention detection area is used to assist in the detection of dangerous overflow signals, which can effectively prevent the overflow safety risk caused by the failure of the highest overflow prevention detection position corresponding to the maximum pulping capacity, and is the last safety guarantee to prevent slurry overflow. Therefore, for this embodiment, a third capacitor electrode can be separately set on the substrate above the overflow prevention detection area to serve as the auxiliary dangerous overflow signal detection. At this time, the number of second capacitor electrodes is the same as the number of overflow prevention detection positions, both of which are N, and the detection height of a single second capacitor electrode meets

[0061] As shown in Figure 4, be the circuit layout topology diagram of present embodiment PCB test board, contactless (spaced) PCB test board comprises control section and electrode portion (capacitor electrode piece), electrode portion configures multi-section capacitor electrode piece and is connected one by one with control MCU (control chip) respectively, the device of control section is placed on the other side of substrate relative capacitor electrode piece, the bottom of control section is provided with interface module (output terminal), the terminal of interface module adopts patch mode, control MCU is set on interface section top, reset circuit module, power circuit module, output circuit module and burning port are respectively configured on the both sides of control MCU.Wherein, control MCU has rewritable storage module, can repeatedly update control program to storage module by burning port, can realize the renewal of control program.For present embodiment, by PCB test board topology structure setting, ensure the reliability of control system, simultaneously, the setting of interface position ensures that installation position is minimized, reduces the cost of PCB test board when promoting reliability.In addition, capacitor electrode piece and other device partitions are arranged, are conducive to promoting anti-interference ability, ensure reliability.

[0062] The PCB detection board of this embodiment uses different detection and control methods for different pulping stages. Specifically, during the beverage production process of the food processor of this embodiment, the PCB detection board has a water level detection stage for detecting user-added water or automatic water inflow, and a spill prevention detection stage for monitoring the pulping process.

[0063] 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, and determines whether the user has placed the material to the preset water level. During the real-time detection process, at a certain moment, only one of the multiple first capacitor electrodes is in the sensing state, and the other first capacitor electrodes are grounded, so that it can be ensured that only one first capacitor electrode can generate a capacitance value at each moment, so as not to be affected by the induction of other first capacitor electrodes. The PCB detection board detects the capacitance value change process of each first capacitor electrode from bottom to top. When it is detected that the capacitance value of the first capacitor electrode is in an obvious change process in turn, it is judged to be a material placement process. When the capacitance value of the adjacent first capacitor electrode below a certain first capacitor electrode (that is, the first capacitor electrode detected before the said first capacitor electrode) does not change, the control chip confirms that the current water level is in the water level range corresponding to the capacitor electrode. When it is detected that the capacitance value of the first capacitor plate has not changed significantly, it is determined that the user has completed placing the material, and then the power is turned on to detect the change in the capacitance value difference between adjacent first capacitor plates. When there is a significant change in the capacitance value difference between two adjacent first capacitor plates, the control chip determines that the current water level is in the water level range corresponding to the first capacitor plate located above the two adjacent first capacitor plates.

[0064] As shown in the PCB detection board in Figure 2, the control chip detects the capacitance value of each first capacitor electrode in a cycle at a set time interval t0. The control chip calculates the capacitance difference ΔC between adjacent first capacitor electrodes based on the capacitance value of each first capacitor electrode. Ln-L(n-1) , and confirm that the current water level is in the water level range corresponding to the first capacitor electrode located above between adjacent first capacitor electrodes corresponding to the maximum capacitance difference.

[0065] For example, at time point T1-n*t0 (n is the number of first capacitor plates), the control chip detects that the capacitance value of the first capacitor plate L1 has changed significantly; as the detection time approaches T1, the control chip detects that the capacitance value difference between the first capacitor plate L2 and the first capacitor plate L1 continues to increase, while the capacitance value difference of other first capacitor plates remains basically unchanged. Therefore, the control chip determines that the capacitance value difference ΔC between the first capacitor plate L2 and the first capacitor plate L1 is L2-L1 At maximum, the control chip confirms that the current water level is within the water level range corresponding to the first capacitor electrode L2.

