Digital pressure control method and system for pneumatic vacuum pressure regulating angle valve

Abstract

The present application relates to the technical field of digital control pressure of pneumatic angle valve, and particularly relates to a digital control pressure method and system of a pneumatic vacuum pressure regulating angle valve. The system comprises an angle valve unit, a cylinder assembly, a gas path unit, a valve opening control circuit, a pulse driving circuit, a position feedback unit and a controller. The angle valve unit is arranged between a vacuum cavity and a vacuum pump, the cylinder assembly drives the linear motion of a valve rod and a valve core to change the valve opening. The valve opening control circuit receives a valve opening target and generates a digital control quantity according to the actual opening, and the pulse driving circuit outputs a pulse driving signal accordingly. The gas path unit comprises a first fast switching valve, a second fast switching valve, an intake fine adjustment valve and an exhaust fine adjustment valve. The intake fine adjustment valve and the exhaust fine adjustment valve adjust the intake and exhaust volume of the cylinder assembly according to the pulse driving signal, so that the valve opening approaches the target opening, thereby adjusting the flow area between the vacuum cavity and the vacuum pump and realizing the vacuum pressure regulation.

Description

Technical Field

[0001] This invention relates to the field of digital pressure control technology for pneumatic angle valves, specifically a digital pressure control method and system for a pneumatic vacuum pressure regulating angle valve. Background Technology

[0002] Pneumatic vacuum pressure regulating angle valves are typically installed between the vacuum chamber and the vacuum pump. By changing the distance between the valve core and the valve seat, the valve opening is altered, thus changing the flow area between the vacuum chamber and the vacuum pump, thereby regulating the pressure in the vacuum chamber. These valves are widely used in vacuum systems in semiconductor, photovoltaic, vacuum coating, and scientific research equipment, and their control effect directly impacts the response speed and stability of the vacuum chamber pressure.

[0003] In existing technologies, a combination of pressure detection and valve opening control is used to regulate vacuum pressure. For example, CN106681384A discloses an intelligent low-pressure regulation and control device for a vacuum container. Its main control module receives pressure data detected by a vacuum gauge, calculates the desired valve opening control value based on the difference between the set pressure and the detected pressure, and then outputs a control signal to the outlet valve through a voltage output module. This solution can control the outlet valve opening based on the pressure deviation, but its control logic mainly revolves around the pressure difference and the desired opening control value, without refining the coupling relationship between the cylinder intake and exhaust response, the linear motion state of the valve stem, and the duty cycle of the fine-tuning valve in the pneumatic angle valve.

[0004] For example, CN107461539A discloses a vacuum valve and a vacuum pressure control system using the vacuum valve. The vacuum valve is configured between a vacuum container and a vacuum pump, and its opening is adjusted by an operating fluid. This solution focuses on the structure and sealing components of the vacuum valve, enabling its use in a vacuum pressure control system. However, it primarily focuses on the mechanical structure of the vacuum valve itself and the relationship between the operating fluid and the valve's drive mechanism. It does not further disclose how the fine-tuning valve control quantity is corrected based on the target valve opening, the actual opening trend, and the pneumatic actuation response state during digital pressure control.

[0005] For example, CN102129256B discloses a vacuum control system and vacuum control method, which measures the vacuum pressure inside a vacuum container through a pressure measuring unit, and then controls the opening degree of multiple vacuum control valves based on the measured vacuum pressure. This solution can regulate vacuum pressure and gas flow, but its focus is on the coordinated control of the pressure inside the vacuum container by multiple vacuum control valves. It does not specifically address how to incorporate the opening deviation state and the pneumatic response state of the cylinder assembly into the digital control quantity generation process during the closed-loop control of the opening degree of a single pneumatic vacuum pressure regulating valve.

[0006] Therefore, while existing technologies can achieve vacuum pressure regulation through pressure detection, valve opening control, or operating fluid actuation, in the digital pressure control scenario of pneumatic vacuum pressure regulating angle valves, current control methods typically focus more on pressure deviation or valve opening itself. They fail to simultaneously consider the adjustment range of the opening deviation and the actual pneumatic response state of the cylinder assembly during the generation of the same digital control quantity. This results in the valve using similar adjustment intensities during the rapid approach phase of large deviations and the holding phase of small deviations. In actual operation, this can easily lead to problems such as untimely control quantity decay when the valve approaches the target opening, insufficient cylinder intake and exhaust correction, and frequent reverse switching between the intake and exhaust fine-tuning valves, thus affecting the stability of vacuum pressure regulation. Summary of the Invention

[0007] The purpose of this invention is to provide a digital pressure control method and system for a pneumatic vacuum pressure regulating angle valve, so as to solve the technical problems mentioned in the background art.

