In the hydraulic servo control system, the servo valve is the core control element, and its performance directly affects the response speed and control accuracy of the system. Among them, rotary valve servo valve is widely used in high-precision servo system because of its compact structure, fast response and high control accuracy. However, how to achieve efficient sealing between rotating parts and fixed parts is one of the key technologies to ensure its normal operation. In this paper, the principle and realization of rotary sealing of rotary valve servo valve will be discussed.
First, the basic structure and working principle of rotary valve servo valve
Rotary valve servo valve is mainly composed of valve body, rotary valve core, driving motor and feedback mechanism. The motor drives the spool to rotate, changing the opening of the oil passage, thus accurately controlling the flow and direction of hydraulic oil. Because the valve core needs to rotate to realize the control function, it is necessary to seal the high-pressure hydraulic oil while rotating to prevent leakage and maintain the system pressure.
Second, the technical challenges of rotary seals
Traditional hydraulic valves mostly adopt slide valve structure, and its movement mode is axial sliding, which is easy to realize axial sealing; The rotary valve servo valve is different, and its spool needs to rotate continuously, which makes the sealing structure face the following challenges:
1. High dynamic sealing requirements: During the rotation of the valve core, the sealing parts should maintain good sealing performance under dynamic conditions.
2. Friction and wear problem: The rotating movement will easily lead to the wear of the seal due to friction, which will affect the service life and sealing effect.
3. Adaptability to high-pressure environment: The hydraulic system usually works under high pressure, and the sealing material and structure should have good pressure resistance.
Third, the main ways to realize the rotary seal
At present, the common rotary sealing methods for rotary valve servo valves include the following:
# 1. Mechanical seal (face seal)
Adopt two high-precision machined sealing end faces, one of which is fixed on the valve body and the other rotates with the valve core. The two end faces are tightly attached by spring or hydraulic pretension to form a seal. This method has good sealing performance and is suitable for high-pressure and high-speed rotating occasions, but it requires extremely high manufacturing accuracy and high cost.
# 2. Gap seal
By precisely machining the mating clearance between the valve core and the valve body, a very small annular clearance is formed during the rotation process to limit the leakage. This method is simple in structure and suitable for medium and low pressure systems, but it is difficult to meet the sealing requirements under high pressure.
# 3. Elastic sealing ring sealing
An elastic sealing ring such as rubber or polytetrafluoroethylene (PTFE) is installed outside the rotary valve core, and sealing is realized by its elasticity and friction. This method has simple structure and convenient installation, but the sealing ring is easy to wear and needs to be replaced regularly.
# 4. Composite sealing structure
In order to improve the sealing reliability, some high-performance servo valves adopt composite sealing design, such as “mechanical seal+elastic seal” combination, which not only ensures the sealing performance, but also prolongs the service life.
Fourth, the development trend of rotary seal
With the development of hydraulic servo system towards high pressure, high frequency and high integration, the future rotary sealing technology will pay more attention to the following aspects:
-Material innovation: develop sealing materials with higher wear resistance, high temperature resistance and corrosion resistance.
-Structural optimization: optimizing the seal structure design through computer simulation and fluid mechanics analysis.
-Intelligent monitoring: sensors are introduced to monitor the sealing state in real time, thus improving the reliability of the system.
V. Conclusion
Rotary seal technology is one of the key technologies in the design of rotary valve servo valve, which directly affects its working performance and service life. With the progress of material science, precision manufacturing and intelligent control technology, the rotary sealing scheme will be continuously optimized, which will promote the servo valve to develop in the direction of higher performance and longer life, and provide more reliable hydraulic control solutions for high-end equipment manufacturing industry.