A control system for a vacuum pressure regulating valve

Abstract

The application discloses a control system of a vacuum pressure regulating valve and relates to the field of pressure regulating valves. The control system is characterized in that a first compensation term is introduced based on the reset elastic force of an elastic member and the effective pressure-bearing area of a diaphragm assembly, a second compensation term is introduced based on the atmospheric pressure, the actual pressure of a working port, the cross-sectional area of a first cavity and the effective pressure-bearing area of the diaphragm assembly, and the compensation terms and a basic control instruction generated by an outer ring are combined by an inner ring controller to drive an air inlet pilot valve and an air outlet pilot valve. The application can actively offset the additional force generated by the atmospheric pressure acting on the first valve seat assembly due to the breathing hole arranged on the bottom plate and the interference of the additional force on the main valve force balance, thereby significantly improving the steady-state control precision and dynamic response stability of the vacuum pressure regulating valve under different working port pressure setting conditions.

Description

Technical Field

[0001] This invention relates to the field of pressure regulating valves, and more particularly to a control system for a vacuum pressure regulating valve. Background Technology

[0002] During the initial charge-discharge cycle (formation) of a lithium-ion battery, a solid electrolyte interphase (SEI) film forms on the negative electrode surface, accompanied by the generation of gases such as hydrogen, carbon monoxide, and ethylene. To prevent these gases and entrained electrolyte vapors from remaining within the battery chamber and affecting interface stability and battery performance, negative pressure evacuation or vacuum maintenance methods are typically used to remove the generated gases and vapors promptly. During this process, a vacuum pressure regulating valve is used to precisely maintain the negative pressure state of the working chamber.

[0003] However, in existing technologies, negative pressure proportional valves inevitably draw in trace amounts of battery electrolyte during vacuuming. Because traditional negative pressure regulating valves or vacuum proportional valves generally employ a design that directly exposes the return spring and seals to the medium flowing through the chamber, the drawn-in electrolyte vapor easily condenses and crystallizes on the surfaces of moving parts such as the spring and sealing rings at the bottom of the valve body. These solid crystals accumulate and impede valve stem movement or damage the sealing interface, leading to valve jamming, leakage, or even complete failure. Although this problem can be mitigated by using corrosion-resistant materials or adding external filtering buffers, these solutions still cannot effectively isolate the crystalline medium from the core moving—sealing—components, resulting in continuous contact between electrolyte vapor or condensate and critical components such as the spring and sealing rings.

[0004] To address these issues, an isolation structure can be used to separate moving parts such as springs from the chamber through which the medium flows. However, this isolation scheme itself introduces new control challenges, requiring an innovative valve structure and control method to overcome them. Summary of the Invention

[0005] To overcome the problem of valve seat additional force interfering with the main valve force balance caused by the use of an atmospheric-connected isolation chamber for isolating crystalline media in existing technologies, this invention proposes a control system for a vacuum pressure regulating valve, the vacuum pressure regulating valve comprising: The valve body is equipped with a working port and a vacuum source port; The valve stem is axially movable within the valve body; A first valve seat assembly, connected to the valve stem and having a first sealing surface, is used to open and close the flow path between the working port and the vacuum source port; The base plate is fixed to the valve body and forms a first cavity with the first valve seat assembly, and a breather hole communicating with the external atmosphere is provided on it. An elastic element, disposed within the first cavity, is used to apply a reset elastic force to the first valve seat assembly; The diaphragm assembly and valve plate are mounted on the valve body. The diaphragm assembly is located inside the valve body and is fixedly connected to the valve stem, and together with the valve plate, they form a pilot cavity. The intake pilot valve and the exhaust pilot valve are respectively connected to the pilot chamber to regulate their pressure; The control system includes an outer loop controller and an inner loop controller. The outer loop controller generates basic control commands based on the deviation between the target pressure and the actual pressure at the working port. The inner loop controller generates control signals based on the basic control commands, a first compensation term, and a second compensation term, and outputs them to the intake pilot valve and the exhaust pilot valve after saturation limiting processing. The first compensation item is calculated based on the reset force of the elastic element and the effective pressure-bearing area of ​​the diaphragm assembly, and is used to offset the effect of the reset force applied by the elastic element to the first valve seat assembly. The second compensation term is calculated based on atmospheric pressure, actual pressure at the working port, cross-sectional area of ​​the first cavity, and effective pressure-bearing area of ​​the diaphragm assembly, and is used to offset the effect of the additional force acting on the first valve seat assembly.

[0006] Furthermore, the outer loop controller includes: The first calculation unit is used to calculate the deviation between the target pressure and the actual pressure at the working port, and to obtain the outer loop error value. A proportional calculation unit is used to generate a proportional component based on the outer loop error value; An integration unit is used to perform integration based on the outer loop error value, and apply an upper limit threshold and a lower limit threshold to the integration result to generate a limited integral component. A differential operation unit is used to generate differential components based on the outer loop error value; The second calculation unit is used to add the proportional component, integral component and differential component to obtain the basic control command.

[0007] Furthermore, the inner loop controller includes: The third calculation unit is used to add the basic control command, the first compensation term, and the second compensation term output by the outer loop controller to obtain a composite command signal, and to subtract the composite command signal from the actual pressure value of the pilot chamber after low-pass filtering to obtain the inner loop error signal; A proportional calculation unit is used to generate a proportional component based on the inner loop error signal; An integration unit is used to perform integration operations based on the inner loop error signal, and apply an upper limit threshold and a lower limit threshold to the integration result to generate a limited integral component. A differential operation unit is used to generate differential components based on the inner loop error signal; The fourth calculation unit is used to add the proportional component, integral component and differential component to obtain the control signal output by the inner loop controller.

