Electromagnetic valve guide head high-precision self-adaptive test control method

Abstract

The invention relates to a high-precision self-adaptive test control method for an electromagnetic valve guide head. The method comprises the steps that S1, a controller applies a driving voltage with a preset slope to the electromagnetic valve guide head through a control circuit; s2, in the process of applying the driving voltage, current flowing through the guide head coil is monitored in real time; s3, when it is detected that the current jumps remarkably, the moment when a movable iron core of the guide head starts to act is judged; and S4, taking the moment when the movable iron core starts to act as a timing starting point, and controlling the guide head to maintain the power-on state for a preset effective ventilation time. The device has the advantages that the actual action time of the movable iron core of the electromagnetic valve guide head can be accurately detected, ventilation time control is carried out on the basis, the device can automatically adapt to guide heads in different performance states including aging and abrasion, and it is ensured that the effective ventilation time of opening each time is constant, so that the control precision is greatly improved, and the service life of the guide head is accurately tested.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electromagnetic valve guide head detection systems, and in particular to an electromagnetic valve guide head high-precision adaptive test control method. BACKGROUND

[0002] At present, the electromagnetic valve guide head is one of the key components of the electromagnetic valve, mainly responsible for driving the valve core to act under the action of electromagnetic force, thereby controlling the on-off or flow direction of the fluid, and is the core component for controlling the opening and closing of the electromagnetic valve. Therefore, testing its performance in the industry is a key link to ensure the reliability and service life of the electromagnetic valve.

[0003] At present, the performance of the electromagnetic valve guide head is usually tested by using a PWM control method. The core of PWM control of the electromagnetic valve is to control the average current of the coil by adjusting the duty cycle, thereby realizing the control of the opening and closing of the valve core. The basic principle is that the electromagnetic valve coil is an RL circuit, and the current change is determined by the time constant τ=L / R. PWM adjusts the average value of the voltage by quickly switching, such as MOSFET, to make the coil current change approximately linearly.

[0004] Although the above-mentioned PWM control method can achieve relatively accurate control, however, since the electromagnetic valve guide head is a mechanical structure, in the long-term use process, it will cause the response characteristics to drift due to factors such as wear, increased friction, or changes in the travel of the moving iron core. For example, when the same PWM signal is applied, the time required for the guide head to actually open from power-on, i.e. the "static time", will be prolonged with the performance degradation, thereby causing the actual air time to be shortened, which seriously affects the control accuracy. Especially in application scenarios that require high-precision pneumatic control, such errors are unacceptable. In addition, the traditional scheme lacks the ability to perceive the actual action time of the guide head, and cannot dynamically adapt to the guide head in different states, resulting in poor system robustness and limited service life. SUMMARY

[0005] The application provides an electromagnetic valve guide head high-precision adaptive test control method, which can accurately detect the actual action time of the moving iron core of the electromagnetic valve guide head, and control the air time based on this, can automatically adapt to guide heads in different performance states including aging and wear, ensure the constant effective air time of each opening, and greatly improve the control accuracy and the effect of accurately testing the service life of the guide head.

[0006] The electromagnetic valve guide head high-precision adaptive test control method provided by the application adopts the following technical scheme: An electromagnetic valve guide head high-precision adaptive test control method, comprising: S1, a controller applies a driving voltage with a predetermined slope to the electromagnetic valve guide head through a control circuit; S2, during the application of the driving voltage, the current flowing through the coil of the guide head is monitored in real time; S3, determining the moment when the moving iron core of the guide head starts to act when a significant jump of the current is detected; S4, taking the moment when the moving iron core starts to act as the timing starting point, and controlling the guide head to maintain the energized state for a preset effective ventilation time.

[0007] Preferably, the significant jump refers to a stepwise rise or fall of the current value in unit time exceeding a preset threshold, which is caused by the inductance mutation of the coil due to the movement of the moving iron core in the magnetic field.

[0008] Preferably, the voltage slope is a linear rising slope, which is used to ensure that the guide head is in a controllable excitation establishment process before acting, avoiding instantaneous large current impact.