[0066] For existing non-contact (air-to-water) water level detection, water level detection is basically performed by measuring the capacitance change of a single capacitor electrode. Since the capacitor electrode is discontinuous, the temperature difference between the electrodes is significant, and the capacitance of the capacitor electrode is greatly affected by the slurry temperature and the ambient temperature. Therefore, it is easy to cause misjudgment and increase the probability of water level detection failure. In this embodiment, the control chip dynamically tracks and detects the capacitance difference between two adjacent segmented first capacitor electrodes, and determines the maximum capacitance difference as the current water level position, effectively solving the problem of water level misjudgment. Similarly, this water level detection method can also be applied to overflow signal detection. However, due to the foam characteristics of the slurry, the detection effectiveness of this detection method is slightly poor.

[0067] For this embodiment, the detection of water level signals also includes other detection methods, such as detection based on the capacitance fluctuation amount sensed by a single first capacitor electrode. The control chip still detects the capacitance value of each segmented first capacitor electrode in a cycle within the set time, and at any time, only one capacitor electrode is powered on for detection, while the other capacitor electrodes are in a grounded state. When the capacitance fluctuation amount sensed by a first capacitor electrode is greater than the fluctuation threshold value preset by the control chip, the control chip determines that the water level has reached the pulping water level corresponding to the first capacitor electrode. Otherwise, each segmented capacitor electrode still performs cycle detection.

[0068] For the PCB detection board of this embodiment, the above two water level signal detection methods are compatible. When any of the above methods obtains the current water level signal, the control chip will feed the signal back to the main control device. The main control device determines the corresponding pulping program according to the corresponding water level signal to realize the subsequent slurry production. Of course, for the above methods, when one of the detection methods obtains the water level signal, the other detection method can also be re-checked. By detecting the double water level signal, the water level signal detection can be more accurate and prevent the influence of external parasitic capacitance. For example, when the control chip confirms that the current water level corresponds to the first capacitor electrode L, during the water level recheck detection, the control chip determines whether the capacitance value fluctuation amount greater than the preset fluctuation amount threshold is the first capacitor electrode L based on the capacitance value fluctuation amount sensed by the single first capacitor electrode. When it is determined that it is the first capacitor electrode L, the detection is confirmed to be accurate. When it is determined that it is not the first capacitor electrode L, the control chip will again perform a cyclic detection based on the capacitance difference between the two adjacent first capacitor electrodes until the current water level signal is finally confirmed.

[0069] After the water level detection stage is completed, the slurry production process begins. At the same time, during the slurry production process, the PCB detection board also needs to perform overflow signal detection in the anti-overflow detection stage.

[0070] Overflow prevention detection: For this embodiment, the overflow prevention detection area is rectangular, including multiple second capacitor electrodes, and a dividing groove is provided on the overflow prevention detection area along the diagonal of the rectangle. The dividing groove divides the overflow prevention detection area into two triangular sub-overflow detection areas. At the same time, at the same liquid level height, the sensing areas corresponding to the two sub-overflow detection areas are different.

[0071] As shown in Figure 2, the overflow detection area is divided into two triangle-shaped columns, the first sub-overflow detection area tri1 and the second sub-overflow detection area tri2, with the tip of tri1 facing upward and the tip of tri2 facing downward. Tri1 and tri2 each include multiple sub-electrode pieces. Similarly, when the overflow signal is detected at a certain moment, the control chip detects the capacitance value of each sub-electrode piece in the left and right triangular areas in turn at a set time interval t0, and accumulates the increment of the capacitance value sensed by each sub-electrode piece of tri1 to obtain ΔC tri1 , and the increments of the capacitance values ​​sensed by each sub-electrode of tri2 are accumulated to obtain ΔC tri2 The control chip then calculates the ratio of the accumulated capacitance increments on both sides. Determines the current height of the foam.

