Sealing characteristics and control strategies of hydraulically controllable rod seal for deep-sea hydraulic manipulators

Conventional rod seals are prone to failure, leading to frequent malfunctions in deep-sea hydraulic manipulators. In order to improve the reliability of seal, a novel hydraulically controllable rod seal structure is proposed in this article. The static and dynamic sealing characteristics of seals in deep-sea environments were analyzed, and the influences of regulation behavior and operating conditions on sealing performance were explored based on the established mixed thermal elastohydrodynamic lubrication model. A quantitative control strategy for optimal operation of the seal was established using response surface methodology and nonlinear fitting methods. The research results indicate that the pressure compensation function of the internal cavity enables the seal to adjust the contact state. With an increase in the initial regulation pressure of the cavity, von Mises stress, interface contact pressure, and friction force increase, whereas fluid film thickness and leakage decrease. The greater the seawater depth, the more obvious the control advantage of seals, and the easier it is for the seal to operate reliably in a low-leakage, low-friction state. However, the selection of a sealing material with high-strength and wear-resistant is essential.