[0009] Preferably, the control circuit comprises: a control signal input end for receiving a control signal; a transistor Q4 connected to the control signal input end and turned on when receiving the control signal; a pull-up resistor R6, a transistor Q3 and an operational amplifier U, when there is no control signal, the transistor Q4 does not work, at this time the transistor Q3 is turned on by the pull-up resistor R6, so that the inverting input end 3 pin of the operational amplifier U is at low level; a charging module containing a resistor R2 and a capacitor C4, when Q4 is turned on, the power supply VCC charges C4 through R2, making the voltage of the inverting input end 3 pin of the operational amplifier U rise linearly; a power transistor Q2, whose base is connected to the output end 4 pin of the operational amplifier U, and the current on the measured guide head is controlled according to the change of the output voltage of the operational amplifier U; a current detection resistor R5 located in the current path of the measured guide head, for monitoring the current change in the guide head; a feedback mechanism module including a capacitor C2 and a transistor Q1, when the current mutation caused by the action of the guide head produces a voltage mutation on the current detection resistor R5, the mutation signal triggers a signal output through the operational amplifier U, and the transistor Q1 is turned on through the capacitor C2 to output a feedback signal.

[0010] Preferably, the significant jump waveform is sampled, and at least one of its amplitude, along steepness or high frequency oscillation characteristics is analyzed to evaluate the health status of the guide head; when the evaluated health status is lower than a preset threshold, a fault warning signal is output or the effective ventilation time is adjusted.

[0011] Preferably, the controller collects the voltage across the coil and the loop current while applying the driving voltage with the predetermined slope, calculates the instantaneous impedance Z(t)=V(t) / I(t), and performs short-time Fourier transform or wavelet analysis to extract the following features: The first derivative of the current mutation point ΔI / Δt; The 5-50 kHz high-frequency damped oscillation generated at the action moment is excited by the magnetic circuit mutation; The deviation of the steady-state current after the action from the theoretical value reflects the coil aging or contact resistance change; The deviation of the action delay time T from the historical data.

[0012] Preferably, the slope is adjusted in real time according to the collected ambient temperature, historical action time, and power supply voltage; if the delay of the previous action exceeds a preset value, the slope is increased in the next action; if the current overshoot or oscillation is too strong, the slope is reduced to reduce mechanical impact.

[0013] Preferably, in the non-working period, a microampere standby mode is entered, and when a start instruction is received, a pre-excitation pulse is applied to excite the initial magnetization state of the guide head, and then the ramp drive is started.

[0014] In summary, the present application includes at least one of the following beneficial technical effects: By continuously increasing the voltage of the guide head, the guide head moving iron core has not yet acted, and the control circuit is linearly rising. When the guide head moving iron core acts, the iron core moves in the magnetic field to cause a relatively large jump in the circuit current. The electronic detection circuit obtains the starting point of the guide head action by detecting the jump signal, solves the problem of pre-debugging process caused by inconsistent performance of electromagnetic valve guide heads, greatly improves the control precision of the guide head, and greatly prolongs the service life of the guide head. The product performance and service life are greatly improved. By sampling the significant jump waveform and analyzing at least one of its amplitude, steepness, or high-frequency oscillation characteristics, the health status of the guide head is evaluated. When the evaluated health status is lower than a preset threshold, a fault warning signal or an effective ventilation time is output; Even if the current amplitude is disturbed, as long as the high-frequency oscillation exists, it can be confirmed that it is a real action, which greatly improves the detection robustness. The basis for fault diagnosis is that the oscillation frequency is downshifted, indicating that the spring is fatigued; the oscillation decay is slowed down, indicating that the damping is reduced or the lubrication is abnormal or the structure is loose; and there is no oscillation, indicating that the armature is stuck; Therefore, by calculating the deviation of the steady-state current after the action from the theoretical value, the coil aging or contact resistance change can be reflected, and the coil aging, poor contact, or temperature rise effect can be monitored. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a flowchart of the first embodiment of the present application; Figure 2 is a circuit diagram of the control circuit of the first embodiment of the present application; Figure 3 is a flowchart of the second embodiment of the present application. Detailed Implementation

[0016] The present application will be further described in detail below with reference to the accompanying drawings.