[0072] At the same time, during the pulping process, the foam on the surface of the slurry is not flat, and some areas are higher and some areas are lower. Therefore, during the overflow detection process, the capacitance values ​​sensed by the sub-electrodes of tri1 and tri2 jump. In addition, the structures of different liquid heaters are different, and the installation methods of the PCB detection board relative to the pulping container are also different. Based on this, the ratio Corresponding corrections need to be made, namely (η is the correction coefficient, and liquid heaters with different structures have corresponding correction coefficients).

[0073] At the same time, the control chip is also preset with K0, wherein the preset value K0 is the area ratio of the first sub-overflow detection zone to the second sub-overflow detection zone at the same height (it can be understood that the height is below the top of the overflow detection zone, and the area ratio is the ratio of the area of ​​the first sub-overflow detection zone below the height to the area of ​​the second sub-overflow detection zone below the height). When K is close to or equal to K0, the control chip confirms the current height reached by the foam, and the control chip then feeds back the overflow signal to the main control device to implement corresponding program operations, such as motor stop or heating stop, etc., thereby effectively preventing the safety risk of foam overflow. Of course, for this embodiment, the control chip can also preset the total height H of the overflow detection zone. 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 height of the foam based on the ratio of K to H. Of course, different liquid heaters have different correction coefficients η,

[0074] Since the existing non-contact (air-to-air) liquid level detection basically uses the change in the capacitance value of a single electrode to detect overflow liquid level, there will be a thicker slurry layer above the liquid surface during slurrying, and the presence of foam in the slurry layer will prevent the slurry from contacting the cup wall, resulting in a distance gap between the slurry and the cup wall, which will affect the capacitance value sensed by a single electrode. Moreover, the surface of the slurry layer is not flat, and the slurry in the center area of ​​the slurrying container is not the same height as the slurry on the cup wall. Even the height of the slurry at different positions on the cup wall is different. A single electrode can only sense a certain value, and this certain value does not necessarily reflect the current slurry height. For example, when there are large bubbles in the middle layer of the slurry, the slurry in the lower layer of the bubbles and the slurry in the upper layer of the bubbles will be sensed by a single electrode. However, a single electrode can only sense a maximum capacitance value. Based on this, a single electrode has no way to convey to the control chip the presence of slurry in the upper layer of the bubbles, causing the control chip to be unable to recognize the slurry overflow signal in the upper layer of the bubbles. At the same time, the change in capacitance sensed by a single electrode will also be affected by the slurry temperature, ambient temperature, etc., and it is impossible to accurately detect the anti-overflow position. There is a problem of large detection deviation. Therefore, during the slurrying process, it is easy to misjudge the anti-overflow and cause the anti-overflow failure and slurry overflow. The inventor found through research that by using multiple capacitor electrodes to be spaced apart, using each capacitor electrode to sense the capacitance value of different positions respectively, and then using the capacitance value increment ratio of the two triangles to be equivalent to the area ratio of the two triangles covered by slurry foam, according to this principle, the detected anti-overflow level can be closer to the set anti-overflow level, thereby greatly reducing the probability of slurry overflow and improving the safety risk of anti-overflow.

[0075] The above-mentioned anti-overflow detection method can make the anti-overflow detection position detected by the PCB detection board closer to the actual anti-overflow position, which can effectively prevent the occurrence of overflow. Of course, for this embodiment, a single second capacitor electrode is actually formed by a sub-electrode corresponding to the first sub-anti-overflow detection area and a sub-electrode corresponding to the second anti-overflow detection area. Therefore, the water level detection method can also be used to determine the capacitance value of the corresponding second capacitor electrode by accumulating the capacitance values ​​sensed by the two sub-electrodes. The control chip then determines the current anti-overflow detection position based on whether the capacitance difference between the two adjacent second capacitor electrodes is the largest. It should be noted that for these two overflow signal detection methods, only one of the two can be selected, and both cannot be applied to the detection of overflow signals at the same time. Among them, for this embodiment, the anti-overflow detection position is determined more accurately by comparing the accumulated capacitance values ​​sensed by the left and right triangles, which is closer to the actual anti-overflow position reached by the slurry, and this scheme is also the preferred scheme of this embodiment.

