Constant gas pressure control system and method

Abstract

The application relates to a constant air pressure control system for a water chiller with a buffer structure, which comprises an air inlet module, an air source distribution processor, a constant pressure controller and a valve assembly connected in sequence, wherein the air source distribution processor, the constant pressure controller and the valve assembly are connected with a PLC, the PLC is connected with an upper computer, and the valve assembly is connected with the buffer structure. The application can solve the problem that ordinary water chillers cannot meet the application requirements of water equipment with high vibration stability index due to large vibration disturbance, and can achieve high-precision air charging control of + / -0.01 bar.

Description

Technical Field

[0001] This invention relates to the field of constant air pressure control technology for water chillers, and more specifically to a constant air pressure control system and method. Background Technology

[0002] Currently, ordinary water chillers on the market generally achieve circulation through a water pump, water tank, pipeline, and water-using equipment. They only consider cooling power, cooling effect, and constant temperature control, neglecting the structural optimization design of the circulating water system. The circulating water system of ordinary water chillers directly pumps water from the tank into the water-using equipment and then returns it to the water tank of the chiller, working in a continuous cycle. This structure has the problem of the water pump directly disturbing the water circuit, resulting in water flow vibration, which cannot meet the stability requirements of the water-using equipment in the high-frequency range.

[0003] Existing constant pressure water supply systems typically achieve constant pressure water supply by forming a closed-loop control system consisting of frequency converters, sensors, and water pumps. This solution cannot solve the water flow vibration problem of the chiller itself, does not have constant air pressure control function, and has low control accuracy. Summary of the Invention

[0004] To address the problems in the prior art, the present invention provides a constant air pressure control system and method that enables water to flow out and circulate stably from the chiller and improves control accuracy.

[0005] The present invention provides a constant air pressure control system for a chiller with a buffer structure, comprising an air intake module, an air source distribution processor, a constant pressure controller and a valve assembly connected in sequence. The air source distribution processor, the constant pressure controller and the valve assembly are all connected to a PLC, the PLC is connected to a host computer, and the valve assembly is connected to the buffer structure.

[0006] Furthermore, the air intake module includes an air source inlet, a first right-angle quick connector, and a switching valve connected in sequence. The air source inlet is connected to an air source, and the switching valve is connected to the air source distribution processor.

[0007] Furthermore, the air source distribution processor includes a filter, an air path distribution module, and a pressure reducing valve connected in sequence. The filter is connected to the air intake module, the air path distribution module is connected to a first digital display pressure gauge, and the pressure reducing valve is connected to a second digital display pressure gauge. Both the first and second digital display pressure gauges are connected to the analog input terminal of the PLC.

[0008] Furthermore, the constant pressure controller has an air inlet, an air outlet, and a pressure setpoint interface. The air inlet is connected to the air source distribution processor, the air outlet is connected to the valve assembly, and the pressure setpoint interface is connected to the analog output terminal of the PLC.

[0009] Furthermore, the constant pressure controller is equipped with a first silencer.

[0010] Furthermore, the valve assembly includes a first high-frequency valve, a first proportional throttle valve, and a T-type quick-connect fitting connected in sequence, and a second high-frequency valve, a second proportional throttle valve, and a second right-angle quick-connect fitting connected in sequence. The first proportional throttle valve and the second proportional throttle valve are both connected to the analog output terminal of the PLC, the first high-frequency valve and the second high-frequency valve are both connected to the digital output terminal of the PLC, the first high-frequency valve is connected to the air outlet of the constant pressure controller, and the T-type quick-connect fitting and the second right-angle quick-connect fitting are connected to each other.

[0011] Furthermore, a first plug is installed at the normally open outlet of the first high-frequency valve, a second plug is installed at the normally open outlet of the second high-frequency valve, and a second silencer is installed at the normally closed outlet of the second high-frequency valve.

[0012] Furthermore, the T-shaped three-way quick connector is sequentially connected to the manual switch valve and the third right-angle quick connector, and the third right-angle quick connector is connected to the buffer structure.

[0013] Furthermore, a third digital pressure gauge is installed on the buffer structure, and the third digital pressure gauge is connected to the analog input terminal of the PLC.

[0014] The present invention also provides a constant pressure control method, comprising:

[0015] Step S1: Provide the above-mentioned constant air pressure control system and preset the start-up air pressure threshold of the PLC's PID controller.

