The invention provides a hydrostatic driving method and device for a
snow pressing vehicle and a hydraulic
system, and relates to the technical field of
snow pressing vehicles. The method comprises the steps that the actual rotating speed of an engine is detected and compared with a preset optimal rotating speed range, and a rotating speed deviation
signal is generated; based on the rotating speed deviation
signal, the displacement adjusting amount of a variable pump and the displacement adjusting amount of a variable motor are calculated through an incremental
PID control algorithm; dynamically adjusting the displacement of a variable pump and a variable motor according to the displacement adjusting quantity so as to realize stable control on the rotating speed of the engine; wherein when the load is increased, the
variable displacement motor is adjusted to increase the displacement, and if the displacement of the motor reaches the maximum, the
variable displacement pump is adjusted to reduce the displacement; when the load is reduced, the
variable displacement pump is adjusted to increase the displacement, and if the pump displacement reaches the maximum, the variable displacement motor is adjusted to reduce the displacement. According to the method, the pump and the motor are cooperatively controlled through the incremental PID, the rotating speed of the engine is stabilized, efficient operation of the engine is maintained, and therefore the power
utilization rate and the fuel economy are improved.