A detachable intelligent control proportional electromagnetic valve for a breathing machine

Abstract

The application provides a detachable intelligent control proportional electromagnetic valve for a breathing machine, which comprises a valve seat assembly, an armature assembly, a valve sleeve assembly, an adjusting assembly, a coil assembly and a shell assembly. The proportional electromagnetic valve of the application sets the valve sleeve as a magnetic isolation material to realize a magnetic isolation effect, thereby increasing the magnetic flux in the armature; the guide sleeve with the inclined open notch structure is set, and the guide sleeve does not need to be installed by thermal expansion, and is convenient to maintain; and the shell assembly of the proportional electromagnetic valve of the application is designed to be directly bolted with the air inlet and outlet tooling, and is easy to install and detach the proportional electromagnetic valve. Meanwhile, the application also provides a precise control method for the flow of each stage which is subdivided according to different characteristics by using a PID closed loop control mode, so as to optimize the linearity of the flow curve of the gas medium supplied by the breathing machine.

Description

Technical Field

[0001] This invention relates to the field of precision control of medical devices, and specifically provides an intelligent proportional control solenoid valve device with high flow rate, fast response, small structure, simple and easy disassembly, and stable electromagnetic force that is accurately distributed proportionally. Background Technology

[0002] A ventilator is essentially a ventilation machine used to replace, control, or alter a person's normal physiological breathing, increase lung ventilation, improve respiratory function, and reduce respiratory strain. As an effective means of artificially replacing spontaneous ventilation, ventilators are widely used in the following three major areas:

[0003] (1) Respiratory failure caused by respiratory diseases: such as chronic obstructive pneumonia, lung infection, and asthma;

[0004] (2) Surgical procedures: including respiratory management during major surgical anesthesia, and intraoperative and postoperative ventilation support in pediatric surgery; and

[0005] (3) Sleep apnea: such as snoring and sleep-disordered breathing.

[0006] The main technologies of ventilators include: ventilation modes, control technology, measurement technology, ergonomics and display technology, as well as the overall supporting technology of core components. The proportional solenoid valve is a key component of a ventilator, often considered the "crown jewel" of valves. In treating patients with difficulty breathing spontaneously, doctors need to develop different respiratory assistance plans based on the patient's condition. The computer system then sends different currents to the proportional solenoid valve according to the different volumes and needs of gas release, thereby controlling its opening size and precisely controlling parameters such as the flow rate and oxygen ratio of the incoming and outgoing gas to provide a customized respiratory assistance plan.

[0007] A proportional solenoid valve is not a simple machined component; it comprises a dozen or more parts, connected by electromagnetic force, elasticity, and a precise transmission mechanism. The stroke of the valve disc as it moves up and down is only a fraction of a millimeter, equivalent to the width of a few strands of hair placed side by side. This trajectory places extremely high demands on motion control, reliable sealing, rubber manufacturing precision, and the pressure resistance of the components. A proportional solenoid valve is an electrically controlled device; it opens when energized, allowing gas to flow from one end to the other; when de-energized, it closes, stopping the flow of gas.

[0008] To ensure patient safety during mechanical ventilation, ventilators have stringent requirements for flow control accuracy, typically allowing a flow error within 10%. This parameter is also a crucial performance indicator for evaluating ventilator quality. The ventilator's inspiratory module is usually responsible for tracking and stabilizing the flow rate according to the master controller's instructions. In the inspiratory module's airway, the proportional solenoid valve plays a key role. A significant pressure difference exists across the valve body, and airflow exits through a small gap within the valve body, forming a sonic flow. The flow rate depends on the proportional solenoid valve's flow area. It is generally believed that the flow rate through the proportional solenoid valve is a linear function of the coil current. However, in practical applications, due to the transient characteristics of the proportional valve, this linear function alone cannot be used to control it; closed-loop control is necessary.

[0009] Proportional solenoid valves, as key components of ventilators, possess advantages such as good dynamic characteristics, high control precision, and ease of integration. In ventilator applications, both sides of the proportional solenoid valve contain highly compressible gases, resulting in time-varying, nonlinear, and highly volatile system characteristics, making it difficult to establish accurate mathematical models. Traditional PID controllers often rely on deterministic mathematical models to tune parameters, using a fixed set of parameters to complete the system's control tasks, making it difficult to simultaneously meet all set output flow control requirements. In the past decade or so, scholars both domestically and internationally have conducted extensive research on pneumatic proportional servo systems, applying research findings in control theory, such as adaptive control, fuzzy control, neural network control, variable structure control, and robust control, achieving certain progress. Among these, fuzzy control is an intelligent control method suitable for controlling systems that are difficult to model accurately, exhibit strong nonlinearity, and large time delays. It demonstrates strong robustness to changes in system parameters, strong anti-interference capabilities, and achieves good control performance.

