Pressure valve dual closed loop control system

Abstract

The application discloses a pressure valve double closed loop control system, and relates to the technical field of pneumatic control.The pressure valve double closed loop control system comprises a driving plate, a main control plate, a display plate and a valve body assembly.The driving plate is used for supplying power for a pressure sensor and a pilot valve and outputting a PWM control signal to the pilot valve.The main control plate receives a real-time measurement signal of the pressure sensor and generates an instruction signal for adjusting the PWM duty cycle of the pilot valve based on double closed loop control.The double closed loop control comprises an outer closed loop and an inner closed loop.The outer closed loop generates an inner closed loop target value based on the error between the real-time measurement value of a working port pressure sensor and a user set value.The inner closed loop generates a PWM control signal of the pilot valve.The display plate is used for setting a target pressure value and displaying pressure data in real time.The valve body assembly realizes the opening and closing control of a main valve port in response to the change of a pilot cavity pressure.Through the adoption of the double closed loop control system combined with a PID algorithm and a feedforward formula, the system can accurately maintain the target pressure value, and the accuracy is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pneumatic control, in particular to a pressure valve double closed-loop control system. BACKGROUND

[0002] The pressure regulating valve in the prior art is mainly controlled manually, and its shortcomings include low control accuracy, slow response time, pressure compensation hysteresis and high installation cost.

[0003] In addition, the existing electric control pressure regulating valve on the market has the problems of unstable control and unreasonable control mode, and is prone to pressure oscillation in specific application occasions, thereby limiting the application range of the electric control pressure regulating valve. SUMMARY

[0004] To solve the above problems, the present application provides a pressure control system which innovates the pressure control system by standardizing the electric control proportional valve signal processing process and adopting a double closed-loop controller structure in the controller logic design, to realize stable and accurate pressure control.

[0005] The present application provides a pressure valve double closed-loop control system, comprising:

[0006] A drive board for supplying power to the pressure sensor and the pilot valve and outputting a PWM control signal to the pilot valve;

[0007] A main control board receiving real-time measurement signals of the pressure sensor, generating an instruction signal for adjusting the PWM duty cycle of the pilot valve based on double closed-loop control; the double closed-loop control includes an outer closed loop and an inner closed loop; the outer closed loop generates an inner closed loop target value based on the error between the real-time measurement value of the working port pressure sensor and the user set value based on the PID algorithm; the inner closed loop generates a PWM control signal of the pilot valve based on the error between the real-time measurement value of the pilot cavity pressure sensor and the inner closed loop target value superimposed with the feedforward formula based on the PID algorithm combined with a switching function;

[0008] A display board for setting a target pressure value and displaying pressure data in real time;

[0009] A valve body assembly connected with the drive board, realizing the opening and closing control of the main valve port in response to the pressure change of the pilot cavity.

[0010] The main control board comprises a main control MCU module, a power conversion module, an input / output signal processing module, a pressure sensor module and an electromagnetic valve driving module; the pressure sensor module comprises sensors for monitoring the pressures of the working port and the pilot cavity respectively, and the output signals of the pressure sensors are input to the main control MCU module after low-pass filtering.

[0011] The feedforward formula is: ; wherein, is the pilot cavity feedforward set pressure, A1 is the target working pressure value, A2 is the working pressure area, and F1 and F2 are the sum of the external forces when the diaphragm moves to open the exhaust port and the intake port, respectively.

[0012] The switching function is a continuous hyperbolic tangent function: ;in, Here, b is the calculated value for the continuous switching function, b is the amplitude set based on the pilot valve switching time and the PWM period, and k is the slope. This is the error value.

[0013] Specifically, the magnitude b of the switching function is adjusted to avoid the dead zone of PWM duty cycle control.

[0014] In the PID algorithm:

[0015] The integral feedback section is equipped with an integral saturator to limit the integral output range;

[0016] The differential feedback section is equipped with a differential low-pass filter to suppress noise amplification.

