Water level switch inspection device and water level switch inspection method

Abstract

The invention discloses a water level switch inspection method, belongs to the field of pressure testing, and solves the problem of easy misjudgment in inspection in the prior art, the technical scheme is that the water level is controlled by detecting air pressure change caused by water level change, the water level switch inspection method comprises the following steps: first water pressure verification: setting the verification water pressure to be 0; after the actual water pressure in the target container is set to be 0, the actual water pressure of the target container is obtained, if the difference value between the actual water pressure and the target value does not exceed the first threshold value, it is judged that the water level switch meets the requirement, and otherwise, it is judged that the water level switch is abnormal; checking the water pressure for the second time: setting the checking water pressure as a target value which is greater than zero, setting the actual water pressure in the target container through the water level switch, checking, obtaining the actual water pressure in the target container, judging that the water level switch meets the requirement if the difference value between the actual water pressure and the target value does not exceed a second threshold value, and otherwise, judging that the water level switch is abnormal. According to the invention, misjudgment is effectively reduced. The invention further discloses a water level switch inspection device.

Description

Technical Field

[0001] The present invention relates to the field of pressure testing, and in particular to a water level switch inspection device and a water level switch inspection method. Background Art

[0002] Water level switches are primarily used for water level control in devices such as washing machines, dishwashers, and toilets. To ensure that these devices operate within the required water level range, existing methods and devices for checking water level switches exist. For example, prior art water level switch inspection methods, such as those disclosed in patent CN118010136A, trigger a calibration process using a startup signal to obtain a calibration signal, thereby obtaining a first validity parameter. Simultaneously, flow rate parameters and water level change parameters are obtained within a target period after startup. The flow rate parameters and water level change parameters are compared and calculated to obtain a second validity parameter. The second validity parameter is then determined to determine whether the water level difference exceeds a first threshold. If the water level difference exceeds the first threshold, a fault is determined in the water level sensor. However, these methods lack a check in the no-water-pressure state, a fundamental operating state for the device. Without this check, the normal operation of the water level switch under basic conditions cannot be guaranteed, potentially leading to more false positive or false negative results in tests under pressure. This means that it is possible to judge a device that actually has problems as normal, or conversely, to mistakenly mark a normal device as abnormal. On the other hand, when a pneumatic water level switch is used to monitor the device, as the water level of the device rises, the air space becomes smaller and smaller, and the reduction in air volume also becomes smaller, resulting in a decrease in the rate of change of air pressure. The error in the inspection of the water level switch is larger, and the comparison file always uses the same threshold at different water levels, which can easily cause a normal water level switch to be mistakenly judged as defective.

[0003] Secondly, prior art water level switch inspection devices, such as invention patent CN101290257A, disclose a water level pressure switch production and inspection device and method. These devices employ an air inlet solenoid valve installed on the pipe connecting the buffer airbag and the compressed air pump, while an air outlet solenoid valve for emptying the buffer airbag is also connected to the buffer airbag. A flexible hose is fixedly connected to the buffer airbag at one end, while the other end is connected to the water level switch. A pressure sensor is connected to the buffer airbag and connected to the analog input port of the input / output circuit board. The high and low water level switch contacts of the pressure sensor are connected to the digital input port of the input / output circuit board. The digital output port of the input / output circuit board is connected to the compressed air pump and the air inlet and air outlet solenoid valves, respectively. The input / output circuit board is installed in a computer. However, the analog air pressure of the buffer airbag can produce errors and instabilities, thereby affecting the inspection accuracy of the water level switch. Summary of the Invention

[0004] The purpose to be achieved by the present invention is to provide a water level switch inspection method, which solves the problem of easy misjudgment in the prior art and reduces the occurrence of misjudgment.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions: a water level switch inspection method, wherein the water level switch controls the water level by detecting changes in air pressure caused by changes in water level. The water level switch inspection method includes a first water pressure calibration: after setting the calibration water pressure to 0 and the actual water pressure in the target container to 0, a calibration is performed to obtain the actual water pressure of the target container. If the difference between the actual water pressure and the target value does not exceed a first threshold, the water level switch is judged to meet the requirements; otherwise, the water level switch is judged to be abnormal; Second water pressure check: Set the check water pressure to a target value greater than zero, set the actual water pressure in the target container through the water level switch, perform a check, and obtain the actual water pressure in the target container. If the difference between the actual water pressure and the target value does not exceed the second threshold, the water level switch is judged to meet the requirements; otherwise, the water level switch is judged to be abnormal. The first threshold is smaller than the second threshold.