[0016] In step S2, the gas source provides gas, which passes through the intake module, the gas source distribution processor, and the constant pressure controller in sequence before entering the valve assembly. At this time, the first high-frequency valve and the first proportional throttle valve are in the normally open state, and the gas enters the buffer structure after passing through the valve assembly.

[0017] Step S3: When the value of the third digital display barometer reaches the start-up barometer threshold of the PLC's PID controller, the PLC is turned on.

[0018] Step S4: The first high-frequency valve and the PLC form an inflation system. The inflation PID controller is turned on. The air pressure value in the buffer structure is adjusted by controlling the opening and closing of the first high-frequency valve. The inflation speed is adjusted by controlling the air intake rate of the first proportional throttle valve.

[0019] Step S5: The second high-frequency valve and the PLC form an exhaust system. The exhaust PID controller is turned on. The exhaust system is stably controlled by controlling the opening and closing of the second high-frequency valve. The PID controller parameters are tuned in coordination with the opening of the second proportional throttle valve.

[0020] This invention can regulate the water flow rate by changing the working air pressure, thereby enabling the water in the chiller to flow out stably and circulate. This indirectly solves the problem that ordinary water chillers cannot meet the application requirements of water-using equipment with high vibration stability due to large vibration disturbances. Furthermore, this invention can achieve high-precision air inflation control of ±0.01 bar. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a chiller with a buffer structure.

[0022] Figure 2 This is a schematic diagram of the constant air pressure control system according to the present invention. Detailed Implementation

[0023] To make the objectives, solutions, and advantages of this invention clearer, the specific structure and working principle of this invention will be described in more detail below with reference to the accompanying drawings. The embodiments described are for illustrative purposes only and are not intended to limit the scope of application of this invention.

[0024] The purpose of the following description is to provide the public with a clearer understanding of the present invention, while those skilled in the art will be able to understand the invention clearly even without the following detailed explanation.

[0025] This embodiment provides a constant pressure control system applied to a chiller with a buffer structure, such as... Figure 1 As shown, the chiller includes a condenser 201, a water tank 202, a compressor 203, a water pump 204, a buffer tank 205, and a constant pressure control system 206. The condenser 201 is connected to the water tank 202 and the compressor 203. The water tank 202 is also connected to the compressor 203, the water pump 204, and the buffer tank 205. The water pump 204 is also connected to the buffer tank 205. The buffer tank 205 is also connected to the constant pressure control system 206.

[0026] like Figure 2As shown, the constant pressure control system provided in this embodiment includes an air intake module 11, an air source distribution processor 12, a constant pressure controller 13, and a valve assembly 14 connected in sequence. The air source distribution processor 12, the constant pressure controller 13, and the valve assembly 14 are all connected to a compact PLC 15. The compact PLC 15 is connected to a host computer 16. Furthermore, after the valve assembly 14 is connected to a manual switch valve 171 and a third right-angle quick connector 172, it is connected to a buffer tank 205 in a chiller.

[0027] The air intake module 11 includes an air source inlet 111, a first right-angle quick connector 112, and a switching valve 113 connected in sequence. The air source inlet 111 is connected to an air source, and the switching valve 113 is connected to the air source distribution processor 12. Gas from the air source enters through the air source inlet 111, passes through the first right-angle quick connector 112 and the switching valve 113, and then flows to the air source distribution processor 12.

[0028] The gas source distribution processor 12 is used for gas filtration, gas path distribution, pressure regulation, and pressure monitoring. It includes a filter 121, a gas path distribution module 122, and a pressure reducing valve 123 connected in sequence. The filter 121 is connected to the switching valve 113, the gas path distribution module 122 is connected to the first digital display pressure gauge 124, and the pressure reducing valve 123 is connected to the second digital display pressure gauge 125. Both the first and second digital display pressure gauges 124 and 125 are connected to a compact PLC 15. The first digital display pressure gauge 124 is used to monitor the gas source pressure, and the second digital display pressure gauge 125 is used to monitor the pressure after being regulated by the pressure reducing valve 123.

[0029] The constant pressure controller 13 has an air inlet 131 and an air outlet 132. The air inlet 131 is connected to the pressure reducing valve 123, and the air outlet 132 is connected to the valve assembly 14. The constant pressure controller 13 is also equipped with a first silencer 133 to reduce noise and vibration.

