Application of energy method in the design of hydraulic free piston diesel engines

Based on energy method, parametric design and matching methods for the hydraulic free piston diesel engine are proposed according to its working principle and structural features. The forces acting on the pistons during operation process and the corresponding section areas of the pistons are analyzed. Energy balance equations of the hydraulic free piston diesel engine during operation are established. By solving the equations, the hydraulic free piston diesel engine parameters matching law between structure parameters and performance parameters is obtained. The results provide a theoretical reference to the design of hydraulic free piston diesel engine. Using the design method, a prototype design and experimental verification on the validity of the method are made. The methods can also be applied to other forms of free piston engine designs.