[0006] After adopting the above technical solution, the present invention has the following advantages: in actual operation, the water pressure faced by the water level switch is not an absolutely precise fixed value, but fluctuates within a certain reasonable range. Setting the first threshold and the second threshold defines a clear boundary for the performance evaluation of the water level switch, effectively reducing the misjudgment caused by the fuzzy pressure boundary, and making the inspection result more in line with the actual use scenario. If the first threshold is not less than the second threshold, the characteristic differences of the water level switch under different water pressure conditions are not taken into account, so that the inspection result cannot accurately reflect the true performance of the water level switch in different working states, which means that a large error between the actual water pressure and the target value is allowed in the initial state, which will reduce the inspection requirements for the accuracy of the water level switch in the initial state, and may cause some water level switches with large errors in the initial state to be mistakenly judged as meeting the requirements. These errors may be further amplified under subsequent normal operating water pressure, affecting the overall performance and accuracy of the water level switch, increasing the misjudgment rate of the entire inspection process, and affecting the accurate evaluation of the quality of the water level switch. By setting the first water pressure calibration to a no-water-pressure state (0 water pressure), the water level switch's normal operation can be verified under basic operating conditions, eliminating zero-position errors and providing a baseline state for subsequent calibration and inspection. This minimizes false positive or negative results that might occur during pressure-based inspections due to the lack of this state check, thereby improving the accuracy and reliability of the inspection results. Under zero-pressure conditions (the first calibration), the system is typically in a relatively ideal and controlled state, so a smaller first threshold can be set to ensure high accuracy. Under non-zero-pressure conditions (the second calibration), various factors in the actual operating environment may cause more fluctuations. A larger second threshold allows for a certain degree of normal fluctuation and avoids misjudgments due to minor errors. The second water pressure calibration sets the calibration water pressure at the target value, simulating the water pressure conditions in actual operation. This calibration process, which gradually increases in complexity from no-pressure to pressure, more comprehensively covers the water pressure range that the water level switch may encounter, more scientifically verifies its performance under different water pressure conditions, and avoids inspection gaps caused by a single test condition.

[0007] Furthermore, in the second water pressure check, the water level is checked sequentially from high water level to low water level, and the second threshold value decreases as the water level decreases.

[0008] With this technical solution, the rate of change of air pressure changes as the water level drops. Typically, when the water level is high, the air pressure change is relatively large, allowing for a larger threshold to determine if the water level switch is functioning properly. However, when the water level is low, smaller air pressure changes require higher detection accuracy. By adjusting the threshold so that it decreases as the water level drops, the actual operating status at different water levels can be more accurately reflected, reducing the possibility of misjudgment. Using a tighter error range at low water levels effectively prevents error accumulation.

[0009] Furthermore, the program is set to output multiple sets of frequency numbers corresponding to different target values, wherein the frequency numbers of the different target values represent water levels of different target values, and the frequency numbers corresponding to water levels of different target values are arranged in sequence in different lines of the program. The water level switch inspection method also includes a single-step operation mode: S1: Select single-step operation mode and start drainage state; S2: Set the target frequency according to the current line number; S3: Check whether the current frequency is greater than the target frequency. If so, execute S4; otherwise, continue to maintain the drainage state. S4: Current row number minus 1.

[0010] By adopting the above-mentioned technical solution, multiple groups of frequency numbers corresponding to different target values are output and arranged in sequence according to different lines of the program, providing a more comprehensive and accurate reference system for water level switch inspection. Different target values simulate the actual frequency environment that the water level switch may face under various water levels, avoiding as much as possible the problems missed due to the limited inspection scope, and greatly improving the accuracy and reliability of the inspection results. The design of the single-step operation mode greatly improves the inspection efficiency and operability. The whole process is simple and intuitive, without the need for complicated manual operations. During the inspection process, the system automatically determines the size relationship between the current frequency and the target frequency according to the set program logic, and performs the operation accordingly. This automated inspection process reduces manual intervention, which not only reduces the workload of operators, but also avoids human operational errors, making the inspection process more efficient and smooth, and can quickly complete the performance inspection of the water level switch under different frequency targets.

[0011] Furthermore, a program is set up to output multiple groups of frequency numbers corresponding to different target water levels arranged in descending order. The water level switch inspection method also has an automatic operation mode: S1: Select the automatic operation mode and start the drainage state; S2: Read and execute the program according to the set program number; S3: When the cycle running to the minimum water level is completed, the drainage state stops; S4: The result display interface pops up.

[0012] By adopting the above-mentioned technical solution, by pre-setting the frequency values corresponding to multiple different water levels and executing them in order from large to small, the water level switch can be inspected in an environment close to actual use, which can ensure as much as possible a comprehensive evaluation of the water level switch performance within the entire working range. The user only needs to select the automatic operation mode, and the system can automatically complete all preset steps. After the inspection is completed, the result display interface will automatically pop up, and the operator can intuitively view the inspection results.

[0013] Furthermore, a program is set up to output multiple sets of frequency numbers corresponding to different target water levels. The water level switch inspection method also includes water inlet verification: S1: Select water inlet calibration mode and delay for 1 second; S2: water inlet state is turned on; S3: Check the frequency. If the current frequency is less than the minimum frequency in the current program number, execute S4. Otherwise, continue to maintain the water filling state in S2. S4: Stop water inflow state.

[0014] With the aforementioned technical solution, during normal use, the water entry process is a dynamic one, with the water level gradually rising and the frequency changing accordingly. The water entry verification process simulates this actual entry process, enabling the water level switch to be inspected in an environment close to actual use by turning the water entry state on and off. By programming different target values and corresponding frequency values, water level changes under various actual operating conditions can be more accurately simulated. This ensures a more detailed assessment of the water level switch's response under different conditions, determining whether the water level switch responds normally to frequency changes during water entry, and improving test accuracy.

[0015] Furthermore, a program is set up to output multiple sets of frequency numbers corresponding to different target water levels. The water level switch inspection method also includes drainage verification: S1: Select the drainage verification mode and start the drainage state; S2: Check whether the current frequency is greater than the initial value of the frequency in the current program number. If the current frequency is greater than the initial value of the frequency in the current program number, execute S3, otherwise continue to maintain the drainage state in S1; S3: Stop water inflow state.

