A reverse logic control system for equipment cooling water flow

Abstract

The utility model belongs to the industrial automation control technical field, concretely relates to a kind of reverse logic control system of equipment cooling water flow.It can ensure that the electric regulating valve of cooling water is not in closed state when control component fails, maintain normal opening, so as to guarantee the continuous operation of the cooled equipment.A kind of reverse logic control system of equipment cooling water flow, including PLC controller, electric regulating valve, temperature sensor for collecting the temperature of the cooled equipment;It also includes fault protection circuit, fault protection circuit includes intermediate relay, the coil of intermediate relay is driven by the CPU fault output signal of PLC controller, the normally closed contact of intermediate relay is connected in series in the working power supply loop of electric regulating valve;The analog output module of PLC controller is electrically connected with the instruction signal input end of electric regulating valve;The analog input module of PLC controller is electrically connected with the output end of temperature sensor.

Description

Technical Field

[0001] This utility model belongs to the field of industrial automation control technology, specifically relating to an inverse logic control system for equipment cooling water flow. Background Technology

[0002] In industrial production, many critical pieces of equipment (such as injection molding machines and air compressors) require continuous cooling water for heat dissipation. The cooling water flow control system typically uses a PLC (Programmable Logic Controller, which consists of a central processing unit, memory, input / output modules, and communication interfaces) as the controller. The system collects the equipment temperature through temperature sensors, performs PID calculations, and then controls the opening of the electric regulating valve in the pipeline through the analog output module, thereby precisely regulating the cooling water flow.

[0003] However, the existing system has a significant safety hazard: when the PLC's CPU performs a self-test, experiences an abnormal fault, or the analog output module itself malfunctions, the control signal (usually 0-10V or 4-20mA) output to the electric regulating valve will return to zero.

[0004] For electrically operated control valves using conventional positive logic settings, a 0V (zero) command signal corresponds to the valve being fully closed. This will directly result in the complete cutoff of cooling water, causing the cooled equipment to trigger a protective shutdown due to rapid temperature rise, resulting in significant production and economic losses. Furthermore, if the equipment stops operating, the product may continue moving due to inertia, posing a safety hazard. Summary of the Invention

[0005] In view of the shortcomings of the above-mentioned background technology, the purpose of this utility model is to provide a reverse logic control system for equipment cooling water flow, which can ensure that the electric regulating valve of cooling water is not closed when the control component fails, but remains open, thereby ensuring the continuous operation of the cooled equipment.

[0006] To solve the above-mentioned technical problems, the purpose of this utility model is achieved as follows: A reverse logic control system for equipment cooling water flow includes a PLC controller, an electric regulating valve, and a temperature sensor for acquiring the temperature of the equipment being cooled. It also includes a fault protection circuit, which includes an intermediate relay. The coil of the intermediate relay is driven by the CPU fault output signal of the PLC controller, and the normally closed contact of the intermediate relay is connected in series in the working power supply circuit of the electric regulating valve. The analog output module of the PLC controller is electrically connected to the command signal input terminal of the electric regulating valve; the analog input module of the PLC controller is electrically connected to the output terminal of the temperature sensor.

[0007] Based on the above scheme and as a preferred option, the logical relationship between the voltage at the command signal input terminal of the electric regulating valve and the valve opening degree is reversed.

[0008] Based on the above scheme and as a preferred option, the PLC controller sets a minimum safe opening degree greater than zero for the electric regulating valve.

[0009] Based on the above scheme and as a preferred option, the minimum safe opening degree of the electric regulating valve shall not be less than 5%.

[0010] Based on the above scheme and as the preferred option: the PLC controller adopts Siemens S7-300; the intermediate relay is a DC intermediate relay, and its coil rated voltage matches the CPU fault output signal of the PLC controller.

[0011] The outstanding and beneficial technical effects of this utility model compared to the prior art are: Compared with the prior art, the reverse logic control system for equipment cooling water flow of this utility model adds an intermediate relay. The CPU output signal of the PLC controller drives the coil of the intermediate relay, the normally closed contact of the intermediate relay opens, the valve controller loses power control, the valve actuator opens fully, and the cooling water flows normally through the cooled equipment.

[0012] Furthermore, the logical relationship between the voltage at the command signal input terminal of the electric regulating valve and the valve opening is reversed; this "inverse logic" design alters the conventional control logic (0V corresponds to the valve being fully closed), enabling the valve to automatically open fully when the control signal is lost, providing maximum cooling capacity. This innovative combination with intermediate relays ensures valve safety in the event of a PLC failure.

[0013] By combining hardware protection circuits (intermediate relays to cut off power) and software logic reconstruction (signal inversion logic, minimum opening degree), multiple and redundant safety protections are formed, which greatly reduces the risk of single point of failure.

[0014] This invention addresses the problem in existing technologies where a PLC controller or AO module malfunction causes the control signal to return to zero, leading to cooling water cutoff and equipment shutdown. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the principle of this utility model.

[0016] Figure 2 This is the circuit schematic diagram of this utility model.

