Variable frequency speed regulation hydraulic synchronous control system

Abstract

The utility model provides a variable frequency speed regulation hydraulic synchronous control system, and relates to the field of stage performance equipment. The system comprises an upper computer man-machine interaction system, a PLC (Programmable Logic Controller), a frequency converter, a hydraulic oil pump, a hydraulic cylinder, a lifting tabletop, a variable frequency motor, a hydraulic oil pump, an oil tank and an electromagnetic directional valve. The rotating speed of the variable frequency motor is controlled through the frequency converter to adjust the oil outlet speed of the hydraulic oil pump, then the piston speed of the oil cylinder is adjusted, the response speed is high, variable frequency and speed regulation synchronous operation of the hydraulic lifting platform is achieved, and then stable operation of the lifting platform driven by multiple cylinders synchronously and stepless speed regulation of the hydraulic lifting platform are achieved. The synchronous positioning precision of the hydraulic lifting platform is improved, the domestic and international control performance requirements of the stage lifting platform are met, the synchronous precision is smaller than + / -5mm, the positioning precision is smaller than + / -3mm, the lifting stability and safety of the lifting platform are guaranteed, and the method has wide application prospects.

Description

Technical Field

[0001] This utility model relates to the field of stage performance equipment, and in particular to a variable frequency speed regulation hydraulic synchronous control system. Background Technology

[0002] During stage performances, a heavy-duty lifting platform with high power, high torque, large motion and large workload is often required. It is difficult to guarantee the stability and safety of such a heavy-duty lifting platform by motor drive, so it is driven by hydraulic means, namely hydraulic lifting platform.

[0003] Currently, stage hydraulic lifting platforms are mostly operated by controlling the input and output flow of the hydraulic oil pump through electro-hydraulic proportional valves in a low-voltage electrical control hydraulic system, thereby controlling the lifting speed of the platform and achieving speed-adjustable operation. However, this method suffers from slow response and poor synchronization when multiple cylinders are simultaneously driving a single lifting platform, making it difficult to achieve stable operation with multiple cylinders synchronously lifting a single device, and easily leading to safety accidents. Utility Model Content

[0004] The purpose of this utility model is to address the problems existing in the prior art mentioned above by providing a variable frequency speed regulation hydraulic synchronous control system. This system controls the rotational speed of the motor through a frequency converter to adjust the oil output rate of the hydraulic oil pump, thereby adjusting the piston speed of the oil cylinder. It has a fast response rate, realizes the variable frequency speed regulation synchronous operation of the hydraulic lifting platform, and achieves the smooth operation of a lifting platform driven by multiple cylinders and the stepless speed regulation of the hydraulic lifting platform. It also improves the synchronous positioning accuracy of the hydraulic lifting platform and meets the domestic and international control performance requirements of stage lifting platforms.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] The variable frequency speed regulation hydraulic synchronous control system includes a host computer human-machine interface system, a PLC controller, frequency converters, hydraulic oil pumps, hydraulic cylinders, and a lifting platform. The host computer human-machine interface system is connected to the PLC controller via an industrial Ethernet network. The PLC controller is connected to multiple frequency converters via PROFINET. Each frequency converter is connected to a corresponding variable frequency motor, and each variable frequency motor is connected to a hydraulic oil pump. The inlet pipe of each hydraulic oil pump is connected to an oil tank, and the outlet pipe of each hydraulic oil pump is connected to a solenoid directional valve. Multiple solenoid directional valves correspond one-to-one with multiple hydraulic cylinders. The two outlet ports of each solenoid directional valve are respectively connected to the upper and lower chambers of its corresponding hydraulic cylinder. The return ports of each solenoid directional valve are connected to the oil tank via return pipes. Multiple hydraulic cylinders are symmetrically arranged at the bottom of the lifting platform.

[0007] Furthermore, a shut-off valve is installed on the oil outlet pipe between the electromagnetic directional valve and the lower chamber of the hydraulic cylinder.

[0008] Furthermore, a first suction oil filter is installed on the oil inlet pipe of the hydraulic oil pump, and the first suction oil filter is located inside the oil tank.

[0009] Furthermore, a first check valve is installed on the oil outlet pipe between the hydraulic oil pump and the solenoid directional valve.

[0010] Furthermore, a second oil suction filter is installed on the return oil pipe between the electromagnetic reversing valve and the oil tank.

[0011] Furthermore, a second check valve is installed on the return oil pipe between the second suction oil filter and the solenoid directional valve.

[0012] Furthermore, an overflow pipe is connected to the oil outlet pipe between the first check valve and the solenoid directional valve. A flow sensor and an overflow valve are installed on the overflow pipe. The outlet of the overflow pipe is connected to the oil tank. The flow sensor is connected to the PLC controller for communication.