[0008] Based on the above ideas, the present invention provides the following technical solution: A digital pressure control system for a pneumatic vacuum pressure regulating angle valve includes: It includes an angle valve unit, a cylinder assembly, an air circuit unit, a valve opening control circuit, a pulse drive circuit, a position feedback unit, and a controller; The angle valve unit is disposed between the vacuum chamber and the vacuum pump, and is used to adjust the flow area between the vacuum chamber and the vacuum pump by changing the valve opening. The cylinder assembly is connected to the angle valve unit and is used to drive the valve stem in the angle valve unit to move linearly, so as to drive the valve core to change the valve opening. The air passage unit is connected to the cylinder assembly and is used to supply air to the cylinder assembly or to exhaust air from the cylinder assembly. The valve opening control circuit is communicatively connected to the controller and is used to receive the valve opening target and generate a digital control quantity based on the valve opening target and the actual opening fed back by the position feedback unit. The pulse drive circuit is connected to the valve opening control circuit and is used to output a pulse drive signal according to the digital control quantity. The pneumatic circuit unit includes a first quick-switching valve and a second quick-switching valve for rapid valve opening and closing, as well as an intake fine-tuning valve and an exhaust fine-tuning valve for precise valve opening adjustment. The intake fine-tuning valve and the exhaust fine-tuning valve adjust the intake and exhaust volume of the cylinder assembly according to the pulse drive signal, so that the valve opening of the angle valve unit approaches the valve opening target.

[0009] Preferably, the angle valve unit includes a valve body, a valve stem, and a valve core. The valve stem is connected to the cylinder assembly, and the valve core is disposed at one end of the valve stem. The valve core is used to move closer to or further away from the valve seat as the valve stem moves linearly, thereby changing the valve opening of the angle valve unit.

[0010] Preferably, the cylinder assembly is provided with a flange socket, an exhaust port and an air inlet. The flange socket is used to connect to the controller, the air inlet is used to connect to the air source that drives the cylinder assembly, and the exhaust port is used to discharge the gas in the cylinder assembly or the air circuit unit.

[0011] Preferably, the air circuit unit has an intake end, an exhaust end, and a common end. The intake fine-tuning valve is used to control the amount of gas entering the cylinder assembly, the exhaust fine-tuning valve is used to control the amount of gas exiting the cylinder assembly, and the common end is connected to the cylinder assembly.

[0012] Preferably, the first quick-switching valve and the second quick-switching valve are used to form a large-flow intake and exhaust passage when the valve is opened or closed quickly, and the intake fine-tuning valve and the exhaust fine-tuning valve are used to form a small-flow intake and exhaust passage when the valve opening is precisely adjusted.

[0013] Preferably, the position feedback unit is used to acquire the actual opening degree of the angle valve unit and feed the actual opening degree back to the valve opening control circuit; the position feedback unit includes a potentiometer, or includes a displacement detection element capable of characterizing the valve stem displacement.

[0014] Preferably, the valve opening control circuit is configured to compare the target valve opening with the actual opening and generate the digital control quantity through digital PID calculation. The digital control quantity is used to determine the pulse duty cycle of the intake fine-tuning valve and the exhaust fine-tuning valve.

[0015] Preferably, the controller is connected to a vacuum gauge, which is used to detect the pressure of the vacuum chamber. The controller sends the valve opening target to the valve opening control circuit according to the pressure adjustment requirements of the vacuum chamber.

[0016] A digital pressure control method for a pneumatic vacuum pressure regulating angle valve, executed using the aforementioned digital pressure control system for the pneumatic vacuum pressure regulating angle valve, includes the following steps: S1. Receive valve opening target; S2. The actual opening degree of the angle valve unit is collected through the position feedback unit; S3. The valve opening control circuit calculates the opening deviation based on the target valve opening and the actual opening. S4. Perform digital PID calculations based on the opening deviation to generate digital control quantities for controlling the intake fine-tuning valve and the exhaust fine-tuning valve; S5. The pulse drive circuit outputs a pulse drive signal according to the digital control quantity; S6. Adjust the duty cycle of the intake fine-tuning valve and the exhaust fine-tuning valve according to the pulse drive signal to adjust the intake and exhaust volume of the cylinder assembly; S7. The cylinder assembly drives the valve stem and valve core to move linearly, so that the valve opening of the angle valve unit approaches the target valve opening, thereby adjusting the flow area between the vacuum chamber and the vacuum pump.

[0017] Preferably, in step S6, when the valve is opened rapidly, the first quick-switching valve and the second quick-switching valve form an intake passage to the cylinder assembly; when the valve is closed rapidly, the cylinder assembly forms an exhaust passage through the first quick-switching valve; when the valve opening is precisely adjusted, the pressure of the cylinder assembly is adjusted by the duty cycle of the intake fine-tuning valve and the exhaust fine-tuning valve.

[0018] The technical solution of the present invention may include the following beneficial effects: This invention enables the formation of a complete digital pressure control closed loop for a pneumatic vacuum pressure regulating angle valve. The controller sets a target valve opening based on the vacuum chamber pressure regulation requirements. The valve opening control circuit receives this target and calculates the opening deviation by combining it with the actual opening collected by the position feedback unit. A digital control quantity is then generated through digital PID calculation, and a pulse drive signal is output by the pulse drive circuit. This adjusts the duty cycle of the intake and exhaust fine-tuning valves, causing changes in the intake and exhaust volumes of the cylinder assembly and driving the valve stem and valve core to move linearly. As a result, the valve opening of the angle valve unit approaches the target opening, altering the flow area and conductance between the vacuum chamber and the vacuum pump, thereby achieving vacuum pressure regulation. Compared to coarse on / off control using only ordinary switching valves, this invention integrates the target valve opening, actual opening feedback, digital control quantity, and fine-tuning valve duty cycle adjustment into the same control chain. This ensures that the pneumatic actuation corresponds to the vacuum pressure regulation requirements, improving the controllability and repeatability of the angle valve unit when used as a pressure regulating valve.