[0016] By adopting the above-mentioned technical solution, in actual operation, the drainage process will cause the water level to drop and the frequency to change accordingly, which highly simulates the real drainage process. This allows the water level switch to be inspected in an environment close to actual use to determine whether the water level switch responds normally to the change in frequency during drainage.

[0017] Another object of the present invention is to provide a water level switch inspection device to improve the inspection accuracy. In order to achieve the above object, the present invention adopts the following technical solution: a water level switch inspection device, the target container includes a U-shaped tube for simulating the water level, the water level switch inspection device also includes a water tank, a pressure sensor and an interaction and control module with a display interface, the U-shaped tube is connected to the water tank, the interaction and control module is electrically connected to the water level switch, the pressure sensing end of the pressure sensor is connected to the U-shaped tube, the signal output end of the pressure sensor is electrically connected to the interaction and control module, and the target water level is set through the interaction and control module. The water level value is set and the actual water level of the U-shaped tube is adjusted by the water level switch. The water level difference on both sides of the U-shaped tube forms an air pressure difference. The pressure sensor outputs an inductance signal by sensing the change of air pressure in the U-shaped tube. The interaction and control module identifies the inductance signal to display the water level pressure of the actual water level, and verifies the water level pressure of the actual water level and the water level pressure of the target water level value. The interaction and control module has a programming mode and a water pressure verification mode. The programming mode can set the program of the target water level value and the target frequency value. The water pressure verification mode is used to implement the steps in any of the above-mentioned water level switch inspection methods.

[0018] By adopting the above-mentioned technical solution, when there is a water level difference between the U-shaped tubes on both sides, according to Pascal's law, an air pressure accurately corresponding to the water level height can be stably generated. Compared with the buffer airbag relying on its own elastic deformation to simulate air pressure, this air pressure generation method based on basic physical laws has higher stability and accuracy, thereby realizing more accurate testing of the water level switch. The pressure sensor is directly connected to the U-shaped tube and can capture the air pressure changes caused by the water level difference in the U-shaped tube in the first time. There is no intermediate conversion link, which reduces the possibility of signal attenuation, distortion and external interference. The inductance signal output by the pressure sensor can also quickly and more accurately reflect the air pressure situation in the U-shaped tube, making the inspection of the water level pressure more timely and accurate, effectively avoiding the inspection delay and error caused by the intermediate link, greatly improving the inspection efficiency and stability of the water level switch, and eliminating the need for complex auxiliary equipment (such as a compressed air pump), simplifying the design of the entire inspection device. Finally, the display interface of the interactive and control module brings great convenience to operators. Operators can easily set the target water level value on the interface. The interactive and control module will automatically calibrate the water level pressure corresponding to the actual air pressure generated by the U-tube with the water level pressure of the target water level value and display the results in real time. This process does not require operators to manually calculate the complex relationship between air pressure and water level. Through the intuitive display, they can clearly grasp the working status of the water level switch and check whether it meets the standards. This greatly simplifies the operation process, improves the accuracy and efficiency of the inspection, and reduces the probability of human error. The interactive and control module has a programming mode and a water pressure calibration mode, which greatly enriches the functions of the device. In the programming mode, the target water level value and target frequency value can be freely set, allowing operators to make personalized configurations according to specific test needs. After pre-setting the required parameters, the system can automatically execute the test process according to these settings, reducing the time and complexity of manual adjustment, thereby improving overall work efficiency.

[0019] Furthermore, the water level switch inspection device also includes a frequency detection module connected to the U-shaped tube, the frequency detection module detects the frequency generated by the water level change and outputs an inductance signal, and the interaction and control module identifies the inductance signal to display the frequency of the actual water level.

[0020] The above-mentioned technical solution and the addition of the frequency detection module have enriched the inspection dimension. In the past, relying solely on pressure sensors to detect water level pressure had certain limitations. Frequency, as another key parameter closely related to water level, can provide more information for water level switch performance evaluation, verify water level switch performance from multiple angles, enhance the comprehensiveness of the inspection, further improve the accuracy of the inspection results, and avoid missing hidden faults due to single parameter inspection.

[0021] Furthermore, a pneumatic solenoid valve is provided between the water level switch and the U-shaped tube. When the water level switch is not working, the pneumatic solenoid valve is closed to keep the water level switch and the U-shaped tube closed. When the water level switch is working, the pneumatic solenoid valve is opened to connect the U-shaped tube and the water level switch.

[0022] With the above-mentioned technical solution, since the sealing performance of the water level switch itself has certain limitations and it is difficult to maintain stable air pressure, the closing of the air pressure solenoid valve effectively compensates for this deficiency, maintains the stability of the system air pressure, ensures the accuracy of high water level, and minimizes misjudgment.

[0023] Furthermore, a water pump, a water inlet solenoid valve and a drain solenoid valve are provided between the water tank and the U-shaped tube. The water pump is connected to the U-shaped tube through two branches respectively. The water inlet solenoid valve and the drain solenoid valve are respectively arranged on the two branches. The water pump, the water inlet solenoid valve and the drain solenoid valve are all electrically connected to the interaction and control module. The interaction and control module controls the operation of the water pump, the water inlet solenoid valve and the drain solenoid valve through the signal of the water level switch.

