A constant-voltage and constant-current device

Abstract

The utility model discloses a kind of constant-voltage steady flow devices, including mechanical part and electrical part: the mechanical part includes sequentially connected ball valve, pump group, diaphragm pressure stabilizing tank, electric valve, flowmeter and nozzle;The ball valve is used to accurately control intake, the pump group includes at least two interbackup Roots pumps, provides required pressure for system, the diaphragm pressure stabilizing tank is used to stabilize air pressure and flow, the electric valve is used to adjust flow, the flowmeter is used to measure gas flow, the nozzle is used to output gas, the utility model solves the problem that only relying on ordinary gas tank in prior art is difficult to cope with the peak pressure generated by flow mutation, realizes the accurate stable control to gas pressure and flow, improves the stability and reliability of system operation.

Description

Technical Field

[0001] This utility model belongs to the field of fluid technology and discloses a constant pressure and flow stabilizing device. The main function of this device is to provide a stable flow rate in gas pipeline applications. Background Technology

[0002] In many industrial production processes and experimental research scenarios, there are strict requirements for a stable gas supply. For example, in chemical synthesis reactions, the reactant gases need to maintain constant pressure and stable flow rate to ensure the consistency of the reaction process and the stability of product quality. In semiconductor manufacturing processes, precise control of gas pressure and flow rate is crucial for key steps such as thin film deposition and etching. Existing technologies, such as the CN216046889U patent, only use ordinary gas tanks to store buffer NO gas. Specifically, these ordinary gas tanks lack a structure that integrates pressure detection and pump adjustment, making it impossible to adjust the pump output according to actual pressure conditions, thus affecting the stability of gas delivery. Utility Model Content

[0003] The purpose of this invention is to provide a constant pressure and stable flow device that solves the problem that relying solely on ordinary gas tanks in the prior art is insufficient to cope with the pressure caused by sudden changes in flow rate, thereby achieving precise and stable control of gas pressure and flow rate and improving the stability and reliability of system operation.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A constant pressure and stable flow device includes a mechanical part and an electrical part: the mechanical part includes a ball valve, a pump set, a diaphragm pressure tank, an electric valve, a flow meter, and a nozzle connected in sequence; the ball valve is used to accurately control the intake air, the pump set includes at least two Roots pumps that serve as backups for each other to provide the required pressure to the system, the diaphragm pressure tank is used to stabilize the gas pressure and flow rate, the electric valve is used to regulate the flow rate, the flow meter is used to measure the gas flow rate, and the nozzle is used to output gas. The electrical components include a PLC controller, an AC contactor, a frequency converter, a pressure transmitter, an electrical contact pressure gauge, a valve drive mechanism, and a pressure relief solenoid valve. The pressure transmitter is mounted on the diaphragm pressure tank and monitors the tank pressure in real time, transmitting the pressure data to the PLC controller as the main control signal. The frequency converter is electrically connected to the PLC controller and also to the pump motor, and is controlled by the PLC controller to adjust the pump speed based on the main control signal provided by the pressure transmitter. The electrical contact pressure gauge is electrically connected to the PLC controller and transmits a pressure relief signal to the PLC controller in case of pressure over-limit caused by pressure transmitter failure or other reasons. The PLC controller is electrically connected to the pressure relief solenoid valve and triggers it for safe pressure relief upon receiving a pressure relief signal. The PLC controller is electrically connected to the valve drive mechanism, which is connected to the electric valve. The PLC controller adjusts the valve drive mechanism based on feedback signals from the flow meter, thereby controlling the opening of the electric valve and regulating the flow rate.

[0005] Further preferably, the PLC controller is model SR20, the AC contactor is model 0911, the frequency converter is model ACS510, the pressure transmitter is model P1.6, the electric contact pressure gauge is model P-T1.6, and the pressure relief solenoid valve is model KY.

