Belt automatic tensioning device based on pressure and displacement double closed loop control and control method

Abstract

The application discloses a belt automatic tensioning device and control method based on pressure and displacement double closed loop control, and belongs to the field of belt conveyors. The device comprises a hydraulic system, a mechanical execution unit, a sensing and detecting unit and an intelligent control unit. The hydraulic station is connected with a double-acting hydraulic cylinder through an electro-hydraulic proportional reversing valve and a hydraulic lock, thereby forming a hydraulic power circuit. A pressure sensor is installed in the rodless cavity of the hydraulic cylinder, and is used for detecting the oil cavity pressure in real time to reflect the tensioning force. A displacement sensor is installed on the piston rod, and is used for detecting the stroke to reflect the position of the tensioning drum. A double closed loop algorithm is built in the PLC, the pressure closed loop is used as the inner loop, the displacement closed loop is used as the outer loop, the electro-hydraulic proportional reversing valve is adjusted in a closed loop mode according to the deviation between the target value and the actual feedback signal, and the accurate control of the tensioning force and the synchronous driving of multiple cylinders are realized. The application is automatically operated, has high response speed and control precision, can adaptively compensate the tension fluctuation and buffer the sudden load, and has the functions of remote monitoring and fault diagnosis.

Description

Technical Field

[0001] This invention relates to the field of belt conveyor technology, and in particular to an automatic belt tensioning device and control method based on pressure and displacement dual closed-loop control. Background Technology

[0002] Automatic belt tensioning devices are core components of belt conveyors (especially bulk material conveying equipment such as coal stackers and stacker-reclaimers). They maintain appropriate belt tension, preventing slippage, misalignment, and excessive wear, thus ensuring the stable and efficient operation of the conveying system. In the operation of coal stackers, hydraulic tensioning systems offer advantages over traditional counterweight or manual hydraulic tensioning systems, including strong dynamic adjustment capabilities, high structural adaptability, and comprehensive safety protection. These advantages are crucial for the continuity, safety, and economy of coal production.

[0003] Currently, in practical engineering applications such as the coal stacker at a certain port's second phase, the original belt tensioning system uses mechanical limit switches for control. This method indirectly maintains belt tension by setting fixed mechanical stops or limit switches to limit the position of the tensioning drum. When the belt becomes loose due to long-term operation or changes in load, the tension cannot be automatically adjusted, requiring manual intervention for mechanical limit adjustment. In addition, traditional solutions also use counterweight tensioning devices or ordinary manual hydraulic tensioning devices: the former relies on the gravity of the counterweight to provide constant tension, while the latter relies on manual operation of a hydraulic pump for intermittent tensioning.

[0004] However, the aforementioned existing technologies have obvious drawbacks: (1) Mechanical limit or counterweight tensioning methods cannot adjust the belt tension in real time according to changes in working conditions and load, resulting in the belt always being in the same tension state under light or heavy load (excessive tension under light load can accelerate belt wear, while insufficient tension under heavy load can cause slippage).

[0005] (2) When the belt becomes severely loose or even breaks, the system using mechanical limiters requires manual maintenance using hydraulic jacks. The operation is cumbersome, and each maintenance takes about 4-5 hours, which is time-consuming and labor-intensive, seriously affecting the system's working efficiency and coal transportation capacity.

[0006] (3) The manual hydraulic tensioning system lacks automatic control capability, cannot achieve dynamic and precise adjustment, and is difficult to meet the real-time control requirements under complex working conditions.

