A device and method for measuring fluid forces on a valve disc of a relief valve

Abstract

A kind of overflow valve disc fluid force measuring device and test method for measuring the fluid force on the valve disc under different pressures and different valve openings. The test bench is mainly composed of four parts: oil supply system, control system, valve disc fluid force test system and data acquisition system. The variable frequency motor is used in the oil supply system, and a proportional-integral-derivative (PID) control method is proposed to adjust the motor speed. The motor speed is adjusted in real time to obtain accurate pressure values. The fluid force test system includes a valve opening adjustment mechanism that can accurately adjust the valve opening in cooperation with a laser displacement sensor. The fluid force measuring mechanism mainly measures the lift of the valve disc in real time through an S-shaped force sensor. The valve body is made of transparent material PMMA, which can observe the change of valve disc opening in valve body in real time, and also can observe the action state of hydraulic oil on valve disc. The device has simple structure, high precision and high safety, which provides guarantee for the test of overflow valve fluid force.

Description

Technical Field

[0001] This invention belongs to the field of valve testing technology, and relates to a device and method for measuring fluid force on the valve disc of an overflow valve. Background Technology

[0002] Valves are common industrial devices used to control the flow of fluids such as liquids, gases, and steam. Their existence can be traced back to ancient civilizations, where people used simple materials like stone or wood to make valves for irrigation, water diversion, and transportation. With technological advancements and industrial development, valves have evolved from manual manufacturing to mechanized production, constantly being optimized and improved, and applied in more fields such as petrochemicals, power generation, and mining. Modern valves are mainly divided into different types, including gate valves, regulating valves, safety valves, check valves, and drain valves. Different materials, structures, and actuation methods can be selected according to their actual application to meet the needs of specific working conditions. Relief valves are a typical industrial valve, playing a crucial role in hydraulic systems. Their main function is to control the pressure in the hydraulic system, ensuring the system operates within a safe range. However, during hydraulic system operation, relief valves may experience "chatter" and "frequent jumping" during opening and closing. These phenomena can cause serious consequences such as wear on the sealing surface and media leakage. Improper handling can lead to safety risks to equipment and personnel. Numerous studies have demonstrated that the fluid force on the valve disc is a key factor contributing to valve chatter and frequent skipping. However, the measuring device in the paper "Design and Performance Analysis of Permanent Magnet Spring Pilot-Operated Relief Valve" cannot accurately measure the fluid force acting on the valve disc, nor can it observe the internal changes in this force in real time. Therefore, research on the fluid force on the valve disc of relief valves is of great significance, and there is an urgent need to invent a device and method for testing the fluid force on the valve disc of relief valves. The invention and method presented in this paper effectively solve the aforementioned problems. Summary of the Invention

[0003] To address the problems of existing technologies, this invention provides a simple and highly accurate fluid force measurement device and testing method for precisely measuring the fluid force on the valve disc of an overflow valve. Regarding the testing device, firstly, a valve disc opening adjustment system combining a micrometer function and a gear-rack linear motion mechanism is designed, and a laser displacement sensor is used to achieve precise adjustment of the valve disc opening. Secondly, the valve core is led out of the overflow valve body and connected to an S-type sensor to measure the fluid force. Finally, the valve disc opening adjustment system and the overflow valve are integrated as a whole to achieve precise measurement of the valve disc fluid force. Regarding the testing method, this invention proposes PID control, applying the PID control method to a variable frequency motor. By monitoring the pressure value of the pressure sensor before the valve, the speed of the variable frequency motor is adjusted in real time to achieve stable control of the inlet pressure before the valve.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] A measuring device for measuring the fluid force on the valve disc of an overflow valve is disclosed, used to measure the fluid force exerted on the valve disc under different pressures and valve openings. The measuring device comprises four parts: an oil supply system, a control system, a valve disc fluid force testing system, and a data acquisition system.