[0024] By adopting the above-mentioned technical solution, using a water pump, a water inlet solenoid valve and a drain solenoid valve, the working state of a device with a water level switch can be more realistically simulated, providing a test environment for the water level switch that is closer to actual conditions, thereby improving the accuracy of the inspection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1 It is a flow chart of the single-step operation mode of the present invention; Figure 2 is a flow chart of the automatic operation mode of the present invention; Figure 3 This is a flow chart of the water entry verification of the present invention; Figure 4 It is a flow chart of drainage verification of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0027] The terms "first," "second," "third," "fourth," and so forth (if any) in the description and claims of the present invention and in the accompanying drawings are used to distinguish similar items and are not necessarily used to describe a particular order or sequential sequence. It should be understood that the terms used in this manner are interchangeable where appropriate, such that the embodiments of the present invention described herein can be practiced in sequences other than those illustrated or described herein.

[0028] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the processes does not mean the order of execution. The execution order of the processes should be determined by their functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0029] It should be understood that in the present invention, "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0030] It should be understood that in the present invention, "plurality" refers to two or more. "And / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, X and / or Y can represent three situations: X exists alone, X and Y exist at the same time, and Y exists alone. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "Including X, Y and Z" and "Including X, Y, Z" means that X, Y, and Z are all included. "Including X, Y or Z" means that one of X, Y, and Z is included. "Including X, Y and / or Z" means that any one, any two, or any three of X, Y, and Z are included.

[0031] The following specific embodiments are used to describe the technical solution of the present invention in detail. The following specific embodiments can be combined or replaced with each other according to actual conditions, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0032] Embodiment 1: The present invention provides a water level switch inspection method. The water level switch controls the water level by detecting changes in air pressure caused by changes in the water level. The water level switch inspection method includes a first water pressure calibration: after setting the calibration water pressure to 0 and the actual water pressure in the target container to 0, a calibration is performed to obtain the actual water pressure of the target container. If the difference between the actual water pressure and the target value does not exceed a first threshold, the water level switch is judged to meet the requirements; otherwise, the water level switch is judged to be abnormal. Second water pressure check: Set the check water pressure to the target value, which is greater than zero. Set the actual water pressure in the target container through the water level switch, perform a test, and obtain the actual water pressure in the target container. If the difference between the actual water pressure and the target value does not exceed the second threshold, the water level switch is judged to meet the requirements. Otherwise, the water level switch is judged to be abnormal. The first threshold is smaller than the second threshold.

[0033] In actual operation, the water pressure faced by the water level switch is not an absolutely precise fixed value, but fluctuates within a certain reasonable range. Setting the first and second thresholds clearly defines the boundaries for the performance evaluation of the water level switch, effectively reducing misjudgments caused by fuzzy pressure boundaries, and making the inspection results more in line with actual usage scenarios. If the first threshold is not less than the second threshold, the characteristic differences of the water level switch under different water pressure conditions are not taken into account, so that the inspection results cannot accurately reflect the true performance of the water level switch in different operating conditions. This means that a large error between the actual water pressure and the target value is allowed in the initial state. This will reduce the inspection requirements for the accuracy of the water level switch in the initial state, and may cause some water level switches with large errors in the initial state to be mistakenly judged as meeting the requirements. These errors may be further amplified under subsequent normal operating water pressure, affecting the overall performance and accuracy of the water level switch, increasing the error rate of the entire inspection process, and affecting the accurate evaluation of the water level switch quality. By setting the first water pressure calibration at no water pressure (0 water pressure), the water level switch's normal operation is verified under basic operating conditions, eliminating zero-position errors and providing a baseline for subsequent calibration and inspection. This minimizes false positive or negative results that might occur during pressure-based calibration due to the lack of this calibration, improving the accuracy and reliability of the inspection results. Under zero pressure (the first calibration), the system is typically in a relatively ideal and controlled state, so a smaller first threshold can be set to ensure high accuracy. Under non-zero pressure (the second calibration), various factors in the actual operating environment may cause more fluctuations, so a larger second threshold allows for a certain degree of normal fluctuation and avoids misjudgments due to minor errors. The second water pressure calibration is set at the target water pressure, simulating actual operating water pressure conditions. This calibration process, which gradually increases in complexity from no pressure to pressure, more comprehensively covers the water pressure range the water level switch may encounter, more scientifically verifies its performance under different water pressure conditions, and avoids inspection gaps caused by a single test condition. This ensures that the water level switch meets the requirements of QB / T1292.

[0034] It should be noted that if the initial water pressure calibration indicates an abnormal water level switch, this may be due to poor pipe sealing or other potential air source interference. In this case, the air pressure anomaly should be immediately investigated and resolved, and then the initial water pressure calibration should be repeated. Ensure that the calibration is completed under a stable zero-pressure environment to ensure the accuracy of the baseline value and fundamentally avoid subsequent measurement errors caused by the calibration instrument.

[0035] It should be noted that the target container can also be set with a scale, the actual water level can also be read directly through the scale, the target water pressure can also be converted into the target water level, the first threshold and the second threshold can also be converted into water level thresholds, and the actual water level read can be compared with the target water level to determine whether the water level switch is abnormal.

