Research on a kind of self-compensation variable-clearance sealing hydraulic cylinder with a thin shell structure

Hydraulic cylinder is the most typical hydraulic actuator. The traditional sealing ring used in hydraulic cylinder produces the friction which greatly affects the high speed performance of the hydraulic cylinder. Researchers tried to improve the situation by improving sealing material and structure. But the problem between friction and leakage is not solved radically. Then a kind of high speed hydraulic cylinder with low friction was developed. The constant clearance seal technology was employed in this hydraulic cylinder. This hydraulic cylinder with constant clearance seal has the characteristics of low friction and fast speed. However, the internal leakage always exists, and the hydraulic cylinder volume efficiency is obviously decreased with the working pressure increasing. There is a contradiction between the sealing performance and working pressure in the hydraulic cylinder. To solve the above problems, we propose a kind of self-compensation variable-clearance sealing hydraulic cylinder. The compensation mechanism, compensation effect and adaptability of variable clearance seal are studied. The load analysis model of the piston lip in flow field is established. These provide theoretical basis and technical support for design and manufacture. Then the optimization method of the piston structure of variable clearance hydraulic cylinder is studied. Three different types of piston structures are proposed. And the piston structure with the best sealing effect is determined by the comparison of the study. The test platform is developed. Measure methods are adopted to measure the static and dynamic internal leakage respectively. The validity of the theoretical research is verified through tests.