[0006] Furthermore, the ball valve is connected to the inlet of the pump unit via a pipe, the outlet of the pump unit is connected to the inlet of the diaphragm pressure stabilizing tank via a pipe, and the outlet of the diaphragm pressure stabilizing tank is connected to the electric valve, the flow meter and the nozzle in sequence via pipes; In a further preferred embodiment, the pressure transmitter is installed on the top of the diaphragm pressure tank via a threaded connection, and the electrical contact pressure gauge is installed on the side of the diaphragm pressure tank via a threaded connection.

[0007] In a further preferred embodiment, the valve drive mechanism includes a motor, a lead screw, and a slider. The motor is electrically connected to a PLC controller, the output shaft of the motor is connected to the lead screw, the lead screw is threadedly connected to the slider, and the slider is connected to the valve stem of the electric valve. The rotation of the motor drives the lead screw to rotate, thereby driving the slider to move the valve stem of the electric valve up and down, thereby realizing the adjustment of the opening degree of the electric valve.

[0008] A further preferred embodiment includes a human-machine interface, which is electrically connected to the PLC controller and used by operators to input control parameters, view system operating status and alarm information, etc.

[0009] In a further preferred embodiment, the diaphragm pressure stabilizing tank is provided with an elastic diaphragm inside, which divides the diaphragm pressure stabilizing tank into a gas chamber and a buffer chamber. The gas chamber is connected to the gas inlet and outlet, and the buffer chamber is used to fill the buffer solution. The deformation of the elastic diaphragm is used to buffer gas pressure fluctuations.

[0010] This utility model has the following beneficial effects: By incorporating a diaphragm pressure tank, its structural characteristics buffer pressure fluctuations during gas transport. Compared to ordinary gas tanks, it better handles pressure spikes caused by sudden changes in flow rate, thus initially stabilizing the gas pressure. Simultaneously, the pressure transmitter connected to the diaphragm pressure tank monitors the tank pressure in real time, while the frequency converter connected to the pump set adjusts the operation of the pump set (at least two backup Roots pumps) based on the pressure transmitter's monitoring results. When pressure fluctuations occur, the frequency converter adjusts the pump set's output pressure, further improving system pressure stability and reducing sudden pressure rises and falls. The pump set employs at least two backup Roots pumps; if one Roots pump fails, the other can promptly take over, preventing system shutdown due to a single point of failure and ensuring continuous gas transport. Attached Figure Description

[0011] Figure 1 , Figure 2 This is a system schematic diagram of the present invention; Figure 3 , Figure 4 This is the electrical schematic diagram of this utility model. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings and relevant knowledge. Obviously, the described applications are only some embodiments of the present invention, and not all embodiments.

[0013] The present invention will be further described in detail below with reference to the accompanying drawings.

[0014] Reference Figures 1-4 As shown, a constant pressure and stable flow device includes: a ball valve 1 located at the front end of the pump set for controlling the air intake; a pipeline at the rear end of the pump set connected in parallel with a gas pressure stabilizing tank; when the system pipeline pressure fluctuates, the diaphragm pressure stabilizing tank 4 can buffer the pressure; when the pipeline pressure is insufficient, it can supplement the pipeline pressure; the diaphragm pressure stabilizing tank 4 acts as a buffer to maintain the stability of the pipeline gas pressure; at the same time, an electric valve 7 is used to adjust the required flow rate at the outlet; and a flow meter 8 monitors the outlet flow rate. Further preferred components include a PLC controller SR20, an AC contactor 0911, a frequency converter ACS510, a pressure transmitter P1.6, an electric contact pressure gauge P-T1.6, an electric valve drive mechanism, a flow meter, and a pressure relief solenoid valve KY.

[0015] In this utility model, there are two Roots pumps behind the ball valve 1. The two pumps work alternately to start and stop. When one pump fails, it automatically switches to the next pump. When one pump is running at full load but still cannot reach the set pressure, the first Roots pump 2 is directly started and controlled by the AC contactor. The frequency converter 12 adjusts the frequency of the second Roots pump 3 to stabilize the pressure.

