Method for monitoring position of valve core of electromagnetic directional valve

Abstract

The invention provides a method for monitoring the position of a valve core of an electromagnetic directional valve, and relates to the field of reliability analysis of hydraulic elements, and the method comprises the following steps: constructing a special power supply system, a main circuit and a monitoring circuit, performing Hall element power supply connection, constructing a signal acquisition system, performing a magnetic field change monitoring experiment, and performing a valve core movement magnetic field verification experiment. Magnetic field signal peak values at all positions are recorded through an oscilloscope, data differences are compared, and the influence of valve element movement on the magnetic field is indirectly verified. Mechanical contact with the valve element is not needed, normal work of the valve is prevented from being disturbed, the service life of equipment is remarkably prolonged in a wear-free detection mode, movement monitoring of the valve element in a sealed cavity can be achieved, the on-off state and the valve element position change are detected at the same time, continuous online monitoring of the working state is achieved, and the device is applied to fault early warning of the electromagnetic directional valve of a hydraulic system. Automatic production line valve state monitoring, key process valve reliability verification and valve response characteristic testing are carried out.

Description

Technical Field

[0001] The present invention relates to the field of reliability analysis of hydraulic components, and in particular to a method for monitoring the position of a solenoid directional valve core. Background Art

[0002] A solenoid directional valve with a monitoring device is capable of monitoring the spool position, typically using a Hall effect element to output a signal indicating the spool's status. Solenoid directional valves typically require spool position detection, feedback, and emergency operation capabilities to determine if the spool is stuck or malfunctioning, thereby ensuring the safe operation of the hydraulic circuit and actuators. Real-time monitoring of spool position is particularly important in applications requiring high reliability and automated control, such as hydraulic systems in construction machinery, automated production lines, and aerospace hydraulic control systems, as it is considered a crucial element for ensuring safe and stable system operation.

[0003] In existing technology, these valves primarily rely on power-on status or external control signals to achieve valve core reversal. They typically lack direct or real-time monitoring of valve core movement and typically lack integrated detection devices for valve core position feedback. Consequently, when the valve core experiences slight sticking, response delays, or reversal deviation, the system may struggle to obtain accurate position information and determine whether the valve core is fully in place or has completed reversal.

[0004] In practical applications, this lack of valve core position monitoring will bring many problems: Difficulty in fault diagnosis: When a directional valve experiences abnormal switching or delayed response, existing systems often cannot distinguish whether the fault is an electrical failure, such as a burned-out coil or abnormal control signal, or a mechanical failure, such as a stuck or worn valve core. Identifying the problem often requires disassembling the valve or relying on empirical judgment. This is not only time-consuming and labor-intensive, but can also impact overall system safety and operational stability in high-reliability hydraulic systems or automated production lines.

[0005] Valve core performance degradation is difficult to predict: Over long-term use, valve cores may experience increased response time or reduced switching accuracy due to wear, contamination, or temperature changes. Existing technologies often cannot detect these performance degradations in advance, making it difficult to implement preventive maintenance or assess valve lifespan.

[0006] Difficulties in debugging and performance optimization: Existing directional valves lack real-time feedback, making it impossible to directly observe the valve core motion curve and providing an accurate basis for adjusting system parameters. Performance matching and lifespan assessment often rely on empirical data, which hinders equipment debugging efficiency and the scientific nature of reliability verification in construction machinery, automated production lines, and high-safety hydraulic systems.

[0007] Safety and reliability risks: Slight valve spool sticking or abnormal switching can cause hydraulic system pressure surges or control delays, leading to cascading failures. In automated production lines, a valve spool sticking can cause the entire line to shut down. In construction machinery, delayed switching or abnormal response can lead to unstable equipment operation or even safety accidents.

[0008] Small displacements are difficult to monitor: Existing valves lack highly sensitive detection methods, making it difficult to effectively identify small displacements or transient changes in the valve core. This is especially true when the valve core moves quickly or changes direction frequently. The resolution and sensitivity of traditional current detection or mechanical contact detection methods often cannot meet real-time monitoring requirements.