[0036] The water level switch controls the water level by detecting changes in air pressure caused by changes in the water level. In the prior art, water pressure checks are usually conducted from low to high water levels. Water falling from a high point can cause unstable water pressure, leading to large errors in the test results. Therefore, in the present application, the second water pressure check is conducted sequentially from high to low water levels. This eliminates the need for a water inlet phase, where water falling from a high point increases water pressure instability. During the initial check at a high water level, the water is relatively static, and there is no pressure fluctuation caused by the impact of water drop during water inlet. This provides a more stable initial water pressure condition for the check, effectively reducing the test errors caused by unstable water pressure. Furthermore, when the water level is low, as the water volume increases, the air volume within the closed system decreases rapidly, causing the pressure to rise relatively quickly, making the water level switch easier to check. However, when the water level is high, the air space becomes smaller, and the reduction in air volume also decreases, making the water level switch more difficult to check. In other words, as the water level rises, the pressure change of the internal air slows down, making the water level switch more difficult to check. Therefore, in this application, the second threshold value decreases as the water level decreases, which can more accurately reflect the actual working status under different water levels and reduce the possibility of misjudgment. Using a stricter error range under low water level conditions effectively avoids error accumulation.

[0037] To increase the convenience of inspection, Figure 1 As shown, the program is set to output multiple sets of frequency numbers corresponding to different target values. The frequency numbers of different target values represent different target water levels, and the frequency numbers corresponding to different target water levels are arranged in sequence on different lines of the program. The water level switch inspection method also includes a single-step operation mode: S1: Select single-step operation mode and start drainage state; S2: Set the target frequency according to the current line number; S3: Check whether the current frequency is greater than the target frequency. If so, execute S4; otherwise, continue to maintain the drainage state. S4: Current row number minus 1.

[0038] Output multiple groups of frequency numbers corresponding to different target values and arrange them in sequence according to different lines of the program, providing a more comprehensive and accurate reference system for water level switch inspection. Different target values simulate the actual frequency environment that the water level switch may face under various water levels, avoiding as much as possible the problems missed due to the limited inspection scope, and greatly improving the accuracy and reliability of the inspection results. The design of the single-step operation mode greatly improves the inspection efficiency and operability. The entire process is simple and intuitive, without the need for complex manual operations. During the inspection process, the system automatically determines the size relationship between the current frequency and the target frequency according to the set program logic, and performs the operation accordingly. This automated inspection process reduces manual intervention, which not only reduces the workload of operators, but also avoids human operational errors, making the inspection process more efficient and smooth, and can quickly complete the performance inspection of the water level switch under different frequency targets.

[0039] It should be noted that in this embodiment, there are a total of 8 sets of water levels. The current line number minus 1 in S4 means: if this is the first run, the current program number is downloaded and the program content is read. The program content includes lines for controlling various devices and lines containing frequency numbers, etc. All lines containing frequency numbers are arranged in sequence. According to the program content, the last line with the frequency number is selected as the starting line. Each time a single step is pressed, the current line number is automatically reduced by 1 after the run is completed. In this embodiment, there are a total of 8 sets of water levels, specifically water level 1, water level 2, water level 3, water level 4, water level 5, water level 6, water level 7 and water level 8. The water level is changed by controlling the drainage state. When the frequency line corresponding to water level 8 is completed, the interface switches to the result display, indicating that the program has completed and will start again next time.

[0040] It should be noted that during single-step operation, the result will automatically pop up when the operation reaches the end.

[0041] like Figure 2 As shown, the program is set up to output multiple groups of frequency numbers corresponding to different target water levels arranged in descending order. The water level switch inspection method also has an automatic operation mode: S1: Select the automatic operation mode and start the drainage state; S2: Read and execute the program according to the set program number; S3: When the cycle running to the minimum water level is completed, the drainage state stops; S4: The result display interface pops up.

[0042] By pre-setting frequency values corresponding to multiple different water levels and executing them in descending order, the water level switch can be inspected in an environment close to its actual use. This can ensure as comprehensive an evaluation of the water level switch performance as possible throughout the entire operating range. The user only needs to select the automatic operation mode, and the system will automatically complete all preset steps. After the inspection is completed, the result display interface will automatically pop up, and the operator can intuitively view the inspection results.

[0043] It should be noted that the frequency is proportional to the water level. When the water levels are sorted in eight groups from high to low: Water level 1: The frequency is 36.58HZ, the target water level is 460±26mm, and the actual water level is 457mm, which meets the requirements; Water level 2: The frequency is 37.10HZ, the target water level is 410±23mm, and the actual water level is 409mm, which meets the requirements; Water level 3: The frequency is 37.66HZ, the target water level is 360±20mm, and the actual water level is 359mm, which meets the requirements; Water level 4: The frequency is 38.38HZ, the target water level is 300±17mm, and the actual water level is 299mm, which meets the requirements; Water level 5: The frequency is 39.01HZ, the target water level is 250±15mm, and the actual water level is 250mm, which meets the requirements; Water level 6: The frequency is 39.46HZ, the target water level is 215±12mm, and the actual water level is 214mm, which meets the requirements; Water level 7: The frequency is 40.54HZ, the target water level is 130±8mm, and the actual water level is 127mm, which meets the requirements; Water level 8: The frequency is 41.15HZ, the target water level is 80±5mm, and the actual water level is 76mm, which meets the requirements; It should be noted that the second threshold value is ± the value of the above content, and the second threshold value decreases proportionally as the water level drops.

[0044] In normal use, the water entry process is a dynamic process. The water level gradually rises and the frequency will change accordingly. Therefore, in this application, Figure 3 As shown, the program is set up to output multiple sets of frequencies corresponding to different target water levels. The water level switch inspection method also includes water inlet verification: S1: Select water inlet calibration mode and delay for 1 second; S2: water inlet state is turned on; S3: Check the frequency. If the current frequency is less than the minimum frequency in the current program number, execute S4. Otherwise, continue to maintain the water filling state in S2. S4: Stop water inflow state.