[0010] Proportional solenoid valves are based on proportional electromagnet technology. They are proportional control valves that use proportional electromagnets as electromechanical conversion elements. They convert the input current signal into force and displacement mechanical signals for output, thereby continuously and proportionally controlling the flow, pressure and direction of the hydraulic system. The output flow and pressure are unaffected by load changes. Thus, the valve opening can be adjusted by changing the input current, thereby achieving stepless flow regulation. They have the advantages of simple structure, easy processing, easy assembly, fast response, high reliability and low cost, and are very suitable for the application requirements of flow regulation in ventilator systems. However, general proportional solenoid valves have the following limitations in application: (1) They cannot adapt to high load conditions. When the working pressure is high or the valve diameter is large, a high pressure difference will be formed between the upstream and downstream of the valve. A large electromagnetic force is required to overcome the pressure difference and open the valve. However, once the valve is opened, the pressure difference will drop significantly, which will break the force balance relationship of the valve core, making it difficult for the valve armature to remain in a stationary throttling position. Therefore, most proportional solenoid valves can only be applied to low load and low flow conditions. (2) The nonlinearity and hysteresis characteristics of the BH curve of electromagnetic materials will seriously affect the proportional characteristics of valve current input and flow output, which is not conducive to the open-loop control of the system.

[0011] Specifically, ventilators used in hospital clinical settings and emergency medical care require a flow rate of up to 180 L / min, an extremely short response time, and a master control valve assembly that accurately distributes and mixes fluids. For a relatively advanced ventilator, if these prerequisites are met, it can provide the patient with adequate ventilation and extremely comfortable respiratory support according to a specific control algorithm.

[0012] Furthermore, the installation of proportional solenoid valves in ventilators typically involves bolting the proportional solenoid valve to the inlet / outlet fixture (e.g., in patent CN215780800U). For the bolted connection on the inlet / outlet side, during installation, because the fixture surface is larger than the proportional solenoid valve end face, the bolt needs to be inserted from the valve seat side. Due to product dimensions, part of the bolt hole surface is obstructed by the outer casing. Therefore, during installation, the outer casing fastening nut of the proportional solenoid valve needs to be removed, the outer casing assembly removed, the valve seat and fixture bolted together, the outer casing assembly reinstalled, and the fastening nut reinstalled. This installation process is cumbersome; and although the probability is low, it can still cause contamination of the device and slight deviations in structure and magnetic field.

[0013] Meanwhile, in existing technologies, to achieve stable electromagnetic force, a magnetic isolation ring structure is often added between the upper and lower iron cores. This alters the magnetic circuit, directing the force to the armature, thus stabilizing the electromagnetic force and improving the performance of the proportional solenoid valve. However, as a delicate and minute component, any addition of components or parts to the proportional solenoid valve will inevitably impact manufacturing and assembly difficulty and precision, or pose certain risks. While pursuing stable electromagnetic force and customized performance, structural simplification, component integration, or the widespread application of existing / pre-existing components are also crucial factors that need to be considered. Summary of the Invention

[0014] To address the technical problems in existing proportional solenoid valves regarding integration and linear flow control, this invention provides an easily detachable, intelligently controlled proportional solenoid valve device for ventilators. The proportional solenoid valve of this invention uses a magnetically shielding material for the valve sleeve to achieve magnetic isolation, thereby increasing the magnetic flux in the armature; the guide sleeve with a beveled structure eliminates the need for thermal expansion during installation, facilitating maintenance; and the outer casing assembly of the proportional solenoid valve is designed for direct bolt mounting to the inlet / outlet fixture, facilitating installation and disassembly. Furthermore, this invention provides a method for precise flow control at different stages based on different characteristics using PID closed-loop control, thereby optimizing the linearity of the flow curve of the gas supplied to the ventilator.