[0013] Furthermore, the hydraulic cylinder is equipped with a displacement sensor, which is communicatively connected to the PLC controller.

[0014] Due to the adoption of the above technical solution, the beneficial technical effects of this utility model are as follows:

[0015] 1. The variable frequency speed regulation hydraulic synchronous control system of this utility model controls the rotational speed of the variable frequency motor through a frequency converter to adjust the oil output rate of the hydraulic oil pump, thereby adjusting the piston speed of the oil cylinder. It has a fast response rate and realizes the variable frequency speed regulation synchronous operation of the hydraulic lifting platform. This enables multiple cylinders to synchronously drive a single lifting platform for stable operation and stepless speed regulation of the hydraulic lifting platform. It improves the synchronous positioning accuracy of the hydraulic lifting platform, meets the domestic and international control performance requirements of stage lifting platforms, and achieves a synchronization accuracy of less than ±5mm and a positioning accuracy of less than ±3mm. This ensures the smoothness and safety of the lifting platform and has broad application prospects.

[0016] 2. The variable frequency speed regulation hydraulic synchronous control system of this utility model not only has the flexibility and speed of electronic control system, but also has the advantages of hydraulic system such as large load-bearing ratio and stable dynamic performance, making the lifting platform more stable and safe to operate, and reducing the risk of stage accidents. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the variable frequency speed regulation hydraulic synchronous control system of this utility model;

[0018] Figure 2 This is a schematic diagram of the synchronization control process of the variable frequency speed regulation hydraulic synchronization control system of this utility model;

[0019] Figure 3 These are the synchronous operation displacement curves of the 2KW and 3KW hydraulic lifting platforms in the test examples of this utility model;

[0020] Figure 4 The test example of this utility model shows the displacement difference between the 2KW and 3KW hydraulic lifting platforms during synchronous operation;

[0021] Reference numerals in the attached diagram: 1-Host computer human-machine interface system, 2-PLC controller, 3-frequency converter, 4-frequency conversion motor, 5-hydraulic oil pump, 6-first suction oil filter, 7-first check valve, 9-relief valve, 8-flow sensor, 10-solenoid directional valve, 11-stop valve, 12-hydraulic cylinder, 13-displacement sensor, 14-lifting platform, 15-second check valve, 16-second suction oil filter, 17-oil tank. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the following describes this utility model in further detail through preferred embodiments.

[0023] Example

[0024] Please see the appendix Figure 1 As shown, the variable frequency speed regulation hydraulic synchronous control system provided in this embodiment includes a host computer human-machine interaction system 1, a PLC controller 2, a frequency converter 3, a hydraulic oil pump 5, a hydraulic cylinder 12, and a lifting platform 14. The host computer human-machine interaction system 1 is connected to the PLC controller 2 via an industrial Ethernet. The PLC controller 2 is connected to multiple frequency converters 3 via PROFINET. Each frequency converter 3 is connected to a variable frequency motor 4. Each variable frequency motor 4 is connected to a hydraulic oil pump 5. The oil inlet pipe of each hydraulic oil pump 5 is connected to an oil tank 17. The oil outlet pipe of each hydraulic oil pump 5 is connected to an electromagnetic directional valve 10. Multiple electromagnetic directional valves 10 correspond one-to-one with multiple hydraulic cylinders 12. The two oil outlets of each electromagnetic directional valve 10 are respectively connected to the upper chamber and lower chamber of its corresponding hydraulic cylinder 12. The oil return port of each electromagnetic directional valve 10 is connected to the oil tank 17 via a return pipe. Multiple hydraulic cylinders 12 are symmetrically arranged at the bottom of the lifting platform 14.

[0025] In this embodiment, the host computer human-machine interface system 1 comprises at least one of a main control console, a mobile control console, a touchscreen, and a remote operation and maintenance center. When multiple human-machine interface components are used together, each component uses the main control console as its core and transmits data and communicates in real time via industrial Ethernet. The PLC controller 2 uses a Siemens S7-1500 series product as its main control unit, which has high diagnostic capabilities and security. Its new backplane bus technology and high baud rate and high transmission protocol enhance the anti-interference capability of the system signal. Based on the characteristics of each CPU in the Siemens S7-1500 series PLC and combined with the high precision requirements of the hydraulic control system, the CPU selected is the 1516-3PN product, which has 1-3 Profinet interfaces, realizing data transmission between the host and slave units with the PLC as the core control unit. The frequency converter 3 is a NORD 3SK545E series frequency converter.