[0009] In these cases, if there is no effective method for monitoring the spool position of the electromagnetic directional valve, adverse effects will occur. Therefore, it is necessary to propose a new method for monitoring the spool position of the electromagnetic directional valve in order to solve the above defects. Summary of the Invention

[0010] In order to solve the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a method for monitoring the position of the valve core of an electromagnetic directional valve. The method does not require mechanical contact with the valve core, can realize the movement monitoring of the valve core in the sealed cavity, monitor the on-off state and position change of the valve core, and realize continuous online monitoring of the working state. The method utilizes the electromagnetic field of the existing electromagnetic directional valve to realize detection, does not require an additional excitation source, is composed of standard industrial components, has strong compatibility, and has a modular design that facilitates integration into the existing control system. The valve core movement speed and displacement-derived parameters can be extracted through signal processing. The method is suitable for monitoring various types of electromagnetically driven valves and provides basic data support for predictive maintenance. Compared with optical detection solutions such as high-speed cameras, the cost is reduced by more than 80%, and there is no need to modify the valve structure. The normal operation of the equipment is not affected during maintenance and inspection. The method can be applied to hydraulic system electromagnetic directional valve fault warning, automated production line valve status monitoring, key process valve reliability verification, and valve response characteristic testing.

[0011] Specifically, the present invention provides a method for monitoring the position of a solenoid directional valve core, comprising the following steps: S1: Main system setup and AC power supply connection And perform AC-DC conversion, step down the voltage through the switching power supply, and output the DC voltage required by the system , connect the positive pole of the switching power supply to the first end of the on-off switch, connect the second end of the on-off switch to the positive pole of the electromagnetic directional valve, and connect the negative pole of the switching power supply to the negative pole of the electromagnetic directional valve; S2: Test system setup: the output of the switching power supply is connected in parallel to the input of the buck module, and the output of the buck module is connected to the input of the Hall element; S3: Set up the signal acquisition system, turn on the oscilloscope and connect the test leads of the oscilloscope in parallel to the signal output pin of the Hall element; S4: Magnetic field change monitoring, closing the on-off switch, controlling the on-off power of the electromagnetic directional valve, and recording and analyzing the signal waveform of the magnetic field change during the on-off process of the circuit through an oscilloscope. Among them, the voltage change ΔV observed by the oscilloscope is H , satisfying the formula: ; Where, is the Hall coefficient, which is determined by the material, is the control current of the Hall element that changes with time, is the thickness of the Hall element perpendicular to the current direction, is the magnetic field distribution after the valve core moves, is the magnetic field distribution before the valve core moves; S5: Determine the position of the valve core. By comparing the changes in the output signal of the Hall element before and after the on-off switch operation, determine whether the valve core of the electromagnetic directional valve has moved. If the monitored signal waveform changes, it is determined that the valve core has moved. If the monitored signal waveform does not change, it is determined that the valve core has not moved effectively. The voltage change ΔV observed by the oscilloscope is H Satisfies the relationship: ; Where, It is the output signal of the Hall element after the on-off switch operation. This is the Hall element output signal before the on-off switch is operated.

[0012] Preferably, the test results are evaluated using a signal-to-noise ratio, where the signal-to-noise ratio satisfies the formula: ; Where, is the signal-to-noise ratio, is the magnetic field sensitivity, The magnetic field changes caused by the movement of the valve core. is the system noise voltage, including circuit noise and oscilloscope noise floor.

[0013] Preferably, the magnetic field sensitivity Satisfies the formula: ; Where, is the magnetic field sensitivity, is the output signal of the Hall voltage, is the magnetic induction intensity perpendicular to the element, is the control current through the Hall element, is the Hall coefficient, which is determined by the material, is the thickness of the Hall element.

[0014] Preferably, the output signal of the Hall voltage Satisfies the formula: ; Where, is the output signal of the Hall voltage, is the control current through the Hall element, is the magnetic induction intensity perpendicular to the Hall element, is the Hall coefficient, which is determined by the material, is the thickness of the Hall element.

[0015] Preferably, in step S5, the Hall element outputs a Hall voltage signal V based on the output time series. H (t) Perform signal processing to extract the movement speed and displacement information of the valve core. The movement speed of the valve core satisfies the formula: ; The displacement of the valve core satisfies the formula: ; Where, is the Hall voltage output signal based on the output time series, is the movement speed of the valve core, is the displacement of the valve core, It is the system conversion coefficient determined by the valve core structure and Hall device characteristics.