[0017] Figure label: 1. PLC controller; 2. Electric regulating valve; 3. Temperature sensor; 4. Fault protection circuit. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments; This embodiment provides an inverse logic control system for equipment cooling water flow, including a PLC controller, which is a Siemens S7-300 or an Omron or Schneider brand; an electric regulating valve, which includes a valve controller and a valve actuator; and a temperature sensor for acquiring the temperature of the equipment being cooled. It also includes a fault protection circuit, which includes an intermediate relay k1. The coil of the intermediate relay k1 is driven by the CPU fault output signal of the PLC controller. The normally closed contact k1-1 of the intermediate relay is connected in series in the working power supply circuit of the electric regulating valve. As described above, under normal operating conditions, the electric regulating valve is open, and cooling water flows through the cooled equipment. In the event of an emergency, the CPU of the PLC controller detects the fault and outputs a signal to energize the coil of the intermediate relay of this invention. The power module of the PLC controller provides power, and the normally closed contact of the intermediate relay changes to the open state, that is, the electric regulating valve is de-energized. The valve controller of the electric regulating valve does not work, and the electric regulating valve remains open, ensuring that the cooling water continues to flow normally and the cooled equipment does not heat up rapidly.

[0019] The analog output module of the PLC controller is electrically connected to the control signal input terminal of the electric regulating valve; the PLC controller outputs command signals to control the valve controller; the analog input module of the PLC controller is electrically connected to the output terminal of the temperature sensor; the PLC controller inputs temperature signals to the analog input module; the electrically controlled regulating valve can be controlled by signals.

[0020] Furthermore, the logical relationship between the voltage at the command signal input terminal of the electric regulating valve and the valve opening degree is set in reverse; As mentioned above, accidents such as PLC controller failure, signal lines being chewed by rats, or signal lines being accidentally torn by workers can occur.

[0021] The PLC controller has no command signal output. That is, when the voltage at the command signal input terminal of the valve controller is 0V, the valve actuator is in the fully open position, ensuring normal flow of cooling water. When the voltage at the control signal input terminal is at its maximum value (10V or 20mA), the valve actuator is in the fully closed position. This reverse logic design also ensures that the electric regulating valve automatically opens fully.

[0022] The reverse logic design works in conjunction with the fault protection circuit to ensure that the regulating valve is automatically fully opened when the PLC controller fails, thus achieving fault-oriented safety.

[0023] Furthermore, the PLC controller sets a minimum safe opening degree greater than zero for the electric regulating valve. This means the electric regulating valve is set to a minimum flow rate, preventing it from fully closing.

[0024] The minimum safe opening degree of the electric regulating valve shall not be less than 5%.

[0025] As described above, this minimum safe opening provides basic cooling flow during normal operation and forms redundant protection with the reverse logic design to prevent accidental closure of the electrically controlled regulating valve.

[0026] Furthermore, the intermediate relay is a DC intermediate relay, and its coil rated voltage is matched with the CPU fault output signal (24VDC) of the PLC controller to ensure reliable operation.

[0027] Furthermore, the PLC controller is electrically connected to an audible and visual alarm; when a system fault is detected (such as CPU failure, communication interruption, etc.), the PLC controller can trigger an alarm through the audible and visual alarm device to facilitate quick location and repair.

[0028] In the description of this utility model, it should be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this utility model and simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In this utility model, unless otherwise expressly specified and limited, the terms "installation," "setting," "connection," "fixing," and "screw-on," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection. The above embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Therefore, all equivalent changes made to the structure, shape, and principle of the present utility model should be covered within the scope of protection of the present utility model.

Claims

1. A reverse logic control system for equipment cooling water flow rate, characterized in that: Includes a PLC controller, an electric regulating valve, and a temperature sensor for acquiring the temperature of the cooled equipment; It also includes a fault protection circuit, which includes an intermediate relay. The coil of the intermediate relay is driven by the CPU fault output signal of the PLC controller, and the normally closed contact of the intermediate relay is connected in series in the working power supply circuit of the electric regulating valve. The analog output module of the PLC controller is electrically connected to the command signal input terminal of the electric regulating valve; the analog input module of the PLC controller is electrically connected to the output terminal of the temperature sensor.

2. The reverse logic control system for equipment cooling water flow rate according to claim 1, characterized in that: The logical relationship between the voltage at the command signal input terminal of the electric regulating valve and the valve opening degree is set in reverse.

3. The reverse logic control system for equipment cooling water flow rate according to claim 1, characterized in that: The PLC controller sets a minimum safe opening degree greater than zero for the electric regulating valve.

4. The reverse logic control system for equipment cooling water flow rate according to claim 3, characterized in that: The minimum safe opening degree of the electric regulating valve shall not be less than 5%.

5. The reverse logic control system for equipment cooling water flow rate according to claim 1, characterized in that: The PLC controller uses a Siemens S7-300; the intermediate relay is a DC intermediate relay, and its coil rated voltage is matched with the CPU fault output signal of the PLC controller.

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