[0015] Specifically, in order to achieve the above objectives, the technical solution of the present invention is as follows:

[0016] A first aspect of the present invention provides a proportional solenoid valve for easy disassembly and intelligent control of a ventilator, comprising a valve seat assembly, an armature assembly, a valve sleeve assembly, an adjusting assembly, a coil assembly, and a housing assembly. The valve seat assembly is connected to a fixture for the inflow and outflow of a gaseous medium, including a valve seat having a fluidly communicating inlet channel and an outlet channel. The adjusting assembly (via a spring) applies a preload force to the armature assembly. The coil assembly surrounds the valve sleeve assembly, providing a magnetic field to the armature assembly, causing the armature assembly to displace within the valve sleeve assembly to control the opening and closing (connection and blocking) of the inlet channel and the outlet channel. The valve sleeve assembly abuts against and connects to the valve seat assembly, located on the side of the valve seat away from the fixture.

[0017] Furthermore, the housing assembly includes three supports located at both ends of the coil assembly and assembled to the valve sleeve assembly, a liner for pressing the supports to the valve sleeve assembly, and an injection-molded housing. The injection-molded housing has an extension hole for the bolt hole in the valve seat used to connect to the tooling, for using long bolts to secure the housing as a whole to the tooling. The circuit board in the coil assembly is located inside the injection-molded housing and is used to control the current of the coil in the coil assembly. The liner presses the supports to the valve sleeve assembly (at the sealing connection between the valve sleeve and the valve seat) and secures the liner to the valve seat with bolts, thereby fixing the supports. The supports are made of magnetically conductive material. The injection-molded housing is integrally molded, protecting the internal components of the proportional solenoid valve and forming a single integrated device, facilitating compatibility with various target ventilators and easy installation and disassembly.

[0018] Preferably, the injection-molded housing and the valve seat assembly form a rectangular parallelepiped as a whole. Except for the surface that protrudes to support the circuit board, the three brackets are located on the other three sides of the injection-molded housing as internal supports.

[0019] Preferably, the valve sleeve assembly includes a valve sleeve, an adjusting seat, and a sealing element (preferably a sealing ring) for sealing connection with the valve seat assembly; wherein, the valve sleeve and the adjusting seat are welded as a whole, respectively cooperating with the armature assembly and the adjusting assembly, and providing movement guidance for the armature assembly and the adjusting assembly; the valve sleeve is made of a magnetically shielding material. The valve sleeve achieves the effect of a magnetically shielding ring, increasing the magnetic flux in the armature, eliminating the need for a magnetically shielding ring and simplifying the structure. Preferably, in the coil direction, the length of the valve sleeve on the side away from the valve seat exceeds the distal end face of the armature (the side away from the valve seat), but does not exceed the distal end of the coil. The thickness of the valve sleeve (the guide portion accommodating the armature) is preferably between 0.5-1.5 mm; too thin or too thick will result in a decrease in electromagnetic force.

[0020] Preferably, the valve seat assembly further includes an inlet sealing ring and an outlet sealing ring to respectively seal the inlet passage and the outlet passage.

[0021] Preferably, the armature assembly includes an armature, a sealing block, and a guide sleeve. The armature, under the action of the magnetic field of the coil assembly and the spring of the adjusting assembly, pushes the sealing block to reciprocate, thereby controlling the opening and closing (and flow control) of the air inlet of the air intake channel. The armature has two through holes on its left and right sides to balance the air pressure on the adjusting assembly side and the valve seat side. The guide sleeve is installed in a corresponding groove on the outer surface of the armature, for abutting / contacting the valve sleeve. When subjected to magnetic force, the armature moves within the valve sleeve, overcoming the friction between the guide sleeve and the valve sleeve. The guide sleeve is a cylindrical structure with a beveled fracture. Due to this beveled fracture, the guide sleeve does not require thermal expansion during installation and can be directly snapped into place, facilitating maintenance.

[0022] Preferably, the adjusting assembly includes a spring, an adjusting rod, and a seal. The two ends of the spring abut against the adjusting rod and spring grooves pre-drilled in the armature, respectively. The adjusting rod is threadedly connected to the adjusting seat and sealed by the seal (preferably a sealing ring). Adjusting the position of the adjusting rod via the thread adjusts the preload of the spring connected to the adjusting rod (at the other end) on the armature.