[0006] The oil supply system includes a variable frequency motor 1, an oil tank 3, pressure gauges A4 and B4, a control cabinet 5, an oil delivery pipe 6, an oil return pipe A17 and B18, an oil delivery pipe fixing base 7, and an accumulator 19. The variable frequency motor 1 is vertically mounted above the oil tank 3 via fixing bolts. One end of the motor extends into a cable connected to the control cabinet 5, which is connected to a PC. The motor 1 primarily receives control commands from the control cabinet 5. An accumulator 19 is fixed to the side of the oil tank 3. The accumulator 19 contains a large amount of air and a certain amount of liquid; the air acts as a spring, storing a certain amount of energy. Two pipes, the oil delivery pipe 6 and the oil return pipe A17, extend from the beginning of the oil tank 3. A pressure gauge B4 is installed on the oil delivery pipe 6 to monitor the outlet pressure. After being controlled by the variable frequency motor 1, the end of the oil delivery pipe 6 is connected to the inlet of an overflow valve. Simultaneously, eight pipeline pressure sensors 8 are installed along the transmission path of the oil delivery pipe 6. The return oil pipe is equipped with a pressure gauge A4. After passing through an adapter, it splits into two paths: the first return oil pipe B18 is a loop that does not pass through the overflow valve, and the second return oil pipe A17 is a loop that passes through the overflow valve. Specifically: the first path, called return oil pipe B18, is the pipeline through which the oil supply pipe 6 flows directly back to the oil tank via the oil supply pipeline fixed base 7 and the overflow valve inlet; the second path, called return oil pipe A17, is the pipeline through which the oil supply pipe 6 passes through the oil supply pipeline fixed base 7, acts on the overflow valve disc, and flows back to the oil tank from the overflow valve outlet. Different oil supply volumes are obtained by adjusting the speed of the variable frequency motor 1, and the speed of the variable frequency motor 1 is adjusted in real time by monitoring the pressure value of the pressure sensor 9 before the valve, thereby achieving stable control of the inlet pressure before the valve.

[0007] The control system consists of a control cabinet 5 and a control device. The control system is connected to the variable frequency motor 1 via a cable to transmit control signals.

[0008] The valve disc fluid dynamics testing system includes a pre-valve pressure sensor 9, a post-valve pressure sensor 11, a valve core 12, a transparent valve body under test 10, an iron sheet 13, an S-type force sensor 14, a laser displacement sensor 15, a display 16, a ball valve manifold block 21, a valve seat 22, a valve disc 23, an outlet pipe 24, a main valve body 25, a valve opening adjustment mechanism 31, and a valve opening adjustment knob 32. The fluid dynamics testing system ( Figure 2b) The front end is connected to the oil supply pipe 6, and the rear end is connected to the return oil pipe A17. The entire overflow valve assembly is bolted to the right side of the oil supply pipe fixing base 7, with the valve body placed vertically. The system is described from bottom to top as follows: A Keyence pressure sensor 9 and 11 are installed before and after the valve under test, respectively, to monitor the pressure at the valve inlet and outlet, providing accurate boundary conditions for numerical simulation. Specifically: The pre-valve pressure sensor 9 is installed after the oil supply pipe 6 and connected to the overflow valve input port to monitor the valve inlet pressure. The post-valve pressure sensor 11 is installed at the valve outlet to monitor the valve outlet pressure. The lower end of the transparent valve body 10 is threadedly connected to the oil supply pipe, and the valve body outlet is connected to the return oil pipe A17. The main valve body 25 is nested on the transparent valve body 10. Within the transparent valve body 10, the ball valve manifold block 21, valve seat 22, valve disc 23, main valve body 25, return spring 26, spring seat 27, stop 28, locking nut 29, and valve core 12 are sequentially nested together from bottom to top. Finally, these components are fixed in the transparent valve body 10 by the locking nut. The ball valve manifold block 21 is fixed below the valve seat 22, controlling the direction, pressure, and flow rate of the fluid. The valve seat 22 is located below the valve disc 23; when the system is not running, the two are close together, and when the system is running, it lifts the valve disc 23. The upper end of the valve disc 23 is threadedly connected to the valve core 12. The iron plate 13 and the valve core 12 are connected in series by bolts and rise as the valve disc 23 rises. The return spring 26 is removed in this invention for more intuitive and accurate measurement of fluid force; the valve disc 23 and valve core 12 are physically connected as a single unit. Figure 2 a to 2b. The lower end of the S-type sensor 14 is threaded to the valve core 12, and the upper end is bolted to the movable part 32. The S-type sensor deforms as the valve disc 23 rises, thereby obtaining the magnitude of the fluid force on the valve seat 23. The laser displacement sensor 15 is fixed to the transparent valve body 10 via a connector and is located directly above the iron plate 13. The reading on the display 16 changes as the iron plate 13 rises. The display 16 integrates the transmitted data from the laser displacement sensor 15 and the S-type force sensor 14, and can display them simultaneously. The valve opening adjustment mechanism 31 consists of a micrometer and a gear-rack linear motion mechanism, located directly behind the S-type force sensor 14. Its upper end is connected to the S-type force sensor 14 by a fixing bolt 34, and its lower end is connected to the transparent valve body by a bolt through a connector 30. The valve opening adjustment mechanism 31 is equipped with a movable part 32 and a valve opening adjustment knob 33. During use, the movable part 32 is driven to move linearly along the axis by the valve opening adjustment knob 33 to achieve the adjustment of different valve openings.