[0008] Furthermore, the control system also includes a saturator connected between the output of the inner loop controller and the intake pilot valve and the exhaust pilot valve. The saturator is used to limit the amplitude of the control signal output by the inner loop controller and generate a first PWM signal and a second PWM signal to drive the intake pilot valve and the exhaust pilot valve, respectively.

[0009] Furthermore, the amplitude limitation of the output signal of the inner loop controller and the generation of a first PWM signal and a second PWM signal to drive the intake pilot valve and the exhaust pilot valve respectively specifically include: The output signal of the inner loop controller is normalized and then mapped into a control quantity with an amplitude between negative one and positive one. When the control quantity is greater than zero, a first PWM signal with a continuously adjustable duty cycle between 0% and 100% is generated according to the magnitude of the control quantity to drive the intake pilot valve, and the duty cycle of the second PWM signal is zero. When the control quantity is less than zero, a second PWM signal with a continuously adjustable duty cycle between 0% and 100% is generated based on the absolute value of the control quantity to drive the exhaust pilot valve and make the duty cycle of the first PWM signal zero. When the control quantity is equal to zero, the duty cycle of both the first PWM signal and the second PWM signal is zero.

[0010] Furthermore, the effective pressure-bearing area of ​​the diaphragm assembly is the projected area of ​​the diaphragm assembly in the direction perpendicular to the valve stem axis, and this area is equal to the equivalent force-bearing area of ​​the diaphragm assembly subjected to pressure in the pilot chamber.

[0011] Furthermore, the first compensation term is the ratio of the restoring elastic force of the elastic element to the effective pressure-bearing area of ​​the diaphragm assembly.

[0012] Furthermore, the second compensation item is: The ratio of the difference between standard atmospheric pressure and the actual pressure at the working port, multiplied by the cross-sectional area of ​​the first cavity, to the effective pressure-bearing area of ​​the diaphragm assembly.

[0013] Furthermore, the second compensation item is: The product of the actual pressure at the vacuum source port and the difference between the effective circular area of ​​the top step of the first valve seat and the cross-sectional area of ​​the first cavity, minus the product of the actual pressure at the working port and the effective circular area of ​​the top step of the first valve seat, plus the product of standard atmospheric pressure and the cross-sectional area of ​​the first cavity, is divided by the effective pressure-bearing area of ​​the diaphragm assembly; where: The effective circular area of ​​the top step of the first valve seat refers to the circular area formed by subtracting the width of the first sealing surface from the outer diameter of the top step of the first valve seat from the width of the first sealing surface that fits against the valve body.

[0014] Furthermore, the vacuum pressure regulating valve also includes: A second valve seat assembly connected to the valve stem, the second valve seat assembly having a second sealing surface, and the valve body having an atmospheric port, wherein the first sealing surface is used to control the connection between the working port and the vacuum source port, and the second sealing surface is used to control the connection between the working port and the atmospheric port; When the pilot chamber is pressurized, the diaphragm assembly drives the valve stem to move, so that the second valve seat assembly first closes the passage from the working port to the atmospheric port, and then the first sealing surface opens the passage from the working port to the vacuum source port.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention introduces a first compensation term based on the reset elastic force of the elastic element and the effective pressure bearing area of ​​the diaphragm assembly, and a second compensation term based on atmospheric pressure, actual working port pressure, cross-sectional area of ​​the first cavity and effective pressure bearing area of ​​the diaphragm assembly. The inner loop controller combines the compensation term with the basic control command generated by the outer loop to drive the intake pilot valve and the exhaust pilot valve. The present invention can actively counteract the additional force generated by the atmospheric pressure introduced by the breather hole on the bottom plate acting on the first valve seat assembly and its interference on the main valve force balance, which significantly improves the steady-state control accuracy and dynamic response stability of the vacuum pressure regulating valve under different working port pressure setting conditions.

[0016] (2) The present invention adopts an outer-inner loop cascade control structure. The outer loop generates basic control commands based on the working port pressure tracking error. The inner loop uses the actual pressure of the pilot cavity as feedback quantity for rapid adjustment. The first and second compensation terms based on elastic force and pressure difference disturbance are introduced as feedforward suppression means, which greatly improves the system's ability to track changes in the working port pressure setpoint and its anti-interference performance.

[0017] (3) The control signal output by the inner loop controller of the present invention is normalized by the saturator to generate mutually exclusive PWM drive signals: the positive control quantity drives only the intake pilot valve, and the negative control quantity drives only the exhaust pilot valve. The duty cycle of the two is continuously adjustable, and only one pilot valve is driven at the same time. This avoids the pilot chamber pressure oscillation caused by the simultaneous opening of the intake and exhaust pilot valves, and realizes high-resolution, low-energy proportional control of the pilot chamber pressure, which is beneficial to extend the life of the pilot valve and reduce the power consumption of the system.

[0018] (4) By retaining the bottom plate vent, the present invention effectively eliminates the additional force disturbance caused by the vent while maintaining effective medium isolation of core moving-sealing components such as elastic elements (preventing electrolyte crystallization intrusion). Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the overall structure of the vacuum pressure regulating valve in an embodiment of the present invention; Figure 2 This is a control structure diagram of a control system for a vacuum pressure regulating valve according to an embodiment of the present invention.

