Clearance Design And Dynamic Simulation For The Displacer And Cylinder Of Stirling Engine

Compared with the traditional internal combustion engine, the stirling engine had thecharacteristics such as simple structure, stable operation, easy maintenance and no knock. It wassufficient to achieve a high efficiency, low noise, low pollution and low running costs. With theimprovement of the energy crisis and exacerbated Stirling engine technology, the application ofthe stirling engine on the vehicle had been paid attention to once again. The question of the gapbetween displacer and cylinder was an important issue of free-piston engine design. If the gap wastoo big, it would affect the efficiency of gas distribution. The too small gap would stick anddamage the cylinder. This paper studied the characteristics of the gap between displacer andcylinder of the free-piston engine piston. The main work was as follows:（1）The main structural dimensions of a4kW free piston Stirling engine had been designed.The parameters such as average cycle pressure, operating frequency, stroke, cylinder diameter,dead volume of the heat transfer system.etc were determined. And then the engine heat exchangersystems, cylinders, pistons and other parts were designed.（2）Based on ADAMS, the dynamic analysis on the displacer was accomplished. It analyzedthe mechanical properties of the deformation characteristics of the flexible piston spring, force,kinetic and potential energy, axial and lateral piston spectral characteristics.（3）Performance simulation was conducted on the flexible spring using ANSYS. Therelationship between the thickness, length of involute spline, closed radius.etc structuralparameters and the axial stiffness and radial stiffness were obtained. The maximum stress wasoptimized by Workbench to the flexible spring. The result shows that by changing the part size ofthe flexible spring, the maximum stress of the flexible spring can be effectively optimized. Themaximum stress are decreased by25%, and the life of the flexible spring are effectively improved.（4）The characteristics of the displacer caused by the various factors affecting the gapbetween displacer and cylinder were analyzed. A clearance design method was proposed, and theengine of the designed gap was determined using this design method. A simulation was conductedusing ADAMS. The results show that the minimum design clearance of the piston and cylinderwas0.168mm，the minimum clearance of the steady vibration state is0.145mm. Then it provideda reference for the design for the same type of engine.