[0019] This invention employs a tiered pneumatic control system comprised of a first quick-switching valve, a second quick-switching valve, an inlet fine-tuning valve, and an exhaust fine-tuning valve. This allows the pneumatic vacuum pressure regulating angle valve to meet both rapid opening and closing requirements and precise adjustment needs around the target opening degree. The first and second quick-switching valves create high-flow-rate inlet and outlet passages, enabling rapid valve operation during opening or closing. The inlet and exhaust fine-tuning valves provide low-flow-rate inlet and outlet control during valve opening adjustment, avoiding the problems of excessively rapid opening changes and insufficient fine-tuning capability that occur when relying solely on high-flow-rate valve adjustment. This solution combines the mechanical actuation characteristics of the pneumatic angle valve, the inlet and outlet characteristics of the pneumatic path, and digital opening closed-loop control, allowing for more precise control of the distance change between the valve core and valve seat. This results in a smoother vacuum chamber pressure regulation process and reduces the impact of valve opening adjustment on vacuum system pressure fluctuations.

[0020] Furthermore, this invention optimizes the digital PID calculation process. It identifies the valve's current state as either rapidly approaching, precisely adjusting, or maintaining the target by using a deviation partitioning coefficient. It also reflects the sufficiency of the cylinder assembly's intake and exhaust responses using a pneumatic correction coefficient. The basic digital PID output is then corrected based on the deviation partitioning coefficient and the pneumatic correction coefficient to obtain the final digital control quantity U. This improvement addresses the different control requirements of pneumatic vacuum pressure regulating angle valves when approaching the target with large deviations and maintaining the target with small deviations, allowing the digital control quantity to be simultaneously constrained by both the opening deviation state and the pneumatic response state. Therefore, sufficient regulation capability is retained during the rapid approach phase, overshoot and oscillation are reduced during the approach to the target opening phase, and frequent reverse switching between the intake and exhaust fine-tuning valves near the target is reduced, thereby further improving stability and vacuum pressure regulation accuracy near the target opening. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the external structure of the pneumatic vacuum pressure regulating angle valve of Embodiment 1 of this application; Figure 2 This is a cross-sectional view of the pneumatic vacuum pressure regulating angle valve of Embodiment 1 of this application; Figure 3 This is a schematic diagram of the angle valve unit in Embodiment 1 of this application under different opening states. Wherein, (a) is a schematic diagram of the valve in the closed state, and (b) is a schematic diagram of the valve in the open state; Figure 4 This is a schematic diagram of the pneumatic vacuum pressure regulating angle valve of Embodiment 1 of this application applied in the downstream pressure control mode; Figure 5 This is a schematic diagram of the digital pressure control system of the pneumatic vacuum pressure regulating angle valve in Embodiment 1 of this application; Figure 6This is a schematic diagram of the controller structure in Embodiment 1 of this application; Figure 7 This is a flowchart of the digital pressure control method for the pneumatic vacuum pressure regulating angle valve in Embodiment 1 of this application.

[0022] Figure 8 This is a flowchart of the digital pressure control method for the pneumatic vacuum pressure regulating angle valve in Embodiment 2 of this application. In the picture: 1. Angle valve unit; 101. Valve body; 102. Valve stem; 103. Valve core; 2. Cylinder assembly; 201. Flange socket; 202. Exhaust port; 203. Inlet port. Detailed Implementation

[0023] Example 1 like Figures 1 to 7 As shown, This embodiment provides a digital pressure control method and system for a pneumatic vacuum pressure regulating angle valve, used in downstream pressure control scenarios between a vacuum chamber and a vacuum pump. The system drives the valve core of the angle valve unit to move linearly via pneumatic means and adjusts the valve opening through digital control, thereby changing the flow area between the vacuum chamber and the vacuum pump and achieving vacuum pressure regulation.

[0024] like Figure 1 and Figure 2 As shown, the system includes an angle valve unit 1 and a cylinder assembly 2. The angle valve unit 1 includes a valve body 101, a valve stem 102, and a valve core 103. A vacuum flow channel for gas flow is formed inside the valve body 101. The valve stem 102 is drively connected to the cylinder assembly 2, and the valve core 103 is located at the lower end of the valve stem 102. The angle valve unit 1 also includes a valve seat that mates with the valve core 103, which is not shown separately in the figure. The cylinder assembly 2 drives the valve stem 102 to move in a linear direction, causing the valve core 103 to move closer to or further away from the valve seat, thereby changing the distance between the valve core 103 and the valve seat, and thus changing the valve opening, flow area, and flow conductance of the angle valve unit 1.

