Design Of Variable Compression Ratio Mechanism Based On Electrically Driven Variable Height Piston

Variable Compression Ratio(VCR)technology can effectively improve the power at low-load and thermal efficiency at high-load.This paper proposed a most feasible solution based on the research from domestic and foreign scholars and applied patents,and verified the feasibility of the designed mechanism from four aspects: simulation-design-experimentoptimization.This paper designed the mechanism based on ZS1100 single-cylinder diesel engine as the prototype.After comparing the various research program,adopted the scheme which used a transmission mechanism with trapezoidal thread and tooth structure at the final variable compression ratio piston design.By cooperating between gears and threads,the torque is transmitted from the mechanism of motor-bevel gear-spur gear-tooth structuretrapezoidal thread to the piston head.This causes an axial displacement of the piston so that compression ratio can be changed.In addition,the scheme also changes the motor from the piston pin seat to inside the piston pin design which not only reduces the modification of the original machine,but also saves the space.In this paper,CATIA was used to draw a three-dimensional model,and ADAMS and ANSYS were used to perform dynamic and static simulations.The piston displacement curves,speed curves,and acceleration curves at 500 r / min,1500 r / min,and 2200 r / min,and the mechanical stress simulation and thermo-mechanical coupling simulation results were obtained.And based on the simulation calculations,CAD was used to redesign the weak parts and stress concentration points.This paper used the backward drag static experiment to verify the feasibility experiment of the variable compression ratio piston scheme.With the change of piston height,in-cylinder pressure curve and compression ratio curve were obtained,which verified the feasibility of the scheme.In the end of this article,GT-power was used to calculate and verify the experimental cylinder pressure,and there was a further optimized on the processed variable compression ratio piston.Finally,it obtained a variable compression ratio piston based on electrically driven variable height piston with more matching with the original machine,faster response and better strength.