A valve opening control method and a pneumatic circuit device with controllable valve opening

Abstract

The present invention relates to the field of pneumatic control technology, and more specifically, to a valve opening control method and a pneumatic circuit device with controllable valve opening. When the valve needs to be opened, the three-way solenoid valve is opened and is in a normally open state. Then, the opening and closing actions of the two-way solenoid valve are repeated according to a pre-set valve opening broken line, so that the instrument air intermittently enters the valve actuator, causing the valve to slowly and gradually open. When the valve needs to be closed, the two-way solenoid valve and the three-way solenoid valve are first closed, and the air in the valve actuator is discharged from the three-way solenoid valve, closing the valve. The present invention intermittently controls the switching action of the two-way solenoid valve so that the valve is slowly and gradually opened, and the valve can be closed in time by setting the three-way solenoid valve. The overall air circuit can simply and conveniently control the opening and closing and opening of the valve through the mutual cooperation of the two-way solenoid valve, the three-way solenoid valve and the valve actuator.

Description

Technical Field

[0001] The present invention relates to the technical field of pneumatic control, and more particularly to a method for controlling valve opening and a pneumatic circuit device with controllable valve opening. Background Art

[0002] In small nitrogen generators, pressure balance within the molecular sieve adsorber in the air purification system is typically achieved using an on-off valve controlled by the control system, coupled with a manual valve or a flow-restricting orifice plate. During the pressure balance process, the on-off valve's inability to adjust can result in excessively rapid pressure buildup in the initial phase and excessively slow pressure buildup at the end. This rapid initial pressure buildup can increase mechanical wear and shorten the molecular sieve adsorber's service life, while a slow pressure buildup at the end can impact the operating cycle. Summary of the Invention

[0003] In order to overcome the technical problems of the above-mentioned prior art that the opening of the switch valve cannot be adjusted and the valve opens too quickly, the present invention provides a valve opening control method and a pneumatic circuit device with controllable valve opening, which have a simple structure and can effectively control the valve opening so that the valve can open slowly and gradually.

[0004] To solve the above technical problems, the present invention adopts a technical solution: a method for controlling valve opening, including a method for controlling the valve from closed to fully open and a method for controlling the valve from fully open to closed, as follows:

[0005] The control method for adjusting the valve from the closed state to the fully open state is as follows: first open the three-way solenoid valve and keep it in the normally open state, then open the two-way solenoid valve, and the instrument air enters the valve actuator, causing the valve to open to a certain opening. Then close the two-way solenoid valve, and the instrument air does not enter the valve actuator, so the valve remains at the current opening. Repeat the opening and closing actions of the two-way solenoid valve according to the pre-set valve opening broken line until the valve is fully opened.

[0006] When the valve is in the fully open state, the two-way solenoid valve is in the normally open state;

[0007] The control method for adjusting the valve from the fully open state to the closed state is: close the two-way solenoid valve and the three-way solenoid valve, exhaust the air in the valve actuator from the three-way solenoid valve, and rely on the valve actuator to close the valve.

[0008] When the present invention adjusts the valve from a closed state to a fully open state, the three-way solenoid valve must be opened first. When the two-way solenoid valve is opened, instrument air can smoothly enter the valve actuator through the two-way solenoid valve and the three-way solenoid valve, causing the valve to open. When the two-way solenoid valve is closed, instrument air cannot enter the valve actuator through the two-way solenoid valve. At this time, the valve remains unchanged at its current opening. Repeating the opening and closing actions of the two-way solenoid valve according to a pre-set valve opening broken line can slowly and gradually open the valve. The three-way solenoid valve is mainly set to close the valve. When the valve needs to be closed, the two-way solenoid valve and the three-way solenoid valve are closed, so that instrument air cannot enter the valve actuator, and the air in the valve actuator is discharged through the three-way solenoid valve to close the valve in time.

[0009] The present invention intermittently controls the switching action of the two-way solenoid valve so that the valve is slowly and gradually opened, and closes the valve in time through the setting of the three-way solenoid valve. The overall air circuit can simply and conveniently and effectively control the opening and closing and the opening degree of the valve through the mutual cooperation of the two-way solenoid valve and the three-way solenoid valve. If it is applied to an air purification molecular sieve adsorber, the valve can be slowly and gradually opened by adjusting the opening degree of the valve during the pressure balance process, so that the pressure rise in the initial stage will not be too fast, which can effectively reduce the wear on the molecular sieve adsorber and increase the normal service life of the molecular sieve adsorber.

[0010] Preferably, the valve opening broken line is obtained based on the predetermined valve opening. The predetermined valve openings at several time points are calculated during the entire downstream pressure boosting process, and the time when the valve reaches the predetermined valve opening is obtained through on-site debugging to obtain the valve opening broken line.