[0025] The cylinder assembly 2 is equipped with a flange socket 201, an exhaust port 202, and an air inlet 203. The flange socket 201 is used to connect a controller or external control cable, the air inlet 203 is used to connect compressed air, and the exhaust port 202 is used to discharge gas from the cylinder assembly 2 or the air circuit unit. An electrical conversion module may be installed inside the cylinder assembly 2. This electrical conversion module, not shown separately in the figure, is used to switch the intake and exhaust states of the cylinder assembly 2 according to the control signal output by the controller.

[0026] like Figure 3As shown, the angle valve unit 1 has different opening states. When the cylinder assembly 2 drives the valve stem 102 to move the valve core 103 away from the valve seat, the flow area of ​​the angle valve unit 1 increases; when the valve core 103 moves closer to the valve seat, the flow area of ​​the angle valve unit 1 decreases. By changing the position of the valve core 103, the pumping state between the vacuum chamber and the vacuum pump can be adjusted.

[0027] like Figure 4 As shown, angle valve unit 1, acting as a control valve, is positioned between the vacuum chamber and the vacuum pump. The vacuum chamber is connected to a vacuum gauge and also has an air inlet. A controller is connected to the vacuum gauge to acquire the pressure status of the vacuum chamber; the controller is also connected to the control section of angle valve unit 1 to send a target valve opening to angle valve unit 1 based on the pressure regulation requirements of the vacuum chamber. By changing the valve opening of angle valve unit 1, the flow area between the vacuum chamber and the vacuum pump can be altered, thereby achieving downstream vacuum pressure regulation.

[0028] like Figure 5 As shown, the system also includes an air path unit, a valve opening control circuit, a pulse drive circuit, and a position feedback unit. The air path unit is connected to the inlet end, the exhaust end, and the cylinder assembly 2, respectively, and is used to control the intake and exhaust volume of the cylinder assembly 2. The valve opening control circuit receives the target valve opening via RS485 communication and receives the actual opening from the position feedback unit. The position feedback unit can be a potentiometer or a displacement detection device capable of characterizing the displacement of the valve stem 102; in this embodiment, the position feedback unit acquires the actual valve opening through the potentiometer and feeds the actual opening back to the valve opening control circuit.

[0029] To facilitate the description of the gas path control relationship, this embodiment will... Figure 5 The letter valve names in the text are converted into function names for explanation: Figure 5 Valve A in the diagram is the first quick-switching valve. Figure 5 Valve B in the middle is the second quick-switching valve. Figure 5 The P valve in the figure is the intake fine-tuning valve. Figure 5 The R valve in the figure is the exhaust fine-tuning valve. The first and second quick-switching valves are used for the rapid opening and closing of the valve, while the intake and exhaust fine-tuning valves are used for the precise adjustment of the valve opening.

[0030] Specifically, when the valve opens rapidly, the first and second rapid switching valves form an intake passage to the cylinder assembly 2, and compressed air enters the cylinder assembly 2, pushing the cylinder assembly 2 to move, causing the valve stem 102 to drive the valve core 103 to move rapidly; when the valve closes rapidly, the cylinder assembly 2 forms an exhaust passage through the first rapid switching valve, causing the angle valve unit 1 to move in the closing direction; when the valve opening is precisely adjusted, the intake fine-tuning valve and the exhaust fine-tuning valve adjust the duty cycle according to the pulse drive signal output by the pulse drive circuit, thereby precisely adjusting the intake and exhaust volume of the cylinder assembly 2, so that the valve opening gradually approaches the valve opening target.

[0031] The valve opening control circuit compares the received target valve opening with the actual opening fed back by the position feedback unit to obtain the opening deviation, and performs digital PID calculations based on the opening deviation to generate a digital control quantity. The pulse drive circuit outputs a pulse drive signal based on the digital control quantity, which is used to control the pulse duty cycle of the intake and exhaust fine-tuning valves. By adjusting the duty cycle of the intake and exhaust fine-tuning valves, the amount of gas entering or exiting the cylinder assembly 2 can be changed, thereby changing the pressure state of the cylinder assembly 2, causing the cylinder assembly 2 to drive the valve stem 102 and valve core 103 to move linearly.

[0032] like Figure 6 As shown, the controller can be an independent controller, which connects to the valve opening control circuit via a communication interface and is used to receive the valve opening target given by the host computer or external control system. The controller can output the corresponding valve opening target according to the vacuum chamber pressure regulation requirements, enabling the angle valve unit 1 to participate in vacuum pressure regulation in a digital control manner.

[0033] like Figure 7 As shown, the digital pressure control method in this embodiment includes the following steps: S1. Receive valve opening target; S2. Collect the actual opening degree of the angle valve unit; S3. Calculate the opening deviation between the target valve opening and the actual valve opening; S4. Perform digital PID calculations based on the opening deviation and generate digital control quantities; S5. Output pulse drive signals according to digital control quantities; S6. Adjust the duty cycle of the intake and exhaust fine-tuning valves; S7. Drives the valve stem and valve core to move linearly and achieves vacuum pressure regulation.

[0034] In step S1, the valve opening target can be generated by the controller according to the pressure adjustment requirements of the vacuum chamber, or it can be sent to the controller by the host computer via communication, and then sent to the valve opening control circuit by the controller.