[0016] Preferably, step S3 includes detecting magnetic field verification of valve core movement, specifically including the following sub-steps: S31: Place the Hall element close to the valve core of the solenoid directional valve to ensure that it is stable and does not interfere with the normal movement of the valve core; S32: Close the on-off switch to energize the electromagnetic directional valve, and the Hall element begins to detect the magnetic field signal; S33: Fix the Hall element at the reference position on the axial side of the electromagnetic coil close to the valve core, record the peak value of the collected magnetic field signal through an oscilloscope, repeatedly move the position of the Hall element to obtain a square wave signal, which is the current position of the valve core, thereby verifying the magnetic field experiment of the valve core movement.

[0017] Preferably, step S4 specifically includes the following sub-steps: S41: Check the status of the on-off switch and whether the circuit connection between the on-off switch and the solenoid directional valve is normal. If normal, proceed to step S2. If abnormal, check each component step by step, adjust the wiring position or fix the loose terminals, clean the switch contacts, remove oxides or impurities, replace the switch element or related connecting devices, reinforce or re-solder the wires or contacts to ensure mechanical stability, adjust the contact pressure of the power terminal to ensure stable voltage supply during switching, and detect the circuit for short circuit or open circuit to eliminate potential circuit abnormalities; S42: Close the on-off switch to energize the electromagnetic directional valve, adjust the oscilloscope parameters and press the acquisition button to start recording the magnetic field change signal; S43: Observe the magnetic field change signal waveform displayed on the oscilloscope to check whether the rising edge corresponding to the magnetic field enhancement detected by the Hall element when the power is on and the falling edge corresponding to the magnetic field weakening detected when the power is off are obvious. The judgment is based on analyzing the magnetic field signal waveform recorded by the oscilloscope, measuring the rising edge amplitude ΔVrise when the power is on and the falling edge amplitude ΔVfall when the power is off. If ΔVrise and ΔVfall are both greater than the judgment threshold Vh, then the rising edge corresponding to the magnetic field enhancement detected by the Hall element and the falling edge corresponding to the magnetic field weakening detected when the power is off are obvious. If ΔVrise or ΔVfall is less than the judgment threshold Vh, then the rising edge corresponding to the magnetic field enhancement detected by the Hall element and the falling edge corresponding to the magnetic field weakening detected when the power is off are not obvious. The threshold Vh is set to 15% of the initial value of the magnetic field change signal waveform amplitude. S44: Compare and analyze the waveforms of the magnetic field change signals when the power is on and off to confirm whether the magnetic field change caused by the power on and off can be detected. If so, execute step S4; if not, execute step S1.

[0018] Further, it is preferred that the Hall element is mounted on the housing surface of the electromagnetic directional valve and is arranged in a relatively fixed position with respect to the axial direction and radial direction of the valve core of the electromagnetic directional valve.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention is equipped with an independent step-down module, which effectively overcomes the problem of signal distortion caused by power supply fluctuations in traditional measurements. At the same time, it adapts to common industrial voltage standards, improving equipment compatibility and experimental repeatability.

[0020] 2. Compared with traditional methods, the present invention requires a mechanical probe to contact the valve core or disassemble the valve body to install a displacement sensor, which may cause seal failure or mechanical wear. The present invention indirectly monitors the magnetic field changes through Hall elements, avoiding the mechanical wear or sealing damage caused by direct contact with the valve core, significantly improving the long-term stability and reliability of the monitoring system, and is particularly suitable for high-pressure or polluted environments.

[0021] 3. The present invention combines on-off circuit control with real-time signal acquisition by an oscilloscope, which can dynamically capture transient changes in the magnetic field at the moment when the electromagnetic directional valve is powered on and off, and can identify small amplitude fluctuations. Its sensitivity is significantly improved compared to traditional current detection methods, providing a new way to detect small displacements of the valve core.

[0022] 4. The dynamic magnetic field detection of the existing technology relies on high-sampling rate acquisition cards or customized sensors, which have high deployment costs. The present invention uses a step-down module and a universal oscilloscope to replace high-precision customized acquisition equipment, simplifying the circuit design and debugging process, reducing hardware costs, and supporting rapid replacement or expansion, facilitating industrial field application and maintenance.