[0009] The data acquisition system is built using the DAQ system on the LabVIEW platform. This platform consists of an industrial control computer and a data acquisition card, which are integrated into a control cabinet for the sake of neatness.

[0010] Furthermore, the speed adjustment of the variable frequency motor 1 is achieved by using a proportional-integral-derivative (PID) control method, and the maximum oil supply flow rate of the oil supply system can reach 75L / min.

[0011] Furthermore, the transparent test body 10 is an improvement on a commercially available direct-acting safety relief valve, which is installed vertically. The transparent test valve is made of PMMA material, and the flow state of the fluid inside the valve can be directly observed during the test.

[0012] A method for testing the fluid dynamics of an overflow valve disc based on the aforementioned testing apparatus is proposed. A PID control method is applied to the variable frequency motor 1, and the speed of the variable frequency motor 1 is adjusted in real time by monitoring the pressure value of the pressure sensor 9 before the valve, thereby achieving stable control of the inlet pressure before the valve. The method includes the following steps:

[0013] First, turn on all power. Adjust the opening of the overflow valve using the valve opening adjustment mechanism 31, and use the laser displacement sensor 15 to provide feedback on the adjusted distance to achieve the desired opening. Turn on the PC and, in the industrial software, determine whether the output mode of the variable frequency motor 1 is flow or pressure. Generally, we control the output by controlling the pressure.

[0014] The second step involves confirming the start-up on the PC. At this point, the variable frequency motor 1 begins to run, and the liquid in the oil tank 3 begins to be output through the output pipe 6. Eight pressure sensors 8 in the oil supply pipeline simultaneously collect pressure data at different locations within the pipeline. The pre-valve and post-valve pressure sensors 9 and 10 also begin collecting data. The laser displacement sensor 15 and the S-type force sensor 14 transmit data to the display 16, which displays the opening degree and fluid force in real time. Simultaneously, the variable frequency motor adjusts the output pressure in real time based on the data from the pre-valve pressure sensor 9, thereby outputting a stable liquid pressure to ensure stable fluid force. After the force magnitude and valve opening degree data stabilize, the data is collected and recorded.

[0015] In the third step, the data from the laser displacement sensor 15 and the S-type force sensor 14 are transmitted to the PC via a data cable. After processing by industrial software, the fluid force curve, as well as the data from the eight pressure sensors 8 and the pre-valve and post-valve pressure sensors 9 and 10, are displayed in real time. The processed data is then saved, completing one experiment. By determining the final stable value of the fluid force, the purpose of measuring fluid force in the device and method of this invention is achieved.

[0016] To test data under different opening degrees and pressures, the experiment needs to be repeated by changing the valve opening height or pressure and refilling with oil. After completing the experiments with all different parameters, the test system is shut down, and the experiment ends. After all experiments are completed, the collected data and the data curves displayed on the PC are analyzed to obtain the hydrodynamic characteristics of the relief valve disc and to study other related performance characteristics.