[0035] In step S2, the position feedback unit acquires the actual opening degree of the angle valve unit 1. The actual opening degree can be obtained by detecting the displacement of the valve stem 102 using a potentiometer, or by other displacement detection devices. The actual opening degree is used to characterize the position state of the valve core 103 relative to the valve seat.

[0036] In step S3, the valve opening control circuit compares the target valve opening with the actual opening to obtain the opening deviation. The opening deviation is used to characterize the difference between the current valve opening and the target opening.

[0037] In step S4, the valve opening control circuit performs digital PID calculations based on the opening deviation and generates a digital control quantity. This digital control quantity is used to determine the adjustment direction and adjustment range of the intake and exhaust fine-tuning valves.

[0038] In step S5, the pulse drive circuit outputs a pulse drive signal according to the digital control quantity. The pulse drive signal is a PWM signal used to drive the intake fine-tuning valve and the exhaust fine-tuning valve.

[0039] In step S6, the intake and exhaust fine-tuning valves change their respective duty cycles according to the pulse drive signal, thereby changing the intake and exhaust volumes of the cylinder assembly 2. Through precise adjustment of the intake and exhaust volumes, the internal pressure of the cylinder assembly 2 can be regulated.

[0040] In step S7, the cylinder assembly 2 drives the valve stem 102 and valve core 103 to move linearly under air pressure, causing the valve core 103 to move closer to or away from the valve seat, thereby making the valve opening of the angle valve unit 1 approach the target valve opening. As the valve opening changes, the flow area between the vacuum chamber and the vacuum pump changes, thereby achieving vacuum pressure regulation.

[0041] Through the above implementation method, this embodiment can realize the rapid action of the angle valve unit 1 by using the first rapid switching valve and the second rapid switching valve during the rapid opening and closing phase, and use the intake fine adjustment valve and the exhaust fine adjustment valve for small flow pneumatic adjustment during the opening precision adjustment phase, so that the cylinder assembly 2 drives the valve stem 102 and the valve core 103 to move smoothly, thereby realizing the digital pressure control of the pneumatic vacuum pressure regulating angle valve.

[0042] Example 2 This embodiment further optimizes the digital pressure control method for the pneumatic vacuum pressure regulating angle valve. Instead of directly outputting a digital control quantity based solely on the opening deviation, the digital PID calculation now incorporates the opening deviation zone state and the pneumatic response state of cylinder assembly 2 to correct the basic digital PID output. This corrected final digital control quantity is still used as the input to step S5, and the pulse drive circuit outputs a pulse drive signal based on this final digital control quantity.

[0043] The digital pressure control method in this embodiment includes the following steps: S1. Receive valve opening target; S2. Collect the actual opening degree of the angle valve unit; S3. Calculate the opening deviation between the target valve opening and the actual valve opening; S4. Perform digital PID calculations based on the opening deviation and generate digital control quantities; Step S4 further includes: S4.1. Calculate the deviation partition coefficient X based on the opening deviation, the opening deviation change rate and the valve's allowable adjustment stroke. The deviation partition coefficient X is used to characterize the current valve's tendency to be in the rapid approach zone, the precision adjustment zone or the target holding zone. S4.2. Calculate the pneumatic correction coefficient Y based on the opening deviation, the rate of change of the opening deviation and the pneumatic response state of the cylinder assembly. The pneumatic correction coefficient Y is used to characterize the strength of the cylinder assembly's response to the pulse drive signal under the current intake and exhaust conditions. S4.3. Based on the deviation partitioning coefficient X and the aerodynamic correction coefficient Y, the basic digital PID output is corrected to generate the final digital control quantity U; S5. Output a pulse drive signal according to the final digital control quantity U; S6. Adjust the duty cycle of the intake and exhaust fine-tuning valves; S7. Drives the valve stem and valve core to move linearly and achieves vacuum pressure regulation.

[0044] In this embodiment, the valve opening target in step S1 can be generated by the controller based on the vacuum chamber pressure adjustment requirements, or it can be sent to the controller by the host computer via communication. The valve opening target can be expressed as a percentage opening, with a value range of 0%-100%; it can also be expressed as a displacement value corresponding to the valve stem stroke. For ease of explanation, this embodiment uses percentage opening to represent the valve opening target and actual opening, where 0% represents the closed state and 100% represents the fully open state.

[0045] In step S2, the position feedback unit acquires the actual opening degree of the angle valve unit. The position feedback unit can be a potentiometer, whose output signal is converted into the actual opening degree value by the valve opening control circuit; alternatively, a displacement detection device capable of characterizing valve stem displacement can be used. Preferably, the sampling period for the target and actual valve opening degrees is 10ms-100ms, more preferably 20ms. Before proceeding to step S3, the actual opening degree can be processed by a moving average, with a moving average window of 3 to 8 sampling periods, to reduce the impact of short-term jitter in the position feedback signal on the digital PID calculation.