[0007] Therefore, existing tensioning devices generally suffer from problems such as short service life, high belt replacement frequency, long maintenance time, and low working efficiency. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide an automatic belt tensioning device and control method based on pressure and displacement dual closed-loop control. It aims to solve the problems of existing belt tensioning devices that cannot adjust the tension force in real time according to working conditions, have long maintenance time, and short system service life. The system can adjust the belt tension force (i.e., hydraulic cylinder pressure) and tension requirements in real time by controlling the displacement of the hydraulic cylinder, thereby significantly improving the service life of the system, reducing the frequency of belt replacement, improving the system working efficiency, and achieving the effect of saving time and labor.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: An automatic belt tensioning device based on pressure and displacement dual closed-loop control includes: The hydraulic system includes a hydraulic power unit, an electro-hydraulic proportional directional valve, and a hydraulic lock; the hydraulic power unit is connected to the electro-hydraulic proportional directional valve and the hydraulic lock in sequence through oil circuits, and is connected to the mechanical actuator to form a hydraulic power circuit; The mechanical actuator includes at least one double-acting hydraulic cylinder, the cylinder barrel of which is hinged to the equipment frame, and its piston rod is directly or through a connector connected to the tensioning roller seat for driving the tensioning roller to move. The sensing and detection unit includes a pressure sensor and a displacement sensor; the pressure sensor is installed in the rodless chamber or the tension output end of the double-acting hydraulic cylinder to detect the oil chamber pressure to reflect the belt tension; the displacement sensor is installed on the piston rod of the double-acting hydraulic cylinder to detect the piston rod displacement. The intelligent control unit, with a programmable logic controller (PLC) as its core, has its input terminal electrically connected to the sensing and detection unit and its output terminal electrically connected to the control terminal of the electro-hydraulic proportional directional valve. The PLC has a built-in dual closed-loop control algorithm, with a pressure closed loop as the inner loop and a displacement closed loop as the outer loop. Based on the target tension, actual pressure signal, target displacement, and actual displacement signal, the PLC performs closed-loop adjustment of the electro-hydraulic proportional directional valve to achieve belt tension adjustment and multi-cylinder synchronous control.

[0010] A further improvement of the technical solution of the present invention is that the displacement sensor is a magnetostrictive displacement sensor, the housing of which is fixedly installed on the outer wall of the cylinder of the double-acting hydraulic cylinder, and its measuring rod is rigidly connected to the piston rod of the double-acting hydraulic cylinder to collect the position signal of the tensioning wheel in real time, with a measurement accuracy of ±0.1mm.

[0011] A further improvement of the technical solution of the present invention is that the hydraulic lock is a hydraulically controlled check valve, which is directly installed on the oil port of the double-acting hydraulic cylinder and is used to lock the oil circuit when the hydraulic system loses pressure or stops, so as to prevent the belt from loosening.

[0012] A further improvement of the technical solution of the present invention is that: the A port of the electro-hydraulic proportional directional valve is connected to the rodless chamber of the double-acting hydraulic cylinder to directly control the belt tension.

[0013] A further improvement of the technical solution of the present invention is that: the intelligent control unit further includes a human-machine interface and an industrial Ethernet communication module; the human-machine interface is set on the electrical control cabinet at the installation site and is used to provide a local monitoring interface, which at least displays the dynamic curve of belt tension, displacement of double-acting hydraulic cylinder, system pressure, oil temperature and fault alarm information in real time, and supports online modification and writing of target tension force, displacement safety limit and PID control parameters; the industrial Ethernet communication module is used to establish a data communication link between the programming logic controller and the remote host computer, and has at least the functions of remote parameter setting, operation status monitoring, system fault diagnosis and historical data query and export.

[0014] A further improvement of the technical solution of this invention lies in the following: the programmable logic controller integrates a first PID controller and a second PID controller, which together form a dual closed-loop control structure of pressure inner loop and displacement outer loop; the first PID controller is used to perform pressure closed-loop regulation based on the detection signal of the pressure sensor and outputs a preliminary control quantity; the second PID controller is used to perform synchronous control of the displacement outer loop, and its control algorithm is as follows: the displacement sensor detection signals of the two double-acting hydraulic cylinders are collected in real time through the analog input module, the real-time displacement deviation between the two is calculated, and when the deviation exceeds a preset threshold, a synchronous compensation quantity is dynamically calculated based on the deviation; the programmable logic controller superimposes the synchronous compensation quantity with the preliminary control quantity to generate a final control command, and outputs it to the electromagnets of the first electro-hydraulic proportional directional valve and the second electro-hydraulic proportional directional valve respectively through the drive cable, so as to independently adjust the opening degree and flow direction of each valve port, implement differentiated dynamic compensation for the two double-acting hydraulic cylinders, and control the synchronous displacement deviation between the two to within 0.5mm.