[0017] The drive board controls the pilot valve, which includes an intake pilot valve and an exhaust pilot valve. The inflation rate and exhaust rate of the pilot chamber are controlled by adjusting the PWM duty cycle of the two valves respectively.

[0018] The valve body assembly includes:

[0019] The valve core assembly and the valve seat assembly together constitute the piston movement structure;

[0020] The diaphragm assembly and the diaphragm spring are linked together to drive the main valve port to open and close in response to changes in pilot chamber pressure.

[0021] The system includes a main air inlet, a working port, and an exhaust port. The main air inlet is used to connect to a high-pressure air source, the working port is used to connect to a controlled air chamber, and the exhaust port is used to discharge gas into the atmosphere.

[0022] The valve core assembly and valve seat assembly form a series sealing structure based on interference fit, with the main air inlet and working port normally closed, and the working port and exhaust port normally open.

[0023] The duty cycle of the PWM control signal is limited to -100% to 100% by a normalized saturator, where a positive value corresponds to the intake pilot valve and a negative value corresponds to the exhaust pilot valve.

[0024] Due to the adoption of the above technical solution, this application has at least one of the following beneficial effects compared with the prior art:

[0025] 1. By adopting a double closed-loop control system (outer closed loop and inner closed loop), combining PID algorithm and feedforward formula, the system can accurately maintain the target pressure value, significantly improving the accuracy of air pressure control.

[0026] 2. By using double closed-loop control structure and adding switching function in the inner closed loop, the air pressure oscillation phenomenon caused by external interference and other factors can be effectively avoided, ensuring stable operation of the system.

[0027] 3. By introducing the feedforward formula to adjust the target setting value of the inner closed loop, and flexibly adjusting the parameters of the switching function according to actual needs, the demand for outer closed loop control quantity can be reduced.

[0028] 4. The design method of combining control logic with mechanical characteristics not only helps to simplify the subsequent parameter adjustment process, but also makes the operation of the entire system more intuitive and easy to understand. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating creative labor. Among them:

[0030] Figure 1 A frame diagram of a pressure valve double closed-loop control system provided by the present application;

[0031] Figure 2 A frame diagram of an embodiment of double closed-loop control provided by the present application;

[0032] Figure 3 A longitudinal sectional view of an embodiment of the pressure valve double closed-loop control device provided by the present application;

[0033] Figure 4 An external view of the pressure valve double closed-loop control device in Figure 3

[0034] Figure 5 A frame diagram of an embodiment of the main control board provided by the present application.

[0035] In the figure: valve housing 101, valve seat assembly 102, valve core assembly 103, diaphragm assembly 104, valve plate assembly 105, main air inlet 1, working port 2, exhaust port 3, valve stem seal 4, housing sealing structure 5, valve core sealing structure 6, valve seat sealing element 7, diaphragm 8, valve core spring 9, diaphragm spring 10, display circuit board 11, control circuit board 12, drive circuit board 13, pilot valve 14, pressure sensor chip 15. ​DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, only parts related to the present application are shown in the drawings, but not all structures. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0037] The terms "first", "second", and the like in the present application are used to distinguish different objects, and are not used to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units not listed, or optionally includes other steps or units inherent to the process, method, product or device.

[0038] Reference herein to "embodiments" means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily all refer to the same embodiments, nor is it necessarily independent or alternative embodiments to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] The pressure regulating valve in the prior art mainly relies on manual control, and has problems of low control accuracy, slow response time, pressure compensation hysteresis, high installation cost, etc. At the same time, the electric control pressure regulating valve on the market also faces the situation of unstable control and unreasonable control mode, and is easy to produce air pressure oscillation in specific application occasions, which limits its application range. The electric control pilot pressure valve double closed loop control system proposed in the present application, by adopting advanced double closed loop control logic and feedforward formula, combined with accurate PWM signal regulation and control mechanism, not only improves the accuracy of pressure control and the stability of the system, but also effectively avoids the air pressure oscillation phenomenon; as shown in Figure 1 , Figure 1 A frame schematic diagram of a pressure valve double closed loop control system provided in the present application, including a driving board, a main control board, a display board and a valve body assembly.

