Design And Experimental Study Of Pressure Compensated Hydraulic Reciprocating Seal

Hydraulic cylinders are the most common and primary actuators in hydraulic systems,and the effectiveness of the seal is a key factor in ensuring proper operation of the cylinder.The common sealing ring of the hydraulic cylinder has the disadvantages of fast wear,easy aging of the seal and short working life,etc,and the seal with compensation function can improve the sealing performance by increasing the sealing contact pressure,which makes the reliability and service life of the seal increase.Compared to the conventional seal compensation method,the pressure compensated hydraulic reciprocating seal can improve the sealing performance by increasing the compensation pressure.Due to the autonomy and adjustability of the pressure compensation,the compensation seal has high research value and applicability.However,as the pressure-compensated seal improves in sealing performance,the friction of the seal pair will also increase,which will result in a decrease in the reliability of the seal and the mechanical efficiency of the hydraulic cylinder.Therefore,for pressure-compensated seals with different degrees of wear,in the case of comprehensive consideration of sealing performance and friction,it is necessary to optimize the compensation pressure so that the compensation sealing performance is kept in an optimal state.Moreover,due to the complexity of the contact state of the seal pair,it is necessary to design a test plan for multi-sensor monitoring to accurately extract the indexes and parameters reflecting the performance of the seal ring.In this paper,the design and experimental research of the pressure-compensated hydraulic reciprocating seal are carried out with the piston rod seal of the hydraulic cylinder as the object.The research work on the following aspects is mainly completed:(1)Based on the theory of failure probability of seal pair,the pressure-compensated hydraulic reciprocating seal was designed and optimized,and proved by finite element simulation: Compared to the common Y-shaped seal,the designed seal can improve the sealing performance by increasing the compensation pressure.(2)A system device for adjusting the compensation pressure online and a multi-sensor test protocol for monitoring the sealing contact state are designed.Through the data processing,based on the static sealing mechanism,fluid lubrication theory,wavelet packet analysis,time domain analysis,power spectrum analysis,etc,Nine indicators reflecting the sealing performance and friction characteristics of the pressure compensation seal were extracted: the minimum contact pressure and root mean square of external stroke static seal,the contact pressure root mean square of external stroke dynamic seal,the leakage of external stroke,the entropy of wavelet packet,the energy ratio of the lowest layer of wavelet packet,the root mean square of the oil film thickness of the outer stroke,the peak of the friction power spectrum,and the external frictional force are root mean square.(3)The relationship between compensation pressure and dynamic and static sealing performance and friction characteristic parameters was analyzed.(4)Based on the fuzzy analytic hierarchy process(FAHP),a comprehensive performance evaluation system for pressure compensation seals is established based on the extracted nine performance indicators.And through evaluation and optimization,the optimal compensation pressure value is given for the compensation seal of four different wear levels.