Variable pressure differential gas supply mechanical valve train and control method

Abstract

This invention relates to the field of gas supply control technology and discloses a mechanical valve group for variable differential pressure gas supply, including pneumatic control valve I, pneumatic control valve II, pneumatic control valve III, and a pneumatic ball valve, as well as three self-relief pressure reducing valves. The pneumatic ball valve is connected upstream and downstream to a product gas pipe and a user gas pipe with a pressure of 1.0 MPa, respectively. The three self-relief pressure reducing valves are connected to the gas station using 1.2 MPa argon gas as the control gas source, and after pressure reduction, they form pressure reducing valve I, pressure reducing valve II, and pressure reducing valve III. By using a two-position three-way pneumatic control valve, self-relief pressure reducing valve, and pneumatic ball valve, the entire device uses only pneumatic components, without any electrical equipment, eliminating the need to upgrade the explosion-proof rating of the site, significantly reducing the cost of explosion-proof modification for hazardous environments such as oxygen stations, achieving a zero-electricity design, excellent explosion-proof performance, and pure mechanical pneumatic control, unaffected by electromagnetic interference, voltage fluctuations, power outages, etc., and can operate stably for a long time.

Description

Technical Field

[0001] This invention relates to the field of gas supply control technology, specifically to a mechanical valve assembly and control method for variable differential pressure gas supply. Background Technology

[0002] In industrial gas (especially oxygen) station applications, to ensure safe and stable gas supply, it is typically necessary to automatically control the opening and closing of the gas supply valve based on the downstream gas pressure. A typical scenario is: gas supply begins when the gas pressure is lower than the set opening pressure (e.g., 0.6 MPa), and stops when the pressure exceeds the set stopping pressure (e.g., 0.8 MPa), thus achieving stable control within the gas pressure range. Currently, the mainstream solution for implementing this control logic is a closed-loop control system using an electromagnetic valve and a pressure sensor. This solution acquires the downstream pressure signal through the pressure sensor, and then the controller drives the electromagnetic valve to achieve valve opening and closing control. However, this solution has some shortcomings, as follows:

[0003] Industrial gas sites such as oxygen stations are explosive hazardous environments. The use of electrical equipment (solenoid valves, pressure sensors, controllers) requires upgrading the explosion-proof level of the site according to explosion-proof specifications, which increases the additional costs of equipment procurement, construction and maintenance. The electrical signal control system is susceptible to electromagnetic interference and voltage fluctuations at the site, and cannot work properly in the event of a power outage, posing a risk of gas supply interruption or loss of control. Furthermore, electronic components are prone to aging and failure, requiring regular inspection and calibration, which places high demands on the professional skills of on-site maintenance personnel. Therefore, there is an urgent need for an automatic gas supply pressure control device that does not require electricity and is purely mechanically and pneumatically controlled. Summary of the Invention

[0004] This invention provides a mechanical valve assembly and control method for variable differential pressure gas supply, which has the advantages of being electrically-free, explosion-proof, highly reliable, and highly adaptable, thus solving the problems mentioned in the background art.

[0005] This invention provides the following technical solution: a mechanical valve group for variable differential pressure gas supply, including pneumatic control valve I, pneumatic control valve II, pneumatic control valve III, and a pneumatic ball valve, as well as three self-relief pressure reducing valves. The pneumatic ball valve is connected upstream and downstream to a product gas pipe and a user gas pipe with a pressure of 1.0 MPa, respectively. The three self-relief pressure reducing valves are connected to a 1.2 MPa argon gas source provided at the gas station as the control gas source, and after pressure reduction, they form pressure reducing valve I, pressure reducing valve II, and pressure reducing valve III. The outlet of pressure reducing valve I is simultaneously connected to the inlet of pneumatic control valves I, II, and III via a pipeline, maintaining a gas pressure of 0.5 MPa at the inlet of pneumatic control valves I, II, and III. The outlet of pressure reducing valve II is connected to the left side of pneumatic control valve II. The control ports are connected via pipelines, maintaining a pneumatic pressure of 0.8 MPa at the left control port of pneumatic control valve II; the outlet of pressure reducing valve III is connected to the right control port of pneumatic control valve III via a pipeline, maintaining a pneumatic pressure of 0.6 MPa at the right control port of pneumatic control valve III; the outlet of pneumatic control valve II is connected to the left control port of pneumatic control valve I via a pipeline; the outlet of pneumatic control valve III is connected to the right control port of pneumatic control valve I via a pipeline; the exhaust ports of pneumatic control valve I, pneumatic control valve II, and pneumatic control valve III are all directly connected to the atmosphere; the outlet of pneumatic control valve I is connected to the actuator of the pneumatic ball valve via a pipeline; a pressure tee is provided on the air-using pipeline, which is connected to the right control port of pneumatic control valve II and the left control port of pneumatic control valve III via pipelines respectively.

