Structural Design And Characteristics Analysis On Power Transmission Of An Opposite-cylinder Engine In Small Scale

Thermal power source in small scale is an ideal power supply which has the advantages of technology ripening,high reliability,fine dynamic characteristics and easy implementation.Opposite-cylinder piston engine in small scale is a novel type of cam engine used for thermal power source in small scale,the reciprocating movement of the piston is transformed into the rotation of the CAM.Breaking the traditional design ideas of engine by the use of spatial CAM mechanism characteristics of compact structure,the engine cylinders are circumferential opposed along the spatial CAM,the volume and quality of engine are maximum limited.By controlling the shape of CAM work face,the working frequency of pistons are fully improved,the engine's power density gets a big promotion.The main jobs of this thesis are as followed:(1)Design of the novel power-transmission mechanism.We applied the Geometric closed spatial cam mechanism with elastic roller seat into the novel power-transmission mechanism,and analyzed the composition and working principle of the engine.According to the parameters of the power source,we put forward the design index of the engine.Geometric-closed spatial cam was applied to power-transmission,the spatial CAM and tapered roller profile was calculated and analyzed,the pistons and cylinder body were designed,and the area of heat sink was calculated.(2)Power-transmission mechanism dynamics modeling and analysis.We established the mathematic model of the power-transmission mechanism.The elastic roller seat was equivalent to compensating spring and we designed the stiffness of it.We solved the model and got the angular displacement and angular velocity response of spatial CAM and displacement error of roller.Through the analysis,we found that the stiffness of the roller seat had a great influence on dynamic performance,and negatively correlated with displacement error of rollers.(3)Spatial CAM contact fatigue analysis.We studied the mechanism of contact fatigue failure of the CAM under the action of stress field in the circulation and analyzed the force situation of the power-transmission mechanism.The maximum contact stress on the work surface were less than the allowable stress of material,meet the requirements.The parameters of contact model were analyzed to provide theoretical base of simulation.(4)Movement and dynamics property of the power-transmission mechanism simulation research.We used ADAMS to build the virtual prototype model of the powertransmission mechanism,and verified the accuracy of the model through the kinematics simulation.The stiffness of the roller seat was optimized on the base of the model.The simulation results indicated that the engine torque reached the design target.