[0023] Preferably, the coil assembly includes a coil frame, a coil, and a circuit board. The circuit board is located within the protruding end of the injection-molded housing and is used to control the current of the coil. The coil is arranged around the coil frame to provide the required magnetic field for the armature. The circuit board contains a control algorithm for controlling the coil current and optimizing the linearity of the flow curve. The circuit board can also be modified according to the needs of different operating modes, facilitating product upgrades and increasing the expandability of the proportional solenoid valve.

[0024] Furthermore, a second aspect of the present invention provides an intelligent and precise control method for a proportional solenoid valve. During operation, the proportional solenoid valve experiences a continuous change in the relationship curve between the output gas flow rate and the input current due to the combined effects of factors such as the hysteresis effect of the magnetic material, gas medium pressure, spring force, and friction. For example, Figure 5The diagram shows the flow rate curve as the current increases from 0A to its maximum and then gradually decreases back to 0A. The electromagnet (armature) in the proportional solenoid valve requires a certain current to open (starting current). After opening, the flow rate curve has a smaller slope in the early stage (Q0 to Q1), a larger slope in the middle stage (Q1 to Q2), and a smaller slope in the later stage (Q2 to Q3). Furthermore, there is a hysteresis between the flow rate curve when the current decreases and the flow rate curve when the current increases. Additionally, when using a current greater than the starting current as the starting current, different starting currents will produce different flow rate curves. These characteristics ultimately result in a certain (uncertain / stable) error between the actual flow rate and the set flow rate value corresponding to the set current, thus making the output flow rate less accurate.

[0025] To address this technical problem, the present invention also provides an intelligent and precise control method for a proportional solenoid valve, employing PID closed-loop control to achieve precise flow control. Based on the actual flow value fed back by the system, a PID algorithm is used to control the current of the proportional solenoid valve in real time, thereby achieving precise flow output from the proportional solenoid valve.

[0026] Specifically, a method for intelligent and precise control of a proportional solenoid valve includes the following steps:

[0027] (1) Based on the slope characteristics of the flow curve of the proportional solenoid valve and the range of the actual flow rate Qc and the flow change ΔQ, the flow rate Q is divided into several intervals; each interval has a set of PID control parameters; wherein, the flow change ΔQ is the difference between the target flow rate Qt and the actual flow rate Qc;

[0028] (2) For the flow adjustment range of each interval, the PID parameters of each interval are adjusted, and the PID parameters of each interval are determined accordingly.

[0029] (3) Based on the PID parameters determined for each interval, store them in the storage module and write the control program into the chip of the circuit board. When using a proportional solenoid valve, the program will select the corresponding interval and automatically call the matching PID parameters based on the detected actual flow rate Qc and the flow difference ΔQ, thereby outputting the corresponding current signal to achieve real-time flow control.

[0030] Preferably, the PID parameter tuning consists of three parts: proportional control, integral control, and derivative control; wherein the PID parameters include the proportional parameter K. p Integral parameter K i and differential parameter K d .

[0031] Preferably, in step (3), the output current signal u(t) is calculated according to the following formula:

[0032] u(t) = K p *ΔQ(t)+K i *∫ΔQ(t)dt+K d *dΔQ(t) / dt

[0033] in,

[0034] t represents time;

[0035] u(t) is the output current signal at time t;

[0036] K p This is a proportional parameter;

[0037] K i For integration parameters;

[0038] K d Let be the differential parameter; and

[0039] ΔQ(t) is the difference between the target flow rate Qt and the detected actual flow rate Qc at time t.

[0040] Furthermore, the PID parameter tuning in step (2) is generally achieved through the following steps:

[0041] a. Determine the proportional parameter K p First let K i =0, K d = 0, making the PID control a pure proportional controller; then, gradually increase the proportional parameter from 0 until the system (the output signal of the PID control system) oscillates, at which point the oscillating proportional parameter K is obtained. p1 Then, from the oscillation proportional parameter K... p1 Gradually decrease the value until the system oscillation disappears; at this point, the proportional parameter K is obtained. p2 Therefore, the proportional parameter K is set. p For K p2 60% to 70%;

[0042] b. Determine the integration parameter K i : Proportional parameter K p Once determined, set a relatively large initial integration parameter K. i0 , by K io Gradually decrease until the system oscillates (K) i1 Then gradually increase the value until the system oscillation disappears, at which point the integral parameter K is obtained. i2 Therefore, the integral parameter K of the PID controller is set. i For K i2 150% to 180% of;

[0043] c. Determine the differential parameter K d : In the proportional parameter K p and integration parameter Ki After setting, the differential parameter K d It can be set to 0; or, optionally, in the scaling parameter K p and integration parameter K i After setting, the differential parameter is gradually increased from 0 until the oscillation disappears, at which point the differential parameter K is obtained. d1 and the differential parameter K d Set as K d1 30%.