[0006] Preferably, the pneumatic control valve I, pneumatic control valve II and pneumatic control valve III are all differential pressure type two-position three-way pneumatic control valves, and the valves are equipped with piston valve cores that can slide left and right according to the pressure difference between the two pneumatic control ports. By switching the position of the piston valve core, the air inlet and the air outlet can be connected or the air outlet and the exhaust port can be connected.

[0007] Preferably, the pneumatic ball valve is an air-to-open pneumatic ball valve, which opens when the actuator inside is connected to a control pressure of 0.5MPa, and closes when the actuator is connected to atmospheric pressure.

[0008] Preferably, when the pressure in the gas supply pipe is less than 0.6 MPa, the piston in pneumatic control valve II moves to the right, the piston in pneumatic control valve III moves to the left, the piston in pneumatic control valve I moves to the left, the air inlet of pneumatic control valve I is connected to the actuator of the pneumatic ball valve, the valve of the pneumatic ball valve opens, and gas is supplied to the gas supply pipe.

[0009] Preferably, when the pressure in the gas supply pipe is between 0.6MPa and 0.8MPa, the piston position in the pneumatic control valve II remains unchanged, the piston in the pneumatic control valve III moves to the right, the piston position in the pneumatic control valve I remains unchanged, the air inlet of the pneumatic control valve I is connected to the pneumatic ball valve actuator, the pneumatic ball valve remains open, and gas is continuously supplied downstream.

[0010] Preferably, when the pressure in the gas supply pipe is greater than 0.8 MPa, the piston in pneumatic control valve II is pushed to the left, the piston in pneumatic control valve III remains unchanged, the piston in pneumatic control valve I is pushed to the right, the exhaust port of pneumatic control valve I is connected to the pneumatic ball valve actuator, the pneumatic ball valve is closed, and the gas supply to the gas supply pipe is stopped.

[0011] Preferably, when the pressure in the gas supply pipe falls between 0.6MPa and 0.8MPa again due to continuous use, the piston in pneumatic control valve II moves to the right, the piston in pneumatic control valve III remains unchanged, the piston in pneumatic control valve I remains unchanged, the exhaust port of pneumatic control valve I is connected to the actuator of the pneumatic ball valve, the valve of the pneumatic ball valve remains closed, and no gas is supplied to the gas supply pipe.

[0012] A method for controlling a mechanical valve group for variable differential pressure gas supply, the steps of which are as follows:

[0013] S1: Start gas production: When the pressure in the gas supply pipe is less than 0.6MPa, the pressure at the left control port of gas control valve II is greater than the pressure at the right control port. The piston inside gas control valve II is pushed to the right, and the exhaust port and outlet of gas control valve II are connected to the left control port of gas control valve I in sequence, with the pressure being atmospheric pressure. The pressure at the left control port of gas control valve III is less than the pressure at the right control port, and the piston inside gas control valve III is pushed to the left. The inlet and outlet of gas control valve III are connected to the right control port of gas control valve I in sequence, with the pressure being 0.5MPa. At this time, the pressure at the left control port of gas control valve I is less than the pressure at the right control port, and the piston inside gas control valve I is pushed to the left. The inlet of gas control valve I is connected to the actuator of the pneumatic ball valve, and the valve of the pneumatic ball valve opens, starting to supply gas to the gas supply pipe.

[0014] S2: Continuous gas supply: When the pressure in the gas supply pipe is between 0.6MPa and 0.8MPa, the pressure at the left control port of gas control valve II is greater than that at the right control port. The piston position inside gas control valve II remains unchanged. The exhaust port and outlet port of gas control valve II are sequentially connected to the left control port of gas control valve I, and the pressure is atmospheric pressure. The pressure at the left control port of gas control valve III is greater than that at the right control port. The piston inside gas control valve III is pushed to the right. The exhaust port and outlet port of gas control valve III are sequentially connected to the right control port of gas control valve I, and the pressure is atmospheric pressure. At this time, the pressure at the left control port of gas control valve I is equal to that at the right control port. The piston position inside gas control valve I remains unchanged. The inlet port of gas control valve I is connected to the pneumatic ball valve actuator. The valve of the pneumatic ball valve remains open, continuously supplying gas downstream.