[0040] The drive board is responsible for providing the necessary power support for the pressure sensors and pilot valves in the system. For example, in an electric proportional valve system, the drive board powers two pressure sensors that monitor the gas pressure in the working port and the pilot chamber respectively, ensuring that they can accurately measure and feedback pressure data.

[0041] The drive board generates and outputs PWM control signals to the pilot valves according to the instructions from the main control board. These PWM signals are used to adjust the action frequency and duty cycle of the pilot valves, thereby achieving precise control over the inflation and deflation rates of the pilot chamber. For example, when it is necessary to increase the pressure in the pilot chamber, the drive board will adjust the PWM signal duty cycle of the intake pilot valve so that more air enters the pilot chamber; conversely, by adjusting the PWM signal of the exhaust pilot valve, the pressure in the pilot chamber is reduced.

[0042] As shown in Figure 2 , the framework diagram of an embodiment of the double closed-loop control provided in this application is provided. Figure 2

[0043] The main control board receives real-time measurement signals from the pressure sensors, that is, the main control board obtains real-time data from two pressure sensors, one is a pressure sensor that monitors the working port, and the other is a pressure sensor that monitors the pilot chamber; the pressure sensor converts the detected pressure value into an electrical signal and transmits it to the main control board for processing.

[0044] Generate an instruction signal to adjust the PWM duty cycle of the pilot valve based on double closed-loop control; double closed-loop control includes outer loop and inner loop; the outer loop generates the inner loop target value based on the error between the real-time measurement value of the working port pressure sensor and the user set value based on the PID algorithm; the inner loop generates the PWM control signal of the pilot valve based on the error between the real-time measurement value of the pilot chamber pressure sensor and the inner loop target value superimposed with the feedforward formula based on the PID algorithm combined with the switching function; through the double closed-loop structure combined with the PID algorithm and the application of the feedforward formula, the system can maintain a highly stable output pressure in a dynamic environment, greatly improving the control accuracy.

[0045] The display board is used to set the target pressure value and display the pressure data in real time; the operator can input the desired pressure set value through the user interface on the display board; this is usually achieved through buttons or touch screens, allowing users to conveniently adjust the required working port output air pressure value.

[0046] In addition, the display board can display the data obtained from the pressure sensor in real time, including the current pressure values of the working port and the pilot chamber; the real-time data display function allows the operator to immediately see any pressure changes, which helps to quickly find and solve problems, improving the transparency of the system and the trust of the user.

[0047] As​Figures 3-4 as shown, Figure 3 Fig. 1 is a longitudinal sectional view of an embodiment of the pressure valve double closed-loop control device provided in the present application, Figure 4 as shown, Figure 3 Fig. 2 is an external view of the pressure valve double closed-loop control device provided in the present application.

[0048] The valve body assembly is connected with the drive board and realizes the opening and closing control of the main valve port in response to the change of the pilot cavity pressure. The working principle of the control device is described in detail as follows: after the main control board calculates the new PWM duty cycle based on the double closed-loop control logic, it sends the instruction to the drive board, which then outputs the corresponding PWM signal to the pilot valve. These pilot valves are responsible for adjusting the gas flow into or out of the pilot cavity, thereby changing the pressure of the pilot cavity. With the change of the pilot cavity pressure, the diaphragm assembly moves up and down under the action of the diaphragm spring, thereby causing the position of the valve core assembly relative to the valve seat assembly to change, and finally realizing the opening or closing of the passage between the main air inlet 1 and the working port 2 and between the working port 2 and the exhaust port 3.