[0017] The beneficial effects of this invention are as follows:

[0018] (1) This test device is suitable for testing the fluid force of valve discs of valves similar to those of overflow valves. The entire test device has a simple structure and is easy to implement.

[0019] (2) This test device adjusts the opening of the overflow valve disc through the valve opening adjustment mechanism, and the laser displacement sensor can provide feedback on the distance the iron plate moves so as to know the opening of the overflow valve disc. The minimum adjustment is 0.01mm each time, which makes the valve opening adjustment more accurate.

[0020] (3) The motor used in this test device is a variable frequency motor. The speed regulation of the motor is achieved by proportional-integral-derivative (PID) control method. The motor speed is adjusted in real time by monitoring the pressure value of the pressure sensor in front of the valve, so as to achieve stable control of the inlet pressure in front of the valve.

[0021] (4) The overflow valve body of this test device is made of industrial-grade transparent PMMA material, which allows for real-time observation of changes in the valve disc opening and eliminates issues such as valve disc tilting or jamming. This greatly improves the safety, reliability, and observability of the experiment.

[0022] (5) This test setup can perform experiments with different parameters. The valve opening adjustment device can adjust different valve openings. The variable frequency motor can handle both low-pressure and high-pressure tests. Under the control system, the pressure accuracy can be maintained at around 0.1 MPa. This greatly expands the pressure testing range and ensures the accuracy of pressure testing.

[0023] (6) This testing device uses a data acquisition card to acquire signals from displacement, air pressure, and force sensors, which has high acquisition accuracy and is convenient. The PC has supporting programs to process and save data and display data curves in real time, providing good data visualization. Attached Figure Description

[0024] Figure 1 Overall structural diagram of the test device for the hydrodynamics of the overflow valve disc;

[0025] Figure 2 A schematic diagram of the original structure of the overflow valve body (a); a schematic diagram of the structure of the overflow valve body according to the present invention (b);

[0026] Figure 3 Schematic diagram of valve opening adjustment device;

[0027] Figure 4 Workflow diagram of the overflow valve disc hydrodynamic testing device;

[0028] In the diagram: 1. Variable frequency motor; 2. Pressure gauge A; 3. Oil tank; 4. Pressure gauge B; 5. Control cabinet; 6. Oil delivery pipe; 7. Oil delivery pipe fixing base; 8. Eight pressure sensors; 9. Pre-valve pressure sensor; 10. Transparent valve body; 11. Post-valve pressure sensor; 12. Valve core; 13. Iron sheet; 14. S-type force sensor; 15. Displacement sensor; 16. Fluid dynamics display; 17. Return oil pipe; 18. Return oil pipe; 19. Accumulator; 20. Nut; 21. Ball valve manifold block; 22. Valve seat; 23. Valve disc; 24. Outlet pipe; 25. Main valve body; 26. Return spring; 27. Spring seat; 28. Stop; 29. ​​Locking nut; 30. Fixed bracket; 31. Valve opening adjustment mechanism; 32. Movable part; 33. Valve opening adjustment knob; 34. Fixing bolt. Detailed Implementation

[0029] The present invention will now be described in more detail with reference to the accompanying drawings;

[0030] A general structural diagram of a testing device for the hydrodynamics of an overflow valve disc is shown below. Figure 1 As shown, it includes an oil supply system, a control system, a valve disc hydrodynamic testing system, and a data acquisition system.