[0045] The water entry verification process simulates this actual water entry process, testing the water level switch in an environment close to actual use by turning water entry on and off. By programming different target values and corresponding frequency settings, water level fluctuations under various actual operating conditions can be more accurately simulated. This ensures a detailed evaluation of the water level switch's response under different conditions, determining whether it responds normally to frequency changes during water entry, and improving test accuracy.

[0046] Also, in actual operation, the drainage process will cause the water level to drop and the frequency to change accordingly. Figure 4 As shown, the program is set up to output multiple sets of frequency corresponding to different target water levels. The water level switch inspection method also includes drainage verification: S1: Select the drainage verification mode and start the drainage state; S2: Check whether the current frequency is greater than the initial value of the frequency in the current program number. If the current frequency is greater than the initial value of the frequency in the current program number, execute S3, otherwise continue to maintain the drainage state in S1; S3: Stop water inflow state.

[0047] In actual operation, the drainage process will cause the water level to drop and the frequency to change accordingly, which highly simulates the real drainage process. This allows the water level switch to be tested in an environment close to actual use to determine whether the water level switch responds normally to the change in frequency during drainage.

[0048] It should be noted that the water level switch inspection method is not only applicable to the inspection of water level switches of washing machines, but can also be extended to other types of equipment and systems that require precise inspection of water level switches, such as industrial water tank level control, intelligent irrigation systems, ship ballast water monitoring and other fields. It has broad application prospects and versatility.

[0049] Embodiment 2: This embodiment provides a water level switch inspection device, the target container includes a U-shaped tube for simulating the water level, the water level switch inspection device also includes a water tank, a pressure sensor and an interaction and control module with a display interface, the U-shaped tube is connected to the water tank, the interaction and control module is electrically connected to the water level switch, the pressure sensing end of the pressure sensor is connected to the U-shaped tube, the signal output end of the pressure sensor is electrically connected to the interaction and control module, the target water level value is set by the interaction and control module and the actual water level of the U-shaped tube is adjusted by the water level switch, the water level difference on both sides of the U-shaped tube forms an air pressure difference, the pressure sensor outputs an inductance signal by sensing the change in air pressure in the U-shaped tube, the interaction and control module identifies the inductance signal to display the water level pressure of the actual water level, and verifies the water level pressure of the actual water level and the water level pressure of the target water level value. The interaction and control module has a programming mode and a water pressure verification mode. The programming mode can set the program of the target water level value and the target frequency value. The water pressure verification mode is used to implement the steps in any of the above-mentioned water level switch inspection methods.

[0050] When there is a water level difference between the two sides of the U-tube, according to Pascal's law, an air pressure accurately corresponding to the water level height can be stably generated. Compared with the buffer airbag relying on its own elastic deformation to simulate air pressure, this air pressure generation method based on basic physical laws has higher stability and accuracy, thereby achieving more accurate testing of the water level switch. The pressure sensor is directly connected to the U-tube and can capture the air pressure changes caused by the water level difference in the U-tube in the first time. There is no intermediate conversion link, which reduces the possibility of signal attenuation, distortion and external interference. The inductance signal output by the pressure sensor can also quickly and more accurately reflect the air pressure situation in the U-tube, making the inspection of water level pressure more timely and accurate, effectively avoiding inspection delays and errors caused by intermediate links, greatly improving the inspection efficiency and stability of the water level switch, and eliminating the need for complex auxiliary equipment (such as compressed air pumps), simplifying the design of the entire inspection device. Finally, the display interface of the interactive and control module brings great convenience to operators. Operators can easily set the target water level value on the interface. The interactive and control module will automatically calibrate the water level pressure corresponding to the actual air pressure generated by the U-tube with the water level pressure of the target water level value and display the results in real time. This process does not require operators to manually calculate the complex relationship between air pressure and water level. Through the intuitive display, they can clearly grasp the working status of the water level switch and check whether it meets the standards. This greatly simplifies the operation process, improves the accuracy and efficiency of the inspection, and reduces the probability of human error. The interactive and control module has a programming mode and a water pressure calibration mode, which greatly enriches the functions of the device. In the programming mode, the target water level value and target frequency value can be freely set, allowing operators to make personalized configurations according to specific test needs. After pre-setting the required parameters, the system can automatically execute the test process according to these settings, reducing the time and complexity of manual adjustment, thereby improving overall work efficiency.

[0051] It should be noted that the existing technology usually uses straight tubes, and the liquid in the straight tubes is easily affected by external interference, such as vibration of the washing machine, water flow impact, etc., resulting in inaccurate measurement. The use of U-shaped tubes can utilize the gravity of the liquid (usually water) to form a more stable liquid level height difference on both sides, thereby more accurately reflecting the pressure changes in the washing machine.

[0052] It should be noted that since the inspection location may be in a plateau or basin with different ambient air pressures, the interaction and control module in this application has a built-in adaptive algorithm. During first use or when making specific settings, the module automatically adjusts the relevant parameters of the water level control by checking the current ambient air pressure and other parameters, so that the inspection device adapts to the local air pressure conditions, ensuring the accuracy of water level control and minimizing misjudgments.

[0053] It should be noted that the U-shaped tube is provided with a scale, the actual water level can also be directly read through the scale, the target water pressure can also be converted into the target water level, the first threshold value and the second threshold value can also be converted into the water level threshold value, and the actual water level read is compared with the target water level to determine whether the water level switch is abnormal.