[0049] For example, when it is necessary to increase the pressure of the controlled cavity, the main control board will instruct the drive board to increase the PWM duty cycle of the air inlet pilot valve, so that more air flows into the pilot cavity, causing the pressure of the pilot cavity to rise. This will push the diaphragm assembly to move downward, open the main valve air supply port, and make the high-pressure gas flow from the main air inlet to the working port, thereby increasing the pressure of the controlled cavity. Conversely, if it is necessary to reduce the pressure, the pressure of the pilot cavity will be reduced, causing the diaphragm assembly to move upward, closing the main valve air supply port and opening the exhaust port, allowing the gas to be discharged to reduce the pressure.

[0050] In summary, the pressure valve double closed-loop control system of the present embodiment comprises: a drive board for supplying power to the pressure sensor and the pilot valve and outputting a PWM control signal to the pilot valve; a main control board receiving the real-time measurement signal of the pressure sensor and generating an instruction signal for adjusting the PWM duty cycle of the pilot valve based on double closed-loop control; the double closed-loop control includes an outer loop and an inner loop; the outer loop generates an inner loop target value based on the error between the real-time measurement value of the working port pressure sensor and the user set value based on the PID algorithm; the inner loop generates the PWM control signal of the pilot valve based on the error between the real-time measurement value of the pilot cavity pressure sensor and the inner loop target value superimposed with the feedforward formula based on the PID algorithm combined with the switching function; a display board for setting the target pressure value and displaying the pressure data in real time; a valve body assembly connected with the drive board and the main control board, realizing the opening and closing control of the main valve port in response to the change of the pilot cavity pressure; by adopting the double closed-loop control system combined with the PID algorithm and the feedforward formula, the system can accurately maintain the target pressure value, improving the accuracy.

[0051] as shown, Figure 5 as shown, Figure 5The frame schematic diagram of an embodiment of the master control board provided in the present application is shown in FIG. 1. The master control board includes a master control MCU module, a power conversion module, an input / output signal processing module, a pressure sensor module, and an electromagnetic valve driving module. The master control MCU module is the core of the entire control system, responsible for processing data from various sensors and generating PWM control signals based on a double closed-loop control algorithm. The pressure sensor module includes sensors for monitoring the pressure of the working port and the pilot chamber, respectively. The output signals of the pressure sensors are input to the master control MCU module after low-pass filtering. The power conversion module provides the required power support for each component in the system, ensuring that all components can operate under stable voltage conditions. The input / output signal processing module is responsible for receiving external input signals (such as user-set target pressure values) and sending control instructions to other components. The electromagnetic valve driving module generates PWM signals to drive the action of the pilot valve according to the instructions from the master control MCU module.

[0052] By using a specially designed pressure sensor module and combining low-pass filtering technology, unnecessary noise can be effectively filtered out, providing more accurate pressure readings and improving the overall control accuracy of the system. Integrating all necessary functions on one master control board not only simplifies hardware design, but also facilitates future maintenance and upgrade work.

[0053] In an embodiment, the feedforward formula is: wherein, PFF is the pilot chamber feedforward set pressure, Ptarget is the target working pressure, A1 is the pilot chamber action area, A2 is the working pressure action area, F1 and F2 are the sum of external forces when the diaphragm moves to open the exhaust port and the intake port, respectively; the application of the feedforward formula will be illustrated below with a specific example. Assume that we have an electrically controlled pilot pressure valve system with the following design parameters:

[0054] Working pressure action area A2 = 9 , pilot chamber action area A1 = 10 , the sum of external forces when the diaphragm moves to open the exhaust port F1 = 11 N, the sum of external forces when the diaphragm moves to open the intake port F2 = 15 N, and the target working pressure Ptarget = 6 bar; before calculation, the units need to be converted to the International System of Units, i.e. , , , ; after substituting into the above formula, we get: .