[0031] The oil supply system includes a variable frequency motor 1, pressure gauge A4, oil tank 3, pressure gauge B4, control cabinet 5, oil delivery pipe 6, oil delivery pipe fixing base 7, return oil pipe A17, return oil pipe B18, and accumulator 19. The variable frequency motor 1 is vertically mounted above the oil tank 3 via fixing bolts. One end of the variable frequency motor 1 extends a cable connected to the control cabinet 5, primarily receiving control commands from the control cabinet 5. An accumulator 19 is fixed to the right side of the oil tank 3, containing a large amount of air and a certain amount of liquid. The air acts as a spring, storing a certain amount of energy. Two pipes extend from the beginning of the oil tank 3: the oil delivery pipe 6 and the return oil pipe A17. The oil delivery pipe 6 is equipped with a pressure gauge 4 for monitoring the outlet pressure. After being controlled by the variable frequency motor 1, the end of the oil delivery pipe 6 is connected to the inlet of an overflow valve. Simultaneously, eight pipeline pressure sensors 8 are installed along the transmission path of the oil delivery pipe 6, mounted on the oil delivery pipe 6 via the oil delivery pipe fixing base 7. The return oil pipe is equipped with a pressure gauge 2. After passing through an adapter, it splits into two paths: the first return oil pipe 18 is a loop that does not pass through the overflow valve, and the second return oil pipe 17 is a loop that passes through the overflow valve. Specifically: the first path, called return oil pipe 18, is the pipeline through which the oil supply pipe 6 passes through the oil supply pipeline fixed base 7, acts on the overflow valve disc, and flows back to the oil tank from the overflow valve outlet. The second return oil pipe 17 is the pipeline through which the oil supply pipe 6 passes through the oil supply pipeline fixed base 7, acts on the overflow valve disc, and flows back to the oil tank from the overflow valve outlet. Different oil supply volumes can be obtained by adjusting the speed of motor 1, and the maximum oil supply flow rate of the oil supply system can reach 75L / min. The motor speed is adjusted using a proportional-integral-derivative (PID) control method. The motor speed is adjusted in real time by monitoring the pressure value of the pressure sensor 9 before the valve, thereby achieving stable control of the inlet pressure before the valve.

[0032] The valve disc fluid dynamics testing system includes a pre-valve pressure sensor 9, a transparent valve body 10, a post-valve pressure sensor 11, a valve core 12, an iron plate 13, an S-type force sensor 14, a displacement sensor 15, a display 16, a nut 20, a ball valve manifold block 21, a valve seat 22, a valve disc 23, an outlet pipe 24, a main valve body 25, a return spring 26, a spring seat 27, a stop 28, and a locking nut 29. The fluid dynamics testing system ( Figure 2b) The front end is bolted to the oil pipeline mounting base 7, with the valve body placed vertically. Keyence pressure sensors 9 and 11 are installed before and after the valve under test, respectively, to monitor the pressure at the valve inlet and outlet, providing accurate boundary conditions for numerical simulation. Specifically: the pre-valve pressure sensor 9 is installed after the oil pipeline 6 and connected to the relief valve input port to monitor the valve inlet pressure. The post-valve pressure sensor 11 is installed at the valve outlet to monitor the valve outlet pressure. The transparent valve body 10 is used for real-time monitoring of the valve body's internal condition throughout the system's operation. The transparent test valve 10 is an improvement on a commercially available direct-acting safety relief valve, installed vertically. Made of PMMA material, the transparent test valve allows for direct observation of the fluid flow within the valve during testing. The main valve body 25 is nested on the transparent valve body 10. Within the main valve body 25, the valve seat 22, valve disc 23, return spring 26, spring seat 27, stop 28, locking nut 29, and valve core 12 are sequentially nested from bottom to top, and finally secured in the valve body by the locking nut 29. The valve seat 22 is fixed in the groove of the valve body 10. Oil flows from the oil supply pipe through the valve seat and then acts on the valve disc 23, thus generating fluid force. The return spring 26 is held in place on the valve disc. To test the steady-state fluid force, the return spring 26 is removed from the transparent valve body 10, and the valve core 12 is led out of the valve body 10. The valve disc 23 and the valve core 12 are physically connected as one unit. Figure 2a to 2b. The extended valve core 12 is connected to the S-type force sensor 14. The sensor has a range of 0–200 N and a measurement accuracy of 0.03% of full scale. The lower end of the S-type force sensor 14 is threaded onto the valve core 12, and the upper end is connected to the movable part 32 of the valve opening adjustment mechanism 31. This mechanism functions as both a guide rail and a micrometer. The valve opening adjustment mechanism is a single-degree-of-freedom linear motion mechanism based on the gear and rack transmission principle, allowing the valve core to move linearly along its axis. During the test, different valve openings can be adjusted by adjusting the valve opening adjustment knob 32, and a valve opening accuracy of 1E-5m can be achieved by using a scale. Because the S-type sensor undergoes slight deformation under stress, a non-contact laser displacement sensor 15 is installed on one side of the valve opening adjustment mechanism to ensure precise valve opening adjustment and to verify the valve opening adjusted by the valve opening mechanism. The sensor measures valve displacement by emitting a laser beam onto an iron plate 13 fixed to the valve core. The laser displacement sensor has a range of 10 mm (measuring range 20 mm to 30 mm from the laser emission position) and a measurement accuracy of 1E-6 m. The pressure sensor has a range of -0.1 to 1 MPa and a measurement accuracy less than ±1% of full scale. The display 16 integrates the transmitted data from the laser displacement sensor 15 and the S-type sensor 14, allowing simultaneous display. The valve opening adjustment mechanism 31 is located directly behind the S-type force sensor 14. Its upper end is connected to the S-type force sensor 14 by a fixing bolt 34, and its lower end is connected to the transparent valve body by a bolt through a connector 30. The valve opening adjustment mechanism 31 is provided with a movable part 32 and a valve opening adjustment knob 33.