[0015] A further improvement of the technical solution of the present invention is that the hydraulic system further includes an electromagnetic unloading valve, the inlet of which is connected to the pipeline between the hydraulic pump outlet and the electro-hydraulic proportional directional valve, and its outlet is connected back to the hydraulic oil tank; when the hydraulic system pressure reaches the set value of the electromagnetic unloading valve, the electromagnetic unloading valve is energized and opened, so that the hydraulic pump is in a low-pressure unloading state to achieve energy-saving operation.

[0016] A further improvement of the technical solution of the present invention is that: the device as a whole adopts a waterproof, dustproof and corrosion-resistant design; the piston rod surface of the double-acting hydraulic cylinder is plated with a hard chrome layer and has an anti-corrosion coating; the hydraulic station box and electrical control cabinet have a protection level of not less than IP65 to adapt to the industrial environment of ports or mines.

[0017] A control method for an automatic belt tensioning device based on dual closed-loop control of pressure and displacement includes the following steps: S1. Set the target tension force through the human-computer interaction interface or host computer. F set and target displacement range S min ~ S max ; S2. Real-time acquisition of pressure sensor signals via programmable logic controller. F actual and displacement sensor signals S actual ; S3, Pressure Inner Loop Control: This controls the pressure sensor signal... F actual Tension with the target F set A comparison is made, and the initial control quantity is calculated by the first PID controller. U p ; S4, Displacement Outer Loop Synchronization Control: This involves controlling the displacement sensor signals of two double-acting hydraulic cylinders. S actual The synchronization deviation ΔS is calculated by comparison, and the synchronization compensation amount is calculated by the second PID controller. U s ; S5. Control quantity superposition: The initial control quantity is then superimposed... U p With the aforementioned synchronization compensation amount U s The commands are superimposed to generate the final control command and output to the electro-hydraulic proportional directional valve to drive the double-acting hydraulic cylinder. S6. Repeat steps S2 to S5 to achieve continuous dynamic adjustment of belt tension and synchronous control of dual cylinders.

[0018] A further improvement of the technical solution of the present invention is that: in step S3, the tension adjustment accuracy of the inner pressure ring control is ≤5%; in step S4, the displacement synchronization deviation control accuracy of the two double-acting hydraulic cylinders is ≤0.5mm.

[0019] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows: 1. The belt hydraulic automatic tensioning device provided by this invention acquires system data in real time through high-precision force sensors and displacement sensors (LVDT), and innovatively achieves dual closed-loop control of tension (pressure) and displacement using a PLC-based control system. The inner pressure closed loop ensures that the tension control error is ≤5%, and the outer displacement closed loop ensures that the synchronization deviation of the two cylinders is no greater than ±0.5mm. This control strategy fundamentally solves the problems of coarse tension control and lag in traditional mechanical or hydraulic tensioning methods, achieving fully automatic adjustment without manual intervention and demonstrating a high degree of intelligence.

[0020] 2. This invention can detect tension fluctuations caused by changes in material load and thermal expansion and contraction of the belt in real time, and quickly compensate through electro-hydraulic proportional valves and redundant drive units. This reduces the belt tension adjustment time from over 4 hours required by traditional manual methods to less than 5 minutes, improving system efficiency by over 98%. This rapid dynamic response capability greatly reduces downtime accidents caused by tension imbalance, effectively ensuring the continuity and stability of the entire coal mining, transportation, and stockpiling production chain.