[0020] In the picture: 1. Valve body; 11. Working port; 12. Vacuum source port; 13. Atmospheric port; 2. Valve stem; 3. First valve seat assembly; 31. First sealing surface; 32. First cavity; 33. First valve seat; 34. First dustproof ring; 35. First sealing ring; 4. Base plate; 41. Breathing hole; 42. Protrusion; 5. Elastic components; 6. Second valve seat assembly; 61. Second sealing surface; 62. Second valve seat; 63. Second sealing ring; 7. Bushing; 8. Diaphragm assembly; 81. Pilot cavity; 9. Valve plate. Detailed Implementation

[0021] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0022] Example 1 During the first charge and discharge cycle of a battery, an SEI film forms on the surface of the negative electrode, along with gases such as hydrogen, carbon monoxide, and ethylene. To prevent gas retention from affecting interface stability and battery performance, the process typically employs negative pressure pumping / vacuum holding to remove the generated gas and entrained vapor in a timely manner.

[0023] In existing technologies, during the vacuuming process of negative pressure proportional valves, battery electrolyte inevitably mixes into the gas, causing the electrolyte to gradually crystallize in the valve. Most existing negative pressure regulating valves / vacuum proportional valves directly expose the springs and seals to the medium flowing through the chamber. The crystals tend to accumulate on the springs or seals at the bottom of the valve body, causing them to fail due to the accumulation of solid crystals. Although this can be mitigated by selecting corrosion-resistant materials or adding filters and buffers, it is still difficult to completely eliminate the intrusion path of the crystallizing medium into the motion-sealing system from the structure. This results in short maintenance cycles and valve lifespan that is significantly limited by the severity of operating conditions.

[0024] In this regard, such as Figure 1 As shown, this embodiment provides a vacuum pressure regulating valve, including a valve body 1, a valve stem 2, a first valve seat assembly 3, a base plate 4, an elastic element 5, a second valve seat assembly 6, a bushing 7, a diaphragm assembly 8, a valve plate 9, an inlet pilot valve, and an exhaust pilot valve.

[0025] Specifically, the valve body 1 has a working port 11, a vacuum source port 12, and an atmospheric port 13. The working port 11 can be connected to either the vacuum source port 12 or the atmospheric port 13. When the working port 11 is connected to the vacuum source port 12, a vacuuming action can be performed. At this time, a medium flow path is formed between the working port 11 and the vacuum source port 12, which allows the gas medium containing electrolyte water vapor to flow. However, the gas medium containing electrolyte water vapor is prone to crystallization in this medium flow path, which can then adhere to the components in this medium flow path, easily causing the entire vacuum pressure regulating valve to fail and resulting in a short service life.

[0026] In this embodiment, the vacuum source port 12 is located to the side and below the atmospheric port 13. If the vacuum source port 12 is located at a high position, liquid-containing gas may form a vortex at the bottom of the valve cavity and accumulate liquid after entering. The low position design utilizes the characteristic of water flowing downhill, making it easier for the entrained condensate and droplets to be carried away by the mainstream airflow and discharged into the subsequent recovery or filtration device, reducing the accumulation of liquid in the valve.

[0027] In this embodiment, the valve stem 2 moves within the valve body 1 along the axial direction, which is vertical in this embodiment. The first valve seat assembly 3 is connected to the valve stem 2 and moves accordingly. The first valve seat assembly 3 is provided with a first sealing surface 31, which is in separable contact with the valve body 1. The first valve seat assembly 3 is arranged in the medium flow path between the working port 11 and the vacuum source port 12. When the first sealing surface 31 rises and abuts against the valve body 1, the first valve seat assembly 3 closes the medium flow path. When the first sealing surface 31 falls and separates from the valve body 1, the second valve seat assembly 6 opens the medium flow path. Therefore, the closing and opening of the medium flow path is controlled by the valve stem 2, while the base plate 4 is fixed. The base plate 4 and the first valve seat assembly 3 are fixed on the valve body 1, forming a first cavity 32 that is isolated from the medium flow path. The elastic member 5 is disposed in the first cavity 32 and is used to apply a reset elastic force to the first valve seat assembly 3. When the valve stem 2 does not apply a driving force, the elastic member 5 can apply an elastic force to keep the first valve seat assembly 3 in a closed medium flow path state. Even when the valve stem 2 drives the first valve seat assembly 3 to open the medium flow path, since the elastic member 5 is located in the first cavity 32, it will not come into contact with the electrolyte liquid in the medium flow path, so it is not easy for crystals to form on the elastic member 5, thus avoiding the failure of the elastic member 5 due to crystallization, thereby ensuring and improving the service life of the valve.

[0028] In this embodiment, the base plate 4 is detachably fixed to the bottom of the valve body 1 by bolts. By removing the base plate 4, the medium flow path between the working port 11 and the vacuum source port 12 can be exposed, thereby facilitating the installation of the first valve seat assembly 3.

[0029] In this embodiment, the displacement of the first valve seat assembly 3 and the elastic member 5 will change the effective volume of the first cavity 32. If the first cavity 32 is completely closed, the displacement of the first valve seat assembly 3 and the elastic member 5 will change the air pressure of the first cavity 32, and its displacement will become very difficult. Therefore, in this embodiment, a vent 41 is provided on the base plate 4 to connect the first cavity 32 with the external atmosphere. Through the vent 41, the air pressure in the first cavity 32 can always be kept consistent with the atmospheric pressure, ensuring the smooth movement of the first valve seat assembly 3 and the elastic member 5.