[0015] S3: Stop gas supply: When the pressure in the gas supply pipe is greater than 0.8MPa, the pressure at the left control port of gas control valve II is less than the pressure at the right control port. The piston inside gas control valve II is pushed to the left. The inlet and outlet of gas control valve II are connected to the left control port of gas control valve I in sequence, and the pressure is 0.5MPa. The pressure at the left control port of gas control valve III is greater than the pressure at the right control port. The piston inside gas control valve III remains unchanged. The exhaust port and outlet of gas control valve III are connected to the right control port of gas control valve I in sequence, and the pressure is atmospheric pressure. At this time, the pressure at the left control port of gas control valve I is greater than the pressure at the right control port. The piston inside gas control valve I is pushed to the right. The exhaust port of gas control valve I is connected to the pneumatic ball valve actuator. The pneumatic ball valve is closed, and the gas supply to the gas supply pipe is stopped.

[0016] S4: Continuous Gas Use: When the pressure in the gas supply pipe falls between 0.6MPa and 0.8MPa again due to continuous use, the pressure at the left control port of gas control valve II is greater than that at the right control port. The piston inside gas control valve II is pushed to the right, and the exhaust port and outlet port of gas control valve II are connected to the left control port of gas control valve I in sequence, with the pressure being atmospheric pressure. The pressure at the left control port of gas control valve III is greater than that at the right control port, and the piston position inside gas control valve III remains unchanged. The exhaust port and outlet port of gas control valve III are connected to the right control port of gas control valve I in sequence, with the pressure being atmospheric pressure. At this time, the pressure at the left control port of gas control valve I is equal to that at the right control port, the piston position inside gas control valve I remains unchanged, and the exhaust port of gas control valve I is connected to the actuator of the pneumatic ball valve. The valve of the pneumatic ball valve remains closed and does not supply gas to the gas supply pipe.

[0017] S5: When the pressure in the gas tube end is less than 0.6MPa again, repeat the above cycle.

[0018] The present invention has the following beneficial effects:

[0019] By incorporating a two-position three-way pneumatic control valve, a self-releasing pressure reducing valve, and a pneumatic ball valve, the entire device utilizes only pneumatic components, eliminating the need for any electrical connections. This eliminates the need to upgrade the explosion-proof rating of the site, significantly reducing the cost of explosion-proof modifications for hazardous environments such as oxygen stations. It achieves a zero-electricity design with excellent explosion-proof performance. Furthermore, its purely mechanical pneumatic control is unaffected by electromagnetic interference, voltage fluctuations, or power outages, ensuring long-term stable operation. It is particularly suitable for unattended, harsh industrial gas environments, offering high reliability and strong adaptability. Composed only of standard pneumatic valve components, its simple structure eliminates complex electronic components, reducing potential failure points and maintenance costs. On-site maintenance personnel only need conventional pneumatic component repair skills to perform maintenance. Finally, through the pressure difference logic of the two-stage pneumatic control valves, it precisely achieves a control cycle of "low-pressure opening, medium-pressure maintenance, high-pressure closing, and medium-pressure maintenance closing," meeting the pressure range control requirements of industrial gas usage scenarios without signal delay or loss of control risk. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the gas path of the present invention when the pressure in the gas pipe end is <0.6MPa (gas production begins);

[0021] Figure 2 This is a schematic diagram of the gas path of the present invention under the condition of continuous gas supply with a pipeline pressure of 0.6MPa-0.8MPa at the end of the gas pipe.

[0022] Figure 3 This is a schematic diagram of the gas path of the present invention when the pressure in the gas pipe end is >0.8MPa (gas production is stopped);

[0023] Figure 4 This is a schematic diagram of the gas path of the present invention under the condition of continuous gas supply with a gas pipe pressure of 0.6MPa-0.8MPa.