[0054] Furthermore, a water pump, a water inlet solenoid valve, and a water discharge solenoid valve are installed between the water tank and the U-shaped tube. The water pump is connected to the U-shaped tube via two branches, and the water inlet solenoid valve and the water discharge solenoid valve are respectively installed on the two branches. The water pump, the water inlet solenoid valve, and the water discharge solenoid valve are all electrically connected to the interactive control module, which controls the operation of the water pump, the water inlet solenoid valve, and the water discharge solenoid valve based on the signal from the water level switch. This can more realistically simulate the operating state of a device with a water level switch, providing a more realistic testing environment for the water level switch, thereby improving the accuracy of the inspection results.

[0055] In the past, water level pressure was checked solely by relying on pressure sensors. This single parameter check has certain limitations and is prone to missed faults. For this reason, in this application, the water level switch inspection device also includes a frequency detection module connected to the U-tube. The frequency detection module detects the frequency generated by the water level change and outputs an inductance signal. The interaction and control module identifies the inductance signal to display the frequency of the actual water level. The addition of the frequency detection module enriches the detection dimension. In the past, relying solely on pressure sensors to detect water level pressure had certain limitations. Frequency, as another key parameter closely related to water level, can provide more information for water level switch performance evaluation, verify water level switch performance from multiple angles, enhance the comprehensiveness of detection, further improve the accuracy of detection results, and avoid missed faults due to single parameter detection.

[0056] It should be noted that the frequency is proportional to the water level. When the water levels are sorted from high to low: When the water level is 460±26mm, the frequency is 36.58HZ; When the water level is 410±23mm, the frequency is 37.10HZ; When the water level is 360±20mm, the frequency is 37.66HZ; When the water level is 300±17m, the frequency is 38.38HZ; When the water level is 250±15mm, the frequency is 39.01HZ; When the water level is 215±12mm, the frequency is 39.46HZ; When the water level is 130±8mm, the frequency is 40.54HZ; When the water level is 80±5mm, the frequency is 41.15HZ.

[0057] Because the water level switch's inherent sealing performance has certain limitations, it's difficult to maintain stable air pressure. Therefore, in this application, a pneumatic solenoid valve is also installed between the water level switch and the U-shaped tube. When the water level switch is not working, the pneumatic solenoid valve closes to keep the water level switch and the U-shaped tube sealed. When the water level switch is working, the pneumatic solenoid valve opens to connect the U-shaped tube and the water level switch. Closing the pneumatic solenoid valve effectively compensates for this deficiency, maintaining stable system air pressure, ensuring high water level accuracy, and minimizing misjudgments.

[0058] It should be noted that during the inspection process, if the liquid level in the U-tube fluctuates, it is necessary to check the sealing of the air pressure solenoid valve and whether there are any leaks in other components of the system.

[0059] It should be noted that in this application, the interaction and control module includes a touch screen, a PLC (Programmable Logic Controller), and a baseboard. The baseboard is connected to a pressure sensor and a PLC, and the PLC is connected to the touch screen. The pressure sensor senses the water level changes in the U-shaped tube and transmits the signal to the baseboard. The baseboard converts the collected frequency signal from a sine wave to a square wave, and the processed signal is transmitted to the PLC, which controls the entire system according to a preset program. The touch screen has a visual display interface. The PLC, with its powerful data processing capabilities, quickly analyzes and processes signals, enabling intelligent judgment of the operating status of the water level switch. Specific programs can also be written to enable real-time display, storage, abnormality alarms, and remote transmission of inspection data, improving inspection efficiency and intelligence.

[0060] The display interface includes a standby screen, a programming screen, a water pressure calibration screen, and a result display screen. The standby screen displays a programming button for entering programming mode, a pressure calibration button for entering water pressure calibration mode, a result viewing button for entering the result screen, a drain button for entering drain calibration, a water refill button for entering water refill calibration, a single-step run button for entering single-step mode, an automatic run button for entering automatic mode, the target frequency, current frequency, target water pressure, current water pressure, and the current program number. The programming screen has input areas for water level frequency and water level pressure. The water pressure calibration screen displays the calibration water pressure and a calibration button. The result display screen displays the sequence number, target frequency, actual frequency, target minimum pressure, target maximum pressure, and actual pressure. If the actual pressure is within the target minimum and maximum pressures, the background color will be green. If it is not within this range, the background color will turn red, indicating that it does not meet the requirements.

[0061] It should be noted that the water level switch inspection device is not only suitable for the inspection of water level switches of washing machines, but can also be expanded to other types of equipment and systems that require precise inspection of water level switches, such as industrial water tank level control, intelligent irrigation systems, ship ballast water monitoring and other fields. It has broad application prospects and versatility.

[0062] It should be noted that through the optimization of the PLC program, a one-click report output function has been added. After completing the water level switch inspection, the instrument automatically generates a report containing inspection data, result determination, and other information. Furthermore, the program integrates an integrated comparative analysis module that compares real-time inspection data with preset standard values, quickly determining whether the inspection results are qualified (i.e., outputting an OK or NG result). It also precisely locates inspection points that meet or fail the standard water level frequency, greatly improving the efficiency and accuracy of inspection result analysis.

[0063] It should be noted that the instrument has a quality trend management function for batch inspection scenarios. After inspecting 20 parts, the system automatically performs statistical analysis on the inspection data and plots a data trend chart. By analyzing data trends, potential quality issues in the water level sensor production process, such as performance drift and consistency deviation, can be promptly identified, providing data support for manufacturers to optimize production processes and improve product quality.