[0055] The feedforward is added to the outer closed-loop PID calculation value to adjust the set value of the inner closed-loop, so that the set value of the inner closed-loop is translated according to the physical relationship between the actual pressure value and the pilot chamber pressure value, to reduce the control amount required by the outer closed-loop to reduce the pressure error required by the customer, and to improve the response time and the stability of the control system.

[0056] In the calculation, A1 and A2 need to consider the case where the air inlet and the air outlet are both closed; F1 and F2 need to calculate the spring below the diaphragm and the spring below the air inlet seal, and do not need to calculate the friction; when calculating F1, attention should be paid to the support force of the valve seat of the air inlet seal part.

[0057] The inner closed-loop increases the switching function on the basis of the original proportional feedback and makes it continuous. The switching function should have the following characteristics:

[0058] 1. The output reaches saturation when the error is large; 2. The output direction is switched according to the sign of the error; 3. After continuous, it has multiple continuous derivatives.

[0059] The switching function is a continuous hyperbolic tangent function: ; wherein, is the calculation value of the continuous switching function part, b is the amplitude set according to the switching time of the pilot valve and the PWM period, k is the slope, which is set based on the actual required switching function slope, in this embodiment, the value of k is 10-15, is the error value.

[0060] The amplitude b of the switching function is adjusted to avoid the dead zone of PWM duty cycle control; the value of b is as follows: since the period of the PWM signal is generally high, and the switching speed of the pilot valve is limited, it generally cannot be normally opened at a low duty cycle. For example, when the PWM signal period is 50Hz and the duty cycle is less than 5%, the corresponding opening time is 1s / 50*5%=0.001s=1ms, if the opening time of the switch valve is 2ms, it cannot be normally opened within 1ms, so the switch valve will remain closed under this signal. According to the reverse calculation, it can be calculated that the dead zone of the duty cycle is 2ms / (1s / 50)=0.1=10%, that is, 10% of the duty cycle is in the control dead zone of the PWM signal. At this time, the value of b corresponding to the duty cycle should be taken as a value slightly less than 10%, for example, if the control amount has been normalized (i.e. ±100% is the control saturation amount), the value of b can be taken between 7% and 8%.

[0061] By adjusting the parameters b and k, the control strategy can be customized and optimized according to the specific application requirements. For example, increasing the value of k can make the controller more sensitive to small errors and speed up the response; and adjusting b can adapt to different hardware characteristics, such as the switching characteristics of the pilot valve and the PWM period.

[0062] Because the hyperbolic tangent function has a limited output range (-1 to +1), the output is approximately saturated when the error is large, which can stabilize the compensation of the PWM control signal dead zone; the continuous hyperbolic tangent function provides smooth and continuous output changes, which helps to reduce mechanical shocks or vibrations caused by sudden changes in the control signal, making the system run more smoothly.

[0063] In the PID algorithm: the integral feedback part is configured with an integral saturator to limit the integral output range; the integral feedback part is responsible for accumulating past error values to eliminate steady-state error. However, without proper limiting measures, the integral term may accumulate too much, leading to "integral saturation" phenomenon, and then causing system response delay or instability.

[0064] In this example, the integral feedback part is configured with an integral saturator that sets the upper and lower limits of the integral output. For example, set the integral output range to [-30, 30]. When the integral value reaches the upper limit 30 or the lower limit -30, the integral value will no longer increase or decrease even if there is further positive or negative error, thereby avoiding the problem of integral saturation.

[0065] The derivative feedback part is configured with a derivative low-pass filter to suppress noise amplification; the derivative feedback part is used to predict the future error trend and make adjustments in advance accordingly. However, direct use of the derivative operation can easily amplify high-frequency noise, affecting the stability of the system.