[0023] 5. The present invention uses the difference in magnetic field peak value to indirectly analyze the movement state of the valve core, which solves the limitations of traditional methods that require disassembly of the valve body or rely on complex sensors, reduces downtime for detection, and improves maintenance efficiency.

[0024] 6. Through technological integration, the present invention reduces system complexity and maintenance costs while ensuring measurement accuracy, providing an efficient, economical and easy-to-implement solution for non-invasive valve core monitoring. It accurately reflects the valve core position without changing the structure and size of the solenoid directional valve, and can promptly detect valve core jamming failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for monitoring the position of a solenoid directional valve core of the present invention; Figure 2 This is a flow chart of a magnetic field verification experiment for detecting valve core movement according to the present invention; Figure 3 This is a flow chart of the system testability check of the present invention; Figure 4 This is a schematic diagram of the electromagnetic directional valve core position monitoring and testing system of the present invention; Figure 5 This is the valve core position monitoring test result of the present invention.

[0026] Main reference numerals: 1. Switching power supply; 2. Solenoid directional valve; 3. Wires; 4. On-off switch; 5. Step-down module; 6. Hall element; 7. Oscilloscope. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0028] The present invention provides a method for monitoring the position of a solenoid directional valve core. Figure 1 and Figure 4 As shown, it includes the following steps: Specifically, the present invention provides a method for monitoring the position of a solenoid directional valve core, comprising the following steps: S1: Main system setup and AC power supply connection And perform AC-DC conversion, step down the voltage through switching power supply 1, and output the DC voltage required by the system , connect the positive pole of the switching power supply 1 to the first end of the on-off switch 4, connect the second end of the on-off switch 4 to the positive pole of the electromagnetic directional valve 2, and connect the negative pole of the switching power supply 1 to the negative pole of the electromagnetic directional valve 2; S2: Test system is set up. The output end of the switching power supply 1 is connected in parallel to the input end of the step-down module 5. The output end of the step-down module 5 is connected to the input end of the Hall element 6. S3: Setting up the signal acquisition system, turning on the oscilloscope 7 and connecting the test leads of the oscilloscope 7 in parallel to the signal output pin of the Hall element 6; S4: Magnetic field change monitoring, close the on-off switch 4, control the on and off of the electromagnetic directional valve 2, and use the oscilloscope 7 to record and analyze the signal waveform of the magnetic field change during the circuit on and off process. The voltage change ΔV observed by the oscilloscope 7 is H , satisfying the formula: ; Where, is the Hall coefficient, which is determined by the material, is the control current of the Hall element 6 that changes with time, is the thickness of the Hall element 6 perpendicular to the current direction, is the magnetic field distribution after the valve core moves, is the magnetic field distribution before the valve core moves; S5: Determine the position of the valve core. By comparing the changes in the output signal of the Hall element 6 before and after the operation of the on-off switch 4, determine whether the valve core of the electromagnetic directional valve 2 has moved. If the monitored signal waveform changes, it is determined that the valve core has moved. If the monitored signal waveform does not change, it is determined that the valve core has not moved effectively. The voltage change ΔV observed by the oscilloscope 7 is H Satisfies the relationship: ; Where, The Hall element 6 outputs a signal after the on-off switch 4 is operated. The Hall element 6 outputs a signal before the on-off switch 4 is operated.

[0029] The test results are evaluated using the signal-to-noise ratio, where the signal-to-noise ratio satisfies the formula: ; Where, is the signal-to-noise ratio, is the magnetic field sensitivity, The magnetic field changes caused by the movement of the valve core. is the system noise voltage, including circuit noise and oscilloscope noise floor.

[0030] Magnetic field sensitivity Satisfies the formula: ; Where, is the magnetic field sensitivity, is the output signal of the Hall voltage, is the magnetic induction intensity perpendicular to the element, is the control current passing through the Hall element 6, is the Hall coefficient, which is determined by the material, is the thickness of the Hall element 6.

[0031] Hall voltage output signal Satisfies the formula: ; Where, is the output signal of the Hall voltage, is the control current passing through the Hall element 6, is the magnetic induction intensity perpendicular to the Hall element 6, is the Hall coefficient, which is determined by the material, is the thickness of the Hall element 6.