[0011] Preferably, the specific calculation formula for the predetermined valve opening is as follows:

[0012] Calculate the air mass M after the downstream equipment is pressurized based on the ideal gas mass model formula:

[0013] M=PVμ / RT=3.485PV / T,

[0014] Where P is the gas pressure (Pa) N / m 2 , V is the volume of a single downstream device and pipeline (m3), T is the upstream gas temperature (K), R is the molar gas constant, specifically 8.31 J / (mol·K), μ is the molar mass of the ideal gas, which is 28.96 g / mol for air;

[0015] Calculate the mass flow rate W when the downstream equipment is boosted:

[0016] W=M / t=3.485PV / (T×t)

[0017] Where M is the air mass after the downstream equipment is pressurized, and t is the pressurization time of the downstream equipment;

[0018] When the differential pressure △P≥P1 / 2, C V =0.003155×W×T 1 / 2 / P1 formula a

[0019] When the differential pressure △P<P1 / 2, C V =0.001958×W×(T / (P1 2 -P1P2)) 1 / 2 Formula b

[0020] Among them, △P=P1-P2, P1 is the upstream gas pressure, P2 is the downstream equipment pressure, C V is the rated C of the valve V value, T is the upstream gas temperature (K);

[0021] In the first t / 2 pressure rise stage, △P≥P1 / 2, according to formula a, since the mass flow rate W, upstream gas temperature T, and upstream gas pressure P1 remain unchanged, the rated C of the valve V The value remains unchanged, the valve opening is a fixed value, at this time the valve opening can be based on the flow characteristics of the valve and the rated C V Value determination;

[0022] In the last t / 2 pressure rise stage, △P<P1 / 2. According to formula b, the mass flow rate W, upstream gas temperature T, and upstream gas pressure P1 remain unchanged, but the downstream pressure P2 changes. The rise of P2 causes C V As the value increases, the valve opening tends to become larger. At several time points per minute, the valve opening can be adjusted based on the flow characteristics of the valve and the rated C V The value is determined.

[0023] Preferably, the valve opening is based on the flow characteristics of the valve and the rated C V The specific method for determining the value is:

[0024] If the flow characteristic of the valve is linear, K=C V / C V '*100%, where K is the valve opening, C V The rated C calculated by formula a V Value, C V ' is the rated flow coefficient of the valve itself, which is a fixed value;

[0025] If the flow characteristic of the valve is nonlinear, the valve opening K cannot be calculated by the formula and can be obtained by looking up the table or the manufacturer.

[0026] After calculating the predetermined valve openings at several time points during the entire downstream pressure boost process, the time for the valve to reach the predetermined valve opening is obtained through on-site debugging, and the valve opening broken line is obtained. Based on the valve opening broken line, the two-way solenoid valve on / off curve corresponding to the valve opening broken line is obtained.

[0027] Preferably, the three-way solenoid valve is a two-position three-way solenoid valve, including an air inlet connected to the air source, an air outlet connected to the valve actuator and an exhaust hole for exhaust; when the three-way solenoid valve is opened, the passage where the air inlet and the air outlet are located is connected, and the exhaust hole is closed. At this time, instrument air can enter through the air inlet and enter the valve actuator through the air outlet; when the three-way solenoid valve is closed, the air inlet is closed, and the passage where the air outlet and the exhaust hole are located is connected. The valve actuator can enter the three-way solenoid valve through the air outlet and be discharged through the exhaust hole.

[0028] Preferably, the valve actuator is a straight-stroke pneumatic actuator, including a spring and a push rod, and the push rod is connected to the spring; the push rod is connected to the valve stem of the valve. When the valve actuator is inflated, the instrument air pushes the push rod to drive the valve stem to move, thereby opening the valve, and at the same time, the push rod drives the spring to deform during the movement; when the valve actuator is deflated, the push rod relies on the reset action of the spring to drive the valve stem to move, thereby closing the valve.

[0029] A pneumatic circuit device with controllable valve opening adopts the above-mentioned valve opening control method, including a valve and a pneumatic circuit component for controlling the valve opening, the pneumatic circuit component being connected to the valve; the pneumatic circuit component including an air source, a two-way solenoid valve, a three-way solenoid valve and a valve actuator connected in sequence; the valve actuator being connected to the valve.