[0024] In the diagram: 1. Pneumatic control valve I; 2. Pneumatic control valve II; 3. Pneumatic control valve III; 4. Pressure reducing valve I; 5. Pressure reducing valve II; 6. Pressure reducing valve III; 7. Pneumatic ball valve. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figure 1-4A mechanical valve assembly for variable differential pressure gas supply includes pneumatic control valve I1, pneumatic control valve II2, pneumatic control valve III3, and pneumatic ball valve 7, as well as three self-relief pressure reducing valves. The pneumatic ball valve 7 is connected upstream and downstream to a product gas pipe and a user gas pipe with a pressure of 1.0 MPa, respectively. The three self-relief pressure reducing valves are connected to a 1.2 MPa argon gas source provided at the gas station as the control gas source, and after pressure reduction, form pressure reducing valves I4, II5, and III6. The outlet of pressure reducing valve I4 is simultaneously connected to the inlets of pneumatic control valves I1, II2, and III3 via pipelines, maintaining a gas pressure of 0.5 MPa at the inlets of pneumatic control valves I1, II2, and III3. The outlet of pressure reducing valve II5 is connected to the left-side control port of pneumatic control valve II2. The air control valve II2 is connected to the pneumatic control valve 3 via a pipeline, maintaining a pneumatic pressure of 0.8 MPa at the left pneumatic control port. The outlet of the pressure reducing valve III6 is connected to the pneumatic control valve III3 via a pipeline, maintaining a pneumatic pressure of 0.6 MPa at the right pneumatic control port. The outlet of the pneumatic control valve II2 is connected to the pneumatic control valve I1 via a pipeline. The outlet of the pneumatic control valve III3 is connected to the pneumatic control valve I1 via a pipeline. The exhaust ports of the pneumatic control valves I1, II2, and III3 are all directly connected to the atmosphere. The outlet of the pneumatic control valve I1 is connected to the actuator of the pneumatic ball valve 7 via a pipeline. A pressure tee is installed on the air-using pipeline, which is connected to the pneumatic control valve II2 via a pipeline and the pneumatic control valve III3 via a pipeline.

[0027] Pneumatic control valve I1, pneumatic control valve II2 and pneumatic control valve III3 are all differential pressure type two-position three-way pneumatic control valves, and the valves are equipped with piston valve cores that can slide left and right according to the pressure difference between the two pneumatic control ports. By switching the position of the piston valve core, the air inlet and outlet can be connected or the air outlet and exhaust port can be connected.

[0028] The pneumatic ball valve 7 is an air-to-open pneumatic ball valve. When the actuator inside is connected to a control pressure of 0.5MPa, the valve opens; when the actuator is connected to atmospheric pressure, the valve closes.

[0029] When the pressure in the air supply pipe is less than 0.6 MPa, the pressure at the right control port of the connected air control valve II2 is <0.6 MPa. Simultaneously, the left control port of air control valve II2 is connected to pressure reducing valve II5, so its pressure is 0.8 MPa. Therefore, the pressure at the left control port of air control valve II2 is greater than the pressure at the right control port, pushing the piston inside air control valve II2 to the right. This causes the exhaust port and outlet port of air control valve II2 to connect sequentially to the left control port of air control valve I1, with all pressures at atmospheric pressure. At the same time, the left control port of air control valve III3 is also connected to the air supply pipe, so its pressure is <0.6 MPa. The right control port of air control valve III3 is connected to pressure reducing valve III6, therefore... The pressure is 0.6 MPa. Therefore, the pressure at the left control port of pneumatic control valve III3 is less than the pressure at the right control port. The piston inside pneumatic control valve III3 is pushed to the left, so that the air inlet and outlet of pneumatic control valve III3 are connected to the right control port of pneumatic control valve I1 in sequence, and the pressure is 0.5 MPa. At this time, the pressure at the left control port of pneumatic control valve I1 is atmospheric pressure, which is less than the pressure at the right control port of pneumatic control valve I1. Therefore, the pressure at the left control port of pneumatic control valve I1 is less than the pressure at the right control port. The piston inside pneumatic control valve I1 is pushed to the left, and the air inlet pressure of pneumatic control valve I1 is 0.5 MPa. It is connected to the actuator of pneumatic ball valve 7. Therefore, the valve of pneumatic ball valve 7 is opened, and air is supplied to the end of the air supply pipe.

[0030] When the pressure inside the air supply pipe is between 0.6 MPa and 0.8 MPa, the pressure at the right-side control port of the connected air control valve II2 is also between 0.6 MPa and 0.8 MPa. Simultaneously, the left-side control port of air control valve II2 is connected to pressure reducing valve II5, so its pressure is 0.8 MPa. Therefore, the pressure at the left-side control port of air control valve II2 is greater than that at the right-side control port, and the piston position inside air control valve II2 remains unchanged. This keeps the exhaust port and outlet port of air control valve II2 connected to the left-side control port of air control valve I1, and both pressures are atmospheric pressure. At the same time, the left-side control port of air control valve III3 is also connected to the air supply pipe, so its pressure is 0.6 MPa. The pressure is 0.6 MPa - 0.8 MPa. Since the right-side control port of pneumatic control valve III3 is connected to pressure reducing valve III6, the pressure is 0.6 MPa. Therefore, the pressure at the left-side control port of pneumatic control valve III3 is greater than that at the right-side control port. The piston inside pneumatic control valve III3 is pushed to the right, causing the exhaust port and outlet of pneumatic control valve III3 to connect sequentially to the right-side control port of pneumatic control valve I1, with both pressures at atmospheric pressure. At this time, the pressure at the left-side control port of pneumatic control valve I1 is also atmospheric pressure, and since the two are equal, the piston position inside pneumatic control valve I1 remains unchanged. The inlet port of pneumatic control valve I1 remains connected to the actuator of pneumatic ball valve 7, and the valve of pneumatic ball valve 7 remains open, continuously supplying air to the end of the air supply pipe.