[0032] In step S5, the Hall element 6 outputs a Hall voltage output signal V based on the output time series. H (t) Perform signal processing to extract the movement speed and displacement information of the valve core. The movement speed of the valve core satisfies the formula: ; The displacement of the valve core satisfies the formula: ; Where, is the Hall voltage output signal based on the output time series, is the movement speed of the valve core, is the displacement of the valve core, It is the system conversion coefficient determined by the valve core structure and Hall device characteristics.

[0033] like Figure 2 As shown, step S3 includes detecting the magnetic field verification of the valve core movement, which specifically includes the following sub-steps: S31: Place the Hall element 6 near the valve core of the solenoid directional valve 2 to ensure that it is stable and does not interfere with the normal movement of the valve core; S32: Close the on-off switch to energize the electromagnetic directional valve 2, and the Hall element 6 starts to detect the magnetic field signal; S33: Fix the Hall element 6 at the reference position of the electromagnetic coil axially close to the valve core side, record the peak value of the collected magnetic field signal through the oscilloscope 7, repeatedly move the position of the Hall element 6 to obtain a square wave signal, which is the current position of the valve core, so that the magnetic field experiment of the valve core movement is verified.

[0034] like Figure 3 As shown, step S4 specifically includes the following sub-steps: S41: Check the status of the on-off switch 4 and whether the circuit connection between the on-off switch 4 and the electromagnetic directional valve 2 is normal. If normal, execute step S2. If abnormal, check each component step by step, adjust the wiring position or fix the loose terminal, clean the switch contacts, remove oxides or impurities, replace the switch element or related connecting components, reinforce or re-solder the wire 3 or the contact to ensure mechanical stability, adjust the contact pressure of the power terminal to ensure stable voltage supply during switching, detect the circuit for short circuit or open circuit, and eliminate potential circuit abnormalities; S42: Close the on-off switch 4 to energize the electromagnetic directional valve 2, and at the same time adjust the parameters of the oscilloscope 7 and press the acquisition button to start recording the magnetic field change signal; S43: Observe the magnetic field change signal waveform displayed on the oscilloscope 7 to check whether the rising edge corresponding to the magnetic field enhancement detected by the Hall element 6 when the power is on and the falling edge corresponding to the magnetic field weakening detected when the power is off are obvious. The judgment is based on analyzing the magnetic field signal waveform recorded by the oscilloscope 7, measuring the rising edge amplitude ΔVrise when the power is on and the falling edge amplitude ΔVfall when the power is off. If ΔVrise and ΔVfall are both greater than the judgment threshold Vh, the rising edge corresponding to the magnetic field enhancement detected by the Hall element 6 and the falling edge corresponding to the magnetic field weakening detected when the power is off are obvious. If ΔVrise or ΔVfall is less than the judgment threshold Vh, the rising edge corresponding to the magnetic field enhancement detected by the Hall element 6 and the falling edge corresponding to the magnetic field weakening detected when the power is off are not obvious. The threshold Vh is set to 15% of the initial value of the magnetic field change signal waveform amplitude. S44: Compare and analyze the waveforms of the magnetic field change signals when the power is on and off to confirm whether the magnetic field change caused by the power on and off can be detected. If so, execute step S4; if not, execute step S1.

[0035] The Hall element 6 is mounted on the outer shell surface of the electromagnetic directional valve 2 and is arranged in a relatively fixed position with respect to the valve core of the electromagnetic directional valve 2 in the axial direction and the valve core of the electromagnetic directional valve 2 in the radial direction.

[0036] In step S4 , after the Hall element 6 is powered on, it is necessary to check whether the power indicator light of the Hall element 6 is normally lit.

[0037] In step S2 , the output voltage of the voltage-reducing module 5 meets the operating voltage requirement of the Hall element 6 .