[0044] Furthermore, the method also includes a step (2') between step (2) and step (3), which is to repeat steps (1) to (2) to obtain updated PID parameters.

[0045] Furthermore, a third aspect of the present invention provides an intelligent and precise control system for a proportional solenoid valve, comprising: a flow sensor for acquiring the current / actual flow rate Qc; an acquisition module for setting a target flow rate Qt; a calculation module for calculating the difference ΔQ based on the target flow rate Qt and the actual flow rate Qc; a PID parameter storage and retrieval module for storing PID parameters adjusted by PID parameters and retrieving matching PID parameters based on the actual flow rate Qc and the difference ΔQ; and a control module for controlling the current of the proportional solenoid valve according to the currently retrieved PID parameters using a PID algorithm until the actual flow rate value fed back by the flow sensor equals the set target value Qt.

[0046] Based on the above solution, the easily detachable intelligent control proportional solenoid valve for ventilators provided by this invention has the following advantages:

[0047] The housing assembly design of the proportional solenoid valve provided by this invention allows it to be installed on the inlet / outlet tooling without disassembling the proportional solenoid valve.

[0048] The armature guide sleeve has an oblique opening structure, which does not require thermal expansion during installation and can be installed directly, making it easy to maintain.

[0049] The valve sleeve is made of magnetic shielding material, which can achieve the effect of a magnetic shielding ring by the valve sleeve, thereby increasing the magnetic flux in the armature. There is no need to design a magnetic shielding ring, making the structure simpler.

[0050] Conventional proportional solenoid valves exhibit non-linear flow curves. This invention incorporates an intelligent control chip, adjusting current variations under different duty cycles to improve the linearity of the flow curve. The circuit board within the proportional solenoid valve allows for program modification to suit different operating modes, facilitating product upgrades and increasing the valve's expandability. Attached Figure Description

[0051] Figure 1This is a cross-sectional view of the easily detachable intelligent control proportional solenoid valve for ventilators according to the present invention.

[0052] Figure 2 This is an isometric view of the unmolded housing of the easily detachable intelligent control proportional solenoid valve for a ventilator according to the present invention.

[0053] Figure 3 This is an isometric view of the product after injection molding of the easily detachable intelligent control proportional solenoid valve for a ventilator according to the present invention.

[0054] Figure 4 This is a schematic diagram of the external structure of the armature assembly of the easily detachable intelligent control proportional solenoid valve for a ventilator according to the present invention.

[0055] Figure 5 This is the curve showing the relationship between the flow rate and current of a proportional solenoid valve.

[0056] Figure 6 This is a schematic diagram of the principle of PID control of the flow rate of a proportional solenoid valve.

[0057] Figure 7 This is a schematic diagram of a system and method for real-time flow control according to the present invention. Detailed Implementation

[0058] The following description, in conjunction with the accompanying drawings, further illustrates the "easily detachable intelligent control proportional solenoid valve for a ventilator" of the present invention.

[0059] like Figure 1-4 The easily detachable intelligent control proportional solenoid valve for ventilators shown consists of a valve seat assembly, an armature assembly, a valve sleeve assembly, an adjustment assembly, a coil assembly, and a housing assembly.

[0060] Specifically, the valve seat assembly includes a valve seat 11, an outlet sealing ring 12, and an inlet sealing ring 13, which respectively seal the outlet passage (e.g., Figure 2 As shown, there are four air outlets inside the top outer ring and an air intake channel (as shown). Figure 2 As described above, the valve seat assembly has one inlet channel at the top center and is used for the inflow and outflow of gaseous media. The valve seat 11 has one inlet channel and four outlet channels, with the two channels in fluid communication. Figure 1 As shown, the air inlet of the air intake passage within the valve seat cavity is positioned opposite to the sealing block 22 in the armature assembly. The sealing block 22 is used to control the connection and blockage between the air inlet and the valve seat cavity (air outlet passage). Simultaneously, the valve seat 11 is also provided with four bolt holes (outermost edge of the top surface) that mate with the tooling, for connecting to the target tooling via bolts.