[0076] In addition, it should be noted that in this embodiment, the dividing groove divides the overflow detection area into two triangular sub-overflow detection areas, so that the sensing areas of the two sub-overflow detection areas at the same liquid level are unequal. It is precisely based on the unequal sensing areas that different overflow prevention heights can be determined according to different ratios. Therefore, for this embodiment, the dividing groove is not limited to dividing the overflow detection area into two equal triangles, but can also divide the overflow detection area into two equal trapezoids. Similarly, the dividing groove is not limited to a straight dividing groove set obliquely relative to the substrate, but can also be a curved dividing groove. For example, the overflow detection area can be divided according to the Tai Chi curve to divide the overflow detection area into a Tai Chi shape.

[0077] It should also be noted that during the water level detection process, the control chip cyclically detects the capacitance value of each first capacitor electrode in a set time sequence, and at any time, only one first capacitor electrode is powered on for detection, while the other first capacitor electrodes are set to ground. Alternatively, during the overflow prevention detection process, the control chip cyclically detects the capacitance value of each second capacitor electrode in a set time sequence, and at any time, only one second capacitor electrode is powered on for detection, while the other second capacitor electrodes are set to ground. This can effectively avoid confusion in capacitance value detection and the influence of external parasitic capacitance on the actual detection signal.

[0078] It should also be noted that, for this embodiment, the pulping container generally requires that at least the mounting area where the PCB detection board is mounted be made of a non-conductive material, such as a pulping container surrounded by an all-glass or all-plastic cup, a pulping container formed by a glass cup with a through bottom and a heating plate, or a pulping container formed by a metal cup and a non-metallic transparent window, with the PCB detection board mounted on the transparent window. Generally speaking, this is to prevent the conductive pulping container from interfering with the detection of the capacitor electrode on the PCB detection board, thereby affecting the actual detected capacitance value change. Furthermore, in this embodiment, the general water level detection area is configured to detect only the water level signal, not the overflow signal, while the anti-overflow detection area is generally configured to detect only the overflow signal, not the water level signal. Of course, for this embodiment, the several second capacitor electrodes in the lower portion of the overflow prevention detection zone can also be used to detect water level signals, while the several second capacitor electrodes in the upper portion of the overflow prevention detection zone are used to detect overflow signals. That is, the maximum pulping capacity of the pulping container is higher than the several second capacitor electrodes in the lower portion of the overflow prevention detection zone, but will not exceed the highest second capacitor electrode, thereby achieving ultra-high water level pulping in the pulping container. Similarly, based on the same principle, the several first capacitor electrodes in the upper portion of the water level detection zone can also be used for ultra-low water level overflow prevention detection. As long as the control chip is programmed accordingly, this can be achieved.

[0079] It should be noted that the structural changes and parameter selections described above for this embodiment are also applicable to other embodiments of the present invention. The present invention also provides a liquid level detection method for the above-mentioned liquid heater. The features of the liquid level detection method correspond to the features of the liquid heater, and can be found in the above-mentioned embodiment, and will not be repeated here.

[0080] Example 2: As shown in Figure 5, this is a schematic diagram of the structure of the PCB detection board of the second embodiment of the present invention. The difference between this embodiment and Example 1 is that there is no dividing groove on the PCB detection board in this embodiment, and each second capacitor electrode 54b on the overflow prevention detection area 55b is a complete capacitor electrode. Similar to Example 1, the water level detection area 55a in this embodiment is formed by a plurality of first capacitor electrodes 54a arranged at equal intervals, and the overflow prevention detection area 55b is formed by a plurality of second capacitor electrodes 54b arranged at equal intervals. In addition, the detection height of a single second capacitor electrode 54b is greater than the detection height of a single first capacitor electrode 54a (the sensing area of ​​a single second capacitor electrode is greater than the sensing area of ​​a single first capacitor electrode).