[0038] Specifically, the embodiments of the present invention include the following operating methods: power supply system preparation, prepare 220V AC power input, connect the switching power supply 1, set the output voltage to 24V DC, and check whether the output voltage of the switching power supply 1 is stable; main circuit connection, connect the 24V output positive pole to the input end of the on-off switch 4, connect the output end of the on-off switch 4 to the positive pole of the electromagnetic directional valve 2, and directly connect the 24V output negative pole to the negative pole of the electromagnetic directional valve 2, and check whether all line connections are firm; step-down module 5 is installed, a branch line is drawn from the 24V output end of the switching power supply 1, the step-down module 5 is connected, and it is confirmed that the output voltage of the step-down module 5 meets the working requirements of the Hall element 6; Hall element 6 is powered Connect the step-down module 5 to the Hall element 6 and check whether the power indicator of the Hall element 6 is lit normally. Set up the signal acquisition system and prepare the oscilloscope 7 and start it to preheat. Connect the signal output pin of the Hall element 6 to the test leads of the oscilloscope 7 and set the basic parameters of the oscilloscope 7. In the magnetic field change monitoring experiment, close the on-off switch 4 to control the power on and off of the electromagnetic directional valve 2. Use the oscilloscope 7 to record the magnetic field change signal during the circuit on and off process. Observe and analyze the signal waveform to confirm whether the magnetic field change caused by the power on and off can be detected. In the valve core movement magnetic field verification experiment, use the position comparison method to place the Hall element 6 at different positions of the electromagnetic directional valve 2, such as close to the valve core and away from the valve core, and repeat the on and off operation. Use the oscilloscope 7 to record the peak value of the magnetic field signal at each position and compare the data differences to indirectly verify the influence of the valve core movement on the magnetic field.

[0039] The components required by the present invention include a switching power supply 1, which provides a stable power supply for the entire system to ensure the normal operation of each component. The step-down module 5 reduces the voltage to an appropriate level to meet the voltage requirements of different components and protect the circuits and equipment. The on-off switch 4 controls the on and off of the circuit and is used to start or stop the monitoring process. The electromagnetic directional valve 2 controls the on and off and flow direction of the fluid and is a key executive element of the system. The Hall element 6 is used to detect the position change of the valve core of the electromagnetic directional valve 2. When the valve core moves, the magnetic field changes, and the Hall element 6 senses this change and generates a corresponding electrical signal. The oscilloscope 7 is used to display and analyze the output electrical signal of the Hall element 6, thereby monitoring the position change of the valve core. The wire 3 connects the various components to ensure the transmission of signals and power.

[0040] Switching power supply 1 provides power to the system, and step-down module 5 regulates the voltage. When on / off switch 4 is closed, solenoid directional valve 2 is energized, and the valve core begins to move. Hall effect element 6 detects changes in the valve core's position and converts the magnetic field changes into an electrical signal. Oscilloscope 7 receives and displays the signal output by Hall effect element 6. Users can observe changes in the valve core's position through oscilloscope 7, thereby enabling monitoring of the valve core position of solenoid directional valve 2.

[0041] Plug the power cord of oscilloscope 7 into a 220V AC power socket, turn on the power switch of oscilloscope 7, and let it start preheating to ensure that the internal circuit of oscilloscope 7 is stable, so that the measurement results are accurate. During the preheating period, observe whether the screen of oscilloscope 7 is displaying normally and whether there are any abnormal prompt information or fault alarms. At the same time, check whether the various knobs and buttons of oscilloscope 7 are flexible and function normally to ensure that oscilloscope 7 is in good working condition and can accurately collect and display signals. Connect the signal output pin of Hall element 6 to the test lead of oscilloscope 7. According to the shape and size of the signal output pin of Hall element 6, select the appropriate type of test lead for oscilloscope 7. When connecting, ensure that the probe is in good contact with the pin to avoid false connection or short circuit. Set the basic parameters of oscilloscope 7. Adjust the time base knob of oscilloscope 7 according to the expected frequency of the magnetic field change signal. Make the signal waveform display complete and clear on the screen of oscilloscope 7, so as to facilitate the observation of the period and frequency characteristics of the signal. Voltage range setting: Set the voltage range of the oscilloscope 7 according to the voltage range of the output signal of the Hall element 6 to ensure that the oscilloscope 7 can accurately display the amplitude change of the signal while avoiding distortion or clipping caused by the signal exceeding the measurement range of the oscilloscope 7.