[0066] To suppress this noise amplification effect, a low-pass filter is added to the derivative feedback path. Suppose a simple first-order low-pass filter is selected, with a cutoff frequency set to 5Hz. This means that signal components above 5Hz will be attenuated at a rate of -20dB / 10Hz, while effective signals below 5Hz will be essentially unaffected. This helps to filter out high-frequency noise introduced by the sensor or other sources, ensuring the effectiveness and reliability of the derivative feedback.

[0067] The drive board controls the pilot valve, which includes an intake pilot valve and an exhaust pilot valve, and controls the charging rate and exhaust rate of the pilot chamber based on adjusting the corresponding PWM duty cycles of the two; suppose at a certain moment, the actual pressure of the working port is lower than the set target pressure, the main control board will first calculate the new pilot chamber target pressure, and adjust the PWM duty cycle of the intake pilot valve accordingly, so that the pressure in the pilot chamber rises, pushing the diaphragm assembly to move downward, opening the main valve gas port, so that high-pressure gas enters the controlled cavity, and finally achieves the purpose of increasing the working port pressure.

[0068] Conversely, if the actual pressure of the working port is higher than the set value, the main control board will adjust the PWM duty ratio of the exhaust pilot valve, let the gas in the pilot cavity exhaust, promote the diaphragm assembly to move upwards, close the main valve gas port and open the exhaust port, release the excess gas, and reduce the pressure of the controlled cavity.

[0069] The PWM control signal duty ratio is normalized and saturated to -100% to 100%, wherein the positive value corresponds to the intake pilot valve and the negative value corresponds to the exhaust pilot valve; all calculated PWM duty ratios are first normalized and limited by a saturator to the range of -100% to 100%. A positive value indicates the operation of the intake pilot valve, and a negative value corresponds to the operation of the exhaust pilot valve; a positive value (such as +60%) will be transmitted to the intake pilot valve, indicating an increase in the air charging rate; a negative value (such as -40%) will be transmitted to the exhaust pilot valve, indicating an increase in the exhaust rate.

[0070] The normalization process makes the control signal more standardized, facilitating the rapid and accurate execution of control instructions, and making the program more suitable for simulation programming and debugging.

[0071] The valve body assembly includes a valve core assembly 103 and a valve seat assembly 102, which constitute a piston movement structure; and a main gas inlet 1, a working port 2, and an exhaust port 3, wherein the main gas inlet 1 is used to connect a high-pressure gas source, the working port 2 is used to connect a controlled gas cavity, and the exhaust port 3 is used to discharge gas to the atmosphere.

[0072] The valve core assembly 103 and the valve seat assembly 102 form a series seal structure based on interference assembly, the main gas inlet 1 and the working port 2 are normally closed, and the working port 2 and the exhaust port 3 are normally open.

[0073] When the main valve gas supply needs to be opened, the pressure in the pilot cavity increases, pushing the diaphragm assembly 104 to move downwards; this movement drives the valve core assembly 103 to overcome the resistance of the diaphragm spring 10, causing the valve core assembly 103 to move away from the valve seat assembly 102, opening the channel between the main gas inlet 1 and the working port 2, and allowing high-pressure gas to flow into the controlled cavity.

[0074] The diaphragm assembly 104 and the diaphragm spring 10 are linked together and respond to changes in the pilot cavity pressure to drive the opening and closing of the main valve port; when the pilot cavity pressure rises, the pressure on the diaphragm assembly 104 increases, pushing it to move downwards; conversely, when the pilot cavity pressure drops, the force of the diaphragm spring 10 pushes the diaphragm assembly 104 back to its original position.

[0075] If the actual pressure of the working port is lower than the set target pressure, the main control board will calculate a new target pressure for the pilot chamber and adjust the PWM duty cycle to increase the pressure of the pilot chamber. As the pressure of the pilot chamber rises, the diaphragm assembly 104 moves downward, driving the spool assembly 103 away from the valve seat assembly 102, opening the passage between the main inlet port 1 and the working port 2, allowing high-pressure gas to enter the controlled cavity, thereby increasing the pressure of the working port.