[0016] The device has a diaphragm pressure stabilizing tank 4 behind the pump set. Inside the diaphragm pressure stabilizing tank 4 is a rubber air bladder. When the pipeline pressure is high, the air bladder deforms to absorb and store pressure. When the pipeline pressure is low, the air bladder rebounds to replenish the pipeline pressure. This prevents shocks and peak air pressure generated during pump set operation switching and valve opening and closing. At the same time, the air bladder can supplement the pipeline pressure at low flow rates, avoiding frequent pump set starts and extending the service life of the pump set.

[0017] The diaphragm pressure tank 4 has a mechanical electric contact pressure gauge 6, which acts as a protective element in the system. When the tank pressure is too high, the mechanical contact controls the PLC to stop the pump and simultaneously controls the pressure relief solenoid valve 10 to release pressure, preventing safety accidents. The flow rate is controlled by adjusting the opening of the electric valve 7 to obtain the required flow rate. This invention is mainly applied in application environments sensitive to changes in pressure and flow rate. Since the equipment pipe diameter is fixed, pressure changes will cause changes and fluctuations in gas flow rate. To ensure stable gas flow and reduce the impact of gas flow fluctuations, a diaphragm pressure tank is connected in parallel to the pipeline after the pump group to buffer and compensate for pressure. The tank will generate a peak pressure when the pump group pressure changes suddenly or the valve is frequently opened and closed. Due to the generation of peak pressure, for ordinary gas tanks and those directly connected to the gas pipeline without a gas tank, it will cause huge flow fluctuations and even damage the pipeline equipment. This invention proposes a gas constant pressure and stable flow solution to address this problem. This method can effectively ensure the stability of the gas injection flow rate and avoid large fluctuations.

[0018] This utility model discloses a constant pressure and stable flow device. By setting a ball valve to accurately control the air intake, it can precisely adjust the air intake volume according to actual needs, providing a foundation for stable subsequent air supply. The pump set employs at least two Roots pumps as backups, ensuring that the system can still provide the required pressure normally even if one pump fails, improving the system's reliability and stability. The diaphragm pressure stabilizing tank effectively stabilizes air pressure and flow, handling pressure spikes caused by sudden flow changes and providing a stable gas input to the system. The electrical components monitor the pressure inside the diaphragm pressure stabilizing tank in real time via a pressure transmitter, transmitting the pressure data as the main control signal to the PLC controller. The PLC controller uses this signal to control the frequency converter to adjust the pump set speed, achieving precise pressure regulation. When the pressure transmitter fails or the pressure exceeds the limit, the electrical contact pressure gauge transmits a pressure relief signal to the PLC controller, triggering the pressure relief solenoid valve for safe pressure relief, further ensuring the safe operation of the system. Meanwhile, the PLC controller adjusts the valve drive mechanism based on the feedback signal from the flow meter, thereby precisely controlling the opening of the electric valve to achieve accurate regulation of gas flow, improving the system's automation level and reducing manual intervention. The valve drive mechanism uses a combination of motor, lead screw, and slider, which can precisely control the opening of the electric valve, improving the accuracy and response speed of flow regulation and better meeting the system's requirements for precise flow control. The human-machine interface allows operators to intuitively input control parameters, view system operating status, and alarm information, improving the system's ease of operation and maintainability. The diaphragm pressure stabilizing tank is equipped with an elastic diaphragm and a buffer chamber. The deformation of the elastic diaphragm buffers gas pressure fluctuations, further enhancing the pressure stabilizing tank's ability to buffer pressure fluctuations and improving system stability.