[0017] This application discloses a high-precision adaptive test and control method for solenoid valve guides. Example

[0018] Reference Figure 1 The high-precision adaptive test and control method for solenoid valve guides includes: S1. The controller applies a drive with a predetermined slope to the solenoid valve guide through the control circuit. Voltage; S2. During the application of the driving voltage, monitor the current flowing through the lead coil in real time; S3. When a significant current jump is detected, it is determined that the moving iron core of the conductor has started to move. The moment; S4. Using the moment when the moving iron core begins to move as the starting point of the timing, control the conductor to maintain the energized state. Continue for a preset effective ventilation time.

[0019] A significant jump refers to a sudden increase or decrease in current value exceeding a preset threshold within a unit of time. This jump is caused by a sudden change in coil inductance due to the movement of the moving iron core in the magnetic field. The voltage slope is a linear rising slope, used to ensure that the conductor is in a controllable excitation setup process before actuation, avoiding instantaneous large current surges. The controller applies a drive voltage to the conductor coil at a preset voltage slope. During this process, the coil current increases slowly with the voltage increase. When the moving iron core has not yet actuated, the coil inductance is basically constant, and the current increases linearly; once the moving iron core begins to move, its displacement in the magnetic field will cause a sudden change in magnetic circuit inductance, resulting in a significant jump in coil current, usually manifested as a sharp drop in current growth rate or the appearance of an inflection point.

[0020] By capturing this transition signal using a high-precision current detection circuit, the start time of the guide head's action can be accurately determined. Subsequently, the system starts timing from this moment and maintains the energized state for a preset effective ventilation time, such as 8ms, ensuring that the actual gas flow time remains constant each time it is turned on.

[0021] The original PWM control method was: 10ms for power-on and 10ms for power-off. The first 2ms of power-on was the voltage rise period, and the moving iron core of the guide was in a stationary state, so the actual air passage time was 8ms. When the performance of the guide decreased, the stationary time became 3ms, so the air passage time also decreased from the original 8ms to 7ms, which led to the error.

[0022] The scheme of the application detects the action time of the guide head to take the guide head action point as the reference, regardless of the static time of the guide head being 2ms or 3ms, and uniformly maintains the energized state for a preset effective ventilation time, so as to ensure that the actual gas flow time of each opening is constant, and thus the error caused by the performance decline of the guide head can be effectively solved.

[0023] As shown in the figure, the control circuit comprises: a control signal input end for receiving a control signal; a transistor Q4, the input end of which is connected to the control signal input end and is turned on when the control signal is received; a pull-up resistor R6 and a transistor Q3, the transistor Q3 being NPN type, the base of the transistor Q3 being connected to the collector of the transistor Q4, the transistor Q4 being not working and being in the off state when there is no control signal, the transistor Q3 being turned on by the pull-up resistor R6 at this time, and the inverting input end 3 pin of the operational amplifier U being in the low level; a charging module comprising a resistor R2 and a capacitor C4, the capacitor C4 being charged by the power supply VCC through the resistor R2 when the transistor Q4 is turned on, so that the voltage line of the inverting input end 3 pin of the operational amplifier U is linearly raised; and a power transistor Q2, the base of which is connected to the output end 4 pin of the operational amplifier U, and the current on the measured guide head is controlled according to the change of the output voltage of the operational amplifier U.

[0024] The control circuit further comprises: a current detection resistor R5, which is located in the current path of the measured guide head and is used for monitoring the current change in the guide head; and a feedback mechanism module comprising a capacitor C2 and a transistor Q1, the transistor Q1 being PNP type, and the capacitor C2 being connected to the base of the transistor Q1 and the output end 4 pin of the operational amplifier U, when the current is suddenly changed due to the action of the guide head and a voltage mutation is generated on the current detection resistor R5, the mutation signal is output by the operational amplifier U to trigger a signal, and the transistor Q1 is turned on through the capacitor C2 to output a feedback signal, so that the signal detection of the guide head action is completed, the signal can be detected as long as the guide head moving core moves without the need of detecting whether the guide head moves through the gas pressure, the detection speed is greatly improved, and the application has very high practical value for high-speed detection.