[0031] When the pressure in the gas supply pipe exceeds 0.8 MPa, the pressure at the right control port of the connected pneumatic control valve II2 also exceeds 0.8 MPa. Simultaneously, the left control port of pneumatic control valve II2 is connected to pressure reducing valve II5, resulting in a pressure of 0.8 MPa. Therefore, the pressure at the left control port of pneumatic control valve II2 is less than that at the right control port, causing the piston inside pneumatic control valve II2 to be pushed to the left. This connects the inlet and outlet of pneumatic control valve II2 sequentially to the left control port of pneumatic control valve I1, with each port having a pressure of 0.5 MPa. At the same time, the left control port of pneumatic control valve III3 is also connected to the gas supply pipe, resulting in a pressure exceeding 0.8 MPa. Meanwhile, the right control port of pneumatic control valve III3 is connected to pressure reducing valve III6. Since the connection is established, the pressure is 0.6 MPa. Therefore, the pressure at the left control port of pneumatic control valve III3 is greater than that at the right control port. The piston position inside pneumatic control valve III3 remains unchanged, causing the exhaust port and outlet of pneumatic control valve III3 to be sequentially connected to the right control port of pneumatic control valve I1, with all pressures at atmospheric pressure. At this time, the pressure at the left control port of pneumatic control valve I1 is 0.5 MPa, which is greater than that at the right control port. Therefore, the pressure at the left control port of pneumatic control valve I1 is greater than that at the right control port, and the piston inside pneumatic control valve I1 is pushed to the right. The exhaust port pressure of pneumatic control valve I1 is atmospheric pressure, and it is connected to the actuator of pneumatic ball valve 7. The valve of pneumatic ball valve 7 is closed, stopping the supply of air to the end of the air supply pipe.

[0032] When the pressure in the air supply pipe is again between 0.6MPa and 0.8MPa, the pressure at the right control port of the connected air control valve II2 is 0.6MPa-0.8MPa. Simultaneously, the left control port of air control valve II2 is connected to pressure reducing valve II5, so its pressure is 0.8MPa. Therefore, the pressure at the left control port of air control valve II2 is greater than that at the right control port, pushing the piston inside air control valve II2 to the right. This connects the exhaust port and outlet port of air control valve II2 sequentially to the left control port of air control valve I1, with all pressures at atmospheric pressure. At the same time, the left control port of air control valve III3 is also connected to the air supply pipe, resulting in a pressure of 0.6MPa-0.8MPa. Pa, and the right air control port of air control valve III3 is connected to pressure reducing valve III6, so the pressure is 0.6MPa. Therefore, the pressure of the left air control port of air control valve III3 is greater than the pressure of the right air control port. The piston position inside air control valve III3 remains unchanged, so the exhaust port and outlet of air control valve III3 are connected to the right air control port of air control valve I1 in sequence, and the pressure is atmospheric pressure. At this time, the pressure of the left air control port of air control valve I1 is atmospheric pressure, which is equal to the pressure of the right air control port of air control valve I1. Therefore, the piston position inside air control valve I1 remains unchanged, the pressure of the exhaust port of air control valve I1 is atmospheric pressure, and it is connected to the actuator of pneumatic ball valve 7. The valve of pneumatic ball valve 7 remains closed, and the supply of air to the end of the air pipe stops.

[0033] A method for controlling a mechanical valve group for variable differential pressure gas supply, the steps of which are as follows:

[0034] S1: Start Gas Production: When the pressure in the gas supply pipe is less than 0.6 MPa, the pressure at the left control port of gas control valve II2 (0.8 MPa) is greater than the pressure at the right control port (<0.6 MPa). The piston inside gas control valve II2 is pushed to the right, and the exhaust port and outlet port of gas control valve II2 are sequentially connected to the left control port of gas control valve I1, with all pressures at atmospheric pressure. The pressure at the left control port of gas control valve III3 (<0.6 MPa) is less than the pressure at the right control port (0.6 MPa). The piston inside pneumatic control valve III3 is pushed to the left, and the inlet and outlet of pneumatic control valve III3 are connected to the right pneumatic control port of pneumatic control valve I1 in sequence, with the pressure being 0.5 MPa. At this time, the pressure (atmospheric pressure) of the left pneumatic control port of pneumatic control valve I1 is less than the pressure (0.5 MPa) of the right pneumatic control port. The piston inside pneumatic control valve I1 is pushed to the left, and the inlet of pneumatic control valve I1 is connected to the actuator of pneumatic ball valve 7. The valve of pneumatic ball valve 7 is opened, and air is supplied to the end of the air supply pipe.