[0019] This utility model provides the following technical solution: A ball valve 1 is installed at the air inlet to control the opening and closing of the air inlet. The ball valve 1 is connected to the pump set via a pipeline. The pump set uses a Roots pump to compress air. The pump set is controlled by a controller 11 to switch and start / stop, and simultaneously adjust the motor operating frequency. The frequency converter 12 adopts a one-to-two design. When the frequency of one pump reaches the upper limit, the controller 11 switches that pump to the mains frequency and starts the second Roots pump. When one pump fails, the controller 11 automatically switches to the normal pump operation. The pump set is connected to a diaphragm pressure tank 4 via a pipeline to store the pressure after the pump set is pressurized. At the same time, due to the presence of the diaphragm pressure tank 4, it can absorb the pipeline pressure fluctuations when there are large fluctuations in the pipeline system air pressure. When running at low flow rates, it can maintain the pipeline air pressure and reduce the number of pump set starts. The pressure transmitter 5 above the tank collects the real-time pressure inside the tank and uses it as the main control signal. The frequency converter 12 adjusts the frequency of the frequency converter 12 to control the motor speed based on the pressure value fed back by the pressure transmitter 5, so that the entire interior reaches a dynamic balance and stable pressure. The pressure gauge 6 with electrical contacts above the tank is used for safety protection. When the pressure is higher than the set value, the controller 11 controls the pressure relief solenoid valve 10 to relieve pressure and protect the pipeline safety.

[0020] In the overall system design, pressure transmitter 5 serves as the main control signal. The frequency converter adjusts the frequency and controls the rotation speed according to the main control signal to maintain constant pipeline pressure. However, if the pressure transmitter 5 signal is lost or malfunctions, it can easily cause the system to run out of control and the pressure to rise, leading to danger. The electric contact pressure gauge 6 is a mechanical structure. When the pressure rises to the safety set value, the electric contact pressure gauge 6 outputs a signal. After receiving the signal from the electric contact pressure gauge 6, the PLC controller 11 stops the machine and opens the pressure relief valve 10. The diaphragm pressure tank 4 is connected to the electric valve 7 via a pipeline. When the user sets the required flow rate, the controller 11 automatically calculates the valve opening based on the flow meter feedback and adjusts it to the set flow rate. This method reduces manual intervention and labor intensity. The flow meter, as the final target flow feedback device, not only participates in the regulation of the electric valve 7 but also serves as a real-time flow display for reference.

[0021] Please see Figure 2 , Figure 3 The present invention provides the following technical solution: A ball valve 1 is installed at the air inlet to control the opening and closing of the air inlet. The ball valve is connected to a Roots pump unit via a pipeline. This pump unit uses Roots pumps to compress air. The outlet pipelines of two Roots pumps are connected in parallel to a diaphragm pressure tank 4 via pipelines. When the air pressure behind the diaphragm pressure tank 4 decreases, pressure is added to the pipeline. When the air pressure behind the diaphragm pressure tank 4 increases, pressure is absorbed from the pipeline. When the pipeline is running at a low flow rate, a certain amount of gas flow can be continuously and stably provided, reducing the number of frequent pump starts. The pressure transmitter 5 above the tank collects the real-time pressure inside the tank and uses it as the main control signal. The frequency converter 12 adjusts the frequency of the frequency converter 12 to control the motor speed based on the pressure value fed back by the main control signal, so that the tank and the entire system achieve a dynamic balance and stable pressure. The frequency converter adopts a one-to-two design. When the frequency of one pump reaches the upper limit, the pump is switched to the mains frequency and the second Roots pump is started. When one pump fails, the controller 11 automatically controls the switch to the normal pump operation. The pressure gauge 6 with electrical contacts on top of the tank is used for safety protection. In the entire system design, the pressure transmitter is the main control signal, and the frequency converter 12 adjusts the frequency and controls the rotation speed according to the main control signal to achieve constant pressure. However, if the pressure transmitter 5 loses or malfunctions, it can easily cause the system to run out of control and the pressure to rise, resulting in danger. The pressure gauge 6 with electrical contacts is a mechanical structure. Its function is to output a signal when the pressure rises to the safety set value. After receiving the signal, the PLC controller 11 stops the machine and opens the pressure relief valve 10. The diaphragm pressure stabilizing tank 4 is connected to the electric valve through a pipeline. When the user sets the required flow rate, the system automatically adjusts to the set flow rate through the flow meter feedback, reducing manual intervention and labor intensity. The flow meter 8, as the final adjustment target flow feedback device, not only participates in the regulation and control of the gas flow by the electric valve 7 to stabilize the output, but also serves as a real-time flow display for reference.