[0081] For this embodiment, the pulping process of the food processor also includes a water level detection stage and an anti-overflow detection stage. In the water level detection stage, the control chip is still used to calculate the capacitance difference ΔC between adjacent capacitor electrodes based on the capacitance value of each capacitor electrode. Ln-L(n-1) , and confirm that the current water level is in the water level range corresponding to the upper capacitor electrode between the adjacent capacitor electrodes corresponding to the maximum capacitance difference. The main control device determines the corresponding pulping program based on the water level signal fed back by the control chip, that is, different water levels correspond to different pulping processes, so that different water levels have different anti-overflow detection positions for pulping, and the pulp beverage is produced efficiently. At the same time, multiple different anti-overflow detection positions also ensure the safety of pulping and effectively prevent the pulp from overflowing. At the same time, during the pulping process, in the anti-overflow detection stage, the control chip will determine the current anti-overflow detection position based on the maximum capacitance difference between the two adjacent second capacitor electrodes, and then perform corresponding program operations based on the relationship between the current anti-overflow detection position and the anti-overflow detection position set by the program, on the one hand, ensuring the detection of the overflow signal, and on the other hand, ensuring that the safety risk of overflow will not occur during the pulping process. Similar to the first embodiment, in this embodiment, since the detection height of the second capacitor electrode is significantly greater than the detection height of the first capacitor electrode, a larger capacitance value can be sensed for slurry bubbles, foam, etc., thereby achieving more accurate detection of the overflow signal and preventing the misjudgment or failure to identify the overflow signal, which may cause safety risks.

[0082] It should be noted that, for this embodiment, the water level detection stage and the anti-overflow detection stage can also be used as needed to determine the water level and / or overflow signal by using a control chip based on the capacitance fluctuation of a single capacitor electrode. The present invention also provides a liquid level detection method for the above-mentioned liquid heater. The characteristics of the liquid level detection method correspond to the characteristics of the liquid heater. Please refer to the above-mentioned embodiment and will not be repeated here. In addition, it should be noted that the liquid heater of the present invention is not limited to the food processor with an integrated motor and cup body disclosed in the embodiment of the present invention, but can also be a soymilk machine with an upper motor, a wall breaking machine with a separate cup body and a machine base, and a food processor that can realize automatic pulp discharge and automatic cleaning without hand washing. Moreover, the liquid heater of the present invention can also be applied to heating appliances that can perform pulp boiling operations, rice paste making, etc., such as health pots, health pots, etc.

[0083] Those skilled in the art should understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. A liquid heater with air-proof overflow detection, comprising a glass cup body forming a pulping container, and a PCB detection board installed on the outer wall of the pulping container for detecting the liquid level height, characterized in that: The PCB detection board is provided with a water level detection area for detecting water and an anti-overflow detection area for detecting foam. The anti-overflow detection area is located above the water level detection area. The water level detection area is used for water level detection of different pulping capacities, and the anti-overflow detection area is used for detecting different overflow signals corresponding to different pulping capacities. The water level detection area has a plurality of first capacitor electrodes for detecting water level signals, and the anti-overflow detection area has a plurality of second capacitor electrodes for detecting overflow signals. The anti-overflow detection area includes a first sub-anti-overflow detection area and a second sub-anti-overflow detection area which are arranged side by side and divided by a dividing groove. Each of the second capacitor electrodes is divided by a dividing groove into two sub-electrode plates respectively located in the first sub-anti-overflow detection area and the second sub-anti-overflow detection area. The PCB detection board is also provided with a control chip which is electrically connected to the first capacitor electrode and each of the sub-electrode plates.