[0030] The present invention controls the opening of the valve through a pneumatic circuit component, so that the valve can be opened slowly and gradually. Specifically, the valve actuator is used to change the opening and closing of the valve. When the valve actuator is inflated, the valve opens, and when the valve actuator is deflated, the valve closes. The air source is used to provide instrument air for the valve actuator, and the valve is opened slowly and gradually by intermittently controlling the switching action of the two-way solenoid valve, and the valve can be closed in time by the setting of the three-way solenoid valve. The overall air circuit can simply and conveniently and effectively control the opening and closing and the opening of the valve through the mutual cooperation of the two-way solenoid valve, the three-way solenoid valve and the valve actuator.

[0031] Preferably, the pneumatic circuit assembly also includes a flow limiter and a control system for controlling the opening and closing operations of the two-way solenoid valve and the opening and closing operations of the three-way solenoid valve, and the control system is communicatively connected to the two-way solenoid valve and the three-way solenoid valve; the flow limiter is arranged between the two-way solenoid valve and the three-way solenoid valve.

[0032] Preferably, the pneumatic circuit assembly further includes an isolation valve and a self-operated pressure reducing valve; the isolation valve and the self-operated pressure reducing valve are sequentially arranged between the air source and the two-way solenoid valve.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1) The present invention intermittently controls the switching action of the two-way solenoid valve to allow the valve to open slowly and gradually, and the three-way solenoid valve can be set to close the valve in time. The overall gas circuit can simply and conveniently control the opening and closing and opening degree of the valve through the mutual cooperation of the two-way solenoid valve, the three-way solenoid valve and the valve actuator;

[0035] 2) The present invention is well suited for use as a control valve for balancing the pressure of a molecular sieve adsorber in an air purification system. During the pressure balancing process, the opening and closing actions of the two-way solenoid valve are repeated according to a pre-set valve opening curve, thereby achieving the purpose of adjusting the valve opening. This allows the valve to open slowly and gradually, effectively avoiding a too rapid pressure increase in the initial stage, and allowing the molecular sieve adsorber pressure to rise evenly, effectively reducing wear on the molecular sieve adsorber and increasing the normal service life of the molecular sieve adsorber. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 1 is a schematic structural diagram of a pneumatic circuit device with controllable valve opening according to a first embodiment of the present invention;

[0037] Figure 2 This is an on / off diagram of a two-way solenoid valve of the present invention;

[0038] Figure 3 It is a broken line graph of valve opening of the present invention;

[0039] Figure 4 This is a specific two-way solenoid valve opening / closing diagram provided by the present invention;

[0040] Figure 5 It is a specific valve opening broken line graph provided by the present invention;

[0041] Figure 6 It is a schematic structural diagram of the Valtek spring cylinder linear actuator of the present invention;

[0042] Figure 7 It is a structural schematic diagram of Example 2 of a pneumatic circuit device with controllable valve opening according to the present invention.

[0043] In the attached figure: 1-valve; 2-two-way solenoid valve; 3-three-way solenoid valve; 4-valve actuator; 41-spring; 42-push rod; 5-isolating valve; 6-self-operated pressure reducing valve; 7-flow limiter; 8-control system. DETAILED DESCRIPTION

[0044] The drawings are for illustrative purposes only and should not be construed as limiting this patent. To better illustrate the embodiments, some components in the drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will understand that some well-known structures and their descriptions may be omitted from the drawings. The positional relationships depicted in the drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0045] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0046] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0047] Example 1

[0048] like Figures 1-6 The figure shows an embodiment 1 of a pneumatic circuit device with controllable valve opening, comprising a valve 1 and a pneumatic circuit assembly. In this embodiment, the valve 1 is installed on a working pipeline. In this embodiment, the valve 1 is a valve with non-adjustable opening, such as an on-off valve. Figure 1 As shown, the working fluid from the upstream process passes through the valve 1 and goes to the downstream process, wherein the pneumatic circuit component is connected to the valve 1 to control the opening and closing of the valve 1 and the opening degree of the valve 1.

[0049] In this embodiment, the valve 1 and the pneumatic circuit assembly are used as a control valve for balancing the pressure of an air purification molecular sieve adsorber, that is, the downstream device in this embodiment is an adsorption tank. During the pressure balancing process, the present invention can effectively avoid the situation where the pressure is increased too quickly in the initial stage and too slowly in the final stage.

[0050] Specifically, the pneumatic circuit assembly includes an air source, a two-way solenoid valve 2 , a three-way solenoid valve 3 and a valve actuator 4 , wherein the valve actuator 4 is connected to the valve 1 , and the valve actuator 4 is used to change the opening of the valve 1 .