[0061] The armature 21, sealing block 22, and guide sleeve 23 constitute the armature assembly. The armature 21 is positioned longitudinally by the magnetic field provided by the coil assembly and the spring 41 of the adjusting assembly (e.g., ...). Figure 1 Under the influence of the force (in the direction of the valve), the valve moves up and down within the cavity defined by the valve seat assembly, thereby driving the sealing block 22 (fixed connection). The sealing block 22 and the valve seat 11 (air inlet within the cavity) can thus open and close to control the outlet air flow rate. The armature 21 has two through holes on its left and right sides to control the balance of air pressure within the valve. Figure 4 The diagram shows the external structure of the armature assembly. Two guide sleeves 23 are cylindrical structures with beveled edges, allowing for direct, slightly deformed insertion into slots on the outer surface of the armature for easy installation and maintenance. The guide sleeves 23 serve as the contact surface between the armature assembly and the valve sleeve 31, facilitating frictional movement of the armature 21 within the cavity defined by the valve sleeve 31.

[0062] The valve sleeve 31 is welded to the adjusting seat 32 as a whole, and together with the sealing ring 33, they form the valve sleeve assembly. When the proportional solenoid valve is working, the armature assembly moves up and down within the valve sleeve assembly, and there is friction between the guide sleeve 23 and the valve sleeve 31.

[0063] The spring 41, adjusting rod 42, and sealing ring 43 constitute the adjusting assembly. The adjusting rod 42 is threadedly connected to the adjusting seat 32 and sealed by the sealing ring 43. By adjusting the position of the adjusting rod 42, the preload of the spring can be adjusted to control the performance of the proportional solenoid valve.

[0064] The coil frame 51, coil 52, and circuit board 53 together form the coil assembly. When the coil is energized, it generates a magnetic field, which is used to control the displacement of the armature 21. The circuit board contains a control algorithm to control the coil current and optimize the linearity of the flow curve.

[0065] The housing assembly consists of brackets 61, 62, and 63, a liner 64, and an injection-molded housing 65. The two ends of brackets 61, 62, and 63 are located at the two ends of the coil assembly and abut against the lower surface of the valve sleeve 31 (where it seals the valve seat 11). The liner 64 is bolted to the valve seat 11, pressing the brackets 61-63 (and the valve sleeve 31) together. The proportional solenoid valve housing 65 is formed by injection molding, providing protection for the proportional solenoid valve. Preferably, as... Figure 2 As shown, the liner 64 has holes at its four corners corresponding to the four tooling mounting holes of the valve seat 11. The lines connecting the holes in the liner 64 and the mounting holes in the valve seat 11 form extended holes in the injection molding 65 for bolt fastening. Preferably, two diagonal holes are used to first fasten the liner 64 and the brackets 61-63 to the valve seat 11 (using short bolts). The proportional solenoid valve obtained after injection molding is then mounted to the target tooling (using long bolts) through the other two diagonal holes.

[0066] Specifically, the working principle of the proportional solenoid valve provided by this invention is as follows:

[0067] See Figure 1 When not energized, the proportional solenoid valve is normally closed, and the spring 41 has a certain preload, causing the armature 21 to press the sealing block 22 against the air inlet of the valve seat 11, thus blocking the flow of gas. When the coil 52 is energized, due to the magnetic shielding effect of the valve sleeve 31, the generated magnetic path enters the armature 21 through the adjusting seat 32, generating an electromagnetic force. This electromagnetic force overcomes the pressure of the spring 41 and the friction between the guide sleeve 23 and the valve sleeve 31, causing the armature 21 to move downward, opening the valve (air inlet) and allowing the medium to flow in. The displacement of the armature 21 changes with the coil current, thereby controlling the flow rate of the proportional solenoid valve. The preset program in the circuit board 53 can control the change of the actual current in the coil to correct the flow rate curve of the medium, making it linear, thereby achieving proportional control of the medium flow rate.

[0068] See Figure 2 Circular holes are drilled in brackets 61 to 63 to reduce weight and ensure sufficient material flow during injection molding of the outer shell, thereby improving its strength. The circuit board in the proportional solenoid valve allows for program modification to suit different operating modes, facilitating product upgrades and increasing the valve's expandability.