[0035] S2: Continuous Gas Supply: When the pressure in the gas supply pipe is between 0.6MPa and 0.8MPa, the pressure at the left control port of gas control valve II2 (0.8MPa) is greater than the pressure at the right control port (0.6MPa-0.8MPa). The piston position inside gas control valve II2 remains unchanged. The exhaust port and outlet port of gas control valve II2 are sequentially connected to the left control port of gas control valve I1, and the pressure is atmospheric pressure. The pressure at the left control port of gas control valve III3 is (0.6MPa-0.8MPa). When the pressure is greater than the pressure at the right air control port (0.6MPa), the piston inside the air control valve Ⅲ3 is pushed to the right. The exhaust port and outlet of the air control valve Ⅲ3 are connected to the right air control port of the air control valve Ⅰ1 in sequence, and the pressure is atmospheric pressure. At this time, the pressure (atmospheric pressure) at the left air control port of the air control valve Ⅰ1 is equal to the pressure (atmospheric pressure) at the right air control port. The position of the piston inside the air control valve Ⅰ1 remains unchanged. The air inlet of the air control valve Ⅰ1 is connected to the actuator of the pneumatic ball valve 7. The valve of the pneumatic ball valve 7 remains open and continues to supply air downstream.

[0036] S3: Stop Gas Production: When the pressure in the gas supply pipe is greater than 0.8 MPa, the pressure at the left control port of gas control valve II2 (0.8 MPa) is less than the pressure at the right control port (>0.8 MPa). The piston inside gas control valve II2 is pushed to the left, and the inlet and outlet of gas control valve II2 are sequentially connected to the left control port of gas control valve I1, with each pressure being 0.5 MPa. The pressure at the left control port of gas control valve III3 (>0.8 MPa) is greater than the pressure at the right control port (>0.8 MPa). (0.6MPa), the piston position inside the pneumatic control valve III3 remains unchanged. The exhaust port and outlet of the pneumatic control valve III3 are connected to the right pneumatic control port of the pneumatic control valve I1 in sequence, and the pressure is atmospheric pressure. At this time, the pressure of the left pneumatic control port (0.5MPa) of the pneumatic control valve I1 is greater than the pressure of the right pneumatic control port (atmospheric pressure). The piston inside the pneumatic control valve I1 is pushed to the right, and the exhaust port of the pneumatic control valve I1 is connected to the actuator of the pneumatic ball valve 7. The valve of the pneumatic ball valve 7 is closed, and the supply of air to the end of the air supply pipe is stopped.

[0037] S4: Continuous Gas Use: When the gas supply line pressure falls between 0.6MPa and 0.8MPa again due to continuous use, the pressure at the left control port of gas control valve II2 (0.8MPa) is greater than the pressure at the right control port (0.6MPa-0.8MPa). The piston inside gas control valve II2 is pushed to the right, and the exhaust port and outlet port of gas control valve II2 are sequentially connected to the left control port of gas control valve I1, with both pressures at atmospheric pressure. The pressure at the left control port of gas control valve III3 (0.6MPa-0.8MPa)... a) When the pressure is greater than the right-side air control port pressure (0.6MPa), the piston position inside the air control valve Ⅲ3 remains unchanged. The exhaust port and outlet of the air control valve Ⅲ3 are connected to the right-side air control port of the air control valve Ⅰ1 in sequence, and the pressure is atmospheric pressure. At this time, the pressure (atmospheric pressure) of the left-side air control port of the air control valve Ⅰ1 is equal to the pressure (atmospheric pressure) of the right-side air control port. The piston position inside the air control valve Ⅰ1 remains unchanged. The exhaust port of the air control valve Ⅰ1 is connected to the actuator of the pneumatic ball valve 7. The valve of the pneumatic ball valve 7 remains closed and does not supply air to the end of the air supply pipe.