[0021] 3. This invention employs a design where the hydraulic lock is directly integrated into the oil cylinder port. Even in extreme situations such as oil pipe rupture or sudden system pressure loss, it can instantly lock the oil, preventing safety accidents caused by belt slack, thus demonstrating superior active safety performance. Simultaneously, precise constant tension control avoids the belt being too tight or too loose, extending belt life from 1-2 years to 3-5 years, and significantly reducing abnormal wear on transmission components such as idlers and bearings, thereby lowering the frequency and cost of maintenance throughout the equipment's lifecycle.

[0022] 4. The hydraulic station in this invention features a compact design, allowing it to be installed below the conveyor belt frame, maximizing space utilization and minimizing coal and dust accumulation. The entire system is rainproof, dustproof, and corrosion-resistant (IP65), making it suitable for harsh industrial environments such as ports and mines. The system also features on-demand output control logic and an unloading energy-saving circuit, activating the power unit only when adjustments are needed, reducing energy consumption by 15%-25% compared to traditional constant-power systems. Furthermore, improved system stability reduces dust pollution caused by belt misalignment and slippage, resulting in significant environmental benefits. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1This is a schematic diagram of the overall hydraulic system principle and structural layout of an automatic belt tensioning device based on pressure and displacement dual closed-loop control provided in an embodiment of the present invention. Figure 2 This is a logic flowchart of the dual closed-loop control method in an embodiment of the present invention; The components include: 1. Drain ball valve; 2. Hydraulic oil tank; 3. Liquid level and temperature sensor; 4. Air filter; 5. Three-phase asynchronous motor; 6. Hydraulic pump; 7. Check valve; 8. High-pressure filter; 9. Pressure sensor; 10. Shock-resistant pressure gauge; 11. Electromagnetic unloading valve; 12. Cooler; 13.1. First return oil filter; 13.2. Second return oil filter; 14. Liquid level gauge; 15.1. First electro-hydraulic proportional directional valve; 15.2. Second electro-hydraulic proportional directional valve; 16.1. First hydraulic lock; 16.2. Second hydraulic lock. Detailed Implementation

[0024] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products or devices.

[0025] In the description of this invention, it should be understood that 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 indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a number" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: like Figure 1 As shown, an automatic belt tensioning device based on pressure and displacement dual closed-loop control is mainly composed of four modules: hydraulic system, mechanical execution unit, sensing and detection unit, and intelligent control unit. The modules are closely connected through hydraulic oil circuits, signal cables and drive cables to form a complete electromechanical-hydraulic integrated closed-loop control system.

[0027] The hydraulic system is the core of the entire device, serving as its power source and transmission mechanism. For example... Figure 1As shown, the hydraulic system includes a hydraulic oil tank 2, a three-phase asynchronous motor 5, a hydraulic pump 6, a high-pressure filter 8, a first electro-hydraulic proportional directional valve 15.1, a second electro-hydraulic proportional directional valve 15.2, a first hydraulic lock 16.1, a second hydraulic lock 16.2, a first return oil filter 13.1, a second return oil filter 13.2, a cooler 12, and a solenoid unloading valve 11. Driven by the three-phase asynchronous motor 5, the hydraulic pump 6 draws oil from the hydraulic oil tank 2. The output pressurized oil first flows through the high-pressure filter 8 for purification to protect downstream precision hydraulic components. Then, the pressurized oil enters the inlet P of the first electro-hydraulic proportional directional valve 15.1 and the second electro-hydraulic proportional directional valve 15.2.