[0033] The data acquisition system was built using the DAQ system on the LabVIEW platform. This platform consists of an industrial control computer and a data acquisition card, which are integrated into a control cabinet for the sake of overall neatness.

[0034] A method for testing the fluid dynamics of an overflow valve disc involves starting the test by activating the data acquisition system, adjusting the valve opening, determining the test pressure or flow rate, and then activating the system. The data acquisition card then collects signal data from pressure, displacement, and force sensors. A PC processes, saves, and displays and records this data in real time. The test is repeated when parameters are changed. If the valve opening is changed, the test is repeated by adjusting the valve opening; if the pressure is changed, the required pressure is set directly in the industrial software, and the test is repeated. The test ends upon completion of all experiments. The specific steps include:

[0035] First, turn on all power. Adjust the opening of the overflow valve using the valve opening adjustment device 31, setting the opening value to 0.5mm. Observe the adjustment distance fed back by the laser displacement sensor 15 on the display 16 until the opening reaches 0.5mm. Turn on the PC and, in the industrial software, determine whether the output mode of the variable frequency motor 1 is flow or pressure. Generally, the output is controlled by the pressure. First, input a small pressure on the pressure control interface and let the equipment run for a period of time to check for liquid leaks in the pipeline and valves, and check whether the value displayed by the force sensor matches the value of the data acquisition system. After confirming that everything is correct, set the pressure to 0.3MPa for this experiment and start the system.

[0036] The second step is to confirm the start-up on the PC. At this time, the variable frequency motor 1 starts to run, and the liquid in the oil tank starts to be output through the oil supply pipe 6. The eight pressure sensors in the oil supply pipe simultaneously collect pressure data at different positions in the pipe. The pressure sensors before and after the valve also start to collect data. The laser displacement sensor displays the opening size in real time on the display, and the S-type force sensor also displays the change in the magnitude of the fluid force in real time. After the magnitude of the force and the valve opening data stabilize, you can see an opening of 0.3MPa and 0.5mm, and the fluid force is 33N. This data is collected and recorded.

[0037] The third step involves transmitting sensor data to a PC via a data cable. Industrial software processes and displays the fluid dynamics curves and data from ten pressure sensors in real time, saving the processed data. This completes the experiment in one go. To test data at different opening degrees and pressures, the software needs to be restarted, the valve opening height changed, or the pressure altered, and oil refilled for testing. After completing experiments with all different parameters, the testing system is shut down, the experiment ends, and all power is turned off. Following the completion of all experiments, the collected data and the data curves displayed on the PC are analyzed to obtain the fluid dynamic characteristics of the overflow valve disc and to conduct further research on other related performance characteristics.

[0038] This specification is merely an enumeration of the implementation forms of the technical solution. The scope of protection of this invention should not be limited to the specific forms described in the embodiments, but should also include equivalent technical means conceived by those skilled in the art based on this technical method.