[0025] By giving the guide head a rising voltage, the guide head moving core has a linear rise before the guide head moving core moves, and after the guide head moving core moves, the core moves in the magnetic field to cause a large jump of the circuit current, and the electronic detection circuit detects the jump signal to obtain the starting point of the guide head action and realize the action detection of the guide head.

[0026] The application solves the pre-debugging process caused by the performance inconsistency of the electromagnetic valve guide head, greatly improves the guide head control precision and the service life of the guide head in a large range, and greatly improves the product performance and service life. Embodiment

[0027] Different from the embodiment one, The electromagnetic valve guide head is essentially an electromechanical coupling system: coil energization generates a magnetic field → the magnetic field attracts the moving iron core → the armature overcomes the spring force and friction force to move → opens the gas path. At the moment when the moving iron core starts to move, the following measurable electrical mutations will be caused: inductance mutation, the movement of the iron core changes the magnetic resistance of the magnetic circuit, resulting in a sudden drop in the equivalent inductance L of the coil; back electromotive force change, manifested as a jump in the slope of the current curve; mechanical-electromagnetic coupling oscillation, the iron core hits the valve seat or is affected by the spring / friction force in motion, which will produce slight vibration, these mechanical vibrations will modulate the magnetic field, and then excite high-frequency damped oscillation of 5-100 kHz in the current signal; energy consumption difference, a guide head with severe wear needs more force to start, and the current jump amplitude at the action moment may be abnormal.

[0028] To solve the above problems, at least one of the amplitude, steepness or high-frequency oscillation characteristics of the significant jump waveform is analyzed to evaluate the health status of the guide head; when the evaluated health status is lower than a preset threshold, a fault warning signal is output or the effective ventilation time is adjusted.

[0029] The specific operation method is: more than 50,000 samples per second are taken to ensure that microsecond-level jumps and tens of kHz oscillations can be captured completely. A short high-speed acquisition window such as 5ms is opened after applying a ramp voltage, covering the whole process from power-on to action completion. The current signal is obtained through a high-precision, low-temperature-drift sampling resistor such as 0.1Ω±0.1%, and is sent to the processor through a differential amplifier. Then the sliding window difference method or the first derivative method is used to quickly locate the inflection point of the current curve, and fine analysis is performed in the window of ±0.2ms around the initial positioning point.

[0030] The amplitude extraction method of the jump waveform is to calculate the difference between the steady-state currents before and after the jump: a difference less than a reference value indicates a coil turn-to-turn short circuit or magnetic circuit aging; a difference greater than a reference value indicates mechanical jamming or a dramatic increase in friction. The extraction method of the steepness is to calculate the average slope of the jump: a significant decrease in the slope value indicates that the armature movement is slow, and an abnormal increase in the slope value indicates that the spring pre-tightening force is too large or the residual magnetism is abnormal. The extraction method of the high-frequency oscillation characteristic is to perform short-time Fourier transform or wavelet packet decomposition on the signal after the jump, and extract the main oscillation frequency, the decay time constant, and the oscillation energy. A decrease in the main oscillation frequency indicates a decrease in spring stiffness, an extension of the decay time constant indicates a decrease in damping, and an excessive lubrication or structural loosening. An abnormal increase in oscillation energy indicates an increase in impact and a large guide gap.

[0031] During the guide head factory shipment or initial operation stage, 10-20 normal action data are collected, the mean μ and standard deviation σ of each feature are calculated as the health baseline. When the evaluated health status is lower than a preset threshold, a fault warning signal is output or the effective ventilation time is adjusted.

[0032] The controller collects the voltage across the coil and the loop current while applying the predetermined slope of the drive voltage, calculates the instantaneous impedance Z(t) = V(t) / I(t), and performs short-time Fourier transform or wavelet analysis to extract the following features: current first derivative sudden change point (ΔI / Δt); 5-50 kHz high-frequency damped oscillation excited by magnetic path mutation at the moment of action; deviation of steady-state current after action from the theoretical value to reflect coil aging or contact resistance change; deviation of action delay time T from historical data.