[0028] The first electro-hydraulic proportional directional valve 15.1 and the second electro-hydraulic proportional directional valve 15.2 are key electro-hydraulic conversion and control components. Their ports A and B serve as working oil ports, connected to the first hydraulic lock 16.1 and the second hydraulic lock 16.2 respectively via pipelines. The first hydraulic lock 16.1 and the second hydraulic lock 16.2 are preferably hydraulically controlled check valves, directly integrated onto the oil ports of the double-acting hydraulic cylinder, forming an integrated locking module. Their function is as follows: when the hydraulic system is working normally, pressurized oil can pass through in both directions; once the hydraulic system loses pressure (such as a pipeline rupture or a sudden pump stop), the first hydraulic lock 16.1 and the second hydraulic lock 16.2 can instantly and automatically lock, firmly locking the oil in the hydraulic cylinder, preventing the hydraulic cylinder piston rod from retracting and the belt from loosening due to reverse belt tension, thus providing extremely high active safety protection.

[0029] The oil lines from the first hydraulic lock 16.1 and the second hydraulic lock 16.2 are respectively connected to the rodless chamber and the rod chamber of the double-acting hydraulic cylinder in the mechanical actuator unit. Preferably, the A port of the first electro-hydraulic proportional directional valve 15.1 and the second electro-hydraulic proportional directional valve 15.2 is always connected to the rodless chamber of the double-acting hydraulic cylinder. The purpose of this is to utilize the larger effective working area of ​​the rodless chamber to generate a larger tension force under the same system pressure, thereby improving the control efficiency and output capacity of the system.

[0030] The return oil from the double-acting hydraulic cylinder is filtered through the first hydraulic lock 16.1 and the second hydraulic lock 16.2, the first return oil filter 13.1 and the second return oil transition device 13.2, and then flows through the cooler 12 for heat exchange to control the hydraulic system oil temperature. Finally, it returns to the hydraulic oil tank 2, forming a complete hydraulic power circulation loop. Furthermore, an electromagnetic unloading valve 11 is connected in parallel on the pipeline between the outlet of the hydraulic pump 6 and the P port of the first electro-hydraulic proportional directional valve 15.1 and the second electro-hydraulic proportional directional valve 15.2. Its function is to open the electromagnetic unloading valve 11 when the hydraulic system pressure reaches the preset safety upper limit, allowing the oil output from the hydraulic pump 6 to flow directly back to the hydraulic oil tank 2 under low pressure, thereby unloading the hydraulic system. This design significantly reduces the no-load energy consumption of the hydraulic pump 6 while maintaining the hydraulic system pressure, achieving energy-saving operation.

[0031] The mechanical actuator is a terminal actuator that directly applies tension to the belt. Its core component is at least one double-acting hydraulic cylinder, preferably two double-acting hydraulic cylinders symmetrically arranged on both sides of the conveyor. The cylinder ends of each double-acting hydraulic cylinder are fixed to the conveyor frame via hinged joints, forming a fixed fulcrum. The piston rod ends are connected to the bearing housing of the tensioning roller via a high-precision pressure sensor 9. The pressure sensor 9 is located on the force transmission path between the piston rod end and the bearing housing, i.e., the tension output end of the double-acting hydraulic cylinder, and is used to collect hydraulic pressure signals reflecting the belt tension in real time. Thus, the pressure sensor 9 can accurately detect the actual output force of each double-acting hydraulic cylinder. This detected value directly corresponds to the real-time belt tension, thereby providing accurate feedback input for the pressure inner loop control.

[0032] The sensing and detection unit constitutes the perception layer of the control system, mainly including a pressure sensor 9 for detecting tension force and a displacement sensor (not shown separately in the figure) for detecting piston rod displacement. As mentioned earlier, the pressure sensor 9 is installed at the force point of the piston rod to collect the output thrust signal of the hydraulic cylinder in real time. The displacement sensor is preferably a magnetostrictive displacement sensor (LVDT), whose body is fixedly installed outside the cylinder barrel of the double-acting hydraulic cylinder. The measuring rod is set along the piston rod axis and rigidly connected to the piston rod to achieve synchronous movement with the piston rod. The measurement accuracy of this displacement sensor is not less than ±0.1mm, used to detect the extension displacement of the piston rod in real time with high precision; this displacement directly represents the actual position of the tensioning roller, serving as the core feedback signal for the synchronous control of the outer displacement loop, providing a precise position reference for the coordinated movement of the two cylinders.