Claims

1. A device for measuring the fluid force on the valve disc of an overflow valve, used to measure the fluid force on the valve disc under different pressures and valve openings, characterized in that, The measuring device comprises four parts: an oil supply system, a control system, a valve disc hydrodynamic testing system, and a data acquisition system. The oil supply system includes a variable frequency motor (1), an oil tank (3), pressure gauge A (2), pressure gauge B (4), a control cabinet (5), an oil delivery pipe (6), an oil return pipe A (17), an oil return pipe B (18), an oil delivery pipe fixing base (7), and an accumulator (19). The variable frequency motor (1) is vertically installed above the oil tank (3), and one end of the variable frequency motor (1) extends a cable to connect to the control cabinet (5), which is connected to a PC. The accumulator (19) is fixed on the side of the oil tank (3). The oil tank (3) has two pipes extending from its beginning: an oil delivery pipe (6) and an oil return pipe. The oil delivery pipe (6) is equipped with a pressure gauge B (4) for monitoring the outlet pressure. After being controlled and output by the variable frequency motor (1), the end of the oil delivery pipe (6) is connected to the inlet of the overflow valve. At the same time, eight pipeline pressure sensors (8) are installed on the transmission path of the oil delivery pipe (6). The oil return pipe is equipped with a pressure gauge A (2). After passing through the adapter, the oil is divided into two paths. The first path, the return oil pipe B (18), is a circuit that does not pass through the overflow valve. The second path, the return oil pipe A (17), is a circuit that passes through the overflow valve. Specifically, the first path, the return oil pipe B (18), is the pipeline through which the oil supply pipe (6) flows directly back to the oil tank after passing through the fixed base (7) of the oil supply pipeline and the valve inlet of the overflow valve. The second path, the return oil pipe A (17), is the pipeline through which the oil supply pipe (6) flows back to the oil tank after passing through the fixed base (7) of the oil supply pipeline and acting on the valve disc of the overflow valve. The return oil pipe A (17) is the pipeline through which the oil supply pipe (6) flows back to the oil tank after passing through the outlet of the overflow valve after acting on the valve disc. Different oil supply quantities are obtained by adjusting the speed of the variable frequency motor (1). The speed of the variable frequency motor (1) is adjusted in real time by monitoring the pressure value of the pressure sensor (9) before the valve, so as to achieve stable control of the inlet pressure before the valve. The control system includes a control cabinet (5), which is connected to the variable frequency motor (1) through a cable for transmission of control signals. The valve disc fluid dynamics testing system includes a pre-valve pressure sensor (9), a post-valve pressure sensor (11), a valve core (12), a transparent valve body under test (10), an iron sheet (13), an S-type force sensor (14), a laser displacement sensor (15), a display (16), a ball valve manifold block (21), a valve seat (22), a valve disc (23), an outlet pipe (24), a main valve body (25), a valve opening adjustment mechanism (31), and a valve opening adjustment knob (33); the front end of the fluid dynamics testing system is connected to the oil supply pipe (6), and the rear end is connected to the return oil pipe A (17); the overflow valve component is fixed as a whole on the oil supply pipeline fixing base (7). On the right side, the valve body is placed vertically, with a pressure sensor (9) before the valve and a pressure sensor (11) after the valve installed before and after the valve being tested, respectively; the lower end of the transparent valve body (10) is connected to the oil supply pipeline, and the valve body outlet is connected to the return oil pipe A (17); the main valve body (25) is nested in the transparent valve body (10), and in the transparent valve body (10), the ball valve oil circuit block (21), valve seat (22), valve disc (23), main valve body (25), and valve core (12) are nested in each other from bottom to top, and finally the components are fixed in the transparent valve body (10) by locking nuts; the iron sheet (13) and the valve core (12) are connected in series. The valve disc (23) rises and rises with the valve core (12), and the valve disc (23) and valve core (12) are physically connected as one unit; the lower end of the S-shaped force sensor (14) is threaded to the valve core (12), and the upper end is tightened to the movable part (32) with bolts. The S-shaped force sensor deforms as the valve disc (23) rises, thereby obtaining the magnitude of the fluid force on the valve disc (23); the laser displacement sensor (15) is fixed to the transparent valve body (10) through a connector and is located directly above the iron plate (13). The reading on the display (16) will change as the iron plate (13) rises; the display (16) displays the laser displacement sensor. The transmission data of the displacement sensor (15) and the S-type force sensor (14) are integrated and can be displayed simultaneously; the valve opening adjustment mechanism (31) is located directly behind the S-type force sensor (14), and its upper end is connected to the S-type force sensor (14) by fixing bolts (34), and its lower end is connected to the transparent valve body by bolts through connectors (30); the valve opening adjustment mechanism (31) is provided with a movable part (32) and a valve opening adjustment knob (33); during use, the movable part (32) is driven to move linearly along the axis by the valve opening adjustment knob (33) to achieve the adjustment of different valve openings; The data acquisition system consists of an industrial control computer and a data acquisition card, which are integrated in the control cabinet (5).

