A Novel Bond Graph Based Model for Buffer System

The damage of cylinder and equipment due to the pile detaching can be avoided by using the buffer device with large flow, which adopts throttle buffer inside the cylinder combining with the control of the relief valve outside the cylinder. To investigate the thermodynamic characteristics of the cylinder chambers and the law of movement of piston, the accurate mathematic model need to be established so the method based on pseudo-bond graph is introduced. According to the conservation equations for mass and energy, the thermal- hydraulic pseudo bond graph C and R elements are developed, and the connection rule for the two elements are determined based on their input and output variables. The bond graph model of the buffer system containing the coupled of multiple energy domains is obtained in a unified way based on the structure and working principle of buffer device, then the system state equations have been derived from the model. The model can be used in variable parameters' simulation with the parameters in the experiment, the pressure simulation data of two chambers of impact cylinder agree well with the experimental results, which indicate that the model can be used for the design and optimization of buffer device of hydraulic pile hammer.