[0030] Furthermore, the first valve seat assembly 3 includes a first valve seat 33 and a first dustproof ring 34. A protrusion 42 is provided on the base plate 4. The first valve seat 33 is sleeved on the outside of the protrusion 42. The first dustproof ring 34 is engaged with the inner wall of the first valve seat 33 and slides against the outside of the protrusion 42 to isolate the first cavity 32 from the medium flow path. The protrusion 42 of the base plate 4 and the first valve seat 33 form a sleeve structure. The first dustproof ring 34, as a dynamic seal, fills the radial gap between the two, achieving complete isolation between the first cavity 32 and the medium flow path, preventing electrolyte gas from entering the first cavity 32, thereby protecting the elastic member 5 located in the first cavity 32.

[0031] Furthermore, the elastic element 5 is configured as a return spring, which is arranged vertically within the first cavity 32. One end of the return spring is connected to the protrusion 42, and the other end is connected to the inner wall of the first valve seat 33. The return spring is always in a compressed state. When the base plate 4 is fixed, the return spring provides a force away from the base plate 4 to the first valve seat 33. In this embodiment, the base plate 4 is located below the first valve seat 33. Therefore, the return spring provides an upward force to the first valve seat 33. The first sealing surface 31 is located at the top of the first valve seat 33, which keeps the first sealing surface 31 in contact with the valve body 1, thereby keeping it in a closed state of the medium flow path.

[0032] Furthermore, the first valve seat assembly 3 also includes a first sealing ring 35. The first sealing ring 35 is engaged with the inner wall of the first valve seat 33 and located within the first cavity 32. The first sealing ring 35 can slide against the outer wall of the protrusion 42. In this embodiment, the first sealing ring 35 is located above the first dustproof ring 34 and is also protected by the first dustproof ring 34 to prevent the electrolyte from crystallizing on the first sealing ring 35 and to prevent the first sealing ring 35 from failing. Moreover, the first sealing ring 35 and the first dustproof ring 34 can achieve a double sealing effect. The first dustproof ring 34 is used to block macroscopic droplets, particles and most high-pressure gases, and bears the main pressure difference and wear. The first sealing ring 35 works in a relatively clean, low-pressure-difference environment and is mainly responsible for fine static or micro-motion sealing.

[0033] Specifically, a second sealing surface 61 is provided on the second valve seat assembly 6, and a vacuum source port 12 and an atmospheric port 13 are also provided on the valve body 1. The first sealing surface 31 is used to control the connection between the working port 11 and the vacuum source port 12, and the second sealing surface 61 is used to control the connection between the working port 11 and the atmospheric port 13. The second valve seat assembly 6 cooperates with the first valve seat assembly 3 to realize the selective connection between the working port 11 and the vacuum source port 12 or the atmospheric port 13.

[0034] Furthermore, the bushing 7 is sleeved on the outside of the valve stem 2. The second valve seat assembly 6 includes a second valve seat 62 and a second sealing ring 63. The second valve seat 62 is connected to the valve stem 2 and is movably disposed at the bottom of the bushing 7. The second sealing ring 63 is engaged on the outside of the second valve seat 62 and slides against the inside of the bushing 7. The second sealing surface 61 is located at the bottom of the second valve seat 62. When the second valve seat 62 moves downward within the bushing 7 until the second sealing surface 61 abuts against the valve body 1, the second valve seat 62 closes the passage between the working port 11 and the atmospheric port 13.

[0035] Under normal conditions without driving force, the first sealing surface 31 seals the passage between the working port 11 and the vacuum source port 12 bracket, while the second sealing surface 61 keeps the passage between the working port 11 and the atmospheric port 13 open. During the lithium-ion battery formation process, if the vacuum system accidentally goes out of control and continues to pump air, it will cause excessive negative pressure inside the cell, which may cause the aluminum-plastic film encapsulation to rupture, the separator to wrinkle, or even the electrode to break. Therefore, under normal conditions, the working port 11 is kept connected to the atmospheric port 13 to avoid accidental vacuuming and protect the cell from damage. In addition, under normal conditions, the working port 11 and the atmospheric port 13 are directly connected, without relying on an additional vacuum breaking valve or manual operation.

[0036] Specifically, the diaphragm assembly 8 is fixedly connected to the valve stem 2. The valve plate 9 and the diaphragm assembly 8 are both located inside the valve body 1 and together form a pilot chamber 81. The inlet pilot valve and the exhaust pilot valve are both connected to the pilot chamber 81 and are used to control the pressure in the pilot chamber 81 to drive the displacement of the diaphragm assembly 8 and the valve stem 2. The inlet pilot valve only needs to provide enough thrust to overcome the area of ​​the pilot chamber 81 to drive the valve stem 2 through the diaphragm assembly 8 to overcome the pressure of the main valve spring and the medium. The effective area of ​​the diaphragm assembly 8 is much larger than the cross-sectional area of ​​the valve stem 2, which can save energy. Moreover, since the diaphragm assembly 8 is elastically connected, even a small change in the pressure of the pilot chamber 81 will be converted into a change in the stroke of the valve stem 2. This makes the valve not only able to perform switching actions, but also usable as a proportional regulating valve to accurately control the target vacuum degree of the working port 11.

[0037] In conjunction with the first cavity 32 mentioned above, the existence of the first cavity 32 means that the internal pressure of the first valve seat 33 is one standard atmosphere. The influence of this pressure on the first valve seat 33 will change with the change of the pressure at the working port 11. As a result, the additional force on the first valve seat 33 will also change. This will affect the midpoint of the main valve force balance control. It is necessary to modify the pressure control of the pilot cavity 81 by adding the pressure of this force divided by the area of ​​the diaphragm assembly 8. Alternatively, it can be controlled by the intake pilot valve.

