Abstract: The water depth pressure exerts great effects on performance and reliability of marine electromechanical equipment. Based on Material-field Model and Contradiction Matrix of TRIZ theory, a case study of deep-sea water hydraulic solenoid valve (DWSV) is chosen to discuss the water depth pressure compensation methods. A new method, which is called as "hard compensation" is presented. A model of the hard-compensated DWSV is developed. A pilot prototype and a test bench are designed and manufactured. Numerical and experimental studies are carried out to investigate the valve's performances and its influence factors. The results show the following:① The hard-compensated DWSV has good performances:the numerical results are consistent with the experimental ones; the opening pressure is small and about 0.3 MPa; the valve has good sealing performance and no leakage in off state; the pressure loss is small when the valve opening completely and it's about 0.25 MPa at the rated flow (7 L/min); the valve has good dynamic response characteristics, the opening time t₁ ≤ 30 ms and closing time t₂ ≤ 63 ms. ② The hard-compensation method can compensate the water depth pressure effectively. The water depth exerts no effects on the relative engaging pressure and the response time of the prototype, while the system working pressure has effects on them when it works undersea (≤ 2 km). A new method is provided for the design of the depth pressure compensation system of marine electromechanical equipment.

Key words: hard compensation, material-field model, pressure compensation, TRIZ theory, water hydraulic solenoid valve