[0076] Conversely, if the actual pressure of the working port is higher than the set value, the main control board will reduce the pressure of the pilot chamber, and the diaphragm assembly 104 will move upward under the action of the diaphragm spring 10, closing the passage between the main inlet port 1 and the working port 2, and opening the passage between the working port 2 and the exhaust port 3, releasing excess gas and reducing the pressure of the controlled cavity.

[0077] The cooperation between the components of the control device is described in detail below:

[0078] The spool assembly 103, the spool spring 9, and the valve housing 101 form a normally closed sealing structure between the main inlet port 1 and the working port 2.

[0079] The diaphragm assembly 104, the spool assembly 103, and the diaphragm spring 10 form a normally open sealing structure between the working port 2 and the exhaust port 3.

[0080] In the diaphragm assembly 104, the valve seat assembly 102 uses vulcanized rubber to form an end face sealing structure with the spool assembly 103, forming a normally open sealing structure under the action of the diaphragm spring 10.

[0081] The spool assembly 103 and the valve seat assembly 102 form a piston motion structure. The upper spool in the spool assembly 103 used for sealing with the valve seat assembly 102 and the lower spool used for sealing with the valve housing 101 are assembled by mechanical pressing.

[0082] The valve stem seal 4 is arranged between the spool assembly 103 and the valve housing 101, used to prevent high-pressure gas from the main inlet port 1 or the working port 2 from leaking along the movement path of the spool rod.

[0083] The housing sealing structure 5 is located at the connection between the valve housing 101 and the valve plate assembly 105, used to seal the pilot chamber and prevent the pressure gas in the pilot chamber from leaking to the external environment or entering the main valve chamber.

[0084] The valve seat seal 7 is arranged on the valve seat assembly 102 and cooperates with the lower spool of the spool assembly 103 to form the main sealing pair between the main inlet port 1 and the working port 2; when the main valve port is closed, the valve seat seal 7 tightly adheres to the spool assembly 103, blocking the flow of high-pressure gas from the main inlet port to the working port.

[0085] The diaphragm 8 is a core component of the diaphragm assembly 104, which separates the valve body internal space into a pilot chamber and a main valve chamber. The upper surface of the diaphragm 8 bears the pressure of the pilot chamber, and the lower surface bears the gas pressure of the working port 2 and the elastic force of the diaphragm spring 10; when the pilot chamber pressure changes, the diaphragm 8 will deform and move up and down, thereby driving the spool assembly 103 to move, thereby opening and closing the main valve port.

[0086] The entire sealing structure forms a series linkage, the main inlet port 1 is sealed and disconnected from the working port 2, the working port 2 is always open to the exhaust port 3, and the compressed air in the system is discharged through the working port 2 to the exhaust port 3; the main inlet port 1 is connected and opened to the working port 2, and the working port 2 is sealed and disconnected from the exhaust port 3, and the main inlet port 1 and the working port 2 are continuously ventilated.

[0087] The pilot valve 14 is divided into a pilot chamber inlet pilot valve and a pilot chamber exhaust pilot valve, and the two pilot valves jointly control the pressure of the pilot chamber composed of the valve plate assembly 105 and the diaphragm assembly 104, to drive the position of the diaphragm assembly 104, thereby controlling the movement of the spool assembly 103, so that the opening and closing of the main inlet port 1 to the working port 2 and the working port 2 to the exhaust port 3 are controlled.

[0088] The driving circuit board 13 supplies power to the pilot valve 14, and the pressure sensor chip 15 in the driving circuit board 13 is used to sense the pressure change of the working port 2, and the opening and closing of the pilot valve is controlled through the control circuit board 12, the pressure of the pilot chamber is controlled, and the opening and closing of the main inlet port 1 to the working port 2 is controlled to obtain stable gas pressure of the working port 2.

[0089] The display circuit board 11 serves as a human-computer interaction interface to set the output gas pressure value of the working port 2.