[0069] Furthermore, this invention also provides an intelligent and precise control method for a proportional solenoid valve. The control principle is as follows: Figure 6 As shown, a PID controller consists of three parts: proportional control, integral control, and derivative control. The proportional control adjusts the output based on the magnitude of the deviation, the integral control adjusts the output based on the integral accumulation of the deviation, and the derivative control adjusts the output based on the derivative of the deviation. The expression for the PID algorithm is:

[0070] u(t) = K p *ΔQ(t)+K i *∫ΔQ(t)dt+K d *dΔQ(t) / dt

[0071] in:

[0072] t: time

[0073] u(t): Output current signal of the PID controller at time t.

[0074] Kp: Scale parameter;

[0075] Ki: Integral parameter;

[0076] Kd: Differential parameter;

[0077] ΔQ(t): The difference between the target flow rate Qt and the actual flow rate Qc at time t.

[0078] Specifically, the overall intelligent and precise debugging control process of the proportional solenoid valve is as follows:

[0079] (1) According to the flow curve characteristics (slope) of the proportional solenoid valve, and based on the range of the actual flow rate Qc and the flow rate change / difference ΔQ, divide the flow rate into several groups of intervals (such as the three groups shown in Figure 5 ), and each group corresponds to a set of PID control parameters.

[0080] (2) Conduct PID control parameter debugging for each group of flow rate adjustment ranges respectively.

[0081] (3) Store each set of PID parameters obtained from the debugging in the storage module, and write the control program into the chip. When using the proportional solenoid valve, the program will automatically call the matching PID parameters according to the values of the actual flow rate Qc and the flow rate difference ΔQ to control the output current signal of the flow rate.

[0082] Among them, in step (1), according to the characteristics of the flow rate-current curve of the proportional solenoid valve, divide the flow rate of the proportional solenoid valve into three intervals, Q0, Q1, Q2, Q3. When the flow rate Qc < Q1, it is in the opening stage of the proportional solenoid valve. At this time, the slope of the flow rate-current curve is small, and the flow rate rises gently. When Q1 < Qc < Q2, the slope of the flow rate-current curve is large, and the flow rate rises rapidly. When the flow rate is in Q2 < Qc < Q3, the stroke of the proportional solenoid valve is the largest. At this time, if the current is continuously increased, the flow rate will remain unchanged.

[0083] If necessary, the flow rate range can be divided into more intervals, and the changes in different intervals correspond to different parameters to adapt to the rapid response of the flow rate.

[0084] In step (2), the general steps of the parameter adjustment process are as follows:

[0085] a. Determine the proportional parameter Kp: When determining the proportional parameter Kp, first remove the integral term and derivative term of the PID, generally set Ki = 0 and Kd = 0 to make the PID a pure proportional regulation. Gradually increase the proportional parameter Kp from 0 until the system (the output current signal of the PID regulation system) oscillates; then, conversely, gradually decrease the proportional parameter Kp from this value until the system oscillation disappears, record the proportional parameter Kp at this time, and set the proportional parameter Kp of the PID to 60% - 70% of the current value. The debugging of the proportional parameter Kp is completed.

[0086] b. Determine the integral parameter Ki: After determining the proportional parameter Kp, set a relatively large initial value of the integral parameter Ki, and then gradually decrease Ki until the system oscillates. Then, conversely, gradually increase Ki until the system oscillation disappears. Record Ki at this time, and set the integral parameter Ki of the PID to 150% - 180% of the current value. The debugging of the integral parameter Ki is completed.

[0087] c. Determine the integration parameter Kd. The integration parameter Kd generally does not need to be set and can be 0. If it needs to be set, gradually increase the integration parameter Kd from 0 until the oscillation disappears, and finally take Kd as 30% of the current value.

[0088] The control flow of the control system when using a proportional solenoid valve:

[0089] Figure 7 This is a flow control system and flowchart for a proportional solenoid valve. Module M1 is a flow sensor used to acquire the actual flow rate Qc (i.e., the current flow rate). Module M2 is an acquisition module used to acquire the set target flow rate value Qt. Module M3 is a calculation module used to calculate the difference ΔQ between the target flow rate Qt and the current flow rate Qc. Module M4 is a PID parameter storage module, which stores the PID parameters for each interval obtained from PID tuning. When adjusting the flow rate, it calls the corresponding PID parameters based on the values ​​of Qc and Qt and transmits them to module M5. Module M5 is a control module, which controls the current of the proportional solenoid valve according to the current PID parameters using a PID algorithm until the flow rate value fed back by module M1 equals the set target value Qt.