[0042] When conducting a magnetic field change monitoring experiment, first check the status of on-off switch 4 and the proper connection between it and the solenoid directional valve 2. Then, slowly but decisively close on-off switch 4 to energize the solenoid directional valve 2 while closely observing any abnormalities. At the moment of closure, quickly adjust the parameters of oscilloscope 7 and press the acquisition button to begin recording the magnetic field change signal. After power is applied, observe the magnetic field change signal waveform displayed on oscilloscope 7 to verify whether the rising edge (corresponding to the magnetic field enhancement detected by Hall element 6 during power-on) and the falling edge (corresponding to the magnetic field weakening during power-off) are clearly detected. The magnetic field signal waveform recorded by the oscilloscope is generally analyzed by observing the rising edge amplitude (ΔVrise) during power-on and the falling edge amplitude (ΔVfall) during power-off to determine whether ΔVrise and ΔVfall exceed a preset threshold (Vh), typically 15% of the initial value. The waveform amplitude and rise time parameters are recorded using the measurement function of oscilloscope 7. Comparative analysis of the magnetic field change signal waveforms during power-on and power-off conditions confirms that the magnetic field changes caused by power-on and power-off are detectable.

[0043] When conducting the valve core movement magnetic field verification experiment, the position comparison method is used. First, place the Hall element 6 at a position close to the valve core of the electromagnetic directional valve 2 to ensure that it is stable and will not interfere with the normal movement of the valve core. Close the on-off switch 4 and power on the electromagnetic directional valve 2. At this time, the Hall element 6 begins to detect the magnetic field signal. Record the peak value of the magnetic field signal at this position through the oscilloscope 7, and pay attention to the stability and repeatability of the signal. Disconnect the switch, change the position of the Hall element 6, move it away from the valve core, repeat the above-mentioned power on and off operation, and record the peak value of the magnetic field signal again. When recording data, ensure that the speed and strength of each power on and off operation are as consistent as possible to reduce experimental errors. Figure 5 As shown, when the electromagnetic directional valve 2 moves normally and is not stuck, the Hall element 6 can detect a periodically changing square wave signal.

[0044] The present invention has a simple structure, reasonable design, high efficiency, convenience, safety and reliability, and can more accurately reflect the position of the valve core without changing the structure and size of the electromagnetic directional valve. It can timely detect the failure of the valve core being stuck and use safety device monitoring to avoid accidents.

[0045] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for monitoring the position of a solenoid directional valve core, characterized by: It includes the following steps: S1: Main system setup and AC power supply connection And perform AC-DC conversion, step down the voltage through the switching power supply, and output the DC voltage required by the system , connect the positive pole of the switching power supply to the first end of the on-off switch, connect the second end of the on-off switch to the positive pole of the electromagnetic directional valve, and connect the negative pole of the switching power supply to the negative pole of the electromagnetic directional valve; S2: Test system setup: the output of the switching power supply is connected in parallel to the input of the buck module, and the output of the buck module is connected to the input of the Hall element; S3: Set up the signal acquisition system, turn on the oscilloscope and connect the test leads of the oscilloscope in parallel to the signal output pin of the Hall element; S4: Magnetic field change monitoring, closing the on-off switch, controlling the on-off power of the electromagnetic directional valve, and recording and analyzing the signal waveform of the magnetic field change during the on-off process of the circuit through an oscilloscope. Among them, the voltage change ΔV observed by the oscilloscope is H , satisfying the formula: ； Where, is the Hall coefficient, which is determined by the material, is the control current of the Hall element that changes with time, is the thickness of the Hall element perpendicular to the current direction, is the magnetic field distribution after the valve core moves, is the magnetic field distribution before the valve core moves; S5: Determine the position of the valve core. By comparing the changes in the output signal of the Hall element before and after the on-off switch operation, determine whether the valve core of the electromagnetic directional valve has moved. If the monitored signal waveform changes, it is determined that the valve core has moved. If the monitored signal waveform does not change, it is determined that the valve core has not moved effectively. The voltage change ΔV observed by the oscilloscope is H Satisfies the relationship: ； Where, It is the output signal of the Hall element after the on-off switch operation. This is the Hall element output signal before the on-off switch is operated.

2. The method for monitoring the position of a solenoid directional valve core according to claim 1, wherein: The test results are evaluated using the signal-to-noise ratio, where the signal-to-noise ratio satisfies the formula: ； Where, is the signal-to-noise ratio, is the magnetic field sensitivity, The magnetic field changes caused by the movement of the valve core. is the system noise voltage, including circuit noise and oscilloscope noise floor.