[0038] Furthermore, when the pilot chamber 81 is pressurized, the diaphragm assembly 8 drives the valve stem 2 to move, so that the second valve seat assembly 6 first closes the passage from the working port 11 to the atmospheric port 13, and then the first sealing surface 31 opens the passage from the working port 11 to the vacuum source port 12. When the pilot chamber 81 is pressurized, it drives the diaphragm assembly 8 to move downward, the diaphragm assembly 8 drives the valve stem 2 to move downward, the valve stem 2 drives the second valve seat assembly 6 to move downward, so that its second sealing surface 61 closes the passage from the working port 11 to the atmospheric port 13, and simultaneously drives the first valve seat assembly 3 to move downward, so that its first sealing surface 31 disengages from the valve body 1 and opens the passage from the working port 11 to the vacuum source port 12.

[0039] In this embodiment, the first valve seat assembly and the base plate together form a first cavity that is isolated from the medium flow path. The reset spring and the first sealing ring are both located in the first cavity, so that the reset spring and the first sealing ring will not come into contact with the medium of electrolyte crystallization, which significantly reduces the probability of jamming and sealing failure and improves the service life of the regulating valve. In addition, the vent in this embodiment connects the first cavity to the outside, which allows the air pressure to remain normal when the return spring moves in the first cavity, without affecting the movement of the return spring and ensuring the smooth displacement of the first valve seat assembly. In this embodiment, the vacuum source port is located to the side and below the working port. When the gas medium containing electrolyte water vapor is pumped away, it is not easy to deposit on the critical moving parts and crystallize.

[0040] The technical solution of the present invention has been described in detail above with reference to the accompanying drawings. The described embodiments are used to help understand the concept of the present invention. The specific embodiments described herein are merely illustrative examples of the spirit of the present invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of the present invention or exceeding the scope defined by the appended claims.

[0041] Example 2 To overcome the problem of valve seat additional force interfering with the main valve force balance caused by the use of atmospheric-connected isolation chambers for isolating crystalline media in existing technologies, such as... Figure 2As shown, this invention proposes a control system for the vacuum pressure regulating valve described in Embodiment 1. The control system includes an outer loop controller and an inner loop controller. The outer loop controller generates a basic control command based on the deviation between the target pressure and the actual pressure at the working port. The inner loop controller generates a control signal based on the basic control command, a first compensation term, and a second compensation term, and outputs it to the intake pilot valve and the exhaust pilot valve after saturation limiting processing. Wherein: The first compensation item is calculated based on the reset force of the elastic element and the effective pressure-bearing area of ​​the diaphragm assembly, and is used to offset the effect of the reset force applied by the elastic element to the first valve seat assembly. The effective pressure-bearing area of ​​the diaphragm assembly is the projected area of ​​the diaphragm assembly in the direction perpendicular to the valve stem axis, and this area is equal to the equivalent force-bearing area of ​​the diaphragm assembly under the pressure in the pilot chamber.

[0042] The first compensation term is the ratio of the restoring elastic force of the elastic element to the effective pressure-bearing area of ​​the diaphragm assembly.

[0043] The second compensation term is calculated based on atmospheric pressure, actual pressure at the working port, cross-sectional area of ​​the first cavity, and effective pressure-bearing area of ​​the diaphragm assembly, and is used to offset the effect of the additional force acting on the first valve seat assembly.

[0044] The calculation of the second compensation item includes two implementation methods. The first implementation method is as follows: The second compensation term is the product of the difference between standard atmospheric pressure and the actual pressure at the working port, and the cross-sectional area of ​​the first cavity, and then the ratio of this product to the effective pressure-bearing area of ​​the diaphragm assembly.

[0045] In this embodiment, to achieve high-precision proportional regulation of the pressure at the working port 11, the control system drives the valve stem 2 and the first valve seat assembly 3 and the second valve seat assembly 6 connected thereto by precisely controlling the pressure within the pilot chamber 81. This control strategy includes two key compensation terms to ensure the accuracy of the force balance of the vacuum pressure regulating valve.

[0046] The first compensation term is used to counteract the effect of the reset force exerted by the elastic element 5 (i.e., the return spring) on ​​the first valve seat assembly 3. This compensation is necessary regardless of whether a breather hole 41 is provided on the base plate 4. The principle is that the elastic element 5 always applies an upward reset force to the first valve seat assembly 3. In order for the control system to perform proportional regulation in a state without bias (no bias means that the pilot chamber pressure has compensated for the spring force, the system is in a neutral state of force balance, and there is no inherent tendency to open or close), as mentioned above, the synthesized command signal of the inner loop controller is obtained by adding the outer loop output, the first compensation term, and the second compensation term. Among them, the first compensation term is represented in the form of pressure (F / A) and is used to balance the reset force of the elastic element 5 in the static state to establish the control midpoint.

[0047] In the first implementation of the second compensation item: The second compensation term is based on the atmospheric pressure at working port 11. The pressure difference between the actual pressure P and the pressure differential offsets the additional force generated by the pressure difference acting on the first valve seat assembly 3. The first cavity 32 is connected to the external atmosphere through the breather 41, and its internal pressure is atmospheric pressure. The outer side of the first valve seat assembly 3 bears the pressure P of the working port 11. When P changes, the net pressure differential force acting on the first valve seat assembly 3 also changes, thus disturbing the force balance of the valve. Therefore, the control system needs to calculate this additional force in real time and convert it into an equivalent pressure correction for the pilot chamber 81. The magnitude of this correction (i.e., the second compensation term) is... ,in, Let A be the cross-sectional area of ​​the first cavity, and let A be the effective pressure-bearing area of ​​the diaphragm assembly.