[0090] It should be understood that the directional indicators such as "left," "right," "up," and "down" mentioned herein are based on the orientation of the device shown in the example diagram. It should also be understood that the terms "left," "right," "up," and "down" are interchangeable in the present invention and do not constitute a substantial limitation on the invention.

[0091] The examples described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the technical solutions of the present invention without departing from the design concept of the present invention shall still fall within the scope of the present invention.

Claims

1. An intelligent and precise control system for a proportional solenoid valve, comprising an intelligent and precise control method for the proportional solenoid valve, characterized in that, The method includes the following steps: (1) According to the slope characteristics of the flow curve of the proportional solenoid valve, and the range of the actual flow rate Qc and the flow rate change ΔQ, the flow rate Q is divided into three intervals Q0 to Q1, Q1 to Q2, and Q2 to Q3; wherein, the flow rate change ΔQ is the difference between the target flow rate Qt and the actual flow rate Qc; wherein, when the actual flow rate Qc < Q1, the slope of the flow rate-current curve is small, and the flow rate rises gently. When the actual flow rate Q1 < Qc < Q2, the slope of the flow rate-current curve is large, and the flow rate rises rapidly. When the flow rate is in the range Q2 < Qc < Q3, the stroke of the proportional solenoid valve is the largest. At this time, if the current is increased continuously, the flow rate will remain unchanged; (2) For the flow rate adjustment range of each interval, perform PID parameter debugging for each interval, and thereby determine the PID parameters of each interval; (3) According to the PID parameters determined for each interval, based on the detected actual flow rate Qc and the flow rate difference ΔQ, automatically call the matching PID parameters, so as to output the corresponding current signal to achieve flow rate control; Wherein, the PID parameter debugging in the step (2) is achieved through the following steps: a. Determine the proportional parameter K p First, set K. i =0, K d = 0, making the PID controller a pure proportional controller; then, gradually increase the proportional parameter from 0 until the system oscillates, at which point the oscillation proportional parameter K is obtained. p1 Then, from the oscillation proportional parameter K... p1 Gradually decrease the value until the system oscillation disappears; at this point, the proportional parameter K is obtained. p2 Set the scaling parameter K p For K p2 60% to 70%; b. Determine the integration parameter K i : Proportional parameter K p Once determined, set a relatively large initial integration parameter K. i0 , by K i0 Gradually decrease the value until the system oscillates, then gradually increase it until the oscillations disappear. At this point, the integral parameter K is obtained. i2 Set the integration parameter K i For K i2 150% to 180% of; c. Determine the differential parameter K d Differential parameter K d It can be set to 0; or, the differential parameter can be gradually increased from 0 until the oscillation disappears, at which point the differential parameter K is obtained. d1 and the differential parameter K d Set as K d1 30%; Wherein, in the step (3), the output current signal is calculated according to the following formula: u(t)=K p *ΔQ(t)+K i *∫ΔQ(t)dt+K d *dΔQ(t) / dt Wherein, t is time; u(t) is the output current signal; K p This is a proportional parameter; K i For integration parameters; K d Let be the differential parameter; and ΔQ(t) is the difference between the target flow rate Qt and the detected actual flow rate Qc.

2. The intelligent and precise control system for the proportional solenoid valve according to claim 1, characterized in that, The method further includes a step (2') between the step (2) and the step (3): repeat the steps (1) to (2) to obtain updated PID parameters.

3. The intelligent and precise control system for the proportional solenoid valve according to claim 1, characterized in that, The control system includes: A flow rate sensor for obtaining the actual flow rate Qc; An acquisition module for setting the target flow rate Qt; A calculation module for calculating the flow rate difference ΔQ according to the target flow rate Qt and the actual flow rate Qc; a PID parameter storage and call module for storing the PID parameters adjusted by the PID parameters, and calling the matching PID parameters according to the actual flow rate Qc and the flow rate difference ΔQ; and A control module for performing current control on the proportional solenoid valve through the PID algorithm according to the called PID parameters until the actual flow rate value feedback by the flow rate sensor is equal to the set target flow rate Qt.

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