3. The method for monitoring the position of a solenoid directional valve core according to claim 2, wherein: Magnetic field sensitivity Satisfies the formula: ； Where, is the magnetic field sensitivity, is the output signal of the Hall voltage, is the magnetic induction intensity perpendicular to the element, is the control current through the Hall element, is the Hall coefficient, which is determined by the material, is the thickness of the Hall element.

4. The method for monitoring the position of a solenoid directional valve core according to claim 3, wherein: Hall voltage output signal Satisfies the formula: ； Where, is the output signal of the Hall voltage, is the control current through the Hall element, is the magnetic induction intensity perpendicular to the Hall element, is the Hall coefficient, which is determined by the material, is the thickness of the Hall element.

5. The method for monitoring the position of a solenoid directional valve core according to claim 1, wherein: In step S5, the Hall element outputs a Hall voltage signal V based on the output time series. H (t) Perform signal processing to extract the movement speed and displacement information of the valve core. The movement speed of the valve core satisfies the formula: ； The displacement of the valve core satisfies the formula: ； Where, is the Hall voltage output signal based on the output time series, is the movement speed of the valve core, is the displacement of the valve core, It is the system conversion coefficient determined by the valve core structure and Hall device characteristics.

6. The method for monitoring the position of a solenoid directional valve core according to claim 1, wherein: Step S3 includes detecting the magnetic field verification of the valve core movement, which specifically includes the following sub-steps: S31: Place the Hall element close to the valve core of the solenoid directional valve to ensure that it is stable and does not interfere with the normal movement of the valve core; S32: Close the on-off switch to energize the electromagnetic directional valve, and the Hall element begins to detect the magnetic field signal; S33: Fix the Hall element at the reference position on the axial side of the electromagnetic coil close to the valve core, record the peak value of the collected magnetic field signal through an oscilloscope, repeatedly move the position of the Hall element to obtain a square wave signal, which is the current position of the valve core, thereby verifying the magnetic field experiment of the valve core movement.

7. The method for monitoring the position of a solenoid directional valve core according to claim 1, wherein: Step S4 specifically includes the following sub-steps: S41: Check the status of the on-off switch and whether the circuit connection between the on-off switch and the solenoid directional valve is normal. If normal, proceed to step S2. If abnormal, check each component step by step, adjust the wiring position or fix the loose terminals, clean the switch contacts, remove oxides or impurities, replace the switch element or related connecting devices, reinforce or re-solder the wires or contacts to ensure mechanical stability, adjust the contact pressure of the power terminal to ensure stable voltage supply during switching, and detect the circuit for short circuit or open circuit to eliminate potential circuit abnormalities; S42: Close the on-off switch to energize the electromagnetic directional valve, adjust the oscilloscope parameters and press the acquisition button to start recording the magnetic field change signal; S43: Observe the magnetic field change signal waveform displayed on the oscilloscope to check whether the rising edge corresponding to the magnetic field enhancement detected by the Hall element when the power is on and the falling edge corresponding to the magnetic field weakening detected when the power is off are obvious. The judgment is based on analyzing the magnetic field signal waveform recorded by the oscilloscope, measuring the rising edge amplitude ΔVrise when the power is on and the falling edge amplitude ΔVfall when the power is off. If ΔVrise and ΔVfall are both greater than the judgment threshold Vh, then the rising edge corresponding to the magnetic field enhancement detected by the Hall element and the falling edge corresponding to the magnetic field weakening detected when the power is off are obvious. If ΔVrise or ΔVfall is less than the judgment threshold Vh, then the rising edge corresponding to the magnetic field enhancement detected by the Hall element and the falling edge corresponding to the magnetic field weakening detected when the power is off are not obvious. The threshold Vh is set to 15% of the initial value of the magnetic field change signal waveform amplitude. S44: Compare and analyze the waveforms of the magnetic field change signals when the power is on and off to confirm whether the magnetic field change caused by the power on and off can be detected. If so, execute step S4; if not, execute step S1.

8. The method for monitoring the position of a solenoid directional valve core according to claim 1, wherein: The Hall element is mounted on the outer shell surface of the electromagnetic directional valve and is arranged in a relatively fixed position with respect to the axial direction of the valve core of the electromagnetic directional valve and the radial direction of the valve core of the electromagnetic directional valve.

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