[0090] In several embodiments provided in the present application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are only illustrative, for example, the division of the modules or units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0091] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or they can be distributed on a plurality of network units. According to actual needs, part or all of the units can be selected to achieve the purpose of the present embodiment scheme.

[0092] In addition, each function unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software function unit.

[0093] The above is only the embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation using the content of the present application specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A pressure valve dual closed-loop control system, characterized in that, include: The driver board is used to power the pressure sensor and pilot valve, and output PWM control signals to the pilot valve; The main control board receives real-time measurement signals from the pressure sensor and generates command signals to adjust the PWM duty cycle of the pilot valve based on dual closed-loop control; the dual closed-loop control includes an outer closed loop and an inner closed loop. The outer closed loop generates the inner closed loop target value based on the error between the real-time measured value of the working port pressure sensor and the user-set value, using a PID algorithm. The inner closed loop generates the pilot valve PWM control signal based on the error between the real-time measured value of the pilot chamber pressure sensor and the inner closed loop target value superimposed with the feedforward formula, using a PID algorithm combined with a switching function. The feedforward formula is: ;in, Set the pressure for the pilot cavity feedforward. The target working pressure is A1, the pilot chamber area is A2, the working pressure area is F1 and F2 are the sum of the external forces when the diaphragm moves to open the exhaust port and the intake port, respectively. The switching function is a continuous hyperbolic tangent function: ;in, Here, b is the calculated value for the continuous switching function, b is the amplitude set based on the pilot valve switching time and the PWM period, and k is the slope. This is the error value; In the PID algorithm: The integral feedback section is equipped with an integral saturator to limit the integral output range; The differential feedback section is equipped with a differential low-pass filter to suppress noise amplification; The display panel is used to set the target pressure value and display the pressure data in real time. The valve body assembly, connected to the drive plate, controls the opening and closing of the main valve port in response to changes in pilot chamber pressure.

2. The pressure valve dual closed-loop control system according to claim 1, characterized in that, The main control board includes: a main control MCU module, a power conversion module, an input / output signal processing module, a pressure sensor module, and a solenoid valve drive module; the pressure sensor module includes sensors that monitor the pressure of the working port and the pilot chamber respectively, and the output signal of the pressure sensor is input to the main control MCU module after low-pass filtering.

3. The pressure valve dual closed-loop control system according to claim 1, characterized in that, The switching function's amplitude b is adjusted to avoid the PWM duty cycle control dead zone.

4. The pressure valve dual closed-loop control system according to claim 1, characterized in that, The drive board controls the pilot valve, which includes an intake pilot valve and an exhaust pilot valve. The inflation rate and exhaust rate of the pilot chamber are controlled by adjusting the corresponding PWM duty cycle of the two valves.

5. The pressure valve dual closed-loop control system according to claim 1, characterized in that, The valve body assembly includes: The valve core assembly (103) and the valve seat assembly (102) together constitute a piston movement structure; The diaphragm assembly (104) and the diaphragm spring (10) are linked together to drive the main valve port to open and close in response to changes in pilot chamber pressure. The main air inlet (1), working port (2) and exhaust port (3) are used to connect to a high-pressure air source, the working port (2) is used to connect to a controlled air chamber, and the exhaust port (3) is used to discharge gas to the atmosphere.

6. The pressure valve dual closed-loop control system according to claim 5, characterized in that, The valve core assembly (103) and the valve seat assembly (102) form a series sealing structure based on interference fit. The main air inlet (1) and the working port (2) are normally closed, and the working port (2) and the exhaust port (3) are normally open.

7. The pressure valve dual closed-loop control system according to claim 1, characterized in that, The duty cycle of the PWM control signal is limited to -100% to 100% by a normalized saturator, where a positive value corresponds to the intake pilot valve and a negative value corresponds to the exhaust pilot valve.

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