[0048] In actual control, the output signal of the outer loop controller is superimposed with the first compensation term (static spring force compensation) and the second compensation term (dynamic differential pressure compensation) to form the input command of the inner loop controller. After being processed by the inner loop controller, the command is output to the saturator, which then generates the first PWM signal and the second PWM signal to drive the intake pilot valve and the exhaust pilot valve. By adjusting the opening of the two pilot valves, the actual pressure of the pilot chamber 81 is made to accurately track the command value, thereby driving the diaphragm assembly 8 and the valve stem 2 to move, realizing high-precision proportional regulation of the pressure at the working port 11.

[0049] Among them, both the first compensation term and the second compensation term are feedforward compensation quantities with clear physical meaning. The first compensation term is a positive value, and its magnitude is equal to the restoring elastic force of the elastic element divided by the effective pressure-bearing area of ​​the diaphragm assembly; the second compensation term is composed of... The calculation shows that its sign automatically reflects the direction of the pressure difference: when the working port pressure is lower than atmospheric pressure, the value is positive, indicating that additional pilot chamber pressure is needed to overcome the additional closing force generated by atmospheric pressure; when the working port pressure is higher than atmospheric pressure, the value is negative, indicating that the fluid pressure generates an auxiliary opening effect.

[0050] The two compensation values ​​mentioned above are algebraically added to the basic command output by the outer loop controller in the third calculation unit to form a synthetic command signal, which is used to generate the inner loop pressure control error, thereby driving the intake or exhaust pilot valve to operate.

[0051] The second implementation method of the second compensation item is as follows: The product of the actual pressure at the vacuum source port and the difference between the effective circular area of ​​the top step of the first valve seat and the cross-sectional area of ​​the first cavity, minus the product of the actual pressure at the working port and the effective circular area of ​​the top step of the first valve seat, plus the product of standard atmospheric pressure and the cross-sectional area of ​​the first cavity, is divided by the effective pressure-bearing area of ​​the diaphragm assembly; where: The effective circular area of ​​the top step of the first valve seat refers to the circular area formed by subtracting the width of the first sealing surface from the outer diameter of the top step of the first valve seat from the width of the first sealing surface that fits against the valve body.

[0052] The calculation formula corresponding to the second implementation method is: ; In the formula, This indicates the actual pressure at the vacuum source port. This indicates the actual pressure at working port 11. This represents the effective circular area of ​​the top step of the first valve seat.

[0053] Compared with the first embodiment which is based solely on the pressure difference between atmospheric pressure and the working port, this second embodiment further introduces vacuum source port pressure and valve seat structural parameters (such as the effective area of ​​the top step of the first valve seat), which can more accurately reflect the actual stress state acting on the first valve seat assembly. Especially under conditions of vacuum source pressure fluctuation or complex valve seat geometry, it significantly improves the stability and control accuracy of pressure regulation.

[0054] The outer loop controller includes: The first calculation unit is used to calculate the deviation between the target pressure and the actual pressure at the working port, and to obtain the outer loop error value. A proportional calculation unit is used to generate a proportional component based on the outer loop error value; An integration unit is used to perform integration based on the outer loop error value, and apply an upper limit threshold and a lower limit threshold to the integration result to generate a limited integral component. A differential operation unit is used to generate differential components based on the outer loop error value; The second calculation unit is used to add the proportional component, integral component and differential component to obtain the basic control command.

[0055] In the outer loop controller of this embodiment: 1. The first calculation unit calculates the difference between the target pressure at the working port and the actual pressure at the working port after low-pass filtering, which is taken as the outer loop error value and denoted as . .

[0056] 2. The proportional calculation unit of the outer loop controller calculates based on the outer loop error value, and its output... for: ; in, This is the outer loop proportional feedback coefficient.

[0057] 3. The integral calculation unit of the outer loop controller performs integral calculation on the outer loop error value, and its original output... for: ; And a saturation constraint is imposed on the integral result, so that the final integral components satisfy: ; in, For the outer loop integral feedback coefficient, This is the limiting threshold for the outer loop integral saturator.

[0058] 4. The differential operation unit of the outer loop controller calculates the outer loop error value. The filtered signal is obtained after low-pass filtering. ,right Further differential calculations are performed, and the output is the differential component. for: ; The differential operation includes a low-pass filter to suppress noise, where is the outer loop differential feedback coefficient.

[0059] The inner loop controller includes: The third calculation unit is used to add the basic control command, the first compensation term, and the second compensation term output by the outer loop controller to obtain a composite command signal, and to subtract the composite command signal from the actual pressure value of the pilot chamber after low-pass filtering to obtain the inner loop error signal; A proportional calculation unit is used to generate a proportional component based on the inner loop error signal; An integration unit is used to perform integration operations based on the inner loop error signal, and apply an upper limit threshold and a lower limit threshold to the integration result to generate a limited integral component. A differential operation unit is used to generate differential components based on the inner loop error signal; The fourth calculation unit is used to add the proportional component, integral component and differential component to obtain the control signal output by the inner loop controller.

[0060] In the inner loop controller of this embodiment: The third calculation unit uses the difference between the synthesized command signal and the actual pilot cavity pressure value after low-pass filtering as the inner loop error value, denoted as . .