[0022] Compared with existing technologies, this utility model optimizes the overall design and internal structure, and adopts advanced electronic control technology to monitor the operating status in real time while meeting basic functional requirements, ensuring stable pressure and achieving constant and adjustable flow. To a certain extent, it can make flow control more stable and precise, meet production needs, simplify the control method, reduce human intervention, and lower labor intensity.

[0023] Specifically, ball valve 1 is located at the front end of the pump unit and is the air intake control component of the entire device. It opens and closes the air intake passage through manual or automatic operation, precisely controlling the start and end of gas entering the pump unit, providing basic passage control for subsequent gas pressurization and stable control.

[0024] Two Roots pumps form a pump unit, installed downstream of the ball valve, serving as the core power component for gas pressurization. They operate in an alternating start-stop mode, with one pump in use and the other on standby. If one pump fails, the system automatically switches to the other, ensuring continuous operation. If one pump, operating at full load, still cannot reach the set pressure, the first Roots pump is started and controlled by an AC contactor, while the second Roots pump works in coordination via a frequency converter to increase the system pressure and ensure the pressure requirement is met.

[0025] The diaphragm pressure regulator 4, connected in parallel with the downstream pipeline of the pump unit, is a key component for pressure buffering and compensation. It contains a rubber bladder; when the pipeline pressure is too high, the bladder deforms to absorb and store the pressure; when the pipeline pressure is insufficient, the bladder rebounds to replenish the pressure. It effectively buffers pressure spikes caused by sudden changes in pump unit pressure or frequent valve opening and closing, preventing large flow fluctuations and pipeline equipment damage that can occur with ordinary gas tanks or without a tank, thus maintaining stable pipeline gas pressure.

[0026] Pressure sensor 5 is installed in the system pipeline. Its main function is to monitor the gas pressure in the pipeline in real time and convert the pressure signal into an electrical signal, which is then transmitted to the PLC controller. This serves as the core basis for the PLC to regulate the system pressure, providing accurate pressure data for dynamic adjustment of the system pressure. Electrical contact pressure gauge 6, as a safety protection component of the system, is installed on the pressure stabilizing tank. When the tank pressure exceeds the set safety value, its mechanical contacts close, sending an over-pressure signal to the PLC controller. This triggers the PLC controller to execute protective actions such as stopping the pump and opening the pressure relief solenoid valve, preventing safety accidents caused by excessive pressure.

[0027] The electric valve 7 is connected to the pipeline downstream of the diaphragm pressure tank and is driven by an electric valve control mechanism. Its main function is to control the flow rate of the outlet gas by adjusting its own opening degree to meet the outlet flow requirements of different application scenarios; it is the actuator for flow regulation.

[0028] The flow meter 8 is installed in the pipeline between the electric valve and the nozzle to monitor the flow rate of the outlet gas in real time and feed the flow data back to the PLC controller. At the same time, it serves as a real-time flow display device to provide flow reference for operators and facilitate monitoring of the system flow status.

[0029] Nozzle 9 is the gas output terminal of the device, which sprays out the gas after stable pressure and flow regulation in a set manner. It is used in environments that are sensitive to changes in pressure and flow to ensure the stability of the gas injection effect.

[0030] The pressure relief solenoid valve 10 is controlled by a PLC controller. When the electric contact pressure gauge detects that the pressure is too high and sends a signal to the PLC, the PLC controller controls it to open, quickly releasing the high-pressure gas in the pipeline, reducing the system pressure, and ensuring the safety of the pipeline and equipment.

