In modern industrial automation and hydraulic control system, flow control servo valve, as one of the key components, is widely used in aerospace, machinery manufacturing, metallurgy, chemical industry and other fields. Its main function is to achieve high-precision control of the speed and position of the actuator (such as hydraulic cylinder or hydraulic motor) by accurately adjusting the flow in the hydraulic system. Therefore, it is very important to measure the flow control servo valve, which is directly related to the control accuracy and operation stability of the system.
First, the basic principle of flow control servo valve
The flow control servo valve is a valve that can adjust the output flow quickly and accurately according to the input electrical signal. It is usually composed of electromagnetic torque motor, nozzle baffle mechanism and slide valve, and has the characteristics of fast response, good dynamic performance and high control accuracy. Its working principle is to control the position of the valve core by controlling the current or voltage signal, so as to change the opening of the valve port and then control the fluid flow through the valve body.
Second, the metering significance of flow control servo valve
Because the performance of servo valve directly affects the control accuracy and efficiency of hydraulic system, it is of great significance to accurately measure its flow. On the one hand, the key parameters such as flow gain, linearity and repeatability of servo valve can be evaluated by measurement; On the other hand, in equipment maintenance and fault diagnosis, flow measurement is also an important basis to judge whether the servo valve works normally.
Third, the method of flow measurement
1. Volumetric method
Volumetric method is a traditional flow measurement method, which calculates the actual flow by measuring the volume of fluid flowing in unit time. This method is suitable for laboratory environment with high accuracy, but the operation process is complicated and it is not suitable for online real-time monitoring.
2. Mass flowmeter method
Coriolis mass flowmeter can directly measure the mass flow of fluid, which is not affected by factors such as fluid density and temperature, and has high measurement accuracy, and is suitable for high-precision servo valve performance test.
3. Differential pressure method
The differential pressure method calculates the flow by measuring the pressure difference before and after flowing through the throttle device, which is suitable for medium and high flow measurement. The cost of this method is low, but the measurement error is large in low flow area.
4. Dynamic response test method
In the dynamic performance test of servo valve, step signal input is often used, and the response time and flow curve of the valve are recorded by high-speed data acquisition system, so as to evaluate its dynamic characteristics.
Four, the factors affecting the measurement accuracy
1. Temperature and pressure fluctuations
The change of fluid temperature and system pressure will affect the viscosity and density of fluid, and then affect the accuracy of flow measurement.
2. Installation conditions
The installation position of the valve, the symmetry of the pipeline and whether there is disturbance will also affect the measurement results.
3. Sensor accuracy
The accuracy of measuring equipment such as flow sensor and pressure sensor directly affects the final measurement result.
V. Conclusion
With the increasing demand for precision and efficiency in industrial control system, the position of flow control servo valve is increasingly prominent. The scientific and accurate measurement of its flow not only helps to improve the control performance of the system, but also provides a reliable basis for the maintenance of equipment. Therefore, it is the key to improve the overall performance of the hydraulic system to establish a sound servo valve testing and metering system, select high-precision measuring equipment and combine advanced data analysis methods.