[0061] The proportional, integral, and derivative operation units of the inner loop controller use the same computational structure, and their outputs are as follows: ; ; ; In the formula, This is the inner loop proportional feedback coefficient. The output of the proportional operation unit is the proportional component. Indicates the inner loop integral feedback coefficient. This represents the integral result before applying saturation constraints; This represents the inner loop differential feedback coefficient. This indicates that the differential operation unit of the inner loop controller has a certain understanding of the inner loop error value. The filtered signal is obtained after low-pass filtering. , This represents the output of the differential operation unit in the inner loop controller, i.e., the differential component.

[0062] The feedback coefficients of the outer loop controller and the inner loop controller are independent of each other, both being positive real numbers greater than zero, and are set separately according to their respective control requirements.

[0063] The control system also includes a saturator connected between the output of the inner loop controller and the intake pilot valve and the exhaust pilot valve. The saturator is used to limit the amplitude of the control signal output by the inner loop controller and generate a first PWM signal and a second PWM signal to drive the intake pilot valve and the exhaust pilot valve, respectively.

[0064] The amplitude limitation of the output signal of the inner loop controller and the generation of a first PWM signal and a second PWM signal to drive the intake pilot valve and the exhaust pilot valve respectively include: The output signal of the inner loop controller is normalized and then mapped into a control quantity with an amplitude between negative one and positive one. Specifically, the normalization process refers to: adjusting the output signal u of the inner loop controller according to its preset physical allowable range. This is mapped to the standard normalized interval [-1, +1] through a linear transformation. Specifically, the normalized control quantity... Calculate using the following formula: ; in, These are the lower and upper limits of the inner loop controller's output, determined during system design, ensuring that any control signal processed in this way satisfies these limits. .

[0065] When the control quantity is greater than zero, a first PWM signal with a continuously adjustable duty cycle between 0% and 100% is generated according to the magnitude of the control quantity to drive the intake pilot valve, and the duty cycle of the second PWM signal is zero. When the control quantity is less than zero, a second PWM signal with a continuously adjustable duty cycle between 0% and 100% is generated based on the absolute value of the control quantity to drive the exhaust pilot valve and make the duty cycle of the first PWM signal zero. When the control quantity is equal to zero, the duty cycle of both the first PWM signal and the second PWM signal is zero.

[0066] In this embodiment, the control system uses the normalized control quantity. The sign of the pilot valve determines how it is driven: when When the actual pressure at the working port is lower than the target pressure, air needs to be injected into the pilot chamber to increase the working port pressure. At this time, a PWM signal (denoted as the first PWM signal) is generated to drive the intake pilot valve. Its duty cycle increases linearly with the value of the control quantity, up to a maximum of 100%. when When the actual pressure at the working port is higher than the target pressure, it indicates that exhaust gas needs to be released from the pilot chamber to reduce the working port pressure. At this time, a PWM signal (denoted as the second PWM signal) is generated to drive the exhaust pilot valve. Its duty cycle increases linearly with the increase of the absolute value of the control quantity, and can reach a maximum of 100%. when At this time, both pilot valves are closed, and the duty cycles of the first PWM signal and the second PWM signal are both 0%.

[0067] Therefore, the first PWM signal corresponds to the intake pilot valve, and the second PWM signal corresponds to the exhaust pilot valve. The two output mutually exclusive control quantities to ensure stable system operation.

[0068] This invention introduces a first compensation term calculated based on the return elastic force of the elastic element and the effective pressure-bearing area of ​​the diaphragm assembly, and a second compensation term calculated based on atmospheric pressure, the actual pressure at the working port, the cross-sectional area of ​​the first cavity, and the effective pressure-bearing area of ​​the diaphragm assembly. The inner loop controller synthesizes the compensation terms with the basic control commands generated by the outer loop to drive the intake pilot valve and the exhaust pilot valve. This invention can actively counteract the additional force generated by the atmospheric pressure introduced by the breather hole on the base plate acting on the first valve seat assembly and its interference with the force balance of the main valve, significantly improving the steady-state control accuracy and dynamic response stability of the vacuum pressure regulating valve under different working port pressure setting conditions.

[0069] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the attached figures). If the specific posture changes, the directional indication will also change accordingly. Furthermore, descriptions involving "first," "second," or "a" in the present invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. In the description of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly defined. In the present invention, unless otherwise explicitly specified and defined, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise explicitly defined. For those skilled in the art, the specific meanings of the above terms in this invention can be understood according to the specific circumstances. Furthermore, the technical solutions of the various embodiments of this invention can be combined with each other, but only on the basis that those skilled in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

Claims

1. A control system for a vacuum pressure regulating valve, characterized in that, Vacuum pressure regulating valve includes: The valve body is equipped with a working port and a vacuum source port; The valve stem is axially movable within the valve body; A first valve seat assembly, connected to the valve stem and having a first sealing surface, is used to open and close the flow path between the working port and the vacuum source port; The base plate is fixed to the valve body and forms a first cavity with the first valve seat assembly, and a breather hole communicating with the external atmosphere is provided on it. An elastic element, disposed within the first cavity, is used to apply a reset elastic force to the first valve seat assembly; The diaphragm assembly and valve plate are mounted on the valve body. The diaphragm assembly is located inside the valve body and is fixedly connected to the valve stem, and together with the valve plate, they form a pilot cavity. The intake pilot valve and the exhaust pilot valve are respectively connected to the pilot chamber to regulate their pressure; The control system includes an outer loop controller and an inner loop controller. The outer loop controller generates basic control commands based on the deviation between the target pressure and the actual pressure at the working port. The inner loop controller generates control signals based on the basic control commands, a first compensation term, and a second compensation term, and outputs them to the intake pilot valve and the exhaust pilot valve after saturation limiting processing. The first compensation item is calculated based on the reset force of the elastic element and the effective pressure-bearing area of ​​the diaphragm assembly, and is used to offset the effect of the reset force applied by the elastic element to the first valve seat assembly. The second compensation term is calculated based on atmospheric pressure, actual pressure at the working port, cross-sectional area of ​​the first cavity, and effective pressure-bearing area of ​​the diaphragm assembly, and is used to offset the effect of the additional force acting on the first valve seat assembly.