[0033] The intelligent control unit, serving as the core of the entire device, is primarily composed of an industrial-grade programmable logic controller (PLC). The detection signals from pressure sensor 9 and displacement sensor are connected to the PLC's analog input module via shielded signal cables. The PLC integrates a first PID controller and a second PID controller. The first PID controller forms the inner pressure loop control, while the second PID controller forms the outer displacement loop synchronous control. The PLC performs internal program calculations, superimposing the initial control output from the first PID controller with the synchronous compensation output from the second PID controller to generate the final control command. This control command is output via drive cables to the electromagnets of the first electro-hydraulic proportional directional valve 15.1 and the second electro-hydraulic proportional directional valve 15.2 to precisely adjust the opening degree and flow direction of each valve port, thereby achieving independent drive and high-precision synchronous movement of the double-acting hydraulic cylinder.

[0034] The intelligent control unit also includes a human-machine interface (HMI) and an industrial Ethernet communication module. The HMI is installed on the electrical control cabinet at the equipment site, providing operators with a local monitoring and operation interface. Its functions include: real-time display of operating status parameters such as belt tension dynamic curves, hydraulic cylinder displacement, system pressure, and oil temperature, as well as fault alarm information. It also supports online setting and modification of key process parameters such as target tension, displacement safety limits, and PID control parameters. The industrial Ethernet communication module establishes a remote data channel for the control system, enabling real-time data interaction between the PLC and the host computer in the remote control room. It supports engineers in remotely setting parameters, monitoring operating status, diagnosing system faults, and querying and exporting historical operating data online, thereby significantly improving the convenience of equipment operation and maintenance and the level of intelligent system management.

[0035] The core of this invention lies in the dual closed-loop control algorithm for pressure and displacement executed by a PLC. The control method flow is as follows: Figure 2 As shown, a control method for an automatic belt tensioning device based on dual closed-loop control of pressure and displacement specifically includes the following steps: S1. Set the target tension through the human-machine interface (HMI) or host computer. F set and target displacement range S min ~ S max ; S2. Real-time acquisition of pressure sensor signals via programmable logic controller (PLC) F actual and displacement sensor signals S actual ; S3, Pressure Inner Loop Control: This controls the pressure sensor signal... F actualTension with the target F set A comparison is made, and the initial control quantity is calculated by the first PID controller. U p The error can be controlled within ≤5%; S4, Displacement Outer Loop Synchronization Control (for dual-cylinder systems): This involves controlling the displacement sensor signals of two double-acting hydraulic cylinders. S actual The synchronization deviation ΔS is calculated by comparison, and the synchronization compensation amount is calculated by the second PID controller. U s When ΔS exceeds the set threshold (e.g., 0.2 mm), the deviation is sent to the second PID controller for calculation, and the output is a compensation control quantity used to correct the asynchrony of the two cylinders. U s This ring ensures the parallel movement of the two tensioning rollers, and the synchronous deviation of the dual-cylinder displacement can be precisely controlled within ≤0.5mm.

[0036] S5. Control Quantity Overlay: Overlay the initial control quantity... U p Synchronization compensation amount U s The commands are superimposed to generate the final control command, which is then sent to the electro-hydraulic proportional directional valves (first electro-hydraulic proportional directional valve 15.1 and second electro-hydraulic proportional directional valve 15.2) through the output module of the programmable logic controller (PLC) to drive the double-acting hydraulic cylinder to move. S6. Repeat steps S2 to S5 to achieve continuous dynamic adjustment of belt tension and synchronous control of dual cylinders.