[0051] When the valve actuator 4 is inflated, the valve 1 opens, and when the valve actuator 4 is deflated, the valve 1 closes. Specifically, the valve actuator 4 is a straight-stroke pneumatic actuator, such as Figure 6 As shown, the valve actuator 4 in this embodiment is a universal Valtek spring cylinder linear actuator, and its structural arrangement and working principle are both prior art, which are only briefly described here. The valve actuator 4 includes a spring 41 and a push rod 42, and the push rod 42 is connected to the spring 41; the push rod 42 is connected to the valve stem of the valve 1.

[0052] The working principle of the valve actuator 4 is as follows: when the valve actuator 4 is inflated, the instrument air pushes the push rod 42 to drive the valve stem of the valve 1 to move, thereby opening the valve 1. At the same time, the push rod 42 drives the spring 41 to deform during the movement; when the valve actuator 4 is deflated, the spring 41 relies on the reset effect of the spring 41 to make the push rod 42 drive the valve stem of the valve 1 to move, thereby closing the valve 1.

[0053] In addition, the valve actuator 4 may also adopt a currently common diaphragm linear actuator, which can also achieve the function of controlling the opening and closing of the valve 1 .

[0054] Among them, the gas source is instrument air, which is used to provide a driving gas source for the valve actuator 4. Among them, the two-way solenoid valve 2 and the three-way solenoid valve 3 are connected between the gas source and the valve actuator 4 in sequence along the direction of the gas source to the valve actuator 4. Among them, the setting of the two-way solenoid valve 2 is mainly used to control the valve opening and control the opening degree of the valve 1. By intermittently controlling the switching action of the two-way solenoid valve 2, the instrument air intermittently enters the valve actuator 4, thereby causing the valve 1 to slowly and gradually open.

[0055] Among them, the setting of the three-way solenoid valve 3 is mainly used for the valve closing operation of the valve 1. Specifically, the three-way solenoid valve 3 is a two-position three-way solenoid valve, including an air inlet connected to the air source, an air outlet connected to the valve actuator 4, and an exhaust hole for exhaust; when the three-way solenoid valve 3 is opened, the passage where the air inlet and the air outlet are located is connected, and the exhaust hole is closed. At this time, the instrument air can enter through the air inlet and enter the valve actuator 4 through the air outlet; when the three-way solenoid valve 3 is closed, the air inlet is closed, and the passage where the air outlet and the exhaust hole are located is connected. The valve actuator 4 can enter the three-way solenoid valve 3 through the air outlet and be discharged through the exhaust hole.

[0056] As a preferred technical solution, this embodiment also includes a control system 8, which is communicatively connected to the two-way solenoid valve 2 and the three-way solenoid valve 3. The control system 8 is used to control the switching action of the two-way solenoid valve 2 and the switching action of the three-way solenoid valve 3. In this embodiment, the control system 8 uses a DCS control system. Specifically, in this embodiment, a valve opening broken line is pre-set in the control system 8. The control system 8 controls the opening and closing of the two-way solenoid valve 2 according to the pre-set valve opening broken line, thereby causing the pressure in the adsorption tank to rise evenly.

[0057] Among them, the valve opening broken line is obtained based on the predetermined valve opening. The predetermined valve openings at several time points are calculated during the entire downstream pressure boosting process, and the time it takes for the valve to change from fully closed to the predetermined valve opening is obtained through on-site debugging to obtain the valve opening broken line.

[0058] Specifically, the specific calculation formula for the predetermined valve opening is as follows:

[0059] Calculate the air mass M after the downstream equipment is pressurized based on the ideal gas mass model formula:

[0060] M=PVμ / RT=3.485PV / T,

[0061] Where P is the gas pressure (Pa) N / m 2 , V is the volume of a single adsorption tank and pipeline (m3), T is the upstream gas temperature (K), R is the molar gas constant, specifically 8.31 J / (mol·K), μ is the molar mass of the ideal gas, which is 28.96 g / mol for air;

[0062] Calculate the mass flow rate W when the adsorption tank is pressurized:

[0063] W=M / t=3.485PV / (T×t)

[0064] Wherein, M is the air mass after the adsorption tank is pressurized, and t is the pressurization time of the adsorption tank. The pressurization time of the adsorption tank is determined in advance according to the characteristics of the adsorption tank itself.