[0026] Specifically, a shut-off valve 11 is installed on the oil outlet pipe between the electromagnetic directional valve 10 and the lower chamber of the hydraulic cylinder 12; a first suction oil filter 6 is installed on the oil inlet pipe of the hydraulic oil pump 5, and the first suction oil filter 6 is located inside the oil tank 17; a first check valve 7 is installed on the oil outlet pipe between the hydraulic oil pump 5 and the electromagnetic directional valve 10; a second suction oil filter 16 is installed on the oil return pipe between the electromagnetic directional valve 10 and the oil tank 17; and a second check valve 15 is installed on the oil return pipe between the second suction oil filter 16 and the electromagnetic directional valve 10.

[0027] Specifically, an overflow pipe is connected to the oil outlet pipe between the first one-way valve 7 and the solenoid directional valve 10. A flow sensor 8 and an overflow valve 9 are installed on the overflow pipe. The outlet of the overflow pipe is connected to the oil tank 17. The flow sensor 8 is connected to the PLC controller 2. A displacement sensor 13 is installed on the hydraulic cylinder 12. The displacement sensor 13 is connected to the PLC controller 2.

[0028] In this embodiment, the design of the overflow valve 9 enables pressure regulation of the hydraulic oil at the outlet of the hydraulic oil pump 5. The hydraulic oil can be regulated via the overflow valve 9. Simultaneously, a flow sensor 8 is installed to detect the oil volume at the outlet of the hydraulic oil pump 5 in real time and upload the data to the host computer human-machine interface 1 via the PLC controller 2, displaying it intuitively on the human-machine interface. The displacement sensor 13 is used to detect the current stroke when the lifting platform 14 rises or falls. The flow sensor 8 and displacement sensor 13 provide feedback signals for the control and adjustment of the system, constantly monitoring the operating status of the lifting platform and improving synchronous positioning accuracy. As a further improvement, a pressure sensor can be installed in the oil circuit near the hydraulic cylinder 12 to detect and provide feedback on the current oil pressure. A balance valve is installed in the lower chamber of the cylinder to ensure that the lifting platform maintains pressure when it stops at any position during rise or fall. Furthermore, the balance valve can also be used to control the descent of an object under load, ensuring displacement control accuracy during the descent process.

[0029] This utility model's variable frequency speed regulation hydraulic synchronous control system belongs to volumetric speed regulation. During operation, the system boasts high efficiency and low energy loss, avoiding the oil temperature rise problem caused by throttling speed regulation. The synchronous motion control of the stage hydraulic lifting platform employs a master-slave synchronous control algorithm to ensure high synchronization among multiple hydraulic actuators during movement. One hydraulic lifting platform actuator is selected as the master actuator, and the others as slave actuators. The master actuator's motion state serves as a reference, and the slave actuators achieve synchronization by tracking the master actuator's motion. To improve synchronization accuracy, a PID control algorithm is added, adjusting the inverter's output frequency based on the real-time operating status feedback from various sensors. This, in turn, adjusts the hydraulic system's flow rate and pressure, achieving precise synchronous control of the hydraulic lifting platform.

[0030] Combination Figure 2 As shown, the working principle of the variable frequency speed regulation hydraulic synchronous control system of this utility model is as follows:

[0031] Ascending Operation: The host computer's human-machine interface system 1 sends an operating command to the PLC controller 2, which in turn controls the frequency converter 3 to rotate the variable frequency motor 4. This causes the hydraulic oil pump 5 to draw oil from the oil tank 17 via the first suction filter 6 and the first check valve 7. The pressurized oil output from the hydraulic oil pump 5 then enters the lower chamber of the hydraulic cylinder 12 via the solenoid directional valve 10 and the shut-off valve 11, pushing the cylinder outwards. The system pressure is pre-set; when the system pressure reaches its maximum, the overflow valve 9 opens to unload excess pressure and protect the system. Using the same principle, multiple hydraulic cylinders 12 extend simultaneously. The displacement sensor 13 provides feedback on the ascending stroke, and the frequency converter 3 controls the rotation speed of the variable frequency motor 4, changing the extension speed of the hydraulic cylinders 12 to ensure that the ascending speeds of multiple hydraulic cylinders 12 are consistent. This results in a smooth overall rise of the stage surface, with a synchronization accuracy of ±3mm.

[0032] Descent mode: Inverter 3 controls the inverter motor 4 to continue rotating, the solenoid directional valve 10 reverses, and hydraulic oil enters the upper chamber of hydraulic cylinder 12 to push the cylinder forward. Using the same principle, multiple hydraulic cylinders 12 retract simultaneously. The displacement sensor 13 provides feedback on the descent stroke, and inverter 3 controls the rotation speed of inverter motor 4, changing the retraction speed of hydraulic cylinders 12 to ensure that the descent speeds of multiple hydraulic cylinders 12 are consistent. This results in a smooth overall descent of the stage surface, with a descent synchronization accuracy of ±3mm.

