Mode switching control device with valve position memory

Abstract

The utility model discloses a mode switching control device with a valve position memory function, which comprises an upper computer, an electric valve serving as an actuator, and a single-chip microcomputer serving as a tail end controller and embedded in the electric valve, and is characterized in that the single-chip microcomputer is a single-chip microcomputer; comprising a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), a parallel input / output (I / O) interface, a serial communication interface, a timer / counter, an interrupt system, a system clock and a system bus functional component, and the functional components are packaged in an integrated circuit chip with a fixed size. Each I / O interface of the single-chip microcomputer is connected with each sensor and each actuator, and a communication interface is configured with a communication network. Signal transmission and conversion links are reduced, and the oscillation problem in operation and control is reduced; good flexibility and expansibility are realized; batch product single-chip microcomputers and a mature network technology are adopted, so that the system is reliable in control and low in cost.

Description

Technical Field

[0001] This utility model relates to an industrial control technology, and more particularly to a mode switching control device with valve position memory in a heating, ventilation and air conditioning equipment control method. Background Technology

[0002] In the field of industrial control, the control methods of HVAC equipment are mainly determined by the process engineering settings. Currently, most of them are still based on the simplest control methods. Therefore, it is of great significance to develop a low-cost terminal control device with intelligent control functions.

[0003] According to ΔP=SL 2 While the pressure of fans and pumps is proportional to the square of their flow rate, the actual operating conditions and selection processes do not reflect this proportional relationship. For example, the pipe resistance coefficient S differs between normal and emergency exhaust conditions. When multiple fans or pumps operate in parallel, the valve openings at the inlet and outlet of each pump and fan need to be adjusted according to the network characteristics to meet the flow rate and head requirements of the main pipe. This is particularly true in the pharmaceutical purification field, where normal operating conditions, disinfection conditions, and shift operating conditions correspond to different valve openings, and the required mixing ratios of air and water valves to suit various operating conditions are numerous.

[0004] Example 1: When switching between emergency modes, if the number of fans changes while the valve opening remains constant, the airflow may be too high, exceeding the design airflow. Prolonged operation may overload the circuit and cause fan overload. The flow matching issue when switching the number of parallel water pumps is similar to that of fans. Example 2: Switching between operating modes, disinfection modes, and duty modes in pharmaceutical cleanrooms is usually done by inputting a series of fan frequency converters and valves, resulting in a relatively long delay. Example 3: Switching between the minimum fresh air volume operating mode and the high-proportion fresh air mode during transitional seasons in comfort air conditioning systems, etc.

[0005] How to quickly switch between different operating modes is a real engineering problem. Furthermore, determining which control mode to use for controlled objects of different sizes is also an urgent issue to be addressed. Summary of the Invention

[0006] The purpose of this invention is to solve the above problems and provide a mode switching control device with valve position memory, which features efficient and rapid adjustment, network control for the scale of the controlled object, and integrated control.

[0007] The above-mentioned technical problems of this utility model are mainly solved by the following technical solution: a mode switching control device with valve position memory, including a host computer, an electric valve as an actuator, and a microcontroller embedded in the electric valve as an end controller. The microcontroller is a single-chip microcomputer, including a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), parallel I / O interface, serial communication interface, timer / counter, interrupt system, system clock, and system bus functional components, and each functional component is packaged in a fixed-size integrated circuit chip; each sensor and actuator is connected to each I / O interface of the microcontroller, and the communication interface is configured with a communication network.

[0008] In the aforementioned mode switching control device with valve position memory, preferably, a management and control adjustment program is written inside the microcontroller.

[0009] In the aforementioned mode switching control device with valve position memory, preferably, the terminal controller is connected to the host computer via a communication interface. The host computer directly issues operation commands such as valve position setting value and testing, while the terminal controller receives valve setting value signals, returns valve position status signals, and other over-limit alarms and motor overload alarm signals.

[0010] In the aforementioned mode switching control device with valve position memory, preferably, the end controller issues commands via two DO channels and an opto-isolator to control the forward and reverse rotation of the motor.

[0011] In the aforementioned mode switching control device with valve position memory, preferably, the measured valve position signal is directly connected to the AI ​​channel of the end controller as a comparison basis for issuing forward or reverse rotation.

[0012] In the aforementioned mode switching control device with valve position memory, preferably, the measured valve position signal is obtained through a valve position feedback variable resistor.

[0013] In the aforementioned mode switching control device with valve position memory, RS485 protocol is preferably used as the fieldbus connection method, twisted pair cable is used to transmit differential signals, half-duplex data transmission is used, master-slave network communication cooperation mechanism is used, the host computer is the master and the end controllers are all slaves.

[0014] In the aforementioned mode switching control device with valve position memory, preferably, when the number of controlled electric valves is ≤32, a microcontroller is set as a host computer that can directly issue operation commands and is networked separately for control; when the number of controlled objects is >32, the microcontroller is set as a distributed controller to form a distributed network and is incorporated into a larger integrated control system.