[0065] When the differential pressure △P≥P1 / 2, C V =0.003155×W×T 1 / 2 / P1 formula a

[0066] When the differential pressure △P<P1 / 2, C V =0.001958×W×(T / (P1 2 -P1P2)) 1 / 2 Formula b

[0067] Among them, △P=P1-P2, P1 is the upstream gas pressure, P2 is the adsorption tank pressure, C V is the rated C of the valveV value, T is the upstream gas temperature (K);

[0068] In the first t / 2 pressure rise stage, △P≥P1 / 2, according to formula a, since the mass flow rate W, upstream gas temperature T, and upstream gas pressure P1 remain unchanged, the rated C of the valve V The value remains unchanged, the valve opening is a fixed value, at this time the valve opening can be based on the flow characteristics of the valve and the rated C V Value determination;

[0069] In the last t / 2 pressure rise stage, △P<P1 / 2. According to formula b, the mass flow rate W, upstream gas temperature T, and upstream gas pressure P1 remain unchanged during this stage, but the adsorption tank P2 changes. The rise of P2 causes C V As the value increases, the valve opening tends to become larger. At several time points per minute, the valve opening can be adjusted based on the flow characteristics of the valve and the rated C V The value is determined.

[0070] The valve opening is determined by the flow characteristics and rated C V The specific method for determining the value is:

[0071] If the flow characteristic of the valve is linear, K=C V / C V '*100%, where K is the valve opening, C V The rated C calculated by formula a V Value, C V ' is the rated flow coefficient of the valve itself;

[0072] If the flow characteristic of the valve is nonlinear, the valve opening K cannot be calculated by the formula. You can query the calculated rated C V The corresponding table of values ​​and valve opening or the rated C calculated by the valve manufacturer V The valve opening corresponding to the value.

[0073] After calculating the predetermined valve opening at several time points during the entire downstream pressure boost process, the following is drawn: Figure 3 The valve opening line graph shown in Figure 2 The on / off curve diagram of the two-way solenoid valve is shown.

[0074] Specifically, in this embodiment, the pressure increase time of the molecular sieve adsorption tank is t, and the t value is a certain value that can be obtained in advance. When the pressure increase is completed, the valve opening reaches 100%, that is, the valve opening corresponding to the time point t is 100%.

[0075] According to the above formula a, the valve opening is fixed in the first t / 2 time. The rated C of the valve in the first t / 2 time is calculated according to formula a.V Value, due to the different valve models, the valve rated C V The corresponding relationship between the value and the valve opening is different. According to the rated C of the specific valve model provided by the manufacturer, V The corresponding table of valve opening and the rated C value of the valve in the first t / 2 time is found. V The valve opening corresponding to the value can be used to obtain the specific value y1% that the valve opening needs to reach before t / 2 time.

[0076] According to the above formula b, the valve opening is on an upward trend after t / 2 time. Select several time points in the time period after t / 2 and calculate the rated C of the valve at the corresponding time points. V In this embodiment, a time point is selected every 2 minutes or 1 minute or other time intervals within the last t / 2 time, such as Figure 3 The P2 value corresponding to each time point t2, t3, t4, t5, and t6 shown, that is, the adsorption tank pressure value, is determined. The P2 value can be obtained by measurement or according to the conventional curve of the corresponding relationship between the P2 value and time. Since the mass flow rate W, upstream gas temperature T, and upstream gas pressure P1 remain unchanged during the last t / 2 period, after determining the P2 value, the rated C at the corresponding time point can be calculated according to formula b. V Value, based on the rated C of the specific valve model provided by the manufacturer V The corresponding table of valve opening and the rated C value of the valve at the corresponding time point in the first t / 2 time is found. V The valve opening corresponding to the value is as follows: Figure 3 As shown, the valve opening corresponding to time point t2 is y2%, the valve opening corresponding to time point t3 is y3%, the valve opening corresponding to time point t4 is y4%, the valve opening corresponding to time point t5 is y5%, and the valve opening corresponding to time point t6 is y6%.

[0077] As for when the valve opening can reach the corresponding opening before the corresponding time point, it is related to the selected valve model and the pressure of the instrument air. That is, the time required for a valve of a specific model to change from one opening to another has a corresponding relationship with the pressure of the upstream instrument air. In actual application, it is only necessary to adjust and measure the pressure of the instrument air. Through simple on-site debugging, the time required for the valve to change from one opening to another can be obtained.

[0078] Through the above calculations and on-site debugging, the following can be drawn: Figure 3 The valve opening broken line shown in the figure can be used to draw the valve opening broken line diagram as shown in the figure. Figure 2 The two-way solenoid valve on / off curve is shown in the figure. In the actual control process, it is only necessary to control the two-way solenoid valve according to the obtained curve. Figure 2The two-way solenoid valve is opened and closed according to the on / off curve diagram shown, ensuring that the valve opening can reach the corresponding opening at the corresponding time point during the entire pressure boosting process, thereby enabling the pressure in the adsorption tank to rise evenly, avoiding excessive pressure boosting and increasing mechanical wear of the molecular sieve adsorber.