[0037] In summary, this invention provides an automatic belt tensioning device and control method based on pressure and displacement dual closed-loop control. A hydraulic station is connected to a double-acting hydraulic cylinder via an electro-hydraulic proportional directional valve and a hydraulic lock, forming a hydraulic power circuit. A pressure sensor is installed in the rodless chamber of the hydraulic cylinder to detect the oil pressure in real time, reflecting the tension force. A displacement sensor is installed on the piston rod to detect the stroke, reflecting the position of the tensioning roller. A PLC serves as the control core, incorporating a dual closed-loop control algorithm with a pressure closed loop as the inner loop and a displacement closed loop as the outer loop. Based on the deviation between the target value and the actual feedback signal, the electro-hydraulic proportional directional valve is adjusted in real time to achieve precise control of the tension force and synchronous drive of multiple cylinders. The entire device is designed to fully consider the application requirements of harsh industrial environments. The hydraulic station housing and electrical control cabinet have a protection rating of no less than IP65, effectively preventing rain and dust. The surface of the hydraulic cylinder piston rod is treated with hard chrome plating and an anti-corrosion coating, and all exposed metal parts are treated with anti-corrosion measures. This allows the device to be reliably applied in outdoor environments with large temperature differences, high dust levels, and strong corrosiveness, such as ports and mines.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic belt tensioning device based on dual closed-loop control of pressure and displacement, characterized in that, include: The hydraulic system includes a hydraulic power unit, an electro-hydraulic proportional directional valve, and a hydraulic lock; the hydraulic power unit is connected to the electro-hydraulic proportional directional valve and the hydraulic lock in sequence through oil circuits, and is connected to the mechanical actuator to form a hydraulic power circuit; The mechanical actuator includes at least one double-acting hydraulic cylinder, the cylinder barrel of which is hinged to the equipment frame, and its piston rod is directly or through a connector connected to the tensioning roller seat for driving the tensioning roller to move. The sensing and detection unit includes a pressure sensor and a displacement sensor; the pressure sensor is installed in the rodless chamber or the tension output end of the double-acting hydraulic cylinder to detect the oil chamber pressure to reflect the belt tension; the displacement sensor is installed on the piston rod of the double-acting hydraulic cylinder to detect the piston rod displacement. The intelligent control unit, with a programmable logic controller (PLC) as its core, has its input terminal electrically connected to the sensing and detection unit and its output terminal electrically connected to the control terminal of the electro-hydraulic proportional directional valve. The PLC has a built-in dual closed-loop control algorithm, with a pressure closed loop as the inner loop and a displacement closed loop as the outer loop. Based on the target tension, actual pressure signal, target displacement, and actual displacement signal, the PLC performs closed-loop adjustment of the electro-hydraulic proportional directional valve to achieve belt tension adjustment and multi-cylinder synchronous control.

2. The automatic belt tensioning device according to claim 1, characterized in that, The displacement sensor is a magnetostrictive displacement sensor. The housing of the displacement sensor is fixedly installed on the outer wall of the cylinder of the double-acting hydraulic cylinder, and its measuring rod is rigidly connected to the piston rod of the double-acting hydraulic cylinder. It collects the position signal of the tension wheel in real time, and the measurement accuracy is ±0.1mm.

3. The automatic belt tensioning device according to claim 1, characterized in that, The hydraulic lock is a hydraulically controlled check valve, which is directly installed on the oil port of the double-acting hydraulic cylinder. It is used to lock the oil circuit when the hydraulic system loses pressure or stops, so as to prevent the belt from loosening.

4. The automatic belt tensioning device according to claim 1, characterized in that, The A port of the electro-hydraulic proportional directional valve is connected to the rodless chamber of the double-acting hydraulic cylinder to directly control the belt tension.