[0038] S5: When the pressure in the gas tube end is less than 0.6MPa again, repeat the above cycle.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A mechanical valve assembly for variable differential pressure gas supply, comprising pneumatic control valve I (1), pneumatic control valve II (2), pneumatic control valve III (3), and a pneumatic ball valve (7), and three self-relief pressure reducing valves, wherein the pneumatic ball valve (7) is connected upstream and downstream to a product gas pipe and a gas supply pipe with a pressure of 1.0 MPa, respectively, characterized in that: After the three self-overflowing pressure reducing valves are connected to the gas station using 1.2MPa argon gas as the control gas source, they are reduced in pressure to form pressure reducing valve I (4), pressure reducing valve II (5), and pressure reducing valve III (6). The outlet of the pressure reducing valve I (4) is simultaneously connected to the air inlets of the pneumatic control valve I (1), pneumatic control valve II (2) and pneumatic control valve III (3) through a pipeline, so that the air inlets of the pneumatic control valve I (1), pneumatic control valve II (2) and pneumatic control valve III (3) maintain a gas pressure of 0.5MPa; The outlet of the pressure reducing valve II (5) is connected to the left air control port of the air control valve II (2) through a pipeline, so that the left air control port of the air control valve II (2) maintains an air pressure of 0.8MPa; The outlet of the pressure reducing valve III (6) is connected to the right air control port of the pneumatic control valve III (3) through a pipeline, so that the right air control port of the pneumatic control valve III (3) maintains a pneumatic pressure of 0.6 MPa. The outlet of the pneumatic control valve II (2) is connected to the left pneumatic control port of the pneumatic control valve I (1) through a pipe; The outlet of the pneumatic control valve Ⅲ (3) is connected to the right pneumatic control port of the pneumatic control valve Ⅰ (1) through a pipe; The exhaust ports of the pneumatic control valve I (1), pneumatic control valve II (2) and pneumatic control valve III (3) are all directly connected to the atmosphere; The outlet of the pneumatic control valve I (1) is connected to the actuator of the pneumatic ball valve (7) through a pipeline; The gas-using end pipeline is equipped with a pressure tee for taking pressure, which is connected to the right air control port of air control valve II (2) and the left air control port of air control valve III (3) through the pipeline.

2. The mechanical valve assembly for variable differential pressure gas supply according to claim 1, characterized in that: The pneumatic control valve I (1), pneumatic control valve II (2) and pneumatic control valve III (3) are all differential pressure type two-position three-way pneumatic control valves, and the valves are equipped with piston valve cores that can slide left and right according to the pressure difference between the two pneumatic control ports. By switching the position of the piston valve core, the air inlet and outlet can be connected or the air outlet and exhaust port can be connected.

3. The mechanical valve assembly for variable differential pressure gas supply according to claim 1, characterized in that: The pneumatic ball valve (7) is an air-to-open pneumatic ball valve. When the actuator inside is connected to a control pressure of 0.5MPa, the valve opens, and when the actuator is connected to atmospheric pressure, the valve closes.

4. The mechanical valve assembly for variable differential pressure gas supply according to claim 1, characterized in that: When the pressure in the gas supply pipe is less than 0.6 MPa, the piston in the pneumatic control valve II (2) moves to the right, the piston in the pneumatic control valve III (3) moves to the left, the piston in the pneumatic control valve I (1) moves to the left, the air inlet of the pneumatic control valve I (1) is connected to the actuator of the pneumatic ball valve (7), the valve of the pneumatic ball valve (7) opens, and gas is supplied to the gas supply pipe.

5. A mechanical valve assembly for variable differential pressure gas supply according to claim 4, characterized in that: When the pressure of the gas pipe end is between 0.6MPa and 0.8MPa, the piston position in the pneumatic control valve II (2) remains unchanged, the piston in the pneumatic control valve III (3) moves to the right, the piston position in the pneumatic control valve I (1) remains unchanged, the air inlet of the pneumatic control valve I (1) is connected to the actuator of the pneumatic ball valve (7), the valve of the pneumatic ball valve (7) remains open, and gas is continuously supplied downstream.

6. A mechanical valve assembly for variable differential pressure gas supply according to claim 5, characterized in that: When the pressure in the gas supply pipe is greater than 0.8 MPa, the piston in the pneumatic control valve II (2) is pushed to the left, the piston in the pneumatic control valve III (3) remains unchanged, the piston in the pneumatic control valve I (1) is pushed to the right, the exhaust port of the pneumatic control valve I (1) is connected to the actuator of the pneumatic ball valve (7), the valve of the pneumatic ball valve (7) is closed, and the gas supply to the gas supply pipe is stopped.

7. A mechanical valve assembly for variable differential pressure gas supply according to claim 6, characterized in that: When the pressure in the gas supply pipe falls between 0.6MPa and 0.8MPa again due to continuous use, the piston in the pneumatic control valve II (2) moves to the right, the piston in the pneumatic control valve III (3) remains unchanged, the piston in the pneumatic control valve I (1) remains unchanged, the exhaust port of the pneumatic control valve I (1) is connected to the actuator of the pneumatic ball valve (7), the valve of the pneumatic ball valve (7) remains closed, and no gas is supplied to the gas supply pipe.