2. The device for measuring fluid force on the valve disc of an overflow valve according to claim 1, characterized in that, In the valve disc fluid dynamics testing system, the inlet pressure sensor (9) is connected to the overflow valve input port to monitor the pressure at the valve inlet; the outlet pressure sensor (11) is installed at the valve outlet to monitor the pressure at the valve outlet.

3. The device for measuring fluid force on the valve disc of an overflow valve according to claim 1, characterized in that, In the valve disc fluid dynamic testing system, the ball valve oil circuit block (21) is fixed below the valve seat (22) and plays the role of controlling the direction, pressure and flow rate of the liquid flow; the valve seat (22) is located below the valve disc (23). When the system is not started, the two are attached together. When the system is turned on, the valve disc (23) is lifted up. The upper end of the valve disc (23) is connected to the valve core (12) by a thread.

4. The device for measuring fluid force on the valve disc of an overflow valve according to claim 1, characterized in that, The maximum oil supply flow rate of the oil supply system can reach 75L / min.

5. A method for testing the fluid dynamics of an overflow valve disc based on the measuring device described in any one of claims 1-4, characterized in that, Based on the PID control method, the PID control method is applied to the variable frequency motor (1). By monitoring the pressure value of the pressure sensor (9) before the valve, the speed of the variable frequency motor (1) is adjusted in real time to achieve stable control of the inlet pressure before the valve.

6. The test method according to claim 5, characterized in that, Includes the following steps: First, turn on all power, adjust the opening of the overflow valve through the valve opening adjustment mechanism (31), and use the laser displacement sensor (15) to provide feedback on the adjustment distance so that it reaches the required opening. Turn on the PC and in the industrial software, determine whether the output mode of the variable frequency motor (1) is flow or pressure; output by controlling the pressure. The second step is to confirm the start on the PC. At this time, the variable frequency motor (1) starts to run, and the liquid in the oil tank (3) starts to be output through the oil pipeline (6). The eight pressure sensors (8) in the oil pipeline simultaneously collect pressure data at different positions in the oil pipeline. The pressure sensor (9) before the valve and the pressure sensor (11) after the valve also start to collect data. The laser displacement sensor (15) and the S-type force sensor (14) transmit the data to the display (16). The display (16) displays the opening degree and the magnitude of the fluid force in real time. At the same time, the variable frequency motor adjusts the output pressure in real time through the data of the pressure sensor (9) before the valve, so as to output a stable liquid pressure to ensure the stability of the fluid force. After the magnitude of the force and the valve opening degree data are stable, the data are collected and recorded. The third step involves transmitting the data from the laser displacement sensor (15) and the S-type force sensor (14) to the PC via a data cable, displaying the fluid force curve in real time, as well as the data from the eight pressure sensors (8), the inlet pressure sensor (9), and the outlet pressure sensor (11), and saving the processed data. By determining the final stable value of the fluid force, the purpose of measuring the fluid force is achieved. To test data at different opening degrees and pressures, the experiment needs to be repeated by changing the valve opening height or pressure and refilling with oil. After completing the experiment with all different parameters, the test system is shut down, and the experiment ends.

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