5. The automatic belt tensioning device according to claim 1, characterized in that, The intelligent control unit also includes a human-machine interface and an industrial Ethernet communication module. The human-machine interface is located on the electrical control cabinet at the installation site and is used to provide a local monitoring interface. It can display at least the dynamic curve of belt tension, displacement of double-acting hydraulic cylinder, system pressure, oil temperature and fault alarm information in real time, and supports online modification and writing of target tension force, displacement safety limit and PID control parameters. The industrial Ethernet communication module is used to establish a data communication link between the programmable logic controller and the remote host computer. It has at least the functions of remote parameter setting, operation status monitoring, system fault diagnosis and historical data query and export.

6. The automatic belt tensioning device according to claim 1, characterized in that, The programmable logic controller (PLC) integrates a first PID controller and a second PID controller, which together form a dual closed-loop control structure consisting of an inner pressure loop and an outer displacement loop. The first PID controller performs closed-loop pressure regulation based on the detection signal from the pressure sensor and outputs a preliminary control quantity. The second PID controller performs synchronous control of the outer displacement loop. Its control algorithm is as follows: it acquires the detection signals from the displacement sensors of the two double-acting hydraulic cylinders in real time through an analog input module, calculates the real-time displacement deviation between the two, and dynamically calculates a synchronous compensation quantity based on the deviation when the deviation exceeds a preset threshold. The PLC superimposes the synchronous compensation quantity with the preliminary control quantity to generate a final control command, which is then output to the electromagnets of the first and second electro-hydraulic proportional directional valves via drive cables to independently adjust the opening degree and flow direction of each valve, thereby implementing differentiated dynamic compensation for the two double-acting hydraulic cylinders and controlling their synchronous displacement deviation within 0.5 mm.

7. The automatic belt tensioning device according to claim 1, characterized in that, The hydraulic system also includes an electromagnetic unloading valve. The inlet of the electromagnetic unloading valve is connected to the pipeline between the hydraulic pump outlet and the electro-hydraulic proportional directional valve, and its outlet is connected back to the hydraulic oil tank. When the hydraulic system pressure reaches the set value of the electromagnetic unloading valve, the electromagnetic unloading valve is energized and opened, so that the hydraulic pump is in a low-pressure unloading state to achieve energy-saving operation.

8. The automatic belt tensioning device according to claim 1, characterized in that, The device is designed to be waterproof, dustproof, and corrosion resistant. The piston rod of the double-acting hydraulic cylinder is plated with a hard chrome layer and has an anti-corrosion coating. The hydraulic station housing and electrical control cabinet have a protection rating of not less than IP65 to adapt to the industrial environment of ports or mines.

9. A control method for an automatic belt tensioning device based on dual closed-loop control of pressure and displacement as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Set the target tension force through the human-computer interaction interface or host computer. F set and target displacement range S min ~ S max ; S2. Real-time acquisition of pressure sensor signals via programmable logic controller. F actual and displacement sensor signals S actual ; S3, Pressure Inner Loop Control: This controls the pressure sensor signal... F actual Tension with the target F set A comparison is made, and the initial control quantity is calculated by the first PID controller. U p ; S4, Displacement Outer Loop Synchronization Control: This involves controlling the displacement sensor signals of two double-acting hydraulic cylinders. S actual The synchronization deviation ΔS is calculated by comparison, and the synchronization compensation amount is calculated by the second PID controller. U s ; S5. Control quantity superposition: The initial control quantity is then superimposed... U p With the aforementioned synchronization compensation amount U s The commands are superimposed to generate the final control command and output to the electro-hydraulic proportional directional valve to drive the double-acting hydraulic cylinder. S6. Repeat steps S2 to S5 to achieve continuous dynamic adjustment of belt tension and synchronous control of dual cylinders.

10. The control method according to claim 9, characterized in that, In step S3, the tension adjustment accuracy of the inner pressure loop control is ≤5%; in step S4, the displacement synchronization deviation control accuracy of the two double-acting hydraulic cylinders is ≤0.5mm.

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