[0046] In step S3, the valve opening control circuit calculates the opening deviation based on the target valve opening and the actual opening. Let the target valve opening in the k-th sampling period be r. k The actual opening is h. k Then the opening deviation e k For r k -h k Opening deviation e k The unit is percentage points. When e k When e is positive, it indicates that the actual valve opening is less than the target valve opening, requiring the valve core to move in the direction of increasing the opening; when e is positive... k When the value is negative, it indicates that the actual opening degree is greater than the target valve opening degree, and the valve core needs to be moved in the direction of reducing the opening degree.

[0047] In step S4.1, the valve opening control circuit determines the valve opening based on the opening deviation e. k , opening deviation change rate v k And the allowable adjustment stroke L of the valve is calculated to determine the deviation zoning coefficient X. k Rate of change of opening deviation v k v is obtained by the difference in opening deviation between two adjacent sampling periods. k =(e k -e k-1 ) / T s T s The sampling period is defined as follows. The allowable adjustment stroke L represents the range of opening change of the angle valve unit from the closed state to the fully open state. When expressed as a percentage opening, L is 100 percentage points; when expressed as valve stem displacement, L is the effective stroke of the valve stem. V represents the allowable opening change rate of the angle valve unit, which can be obtained through opening response calibration of the angle valve unit under rated air source pressure.

[0048] In this embodiment, the deviation partitioning coefficient X k Calculate using the following formula:

[0049] Among them, X k The deviation partitioning coefficient is dimensionless and ranges from 0 to 1; e k L represents the valve opening deviation in the kth sampling period, in percentage points or millimeters; L is the valve's allowable adjustment stroke, in units of e. k Consistent; v k V is the rate of change of opening deviation, expressed in percentage points per second or millimeters per second; V is the allowable rate of change of opening of the angle valve unit, expressed in the same unit as v. k Consistent.

[0050] As can be seen from this formula, when the opening deviation is large or the rate of change of the opening deviation is large, X kAn increase in X indicates that the current state is closer to the rapid approach zone; when the opening deviation is small and the rate of change of the opening deviation is small, X... k Decreasing indicates that the current state is closer to the target preservation region; when X k When it is in the middle range, it indicates that the current state is in the precision adjustment zone. Preferably, when X... k When X is greater than 0.6, the valve opening control circuit is processed according to the rapid approach zone; when X... k When X is 0.2-0.6, it should be processed according to the precision adjustment range; when X... k If the value is less than 0.2, it is treated as a target retention area.

[0051] In step S4.2, the valve opening control circuit determines the valve opening based on the opening deviation e. k , opening deviation change rate v k Calculate the aerodynamic correction factor Y based on the aerodynamic response state of the cylinder assembly. k The pneumatic response state can be obtained from the pressure change of the cylinder assembly, or from the response relationship between the duty cycle change and the actual opening change of the intake and exhaust fine-tuning valves. Preferably, when the pneumatic circuit unit has a pressure sampling signal, the pressure change of the cylinder assembly is used for calculation; when no separate pressure sampling signal is set, the equivalent cylinder pressure change obtained by converting the duty cycle difference between the intake and exhaust fine-tuning valves can be used for calculation.

[0052] Let Δp be the pressure change of the cylinder assembly during the kth sampling period. k P represents the calibrated pressure change of the cylinder assembly within one effective adjustment cycle of the intake or exhaust fine-tuning valve. This calibrated pressure change P can be obtained through calibration, for example, by operating the intake fine-tuning valve at a fixed duty cycle for a sampling window under rated air source pressure, recording the average pressure change of the cylinder assembly, and using this average as P. Pneumatic correction coefficient Y k Calculate using the following formula:

[0053] Among them, Y k e is the aerodynamic correction factor, dimensionless; k For opening deviation; Δp k Δp represents the pressure change of the cylinder assembly during the kth sampling period, in kPa; L represents the allowable adjustment stroke of the valve; P represents the calibrated pressure change, in units of Δp. k Consistent; v k V is the rate of change of opening deviation; V is the allowable rate of change of opening of the angle valve unit. P is obtained from the calibration process of the cylinder assembly.

[0054] From this formula, it can be seen that when the direction of pressure change in the cylinder assembly is consistent with the adjustment direction required for the valve opening deviation, e kWith Δp k The product of Y is positive. k A relative increase indicates that the current pneumatic response is relatively effective; when the direction of pressure change is opposite to the adjustment direction required for valve opening deviation, Y k A relative decrease indicates that the current aerodynamic response has a lag or reverse trend; when the rate of change of the opening deviation is large, Y k This is suppressed to prevent overshoot caused by the continued accumulation of control quantities during the rapid movement of the valve core.

[0055] In step S4.3, the valve opening control circuit first generates a basic digital PID output U according to the digital PID method of Embodiment 1. PID,k The basic digital PID output can be composed of a proportional term, an integral term, and a derivative term, and its input is the opening deviation e. k Subsequently, the valve opening control circuit determines the valve opening based on the deviation partitioning coefficient X. k and aerodynamic correction factor Y k For the basic digital PID output U PID,k Make corrections to generate the final digital control quantity U. k The final digital control quantity U k Calculate using the following formula:

[0056] Among them, U k For the final digital control quantity; U PID,k Basic digital PID output; U max η represents the maximum control quantity corresponding to the allowable duty cycle of the intake and exhaust fine-tuning valves; η is the basic adjustment coefficient for the holding zone, ranging from 0.25 to 0.45; μ is the aerodynamic response compensation coefficient, ranging from 0.2 to 0.6; and sat represents the limiting treatment used to make U k The duty cycle adjustment range allowed by the intake and exhaust fine-tuning valves shall not exceed the range allowed by the intake and exhaust fine-tuning valves.