2. The liquid heater according to claim 1, characterized in that: The inductive area of ​​each second capacitor electrode is larger than the inductive area of ​​each first capacitor electrode.

3. The liquid heater according to claim 1, characterized in that: The dividing groove is a straight dividing groove arranged obliquely relative to the PCB detection board.

4. The liquid heater according to claim 1, characterized in that: Below the same height, the sensing area of ​​the first sub-overflow prevention detection zone is not equal to the sensing area of ​​the second sub-overflow prevention detection zone.

5. The liquid heater according to claim 1, characterized in that: The first capacitor electrode and the second capacitor electrode are arranged on the front surface of the PCB detection board. A grid shielding layer is also arranged on the PCB detection board. The grid shielding layer includes a first shielding layer attached to the rear surface of the PCB detection board and a second shielding layer attached to the front surface of the PCB detection board, and the second shielding layer is enclosed on the outside of the first capacitor electrode and the second capacitor electrode along the edge of the PCB detection board.

6. The liquid heater according to claim 1, characterized in that: The control chip is used to detect the capacitance value of each of the first capacitor electrodes in turn and cyclically at a set time interval during the water level detection process, and at any time, only one of the first capacitor electrodes is powered on for detection, and the other first capacitor electrodes are set to be grounded; Alternatively, the control chip is used to cyclically detect the capacitance value of each second capacitor electrode in sequence at a set time interval during the water level detection process, and at any time, only one second capacitor electrode is powered on for detection, and the remaining second capacitor electrodes are set to ground.

7. The liquid heater according to claim 1, characterized in that: During the anti-overflow detection process of the PCB detection board, the control chip obtains the cumulative value ΔC of the capacitance value increment detected by each sub-electrode piece in the first sub-overflow detection area. tri1 and the cumulative value ΔC of the capacitance increment detected by each sub-electrode piece in the second sub-overflow prevention detection area tri2 , and according to ΔC tri1 With ΔC tri2 The ratio of determines the current height of the foam.

8. The liquid heater according to claim 7, characterized in that: The control chip is preset with an area ratio K0 of the first sub-overflow detection area and the second sub-overflow detection area below the same height. During the overflow detection process, the control chip is used to calculate the incremental ratio K of the capacitance value of the first sub-overflow detection area and the second sub-overflow detection area. The control chip determines the current height of the foam according to the relationship between K and K0; Alternatively, the control chip is preset with a total height H of the anti-overflow detection area. During the anti-overflow detection process, the control chip is used to calculate the incremental ratio K of the capacitance values ​​of the first sub-anti-overflow detection area and the second sub-anti-overflow detection area, and determine the current height of the foam based on the ratio of K to H.

9. The liquid heater according to claim 8, characterized in that: The control chip is used to correct the calculated K value according to the liquid heaters with different structures. η is the correction coefficient.

10. The liquid heater according to claim 1, characterized in that: The first capacitor electrodes are arranged equidistantly in the water level detection area, and the detection height of each first capacitor electrode is Among them, V L is the minimum pulping capacity of the pulping container, V H is the maximum pulping capacity, and at least a portion of the pulping container located between the minimum pulping capacity and the maximum pulping capacity is a cylindrical structure, r is the radius of the cylindrical structure, n is the number of the first capacitor electrodes, and Δh is the spacing between adjacent first capacitor electrodes.

11. The liquid heater according to claim 10, characterized in that: The second capacitor electrodes are arranged equidistantly in the anti-overflow detection area, and the detection height of each second capacitor electrode is Among them, H m is the height difference between the lowermost end of the water level detection area and the uppermost end of the overflow prevention detection area, N is the number of overflow prevention detection positions corresponding to different pulping capacities, and Δh is the spacing between adjacent second capacitor electrodes, which is equal to the spacing between adjacent first capacitor electrodes, wherein, N and n are integers.

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