[0033] When the moving iron core is not in action, the coil is a pure inductive load, and the current rises smoothly, and dI / dt is constant; once the iron core moves, the inductance L drops suddenly, and when V and R are constant, dI / dt increases, which is manifested as a sudden increase in the rising slope of the current curve or the appearance of an inflection point. This point is the real action time. Compared with the first embodiment, it can provide higher time resolution and achieve microsecond-level action detection.

[0034] The acceleration change at the moment of iron core start will excite the natural frequency oscillation of the electromagnetic-mechanical coupling system. This oscillation has a specific frequency band of 5-50 kHz, while power noise, switching interference, etc. are mostly low-frequency or broadband white noise. Therefore, the 5-50 kHz high-frequency damped oscillation excited by the magnetic path mutation can identify the real mechanical action, suppress electrical noise misjudgment, and evaluate the mechanical structure state. Even if the current amplitude is disturbed, as long as the high-frequency oscillation exists, it can be confirmed that it is a real action, greatly improving the detection robustness. The basis for fault diagnosis is that: downward shift of oscillation frequency indicates spring fatigue; slow oscillation decay indicates reduced damping or abnormal lubrication or structural looseness; no oscillation indicates that the armature is stuck.

[0035] After the action is completed, the coil enters a steady state, and if the measured value of the steady-state current deviates from the theoretical value continuously, it indicates that the following situations exist: high current indicates that the coil has local short-circuit turn-to-turn insulation failure; low current indicates that the contact resistance increases or the coil is broken; abnormal temperature drift indicates that the insulation material aging leads to the decrease of thermal stability. Therefore, by calculating the deviation of the steady-state current after action from the theoretical value, the coil aging or contact resistance change can be reflected, and the coil aging, poor contact or temperature rise effect can be monitored.

[0036] The action delay time T = action time - power-on starting time. The increase of T directly reflects the increase of friction, the increase of residual magnetism or the change of spring force. The single T value may fluctuate, but the monotone increase of the continuous 5 T values by more than 10% can be an early warning of "accelerated wear". The increment ΔT of T is used as a feedforward quantity to dynamically increase the slope of the next drive voltage or prolong the effective ventilation time, actively offsetting performance drift and maintaining constant flow, so as to quantify the performance degradation trend and drive adaptive control.

[0037] The solenoid guide head increases friction and accumulates residual magnetism with use time, causing the action delay time to gradually increase, thereby causing the effective ventilation time to be shortened. The slope is adjusted in real time according to the collected ambient temperature, historical action time, and power supply voltage; if the action delay of the previous round exceeds the preset value, the slope is increased in the next round; if the current overshoot or oscillation is too strong, the slope is reduced to reduce mechanical impact.

[0038] If the action delay of the previous round exceeds the preset threshold, it indicates that the guide head is becoming blunt, at which time the system will automatically increase the voltage rising slope in the next round, for example, from 4V / ms to 5V / ms, so that the magnetic field is established faster, thereby actively shortening the excitation time and pulling the action delay back to the normal range. The control accuracy is constant throughout the life cycle, and even if the guide head is aged by 50%, the flow output fluctuation is still <±0.2ms. The built-in temperature sensor and voltage monitoring circuit automatically increase the slope at low temperature or low voltage, and moderately reduce the slope at high temperature to prevent overheating.

[0039] The moving and static iron cores of the solenoid guide head are usually made of soft magnetic material. After the coil is powered off, a part of the material inside will remain magnetic. The residual magnetism will generate an additional biasing force. If the direction of the residual magnetism is consistent with the next time of attraction, the action will be faster, and if the direction of the residual magnetism is opposite, a magnetic resistance will be formed, causing the action to be significantly delayed, and even the first time cannot be attracted. Therefore, in the non-working period, enter the microamp standby mode, when receiving the opening instruction, first apply a pre-excitation pulse to excite the initial magnetization state of the guide head, and then start the slope driving. Before the formal slope driving, a short-time, low-energy unipolar pulse is applied, the function of the pulse is not to drive the iron core to move, but to force the magnetization state of the iron core material to a known and repeatable initial point, thereby eliminating the random influence of historical residual magnetism, and further improving the accuracy of test data, solving the problem of inaccurate first opening, the iron core moves more smoothly, and reduces the mechanical impact of the first opening.