[0057] In the above formula, when X k When X is larger, it indicates that the valve is in the rapid approach zone, and the retention ratio of the basic digital PID output increases, allowing the valve core to approach the target valve opening more quickly; when X k When the value is small, it indicates that the valve is in the target holding region, and the basic digital PID output is reduced, which can reduce overshoot and oscillation near the target; when Y k When the value is low, it indicates that the current response of the cylinder assembly is insufficient or the response direction is unstable. The pneumatic response compensation term in the formula should be appropriately increased to overcome pneumatic hysteresis. k A higher value indicates a more adequate aerodynamic response, reducing the compensation amplitude and preventing further amplification of the control quantity.

[0058] In step S5, the pulse drive circuit determines the final digital control quantity U. k Output pulse drive signal. When U k When U is positive, the pulse drive circuit prioritizes outputting a pulse drive signal to the intake fine-tuning valve, increasing the duty cycle of the intake fine-tuning valve; when U k When U is negative, the pulse drive circuit prioritizes outputting a pulse drive signal to the exhaust fine-tuning valve, causing the duty cycle of the exhaust fine-tuning valve to increase; when U k When the absolute value is within the holding threshold range, the pulse drive circuit maintains the current duty cycle of the intake and exhaust fine-tuning valves, or puts them into a low duty cycle holding state. Preferably, the duty cycle range of the intake and exhaust fine-tuning valves is 0%-100%, and the duty cycle resolution is not less than 1%.

[0059] In step S6, the intake and exhaust fine-tuning valves adjust their respective duty cycles according to the pulse drive signal, thereby changing the intake and exhaust volumes of the cylinder assembly. When the valve opening needs to be increased, the duty cycle of the intake fine-tuning valve increases, increasing the intake volume of the cylinder assembly; when the valve opening needs to be decreased, the duty cycle of the exhaust fine-tuning valve increases, increasing the exhaust volume of cylinder assembly 2. To reduce frequent reverse adjustments of the intake and exhaust fine-tuning valves near the target opening, in X... k Less than 0.2 and U k When the sign of the valve reverses within two consecutive sampling periods, the valve opening control circuit preferably maintains the previous effective duty cycle for one sampling period, and then adjusts the valve opening based on the U value of the next sampling period. k Determine whether to switch the direction of action.

[0060] In step S7, the cylinder assembly drives the valve stem and valve core to move linearly under air pressure. The valve core moves closer to or away from the valve seat, causing the valve opening of the angle valve unit to approach the target valve opening, and changing the flow area between the vacuum chamber and the vacuum pump, thereby achieving vacuum pressure regulation.

[0061] During online operation in this embodiment, the target valve opening, actual valve opening, and cylinder assembly response status are sampled synchronously at fixed intervals. Optionally, the sampling period is 20ms, and both the target and actual valve opening are expressed as percentage openings of 0%-100%. After sampling the actual opening, a 3-point moving average is first performed, and then the opening deviation is calculated with the target valve opening. The rate of change of opening deviation is obtained by the difference between adjacent sampling periods. If the actual opening feedback is missing for a short time, the valve opening control circuit maintains the previous valid actual opening for calculation; if it is missing for more than 5 consecutive sampling periods, the intake and exhaust fine-tuning valves enter a holding state, and the controller outputs an abnormality prompt. If the pressure change signal of the cylinder assembly is missing for a short time, the equivalent pressure change is calculated by converting the duty cycle change of the intake and exhaust fine-tuning valves in the previous sampling window; if the pressure change signal is continuously missing, Y kThe value is fixed at 0.5 to maintain a moderate correction strength in the system and prevent it from directly entering a strong compensation state.

[0062] When the valve approaches the fully open or fully closed position, this embodiment also adjusts the final digital control quantity U. k Boundary processing is performed. When the actual opening is greater than 98% and U... k If it still points in the direction of continuing to widen, then U k The limit is 0; when the actual opening is less than 2% and U k If it still points in the direction of continuing to decrease, then U k The limit is set to 0. This boundary treatment avoids unnecessary continuous actuation of the valve stem and spool near their extreme positions.

