A film-type pressure self-adaptive watertight junction box in deep-sea equipment

Junction box, an important component in deep-sea equipment, is often used for power conversion and distribution, signal processing, and data communication. Its performance, such as watertightness, pressure compensation, is closely associated with work limit of deep-sea equipment. However, its performance has hardly been evaluated. In this paper, a film-type pressure self-adaptive watertight junction box (FPJB) is proposed and proved to possess better compensation performance with pre-compression pressure method. First, the mathematic relationship between water depth and pressure difference is established with the consideration of oil compressibility and residual gas. How the factors, such as depth, pre-compression pressure, film thickness, initial volume and residual gas content, affect FPJB compensation performance is analyzed and discussed via simulation. The results show that the pre-compression method significantly enhances the FPJB compensation performance, and thinner film thickness, smaller initial volume and lower residual gas content help to improve its compensation performance as well. The FPJB prototype test in high pressure-chamber further verifies its feasibility, reliability and pressure-keeping property. This study could provide references for similar deep-sea equipment designs.