[0079] Specifically, such as Figure 3 As shown, during the time period from 0 to t / 2, the valve is fully closed and changes to the required opening y1%, and the opening is maintained until the time point t / 2, so that the valve opening corresponding to the time point t / 2 is y1%, corresponding to Figure 2 The two-way solenoid valve on / off curve shown shows that during the time period from 0 to t / 2, the two-way solenoid valve is opened for a certain period of time. After the valve is fully closed to the desired opening y1%, the two-way solenoid valve is closed to maintain the current opening. In other words, the upstream instrument air pressure determines how long it takes for the valve to fully close to the desired opening y1% during the time period from 0 to t / 2. Therefore, the two-way solenoid valve opening time is the same as the time it takes for the valve to open. In this embodiment, during the time period from 0 to t / 2, the two-way solenoid valve is opened to time t1, achieving the valve opening y1%. After that, the two-way solenoid valve is closed to maintain the valve opening y1%.

[0080] Specifically, based on the specific calculation and drawing methods of the valve opening line graph and the two-way solenoid valve opening / closing curve graph given above, the following is obtained by combining the specific process parameters for calculation and drawing: Figure 5 The valve opening broken line shown and Figure 4 The on / off curve diagram of the two-way solenoid valve is shown.

[0081] like Figure 5 As shown, 1080s is the pressure rise time of the molecular sieve adsorption tank. In the first t / 2 time, that is, 540s, the valve opening is 22%, and the valve opening can reach 22% in 6s. In the second t / 2 time, a time point is taken at a certain interval, that is, 660s, 780s, 800s, 960s and 1020s, and the valve openings at the corresponding time points are 24%, 28%, 37%, 60% and 88%, respectively.

[0082] Through Figure 5 The valve opening line graph shown can be obtained accordingly Figure 4 The two-way solenoid valve opening / closing curve shown in the figure indicates that the two-way solenoid valve is opened at the following time points: 6s, 540s, 660s, 780s, 800s, 960s and 1020s during the entire control process, and the closing time of the two-way solenoid valve can be obtained by on-site debugging combined with the actual instrument air pressure.

[0083] As a preferred technical solution, the pneumatic circuit assembly in this embodiment also includes an isolation valve 5 and a self-operated pressure reducing valve 6, wherein the isolation valve 5 uses an existing general-purpose isolation valve. During normal operation, the isolation valve 5 is manually opened and kept in a normally open state. When inspecting the valve, the isolation valve 5 is manually closed, that is, the instrument gas is manually shut off.

[0084] The self-operated pressure reducing valve 6 is a common self-operated pressure reducing valve, which is mainly used to reduce the pressure of the gas source and stabilize it to a fixed value so that the valve actuator 4 can obtain stable gas source power for regulation and control.

[0085] The present invention also provides a method for controlling valve opening, including a method for controlling the valve 1 from closed to fully open and a method for controlling the valve 1 from fully open to closed, specifically as follows:

[0086] The control method for the process of valve 1 from closed to fully open is: first, open the three-way solenoid valve 3 and make the three-way solenoid valve 3 in the normally open state, then open the two-way solenoid valve 2, instrument air inflates the valve actuator 4, valve 1 opens to a certain opening, then close the two-way solenoid valve 2, instrument air does not inflate the valve actuator 4, valve 1 remains at the current opening, and repeats the opening and closing actions of the two-way solenoid valve 2 according to the pre-set valve opening broken line. The valve opening broken line is obtained according to on-site debugging until valve 1 is fully opened.

[0087] When valve 1 is in the fully open state, the two-way solenoid valve 2 is in the normally open state;

[0088] The control method for adjusting the valve 1 from the fully open state to the closed state is as follows: close the two-way solenoid valve 2 and the three-way solenoid valve 3, the air in the valve actuator 4 is discharged from the three-way solenoid valve 3, and the valve 1 is closed by relying on the thrust of the spring in the valve actuator 4.

[0089] The on / off operations of the two-way solenoid valve 2 and the three-way solenoid valve 3 are controlled by a control system 8 .