[0030] The valve assembly 14 includes a first high-frequency valve 141, a first proportional throttle valve 142, and a T-shaped quick-connect fitting 143 connected in sequence, and a second high-frequency valve 144, a second proportional throttle valve 145, and a second right-angle quick-connect fitting 146 connected in sequence. The first high-frequency valve 141, the first proportional throttle valve 142, the second high-frequency valve 144, and the second proportional throttle valve 145 are all connected to a compact PLC 15. The first high-frequency valve 141 is connected to the outlet 132 of the constant pressure controller 13, and the T-shaped quick-connect fitting 143 and the second right-angle quick-connect fitting 146 are connected to each other. Furthermore, a first plug 147 is installed at the normally open outlet of the first high-frequency valve 141, a second plug 148 is installed at the normally open outlet of the second high-frequency valve 144, and a second silencer 149 is installed at the normally closed outlet of the second high-frequency valve 144.

[0031] In this embodiment, the opening and closing frequencies of the first high-frequency valve 141 and the second high-frequency valve 144 can reach 1 kHz.

[0032] The T-type three-way quick connector 143 is connected to the manual switch valve 171 and the third right-angle quick connector 172. The third right-angle quick connector 172 is connected to the buffer tank 205. The buffer tank 205 is equipped with a third digital display pressure gauge 173, which is connected to the compact PLC 15 to monitor the internal pressure of the buffer tank 205.

[0033] The analog input terminals of the compact PLC 15 are connected to three digital pressure gauges 124, 125, and 173. The analog output terminals are connected to the pressure setpoint interface AI of the constant pressure controller 13, the first proportional throttle valve 142, and the second proportional throttle valve 145. The digital output terminals are connected to the first high-frequency valve 141 and the second high-frequency valve 144. The network port of the compact PLC 15 is interconnected with the Ethernet of the host computer 16. The values ​​of the three digital pressure gauges 124, 125, and 173 can be displayed on the host computer 16, thereby realizing real-time monitoring.

[0034] Based on the above-mentioned constant pressure control system, the present invention also provides a constant pressure control method, which includes the following steps:

[0035] Step S1: Provide the above-mentioned constant air pressure control system, and preset the start-up air pressure threshold of the PID controller of the compact PLC 15, for example, 1 bar.

[0036] In step S2, the gas source provides gas, which passes through the air intake module 11, the gas source distribution processor 12, and the constant pressure controller 13 in sequence before entering the valve assembly 14. At this time, the first high-frequency valve 141 and the first proportional throttle valve 142 are in the normally open state, and the gas enters the buffer tank 205 after passing through the valve assembly 14.

[0037] Step S3: When the value of the third digital display pressure gauge 173 on the buffer tank 205 reaches the start-up pressure threshold of the PID controller of the compact PLC 15, the compact PLC 15 is turned on.

[0038] In step S4, the first high-frequency valve 141 and the compact PLC 15 form an inflation system. The inflation PID controller is activated, and the air pressure in the buffer tank 205 is adjusted by controlling the opening and closing of the first high-frequency valve 141. The inflation speed is adjusted by controlling the air intake rate of the first proportional throttle valve 142. In this embodiment, pulse width modulation technology is used to control the opening and closing of the first high-frequency valve 141.

[0039] In step S5, the second high-frequency valve 144 and the compact PLC 15 form an exhaust system. The exhaust PID controller is activated, and the air pressure in the buffer tank 205 is adjusted by controlling the opening and closing of the second high-frequency valve 144 to achieve stable control of the exhaust system. The second proportional throttle valve 145 is manually and slowly adjusted to adapt to changes in opening degree, thereby tuning the PID controller parameters, including the PID algorithm sampling time, proportional gain, integral action time, derivative action time, derivative delay coefficient, proportional action weight, and derivative action weight. In this embodiment, pulse width modulation technology is used to control the opening and closing of the second high-frequency valve 144.

[0040] In this way, the constant pressure controller 13 works in conjunction with the dual PID controllers (inflation PID controller and exhaust PID controller) to achieve high-precision constant pressure control.