[0040] The above are preferred embodiments of the present application, which do not limit the protection scope of the present application, therefore: any equivalent changes made on the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A high-precision adaptive test and control method for a solenoid valve guide, characterized in that, include: S1. The controller applies a driving voltage with a predetermined slope to the solenoid valve guide through the control circuit. S2. During the application of the driving voltage, the current flowing through the lead coil is monitored in real time; S3. When a significant jump in the current is detected, it is determined to be the moment when the moving iron core of the conductor begins to operate; S4. Taking the moment when the moving iron core begins to operate as the starting point of the timing, control the guide head to maintain the energized state for a preset effective ventilation time.

2. The high-precision adaptive test and control method for the solenoid valve guide head according to claim 1, characterized in that: The significant jump refers to a step increase or decrease in the current value exceeding a preset threshold within a unit time. This jump is caused by a sudden change in the coil inductance due to the movement of the moving iron core in the magnetic field.

3. The high-precision adaptive test and control method for the solenoid valve guide head according to claim 2, characterized in that: The voltage slope is a linear rising slope, used to ensure that the conductor is in a controllable excitation establishment process before operation, avoiding instantaneous large current surges.

4. The high-precision adaptive test and control method for the solenoid valve guide head according to claim 3, characterized in that, The control circuit includes: The control signal input terminal is used to receive control signals; Transistor Q4 is connected to the control signal input terminal and turns on when a control signal is received; Pull-up resistor R6, transistor Q3, and operational amplifier U. When there is no control signal, transistor Q4 does not work, and transistor Q3 is turned on by pull-up resistor R6, so that the inverting input terminal 3 of operational amplifier U is at a low level. The charging module includes a resistor R2 and a capacitor C4. When Q4 is turned on, the power supply VCC charges C4 through R2, causing the voltage at pin 3 of the inverting input of the operational amplifier U to rise linearly. The power transistor Q2 has its base connected to pin 4 of the operational amplifier U. The current on the test lead is controlled by the change in the output voltage of the operational amplifier U. The current sensing resistor R5 is located in the current path of the conductor being tested and is used to monitor the current change in the conductor. The feedback mechanism module includes capacitor C2 and transistor Q1. When the current changes abruptly due to the action of the lead, and a voltage change occurs across the current sensing resistor R5, the change signal is triggered by the operational amplifier U to output a trigger signal, which in turn triggers transistor Q1 to conduct via capacitor C2 to output a feedback signal.

5. The high-precision adaptive test and control method for the solenoid valve guide head according to claim 1, characterized in that: The waveform with significant jumps is sampled, and its amplitude, steepness, or high-frequency oscillation characteristics are analyzed to assess the health status of the probe; when the assessed health status is lower than a preset threshold, a fault warning signal is output or the effective ventilation time is adjusted.

6. The high-precision adaptive test and control method for the solenoid valve guide head according to claim 5, characterized in that: While applying a driving voltage with a predetermined slope, the controller acquires the voltage across the coil and the loop current, calculates the instantaneous impedance Z(t) = V(t) / I(t), and performs short-time Fourier transform or wavelet analysis to extract the following features: The point of abrupt change in the first derivative of the current is ΔI / Δt; The 5–50 kHz high-frequency decaying oscillation generated at the moment of action is excited by a sudden change in the magnetic circuit; The deviation between the steady-state current after operation and the theoretical value is used to reflect coil aging or changes in contact resistance. The deviation of the action delay time T from historical data.

7. The high-precision adaptive test and control method for the solenoid valve guide according to claim 6, characterized in that: The slope is adjusted in real time based on the collected ambient temperature, historical action time, and power supply voltage. If the delay of the previous action exceeds the preset value, the slope is increased in the next action. If current overshoot or excessive oscillation is detected, the slope is reduced to reduce mechanical shock.

8. The high-precision adaptive test and control method for the solenoid valve guide according to claim 7, characterized in that: During non-working cycles, it enters microampere-level standby mode. When a power-on command is received, a pre-excitation pulse is first applied to excite the initial magnetization state of the guide head, and then the ramp drive is started.

Images