[0090] Based on the above-mentioned valve opening control method, the specific working principle of a pneumatic circuit device with controllable valve opening of the present invention is as follows:

[0091] Under normal working conditions, the pressure reducing valve 5 is opened manually and is in a normally open state;

[0092] When it is necessary to open the valve 1, the three-way solenoid valve 3 is opened by the control system 8, and the three-way solenoid valve 3 is in the normally open state. The control system 8 intermittently controls the switching action of the two-way solenoid valve 2 according to the preset valve opening broken line. When the control system 8 controls the two-way solenoid valve 2 to open, the instrument air inflates the valve actuator 4, and the valve opens to a certain opening. Then the control system 8 controls the two-way solenoid valve 2 to close, and the instrument air cannot inflate the valve actuator 4. The valve 1 cannot continue to open and remains at the current opening. The opening and closing actions of the two-way solenoid valve 2 are repeated according to the valve opening broken line, and the valve 1 can be slowly and gradually opened. When the valve 1 is in the fully open state, the two-way solenoid valve 2 is in the normally open state. Since the valve 1 in this embodiment is used as a control valve for balancing the pressure of the air purification molecular sieve adsorber, the opening of the valve 1 can be adjusted during the pressure balancing process so that the pressure rise in the initial stage will not be too fast, thereby effectively reducing the wear on the molecular sieve adsorber and improving the normal service life of the molecular sieve adsorber.

[0093] When the valve 1 needs to be closed, the two-way solenoid valve 2 and the three-way solenoid valve 3 are closed through the control system 8, and the air in the valve actuator 4 is discharged from the three-way solenoid valve 3. The valve 1 is closed by relying on the reset effect of the spring in the valve actuator 4, so that the pressure balance of the molecular sieve adsorber is quickly controlled at the end stage, thereby ensuring the operation cycle of the equipment.

[0094] Compared with the existing traditional switch valve whose opening cannot be adjusted, resulting in too fast pressure increase during the pressure balance process, the present invention adjusts the opening of the switch valve by installing a two-way solenoid valve and a three-way solenoid valve on the pneumatic circuit of the switch valve, so that the switch valve can be opened slowly and gradually, thereby reducing equipment wear and improving the normal service life of the equipment.

[0095] It should be noted that the application of the present invention to the control valve for balancing the pressure of an air purification molecular sieve adsorber is not restrictive and can also be applied to valves in other systems that need to be gradually fully opened, such as the inlet valve of a cryogenic pump.

[0096] Example 2

[0097] like Figure 5 The figure shows a second embodiment of a pneumatic circuit device with controllable valve opening. The difference between this embodiment and the first embodiment is that: Figure 7 As shown, in this embodiment, a flow limiter 7 is provided between the two-way solenoid valve 2 and the three-way solenoid valve 3. The flow limiter 7 is an existing universal standard component, and the flow in the gas circuit is manually adjusted. The function of the flow limiter 7 is to control the valve 1 to have a suitable opening time, so as to facilitate control by the control system 8.

[0098] Example 3

[0099] This embodiment is the third embodiment of a pneumatic circuit device with controllable valve opening. The difference between this embodiment and the first embodiment is that the control system 8 in this embodiment adopts a PLC control system.

[0100] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling valve opening, characterized in that: The invention includes a control method for a valve (1) from being closed to being fully opened and a control method for a valve (1) from being fully opened to being closed, which are specifically as follows: The control method for adjusting the valve (1) from the closed state to the fully open state is as follows: first, the three-way solenoid valve (3) is opened and is in the normally open state, then the two-way solenoid valve (2) is opened, and the instrument air enters the valve actuator (4), so that the valve (1) is opened to a certain opening, then the two-way solenoid valve (2) is closed, and the instrument air does not enter the valve actuator (4), and the valve (1) is kept at the current opening, and the opening and closing actions of the two-way solenoid valve (2) are repeated according to the pre-set valve opening broken line until the valve (1) is fully opened; When the valve (1) is in a fully open state, the two-way solenoid valve (2) is in a normally open state; The control method for adjusting the valve (1) from the fully open state to the closed state is as follows: closing the two-way solenoid valve (2) and the three-way solenoid valve (3), exhausting the air in the valve actuator (4) from the three-way solenoid valve (3), and closing the valve (1) by relying on the valve actuator (4); The valve opening broken line is obtained based on the predetermined valve opening. The predetermined valve openings at several time points are calculated during the entire downstream pressure boosting process. The time when the valve reaches the predetermined valve opening is obtained through on-site debugging to obtain the valve opening broken line. The specific calculation formula for the predetermined valve opening is as follows: Calculate the air mass M after the downstream equipment has completed the pressurization based on the ideal gas mass model formula: M=PVμ / RT=3.485PV / T, Where P is the gas pressure in N / m 2 , V is the volume of a single downstream device and pipeline, in m 3 , T is the upstream gas temperature in K, R is the molar gas constant, specifically 8.31 J / (mol·K), μ is the molar mass of the ideal gas, which is 28.96 g / mol for air; Calculate the mass flow rate W when the downstream equipment is boosted: W=M / t=3.485PV / (T×t) Where M is the air mass after the downstream equipment is pressurized, and t is the pressurization time of the downstream equipment; When the differential pressure △P≥P1 / 2, C V =0.003155×W×T 1 / 2 / P1 formula a When the differential pressure △P<P1 / 2, C V =0.001958×W×(T / (P1 2 -P1P2)) 1 / 2 Formula b Among them, △P=P1-P2, P1 is the upstream gas pressure, P2 is the downstream equipment pressure, C V is the rated C of the valve V value, T is the upstream gas temperature, unit is K; In the first t / 2 pressure rise stage, △P≥P1 / 2, according to formula a, since the mass flow rate W, upstream gas temperature T, and upstream gas pressure P1 remain unchanged, the rated C of the valve V The value remains unchanged, the valve opening is a fixed value, at this time the valve opening is based on the flow characteristics of the valve and the rated C V Value determination; In the last t / 2 pressure rise stage, △P<P1 / 2. According to formula b, the mass flow rate W, upstream gas temperature T, and upstream gas pressure P1 remain unchanged, but the downstream pressure P2 changes. The rise of P2 causes C V As the value increases, the valve opening tends to become larger. At several time points per minute, the valve opening is determined based on the flow characteristics of the valve and the rated C V The value is determined.