[0041] The constant pressure control system of this invention consists of an air intake system, an air source distribution processor, a constant pressure controller, valve components, a digital display pressure gauge, and a compact PLC. It can coordinate with the proportional throttle valve to maintain the flow rate at different set values, and, in conjunction with the constant pressure controller, high-frequency valve, and compact PLC, stably control the air filling and exhaust systems. This ensures that the internal working pressure of the chiller's buffer tank remains consistently high-precision, with a pressure stability of ±0.01 bar. This allows the chiller with the buffer tank to operate and be used stably, achieving high-precision constant pressure control. It solves the problems of difficult water supply, unstable water flow rate, and unstable air pressure after adding a buffer tank, and indirectly solves the problem of large water flow vibration caused by the lack of constant pressure control in ordinary chillers.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A constant gas pressure control system for a water chiller with a buffer structure, characterized by, The constant pressure control system comprises a gas inlet module, a gas source distribution processor, a constant pressure controller and a valve assembly connected in sequence, the gas source distribution processor, the constant pressure controller and the valve assembly are connected with a PLC, the PLC is connected with an upper computer, and the valve assembly is connected with the buffer structure. The valve assembly comprises a first high-frequency valve, a first proportional throttle valve, a T-shaped three-way quick connector connected in sequence, and a second high-frequency valve, a second proportional throttle valve and a second right-angle quick connector connected in sequence, the first proportional throttle valve and the second proportional throttle valve are connected with an analog output end of the PLC, the first high-frequency valve and the second high-frequency valve are connected with a digital output end of the PLC, the first high-frequency valve is connected with a gas outlet of the constant pressure controller, and the T-shaped three-way quick connector and the second right-angle quick connector are connected with each other.

2. The constant gas pressure control system of claim 1, wherein, The gas inlet module comprises a gas source inlet, a first right-angle quick connector and a switch valve connected in sequence, the gas source inlet is connected with a gas source, and the switch valve is connected with the gas source distribution processor.

3. The constant gas pressure control system of claim 1, wherein, The gas source distribution processor comprises a filter, a gas path distribution module and a pressure reducing valve connected in sequence, the filter is connected with the gas inlet module, the gas path distribution module is connected with a first digital display air pressure gauge, the pressure reducing valve is connected with a second digital display air pressure gauge, and the first digital display air pressure gauge and the second digital display air pressure gauge are connected with an analog input end of the PLC.

4. The constant gas pressure control system of claim 1, wherein, The constant pressure controller has a gas inlet, a gas outlet and a pressure setting value interface, the gas inlet is connected with the gas source distribution processor, the gas outlet is connected with the valve assembly, and the pressure setting value interface is connected with an analog output end of the PLC.

5. The constant gas pressure control system of claim 1, wherein, A first silencer is arranged on the constant pressure controller.

6. The constant gas pressure control system of claim 1, wherein, A first plug is arranged on a normally open gas outlet of the first high-frequency valve, a second plug is arranged on a normally open gas outlet of the second high-frequency valve, and a second silencer is arranged on a normally closed gas outlet of the second high-frequency valve.

7. The constant gas pressure control system of claim 1, wherein, The T-shaped three-way quick connector is connected with a manual switch valve and a third right-angle quick connector in sequence, and the third right-angle quick connector is connected with the buffer structure.

8. The constant gas pressure control system of claim 1, wherein, A third digital display air pressure gauge is arranged on the buffer structure and connected with an analog input end of the PLC.

9. A constant gas pressure control method, characterized by, The constant pressure control system comprises: S1, providing the constant pressure control system according to any one of claims 1-8, and presetting a starting pressure threshold of a PID controller of the PLC; S2, the gas source provides gas, the gas passes through the gas inlet module, the gas source distribution processor and the constant pressure controller in sequence, and then enters the valve assembly, at this time, the first high-frequency valve and the first proportional throttle valve are in a normally open state, and the gas enters the buffer structure after passing through the valve assembly; S3, when the value of the third digital display air pressure gauge reaches the starting pressure threshold of the PID controller of the PLC, the PLC is started; S4, the first high-frequency valve and the PLC form an inflation system, the inflation PID controller is started, the gas pressure value in the buffer structure is adjusted by controlling the opening and closing of the first high-frequency valve, and the inflation speed is adjusted by controlling the gas inlet rate of the first proportional throttle valve. Step S5, the second high frequency valve and the PLC form an exhaust system, open the exhaust PID controller, through the control of the second high frequency valve to open and close to realize the stable control of the exhaust system, and cooperate with the opening of the second proportional throttle valve to set the PID controller parameters.

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