[0015] This device allows designers to define multiple operating modes. During actual operation and debugging, each operating mode can obtain the corresponding valve opening degree. The host computer using this configuration effectively records these values, obtaining a series of setpoints. When switching operating modes, these values ​​can be transmitted to the terminal controller as input values ​​to quickly adjust the valve opening degree, enabling the resistance to quickly match the characteristics of the pipeline network, and ensuring that the air volume and water volume meet the operating requirements. For large-scale controlled objects, an integrated control method with network control is adopted.

[0016] According to the principles of this scheme, as long as the sensors and actuators are correctly connected to the I / O channels of the microcontroller, and appropriate management and control programs are written into the microcontroller, a complete controller can be constructed to achieve control and regulation. If a communication network is added through its serial communication interface, it can become a complete distributed control system.

[0017] This device directly embeds a microcontroller within the electric valve as its controller. It utilizes the microcontroller's extensive I / O channels to test the valve's upper and lower limit contact switches, thus achieving comprehensive valve control and monitoring. The terminal controller connects to the host computer via a communication interface. The host computer directly issues valve position setpoints and test commands, while the terminal controller receives valve setpoint signals, returns valve position status signals, and other over-limit alarms, motor overload alarms, etc. By debugging and recording a series of valve openings corresponding to different operating modes, these are used as commands to control the valve during mode switching, effectively improving the accuracy and dynamic characteristics of the automatic control system and achieving the fastest response time.

[0018] Compared with existing technologies, the advantages of this utility model are as follows: integrating the microcontroller into the actuator, directly driving the motor with digital signals through an opto-isolator reduces signal transmission and conversion links; switching working modes by valve position memory corresponding to the working mode reduces oscillation problems in calculation and control; building a network according to the number of controlled objects provides good flexibility and scalability; using mass-produced microcontrollers and mature network technology ensures reliable system control, low cost, and easy promotion. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a structure of an electric actuator that directly uses two switch outputs to control the actuator according to this utility model.

[0020] Figure 2 This is a logic flowchart of a computer-controlled electric valve according to this utility model.

[0021] Figure 3 This is a basic structural diagram of an embodiment of the 8051 microcontroller of this utility model.

[0022] Figure 4This is an application network architecture diagram of this utility model. Detailed Implementation

[0023] The technical solution of this utility model will be further described in detail below through embodiments and with reference to the accompanying drawings. According to conventional terminology in the art, the host computer in the embodiments refers to a microcontroller that can directly issue operation commands.

[0024] This embodiment discloses a mode switching control device with valve position memory, comprising a microcontroller as the host computer, an electric valve as the actuator, and a microcontroller embedded in the electric valve as the end controller. The microcontroller is a single-chip microcomputer, including a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), parallel I / O interface, serial communication interface, timer / counter, interrupt system, system clock, and system bus functional components, and each functional component is packaged in a fixed-size integrated circuit chip. Sensors and actuators are connected to the microcontroller's I / O interface; the communication interface is configured with a communication network.

[0025] Taking the 8051 microcontroller as an example, its basic structure is as follows: Figure 3 As shown:

[0026] The central processing unit (CPU) is the core of a microcontroller. It generates various control signals and performs arithmetic and logical operations and transmits data.

[0027] Random access memory (RAM) is used to store data that can be read and written.

[0028] Read-only memory (ROM) is used to store program instructions or tables of certain constants.

[0029] Four 8-bit parallel I / O ports, P0, P1, P2 and P3, each of which can be used as an input or output.

[0030] Two timers / counters, used as external event counters and also as timers.

[0031] The internal interrupt system has five interrupt sources and a nested interrupt structure with two priorities, enabling two-level nested interrupt service routines. Each interrupt source can be defined by software as a high-priority interrupt or a low-priority interrupt.

[0032] A serial communication interface that can be used for asynchronous receivers / transmitters.

[0033] It has an internal system clock, but the crystal and trimmer capacitor need to be externally connected, and the oscillation frequency can be as high as 40MHz.

[0034] By connecting various sensors and actuators to the microcontroller's I / O interfaces and writing appropriate management and control programs into the microcontroller, a complete controller can be constructed to achieve control and regulation. A communication network is then configured through the communication interface.

[0035] The 8051 microcontroller (chip) is very inexpensive, making this device low-cost and highly reliable. Embedding a single microcontroller directly within an electric valve as a valve controller offers excellent practicality. Furthermore, utilizing the microcontroller's abundant I / O channels to test the valve's upper and lower limit contact switches allows for comprehensive valve control and monitoring. Connecting it to a communication network via its serial communication interface makes it a complete end-point controller in a distributed control system. The same microcontroller is selected as the host computer.

[0036] The terminal controller connects to the host computer via a communication interface. The host computer directly issues operation commands such as valve position setpoints and tests. The terminal controller receives valve setpoint signals, returns valve position status signals, and other signals such as over-limit alarms and motor overload alarms. By debugging and recording a series of valve openings corresponding to the corresponding operating modes, these are used as commands to control the valves during mode switching, effectively improving the accuracy and dynamic characteristics of the automatic control system and achieving the fastest response time.

