Abstract: A new type electro-hydraulic proportional relief valve with G-π bridge pilot hydraulic resistance network is designed. The principle of the valve operation is analyzed. The construction and parameters of the valve are determined. The steady state equations are written out, which describe the flow pressure performances about the hydraulic resistances and force balance characteristic on the main poppet and pilot poppet. Furthermore, the relational equation of the parameters for the valve with zero override is obtained, which offers the calculation method for the design of the valve. The load characteristic of the valve with different hydraulic resistances is simulated by numerical computation. The new valve is developed and the steady state performance of the valve with different hydraulic resistances is measured. The results of experiment and simulation show that load characteristic of the π bridge electro-hydraulic proportional relief valve is much better than traditional pro-portional relief valve.

Key words: G-π bridge hydraulic resistance network, Load characteristics, Numerical computation, Proportional relief valve