Claims

1. A digital pressure control system for a pneumatic vacuum pressure regulating angle valve, characterized in that, include: It includes an angle valve unit (1), a cylinder assembly (2), an air circuit unit, a valve opening control circuit, a pulse drive circuit, a position feedback unit, and a controller; The angle valve unit (1) is disposed between the vacuum chamber and the vacuum pump, and is used to adjust the flow area between the vacuum chamber and the vacuum pump by changing the valve opening. The cylinder assembly (2) is connected to the angle valve unit (1) and is used to drive the valve stem (102) in the angle valve unit (1) to move linearly, so as to drive the valve core (103) to change the valve opening. The air passage unit is connected to the cylinder assembly (2) and is used to supply air to the cylinder assembly (2) or to exhaust air from the cylinder assembly (2); The valve opening control circuit is communicatively connected to the controller and is used to receive the valve opening target and generate a digital control quantity based on the valve opening target and the actual opening fed back by the position feedback unit. The pulse drive circuit is connected to the valve opening control circuit and is used to output a pulse drive signal according to the digital control quantity. The pneumatic circuit unit includes a first quick-switching valve and a second quick-switching valve for rapid valve opening and closing, as well as an intake fine-tuning valve and an exhaust fine-tuning valve for precise valve opening adjustment. The intake fine-tuning valve and the exhaust fine-tuning valve adjust the intake and exhaust volume of the cylinder assembly (2) according to the pulse drive signal, so that the valve opening of the angle valve unit (1) approaches the valve opening target.

2. The digital pressure control system for a pneumatic vacuum pressure regulating angle valve according to claim 1, characterized in that, The angle valve unit (1) includes a valve body (101), a valve stem (102) and a valve core (103). The valve stem (102) is connected to the cylinder assembly (2). The valve core (103) is disposed at one end of the valve stem (102). The valve core (103) is used to move closer to or further away from the valve seat as the valve stem (102) moves linearly, so as to change the valve opening of the angle valve unit (1).

3. The digital pressure control system for a pneumatic vacuum pressure regulating angle valve according to claim 2, characterized in that, The cylinder assembly (2) is provided with a flange socket (201), an exhaust port (202) and an air inlet (203). The flange socket (201) is used to connect to the controller, the air inlet (203) is used to connect to the air source that drives the cylinder assembly (2) to operate, and the exhaust port (202) is used to discharge the gas in the cylinder assembly (2) or the air circuit unit.

4. The digital pressure control system for a pneumatic vacuum pressure regulating angle valve according to claim 3, characterized in that, The air circuit unit has an intake end, an exhaust end and a common end. The intake fine adjustment valve is used to control the amount of gas entering the cylinder assembly (2), the exhaust fine adjustment valve is used to control the amount of gas discharged from the cylinder assembly (2), and the common end is connected to the cylinder assembly (2).

5. The digital pressure control system for a pneumatic vacuum pressure regulating angle valve according to claim 4, characterized in that, The first and second quick-switching valves are used to form a large-flow intake and exhaust passage when the valve is opened or closed quickly, and the intake fine-tuning valve and the exhaust fine-tuning valve are used to form a small-flow intake and exhaust passage when the valve opening is precisely adjusted.

6. The digital pressure control system for the pneumatic vacuum pressure regulating angle valve according to claim 5, characterized in that, The position feedback unit is used to collect the actual opening degree of the angle valve unit (1) and feed the actual opening degree back to the valve opening control circuit; the position feedback unit includes a potentiometer or a displacement detection element that can characterize the displacement of the valve stem (102).

7. The digital pressure control system for the pneumatic vacuum pressure regulating angle valve according to claim 6, characterized in that, The valve opening control circuit is configured to compare the target valve opening with the actual opening and generate the digital control quantity through digital PID calculation. The digital control quantity is used to determine the pulse duty cycle of the intake fine-tuning valve and the exhaust fine-tuning valve.

8. The digital pressure control system for the pneumatic vacuum pressure regulating angle valve according to claim 7, characterized in that, The controller is connected to a vacuum gauge, which is used to detect the pressure of the vacuum chamber. The controller sends the valve opening target to the valve opening control circuit according to the pressure adjustment requirements of the vacuum chamber.

9. A digital pressure control method for a pneumatic vacuum pressure regulating angle valve, characterized in that, The digital pressure control system using the pneumatic vacuum pressure regulating angle valve according to any one of claims 1-8 includes the following steps: S1. Receive valve opening target; S2. The actual opening degree of the angle valve unit (1) is collected through the position feedback unit; S3. The valve opening control circuit calculates the opening deviation based on the target valve opening and the actual opening. S4. Perform digital PID calculations based on the opening deviation to generate digital control quantities for controlling the intake fine-tuning valve and the exhaust fine-tuning valve; S5. The pulse drive circuit outputs a pulse drive signal according to the digital control quantity; S6. Adjust the duty cycle of the intake fine-tuning valve and the exhaust fine-tuning valve according to the pulse drive signal to adjust the intake and exhaust volume of the cylinder assembly (2); S7. The cylinder assembly (2) drives the valve stem (102) and valve core (103) to move linearly, so that the valve opening of the angle valve unit (1) approaches the valve opening target, thereby adjusting the flow area between the vacuum chamber and the vacuum pump.

10. A digital pressure control method for a pneumatic vacuum pressure regulating angle valve according to claim 9, characterized in that: In step S6, when the valve is opened quickly, the first quick-switching valve and the second quick-switching valve form an intake passage to the cylinder assembly (2); when the valve is closed quickly, the cylinder assembly (2) forms an exhaust passage through the first quick-switching valve; when the valve opening is precisely adjusted, the pressure of the cylinder assembly (2) is adjusted by the duty cycle of the intake fine-tuning valve and the exhaust fine-tuning valve.

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