[0031] In the electrical section, the PLC controller 11 serves as the control core of the entire device, using the SR20 model. It receives signals transmitted from components such as pressure sensors, electrical contact pressure gauges, and flow meters, analyzes and processes them according to preset control logic, and issues control commands to the frequency converter, AC contactor, electric valve control mechanism, and pressure relief solenoid valve, coordinating the work of each component to achieve precise control of the pressure and flow of the entire system.

[0032] Inverter 12, model ACS510, is connected to the PLC controller and the Roots pump. Under the control of the PLC controller, the output frequency is adjusted to change the motor speed of the Roots pump, thereby regulating the output pressure of the Roots pump. When the system pressure needs to be adjusted, the PLC controller sends a signal to the inverter, which then changes its frequency accordingly to achieve dynamic adjustment of the pump group pressure and maintain system pressure stability.

[0033] The AC contactor 0911 is used to control the start-up and operation of the Roots pump. When the Roots pump needs to operate at the power frequency, the PLC controller controls the AC contactor to start the pump directly. In conjunction with the frequency converter, it meets the operating requirements of the pump set under different working conditions.

[0034] The electric valve control mechanism receives instructions from the PLC controller, drives the electric valve to operate, and adjusts the valve's opening degree. By precisely controlling the opening degree of the electric valve, accurate regulation of the outlet flow rate is achieved, ensuring the flow rate reaches the set value and remains stable.

[0035] In this invention, upon system startup, the ball valve opens to allow air inflow, and the Roots pump pressurizes the gas. The pressurized gas enters the pipeline, with a portion flowing into the parallel diaphragm pressure stabilizing tank. When pipeline pressure fluctuates, the diaphragm pressure stabilizing tank first buffers and compensates for the pressure through the deformation of its air bladder, initially maintaining pressure stability. Simultaneously, the pressure sensor transmits pressure signals to the PLC controller in real time. The PLC controller adjusts the Roots pump speed via a frequency converter based on the deviation between the pressure value and the set value. If the pressure is lower than the set value, the frequency converter increases the frequency, increasing the pump's output pressure; if the pressure is higher than the set value, the frequency converter decreases the frequency, reducing the pump's output pressure, forming a dynamic adjustment mechanism to ensure pressure stability. When the pressure sensor fails or the pressure suddenly rises above the safe value, the electrical contact pressure gauge triggers a signal, and the PLC controller immediately controls the Roots pump to stop operating and opens the pressure relief solenoid valve to release pressure, ensuring system safety.

[0036] In this invention, based on stable pressure, the operator sets the outlet flow rate according to requirements. The PLC controller receives the real-time flow signal from the flow meter and compares it with the set value. If the actual flow rate deviates from the set value, the PLC controller sends a command to the electric valve control mechanism to adjust the opening of the electric valve. When the actual flow rate is less than the set value, the electric valve increases its opening; when the actual flow rate is greater than the set value, the electric valve decreases its opening, thereby precisely controlling the outlet flow rate and keeping it stable. Simultaneously, the flow meter continuously monitors the flow rate and provides feedback, forming a closed-loop flow regulation system to ensure the flow rate remains stable within the set range.

[0037] In this invention, two Roots pumps are operated alternately under the control of a PLC controller, with one pump in operation and the other on standby. Under normal circumstances, one pump runs while the other is on standby. When the operating pump fails, the PLC controller automatically starts the standby pump via an AC contactor, ensuring continuous system operation. When a single pump, even at full load, cannot reach the set pressure, the PLC controller starts the first Roots pump via an AC contactor and operates it at industrial frequency. Simultaneously, the PLC controller controls the second Roots pump to adjust its frequency and work in coordination via a frequency converter, jointly increasing the system pressure to meet the pressure requirements.

