Modeling and Simulation on the Control System of a Hydro-Mechanical Stepless Steering Mechanism

The paper creates a bond graph model of the control system of a hydro-mechanical stepless steering mechanism for a tracked vehicle in 20Sim software. Based on this model, the dynamic characteristics of combining and separating of the brake during the range shift process is analyzed. The result of simulation shows that there is a 0.1s interval during the shift process of the two brakes which may generate a power interruption in vehicle steering process. In order to resolve this problem, the brake which is coming to combine can be charged oil first, and then the brake which is coming to separate is discharged. That means the two brakes have an oil-filled state at same time. The result of simulation indicates the reasonable value of the time is 0.08 second. At last the paper brings forward an improvement to the control system to meet the requirement of oil-filled state at same time.