2. A valve opening control method according to claim 1, characterized in that: The valve opening is determined by the flow characteristics and rated C V The specific method for determining the value is: If the flow characteristic of the valve is linear, K=C V / C V '*100%, where K is the valve opening, C V The rated C calculated by formula a V Value, C V ' is the rated flow coefficient of the valve itself; If the flow characteristic of the valve is nonlinear, the valve opening K cannot be calculated by the formula and can be obtained by looking up the table or the manufacturer.

3. The method for controlling valve opening according to claim 1, characterized in that: After calculating the predetermined valve openings at several time points during the entire downstream pressure boost process, the time for the valve to reach the predetermined valve opening is obtained through on-site debugging, and the valve opening broken line is obtained. Based on the valve opening broken line graph, the two-way solenoid valve on / off curve corresponding to the valve opening broken line is obtained.

4. The method for controlling valve opening according to claim 1, characterized in that: The three-way solenoid valve (3) is a two-position three-way solenoid valve, comprising an air inlet connected to an air source, an air outlet connected to a valve actuator (4), and an exhaust hole for exhausting air; when the three-way solenoid valve (3) is opened, the passages where the air inlet and the air outlet are located are connected, and the exhaust hole is closed, at which time instrument air can enter through the air inlet and enter the valve actuator (4) through the air outlet; when the three-way solenoid valve (3) is closed, the air inlet is closed, the passages where the air outlet and the exhaust hole are located are connected, and the valve actuator (4) can enter the three-way solenoid valve (3) through the air outlet and be discharged through the exhaust hole.

5. The method for controlling valve opening according to claim 1, characterized in that: The valve actuator (4) is a straight-stroke pneumatic actuator, comprising a spring (41) and a push rod (42), wherein the push rod (42) is connected to the spring (41); the push rod (42) is connected to the valve stem of the valve (1); when the valve actuator (4) is inflated, the instrument air pushes the push rod (42) to drive the valve stem of the valve (1) to move, thereby opening the valve (1); at the same time, the spring (41) is deformed during the movement of the push rod (42); when the valve actuator (4) is deflated, the push rod (42) drives the valve stem of the valve (1) to move by relying on the reset action of the spring (41), thereby closing the valve (1).

6. A pneumatic circuit device with controllable valve opening, adopting the valve opening control method according to any one of claims 1 to 5, characterized in that: The invention comprises a valve (1) and a pneumatic circuit assembly for controlling the opening of the valve (1), wherein the pneumatic circuit assembly is connected to the valve (1); the pneumatic circuit assembly comprises an air source, a two-way solenoid valve (2), a three-way solenoid valve (3) and a valve actuator (4) which are connected in sequence; the valve actuator (4) is connected to the valve (1).

7. A pneumatic circuit device with controllable valve opening according to claim 6, characterized in that: The pneumatic circuit assembly further comprises a flow limiter (7) and a control system (8) for controlling the opening and closing operations of the two-way solenoid valve (2) and the opening and closing operations of the three-way solenoid valve (3); the control system (8) is communicatively connected to both the two-way solenoid valve (2) and the three-way solenoid valve (3); and the flow limiter (7) is arranged between the two-way solenoid valve (2) and the three-way solenoid valve (3).

8. A pneumatic circuit device with controllable valve opening according to claim 7, characterized in that: The pneumatic circuit assembly further comprises an isolation valve (5) and a self-operated pressure reducing valve (6); the isolation valve (5) and the self-operated pressure reducing valve (6) are sequentially arranged between the air source and the two-way solenoid valve (2).

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