8. A method for controlling a mechanical valve group for variable differential pressure gas supply, the method steps of which are as follows: S1: Start gas production: When the pressure in the gas supply pipe is less than 0.6MPa, the pressure of the left gas control port of gas control valve II (2) is greater than the pressure of the right gas control port. The piston inside gas control valve II (2) is pushed to the right. The exhaust port and outlet of gas control valve II (2) are connected to the left gas control port of gas control valve I (1) in sequence, and the pressure is atmospheric pressure. The pressure of the left gas control port of gas control valve III (3) is less than the pressure of the right gas control port. The piston inside gas control valve III (3) is pushed to the left. The inlet and outlet of gas control valve III (3) are connected to the right gas control port of gas control valve I (1) in sequence, and the pressure is 0.5MPa. At this time, the pressure of the left gas control port of gas control valve I (1) is less than the pressure of the right gas control port. The piston inside gas control valve I (1) is pushed to the left. The inlet of gas control valve I (1) is connected to the actuator of pneumatic ball valve (7). The valve of pneumatic ball valve (7) is opened, and gas is supplied to the gas supply pipe. S2: Continuous gas supply: When the pressure of the gas supply pipe is between 0.6MPa and 0.8MPa, the pressure of the left gas control port of gas control valve II (2) is greater than that of the right gas control port. The piston position inside gas control valve II (2) remains unchanged. The exhaust port and outlet of gas control valve II (2) are connected to the left gas control port of gas control valve I (1) in sequence, and the pressure is atmospheric pressure. The pressure of the left gas control port of gas control valve III (3) is greater than that of the right gas control port. The piston inside gas control valve III (3) is pushed to the right. The exhaust port and outlet of gas control valve III (3) are connected to the right gas control port of gas control valve I (1) in sequence, and the pressure is atmospheric pressure. At this time, the pressure of the left gas control port of gas control valve I (1) is equal to that of the right gas control port. The piston position inside gas control valve I (1) remains unchanged. The inlet of gas control valve I (1) is connected to the actuator of pneumatic ball valve (7). The valve of pneumatic ball valve (7) remains open and continues to supply gas downstream. S3: Stop gas supply: When the pressure of the gas supply pipe is greater than 0.8MPa, the pressure of the left gas control port of gas control valve II (2) is less than the pressure of the right gas control port. The piston inside gas control valve II (2) is pushed to the left. The inlet and outlet of gas control valve II (2) are connected to the left gas control port of gas control valve I (1) in sequence, and the pressure is 0.5MPa. The pressure of the left gas control port of gas control valve III (3) is greater than the pressure of the right gas control port. The position of the piston inside gas control valve III (3) remains unchanged. The exhaust port and outlet of gas control valve III (3) are connected to the right gas control port of gas control valve I (1) in sequence, and the pressure is atmospheric pressure. At this time, the pressure of the left gas control port of gas control valve I (1) is greater than the pressure of the right gas control port. The piston inside gas control valve I (1) is pushed to the right. The exhaust port of gas control valve I (1) is connected to the actuator of pneumatic ball valve (7). The valve of pneumatic ball valve (7) is closed, and gas supply to the gas supply pipe is stopped. S4: Continuous gas use: When the pressure of the gas supply pipe is between 0.6MPa and 0.8MPa again due to continuous use, the pressure of the left gas control port of gas control valve II (2) is greater than that of the right gas control port. The piston inside gas control valve II (2) is pushed to the right. The exhaust port and outlet of gas control valve II (2) are connected to the left gas control port of gas control valve I (1) in sequence, and the pressure is atmospheric pressure. The pressure of the left gas control port of gas control valve III (3) is greater than that of the right gas control port. The position of the piston inside gas control valve III (3) remains unchanged. The exhaust port and outlet of gas control valve III (3) are connected to the right gas control port of gas control valve I (1) in sequence, and the pressure is atmospheric pressure. At this time, the pressure of the left gas control port of gas control valve I (1) is equal to that of the right gas control port. The position of the piston inside gas control valve I (1) remains unchanged. The exhaust port of gas control valve I (1) is connected to the actuator of pneumatic ball valve (7). The valve of pneumatic ball valve (7) remains closed and does not supply gas to the gas supply pipe. S5: When the pressure in the gas tube end is less than 0.6MPa again, repeat the above cycle.

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