2. The control system for a vacuum pressure regulating valve according to claim 1, characterized in that, The outer loop controller includes: The first calculation unit is used to calculate the deviation between the target pressure and the actual pressure at the working port, and to obtain the outer loop error value. A proportional calculation unit is used to generate a proportional component based on the outer loop error value; An integration unit is used to perform integration based on the outer loop error value, and apply an upper limit threshold and a lower limit threshold to the integration result to generate a limited integral component. A differential operation unit is used to generate differential components based on the outer loop error value; The second calculation unit is used to add the proportional component, integral component and differential component to obtain the basic control command.

3. The control system for a vacuum pressure regulating valve according to claim 1, characterized in that, The inner loop controller includes: The third calculation unit is used to add the basic control command, the first compensation term, and the second compensation term output by the outer loop controller to obtain a composite command signal, and to subtract the composite command signal from the actual pressure value of the pilot chamber after low-pass filtering to obtain the inner loop error signal; A proportional calculation unit is used to generate a proportional component based on the inner loop error signal; An integration unit is used to perform integration operations based on the inner loop error signal, and apply an upper limit threshold and a lower limit threshold to the integration result to generate a limited integral component. A differential operation unit is used to generate differential components based on the inner loop error signal; The fourth calculation unit is used to add the proportional component, integral component and differential component to obtain the control signal output by the inner loop controller.

4. The control system for a vacuum pressure regulating valve according to claim 1, characterized in that, The control system also includes a saturator connected between the output of the inner loop controller and the intake pilot valve and the exhaust pilot valve. The saturator is used to limit the amplitude of the control signal output by the inner loop controller and generate a first PWM signal and a second PWM signal to drive the intake pilot valve and the exhaust pilot valve, respectively.

5. The control system for a vacuum pressure regulating valve according to claim 4, characterized in that, The amplitude limitation of the output signal of the inner loop controller and the generation of a first PWM signal and a second PWM signal to drive the intake pilot valve and the exhaust pilot valve respectively include: The output signal of the inner loop controller is normalized and then mapped into a control quantity with an amplitude between negative one and positive one. When the control quantity is greater than zero, a first PWM signal with a continuously adjustable duty cycle between 0% and 100% is generated according to the magnitude of the control quantity to drive the intake pilot valve, and the duty cycle of the second PWM signal is zero. When the control quantity is less than zero, a second PWM signal with a continuously adjustable duty cycle between 0% and 100% is generated based on the absolute value of the control quantity to drive the exhaust pilot valve and make the duty cycle of the first PWM signal zero. When the control quantity is equal to zero, the duty cycle of both the first PWM signal and the second PWM signal is zero.

6. The control system for a vacuum pressure regulating valve according to claim 1, characterized in that, The effective pressure-bearing area of ​​the diaphragm assembly is the projected area of ​​the diaphragm assembly in the direction perpendicular to the valve stem axis, and this area is equal to the equivalent force-bearing area of ​​the diaphragm assembly under the pressure in the pilot chamber.

7. The control system for a vacuum pressure regulating valve according to claim 1, characterized in that, The first compensation term is the ratio of the restoring elastic force of the elastic element to the effective pressure-bearing area of ​​the diaphragm assembly.

8. The control system for a vacuum pressure regulating valve according to claim 1, characterized in that, The second compensation item is: The ratio of the difference between standard atmospheric pressure and the actual pressure at the working port, multiplied by the cross-sectional area of ​​the first cavity, to the effective pressure-bearing area of ​​the diaphragm assembly.

9. The control system for a vacuum pressure regulating valve according to claim 1, characterized in that, The second compensation item is: The product of the actual pressure at the vacuum source port and the difference between the effective circular area of ​​the top step of the first valve seat and the cross-sectional area of ​​the first cavity, minus the product of the actual pressure at the working port and the effective circular area of ​​the top step of the first valve seat, plus the product of standard atmospheric pressure and the cross-sectional area of ​​the first cavity, is divided by the effective pressure-bearing area of ​​the diaphragm assembly; where: The effective circular area of ​​the top step of the first valve seat refers to the circular area formed by subtracting the width of the first sealing surface from the outer diameter of the top step of the first valve seat from the width of the first sealing surface that fits against the valve body.

10. The control system for a vacuum pressure regulating valve according to claim 1, characterized in that, The vacuum pressure regulating valve also includes: A second valve seat assembly connected to the valve stem, the second valve seat assembly having a second sealing surface, and the valve body having an atmospheric port, wherein the first sealing surface is used to control the connection between the working port and the vacuum source port, and the second sealing surface is used to control the connection between the working port and the atmospheric port; When the pilot chamber is pressurized, the diaphragm assembly drives the valve stem to move, so that the second valve seat assembly first closes the passage from the working port to the atmospheric port, and then the first sealing surface opens the passage from the working port to the vacuum source port.

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