Energy-saving method and energy-saving device of pressure control hydraulic system

The invention provides an energy-saving device of a pressure control hydraulic system. The energy-saving device comprises a variable pump, an oil tank, an energy accumulator communicated with an oil outlet in the variable pump, and a one-way valve arranged between the energy accumulator and the variable pump; the displacement of the variable pump is controlled by a variable oil cylinder; a rodless cavity of the variable oil cylinder is communicated with the oil tank via a first damping hole. The pressure control hydraulic system energy-saving device is characterized by further comprising an energy-saving control valve group; the energy-saving control valve group is communicated with an oil circuit between the energy accumulator and the one-way valve via a pressure signal oil pipe. According to the invention, an inlet pressure signal of the energy accumulator is transmitted to the energy-saving control valve group via the pressure signal oil pipe, so that when the inlet pressure of the energy accumulator is higher than a set upper limit value of the energy-saving control valve group, the variable pump is in a low-voltage small-displacement standby state, while when the inlet pressure of the energy accumulator is lower than a set lower limit value of the energy-saving control valve group, the variable pump returns to a large-displacement state and supplements oil to the system. During the whole process, energy consumption can be reduced, and the system can work more stably.