[0037] Management and control programs are written inside the end controller. These programs issue commands via two DO channels (DO1 and DO2) and an opto-isolator to control the forward and reverse rotation of the motor. Figure 1 As shown; the measured valve position signal is directly connected to the AI ​​channel of the end controller as a comparison basis for issuing forward or reverse rotation; the measured valve position signal is obtained through a valve position feedback variable resistor. Figure 2 The diagram shows the software logic flowchart for controlling the valve opening in this way.

[0038] Networking characteristics of this embodiment:

[0039] Referring to GB / T26803.2 "Industrial Control Computer System Bus Part 2: General Technical Conditions for System External Bus Serial Interface" and engineering practice, the RS485 protocol is adopted as the fieldbus connection method. It has the following main characteristics:

[0040] Differential signal: Uses twisted pair cable to transmit the voltage difference between lines A and B (typically ±2V), with strong common-mode interference immunity.

[0041] Half-duplex data transmission: 2-wire system (A / B), only one node is allowed to send at a time.

[0042] Master-slave network communication cooperation mechanism: The host computer is set as the master, and the rest are slaves.

[0043] Multi-node support: Theoretically, the maximum number of nodes is 32.

[0044] Transmission distance: Maximum 1200 meters (when the rate is ≤100kbps). The higher the rate, the shorter the distance.

[0045] Communication rate: typically 10kbps to 10Mbps, with a trade-off between rate and distance.

[0046] In building automation system engineering, commonly used upper-layer protocols such as ModBus and BACNet, as well as industrial control buses such as C-BUS, can all be supported by RS485 as the underlying communication protocol.

[0047] RS485 networks transmit digital signals, while traditional controllers output analog signals (AO). Since motor drives require analog signals, two-stage signal conversion (A / D and D / A) is necessary, resulting in a complex system with numerous components, high cost, and a high failure rate. This embodiment's architecture, upon receiving instructions, directly drives the motor with digital signals via an opto-isolator, offering simplicity, efficiency, low cost, and improved reliability.

[0048] When the number of controlled electric valves is ≤32, a microcontroller is set up as a host computer that can directly issue operation commands for independent network control; when the number of controlled objects is >32, the microcontroller is set up as a distributed controller, forming a distributed network and integrating into a larger integrated control system, such as... Figure 4 As shown.

[0049] This embodiment integrates the 8051 microcontroller into the actuator. Through an opto-isolator, the motor is directly driven by digital signals, reducing signal transmission and conversion steps. The operating mode is switched by remembering the valve position corresponding to the operating mode, reducing oscillation issues in calculation and control. Furthermore, the network can be built according to the number of controlled objects, providing good flexibility and scalability. Because it uses the mass-produced 8051 microcontroller and mature network technology, the mode-switching control device with valve position memory in this embodiment is reliable, highly practical, low-cost, and easy to promote.

[0050] The above embodiments are illustrative of the present invention and not intended to limit it. Although the present invention has been described in conjunction with preferred embodiments, it should be understood that the present invention is not limited to the preferred embodiments. Those skilled in the art can make various equivalent modifications and substitutions to the technical solutions of the present invention based on its teachings. Therefore, the scope of the present invention should be defined by the claims, and all such equivalent modifications and substitutions fall within the protection scope of the present invention.

Claims

1. A mode switching control device with valve position memory, comprising a host computer, an electric valve as an actuator, and a microcontroller embedded in the electric valve as an end controller, characterized in that: The microcontroller is a single-chip microcomputer, including a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), parallel I / O interface, serial communication interface, timer / counter, interrupt system, system clock, and system bus functional components, and each functional component is packaged in a fixed-size integrated circuit chip; various sensors and actuators are connected to each I / O interface of the microcontroller, and the communication interface is configured with a communication network.

2. The mode switching control device with valve position memory according to claim 1, characterized in that, The microcontroller contains management and control programs.

3. The mode switching control device with valve position memory according to claim 1, characterized in that, The terminal controller is connected to the host computer via a communication interface. The host computer directly sends valve position setpoints and test operation commands, while the terminal controller receives valve setpoint signals, returns valve position status signals, and over-limit alarm and motor overload alarm signals.

4. A mode switching control device with valve position memory according to claim 1, characterized in that, Its end controller sends commands through two DO channels and an opto-isolator to control the forward and reverse rotation of the motor.

5. A mode switching control device with valve position memory according to claim 3, characterized in that, The measured valve position signal is directly connected to the AI ​​channel of the end controller as a comparison basis for issuing forward or reverse rotation.

6. A mode switching control device with valve position memory according to claim 5, characterized in that, The measured valve position signal is obtained through a valve position feedback variable resistor.

7. A mode switching control device with valve position memory according to claim 4, characterized in that, The RS485 protocol is used as the fieldbus connection method, and twisted-pair cables are used to transmit differential signals, half-duplex data transmission, and master-slave network communication cooperation mechanism. The host computer is set as the master and the end controllers are all slaves.

8. A mode switching control device with valve position memory according to claim 1, characterized in that, When the number of controlled electric valves is ≤32, a microcontroller is set up as a host computer that can directly issue operation commands and is networked separately for control; when the number of controlled objects is >32, the microcontroller is set up as a distributed controller, forming a distributed network and being incorporated into a larger integrated control system.

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