[0038] In this invention, the buffer compensation of the diaphragm pressure stabilizing tank, the flow regulation of the electric valve, and the pressure supply of the pump group work together; the PLC controller of the electrical part is the core, integrating signals such as pressure and flow, and using actuators such as frequency converters and AC contactors to precisely control the mechanical parts, thereby achieving dual stability of pressure and flow.

[0039] Although some embodiments of the present 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 present invention, and all such changes and alterations should fall within the scope of the present invention.

Claims

1. A constant voltage and constant current device, characterized in that, The system comprises, in sequence, a ball valve, a pump assembly, a diaphragm pressure tank, an electric valve, a flow meter, and a nozzle; the ball valve is used for air intake, the pump assembly includes at least two backup Roots pumps to provide the required pressure to the system, the diaphragm pressure tank is used to stabilize gas pressure and flow rate, the electric valve is used to regulate flow rate, the flow meter is used to measure gas flow rate, and the nozzle is used to output gas; the diaphragm pressure tank is connected to a pressure transmitter; the pump assembly is connected to a frequency converter and also includes a PLC controller, an AC contactor, an electrical contact pressure gauge, a valve drive mechanism, and a pressure relief solenoid valve; the pressure transmitter is mounted on the diaphragm pressure tank for real-time monitoring. The system measures the pressure inside the tank and transmits the pressure data to the PLC controller as the main control signal. The frequency converter is electrically connected to the PLC controller and is controlled by the PLC controller. It adjusts the pump speed according to the main control signal provided by the pressure transmitter. The pressure gauge with electrical contacts is electrically connected to the PLC controller. The PLC controller is electrically connected to the pressure relief solenoid valve. When it receives a pressure relief signal, it triggers the pressure relief solenoid valve to safely relieve pressure. The PLC controller is electrically connected to the valve drive mechanism. The valve drive mechanism is connected to the electric valve. The PLC controller adjusts the valve drive mechanism according to the feedback signal from the flow meter, thereby controlling the opening degree of the electric valve and regulating the flow rate.

2. The constant voltage and constant current device according to claim 1, characterized in that, The PLC controller is model SR20, the AC contactor is model 0911, the frequency converter is model ACS510, the pressure transmitter is model P1.6, the electric contact pressure gauge is model P-T1.6, and the pressure relief solenoid valve is model KY.

3. The constant voltage and constant current device according to claim 1, characterized in that, The ball valve is connected to the inlet of the pump unit via a pipe, the outlet of the pump unit is connected to the inlet of the diaphragm pressure stabilizing tank via a pipe, and the outlet of the diaphragm pressure stabilizing tank is connected to the electric valve, flow meter and nozzle in sequence via pipes.

4. The constant voltage and constant current device according to claim 1, characterized in that, The pressure transmitter is installed on the top of the diaphragm pressure tank via a threaded connection, and the electrical contact pressure gauge is installed on the side of the diaphragm pressure tank via a threaded connection.

5. A constant voltage and constant current device according to claim 1, characterized in that, The valve drive mechanism includes a motor, a lead screw, and a slider. The motor is electrically connected to a PLC controller. The output shaft of the motor is connected to the lead screw. The lead screw is threadedly connected to the slider. The slider is connected to the valve stem of the electric valve. The rotation of the motor drives the lead screw to rotate, thereby driving the slider to move the valve stem of the electric valve up and down, thereby adjusting the opening degree of the electric valve.

6. A constant voltage and constant current device according to claim 1, characterized in that, It also includes a human-machine interface, which is electrically connected to the PLC controller and is used by operators to input control parameters, view system operating status and alarm information.

7. A constant voltage and constant current device according to claim 1, characterized in that, The diaphragm pressure stabilizing tank is equipped with an elastic diaphragm that divides the tank into a gas chamber and a buffer chamber. The gas chamber is connected to the gas inlet and outlet, and the buffer chamber is used to fill the buffer solution. The deformation of the elastic diaphragm buffers gas pressure fluctuations.

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