[0033] Test case

[0034] The stopping performance, synchronization accuracy, stability and response characteristics of the variable frequency speed regulation hydraulic synchronous control system of this utility model were tested to ensure that the system can reliably and stably synchronize in practical applications and meet the needs of stage performance application scenarios.

[0035] (1) Stop performance test

[0036] Two hydraulic lifting platforms with variable frequency motor power of 3KW and 4KW were randomly selected. Under stable system conditions and no load, the variable frequency speed regulation hydraulic synchronous control system of the embodiment was started to make the two hydraulic lifting platforms move to the designated position and then remain stationary. The displacement sensor measurement data was recorded, and the positional deviation between the two hydraulic lifting platforms was calculated. The test was repeated 4 times, and the test results are shown in Table 1.

[0037] Table 1. Test results of the hydraulic lifting platform's stopping performance.

[0038]

[0039] As shown in Table 1, the absolute displacement error of the 3KW and 4KW hydraulic lifting platforms during the four movements was less than or equal to ±3mm, which meets the design requirements. This indicates that the control system of this utility model can control the hydraulic lifting platform to stop accurately.

[0040] (2) Synchronization performance test

[0041] Two hydraulic lifting platforms with motors of 2KW and 3KW were randomly selected. The variable frequency speed control hydraulic synchronous control system of this embodiment was started, and the same control command was given. The displacement changes of the two lifting platforms over time were recorded during their movement. The synchronicity of the displacement curves of the two lifting platforms was compared to determine whether they were operating synchronously. The test results are as follows: Figure 3 and Figure 4 As shown.

[0042] Depend on Figure 3 It can be seen that, under the same operating conditions, the displacement of the two lifting platforms detected by the displacement sensors changes with time in a basically consistent manner, according to the 2KW and 3KW hydraulic lifting platforms. Figure 4It can be seen that the absolute displacement error of both lifting platforms is less than ±5mm, which meets the design requirements for synchronous control accuracy.

[0043] The above description is a preferred embodiment of the present utility model, used to explain the technical solution of the present utility model. Those skilled in the art can also make conventional modifications, equivalent substitutions and improvements within the spirit and principles of the present utility model.

Claims

1. A variable frequency speed regulation hydraulic synchronous control system, characterized in that: The system includes a host computer-controlled human-machine interface (HMI) system, a PLC controller, frequency converters, hydraulic oil pumps, hydraulic cylinders, and a lifting platform. The HMI system connects to the PLC controller via an industrial Ethernet network. The PLC controller connects to multiple frequency converters via PROFINET. Each frequency converter is connected to a corresponding variable frequency motor, and each variable frequency motor is connected to a hydraulic oil pump. The inlet pipe of each hydraulic oil pump is connected to an oil tank, and the outlet pipe of each hydraulic oil pump is connected to a solenoid directional valve. Multiple solenoid directional valves correspond one-to-one with multiple hydraulic cylinders. The two outlet ports of each solenoid directional valve are connected to the upper and lower chambers of its corresponding hydraulic cylinder, respectively. The return ports of each solenoid directional valve are connected to the oil tank via return pipes. Multiple hydraulic cylinders are symmetrically arranged at the bottom of the lifting platform.

2. The variable frequency speed regulation hydraulic synchronous control system according to claim 1, characterized in that: A shut-off valve is installed on the oil outlet pipe between the electromagnetic directional valve and the lower chamber of the hydraulic cylinder.

3. The variable frequency speed regulation hydraulic synchronous control system according to claim 2, characterized in that: The hydraulic pump is equipped with a first suction oil filter on its inlet pipe, and the first suction oil filter is located inside the oil tank.

4. The variable frequency speed regulation hydraulic synchronous control system according to claim 3, characterized in that: A first check valve is installed on the oil outlet pipe between the hydraulic oil pump and the solenoid directional valve.

5. The variable frequency speed regulation hydraulic synchronous control system according to claim 4, characterized in that: A second oil suction filter is installed on the return oil pipe between the electromagnetic reversing valve and the oil tank.

6. The variable frequency speed regulation hydraulic synchronous control system according to claim 5, characterized in that: The second check valve is located on the return oil pipe between the second suction oil filter and the solenoid directional valve.

7. The variable frequency speed regulation hydraulic synchronous control system according to claim 6, characterized in that: An overflow pipe is connected to the oil outlet pipe between the first check valve and the solenoid directional valve. A flow sensor and an overflow valve are installed on the overflow pipe. The outlet of the overflow pipe is connected to the oil tank. The flow sensor is connected to the PLC controller.

8. The variable frequency speed regulation hydraulic synchronous control system according to claim 7, characterized in that: The hydraulic cylinder is equipped with a displacement sensor, which is connected to the PLC controller.

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