[0064] In addition to the above-mentioned preferred embodiments, the present invention has other implementation modes. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection requested by the present invention.

Claims

1. A water level switch inspection method, characterized in that: The water level switch controls the water level by detecting changes in air pressure caused by changes in the water level. The water level switch inspection method includes a first water pressure calibration: setting the calibration water pressure to 0 and the actual water pressure in the target container to 0, performing a calibration to obtain the actual water pressure of the target container. If the difference between the actual water pressure and the target value does not exceed a first threshold, the water level switch is judged to meet the requirements; otherwise, the water level switch is judged to be abnormal. Second water pressure check: Set the check water pressure to a target value greater than zero, set the actual water pressure in the target container through the water level switch, perform a check, and obtain the actual water pressure in the target container. If the difference between the actual water pressure and the target value does not exceed the second threshold, the water level switch is judged to meet the requirements; otherwise, the water level switch is judged to be abnormal. The first threshold is smaller than the second threshold.

2. The water level switch inspection method according to claim 1, characterized in that: In the second water pressure check, the water pressure is checked from high water level to low water level, and the second threshold value decreases as the water level decreases.

3. The water level switch inspection method according to claim 1, characterized in that: The program is set to output multiple sets of frequency numbers corresponding to different target values, wherein the frequency numbers of the different target values represent water levels of different target values, and the frequency numbers corresponding to the water levels of different target values are arranged in sequence in different lines of the program. The water level switch inspection method also includes a single-step operation mode: S1: Select single-step operation mode and start drainage state; S2: Set the target frequency according to the current line number; S3: Check whether the current frequency is greater than the target frequency. If so, execute S4; otherwise, continue to maintain the drainage state. S4: Current row number minus 1.

4. The water level switch inspection method according to claim 1, characterized in that: The program is set up to output multiple groups of frequency numbers corresponding to different target water levels arranged in descending order. The water level switch inspection method also has an automatic operation mode: S1: Select the automatic operation mode and start the drainage state; S2: Read and execute the program according to the set program number; S3: When the cycle running to the minimum water level is completed, the drainage state stops; S4: The result display interface pops up.

5. The water level switch inspection method according to claim 1, characterized in that: A program is set up to output multiple sets of frequencies corresponding to different target water levels. The water level switch inspection method also includes water inlet verification: S1: Select water inlet calibration mode and delay for 1 second; S2: water inlet state is turned on; S3: Check the frequency. If the current frequency is less than the minimum frequency in the current program number, execute S4. Otherwise, continue to maintain the water filling state in S2. S4: Stop water inflow state.

6. The water level switch inspection method according to claim 1, characterized in that: A program is set up to output multiple sets of frequency numbers corresponding to different target water levels. The water level switch inspection method also includes drainage verification: S1: Select the drainage verification mode and start the drainage state; S2: Check whether the current frequency is greater than the initial value of the frequency in the current program number. If the current frequency is greater than the initial value of the frequency in the current program number, execute S3, otherwise continue to maintain the drainage state in S1; S3: Stop water inflow state.

7. A water level switch inspection device, characterized in that: The target container includes a U-shaped tube for simulating a water level. The water level switch inspection device also includes a water tank, a pressure sensor, and an interaction and control module with a display interface. The U-shaped tube is connected to the water tank, and the interaction and control module is electrically connected to the water level switch. A pressure sensing end of the pressure sensor is connected to the U-shaped tube, and a signal output end of the pressure sensor is electrically connected to the interaction and control module. A target water level value is set by the interaction and control module, and the actual water level of the U-shaped tube is adjusted by the water level switch. The water level difference on both sides of the U-shaped tube forms an air pressure difference. The pressure sensor outputs an inductance signal by sensing changes in air pressure within the U-shaped tube. The interaction and control module identifies the inductance signal to display the water level pressure of the actual water level and verifies the water level pressure of the actual water level with the water level pressure of the target water level. The interaction and control module has a programming mode and a water pressure verification mode. The programming mode can set programs for the target water level value and the target frequency value. The water pressure verification mode is used to implement the steps of the water level switch inspection method according to any one of claims 1 to 6.

8. The water level switch inspection device according to claim 7, characterized in that: The water level switch inspection device also includes a frequency detection module connected to the U-shaped tube. The frequency detection module detects the frequency generated by the water level change and outputs an inductance signal. The interaction and control module identifies the inductance signal to display the frequency of the actual water level.

9. The water level switch inspection device according to claim 7, characterized in that: A pneumatic solenoid valve is also provided between the water level switch and the U-shaped tube. When the water level switch is not working, the pneumatic solenoid valve is closed to keep the water level switch and the U-shaped tube closed. When the water level switch is working, the pneumatic solenoid valve is opened to connect the U-shaped tube and the water level switch.

10. The water level switch inspection device according to claim 7, characterized in that: A water pump, a water inlet solenoid valve and a drain solenoid valve are provided between the water tank and the U-shaped tube. The water pump is connected to the U-shaped tube through two branches respectively. The water inlet solenoid valve and the drain solenoid valve are respectively arranged on the two branches. The water pump, the water inlet solenoid valve and the drain solenoid valve are all electrically connected to the interaction and control module. The interaction and control module controls the operation of the water pump, the water inlet solenoid valve and the drain solenoid valve through the signal of the water level switch.

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