Design And Research On Key Mechanism Of Portable Scooter

In today's society where the problems of aging and resource shortage are becoming more and more serious,the development of electric walking products plays an important role in improving the quality of life of the elderly and alleviating social pressure.Therefore,it was of great significance to design a product with practical value,considering the existing characteristics of modern scooters.In this paper,a design scheme of portable scooter which could fold automatically was proposed.The folding mechanism,folding frame and locking device were optimized by multi-objective optimization,finite element technology and profile optimization.The main contents were as follows:(1)The shape parameters of the portable scooter were determined according to the analysis of the size,demand of the elderly and the relevant standards.The scheme design of the main mechanism was completed by means of mechanism combination.The preliminary scheme of the whole vehicle was obtained by connecting the mechanisms,and the three-dimensional model of the whole vehicle was established.(2)Based on multi-objective optimization algorithm,the length of six-bar folding mechanism was optimized.Dimension synthesis of unfolding and folding states of six-bar folding mechanism of frame was carried out respectively to establish a mathematical model and determine the design parameters.The optimization model was built to minimize the folded size.Constraints were established according to functional requirements and vehicle stiffness requirements.The multi-objective optimization algorithm in MATLAB was used to calculate the optimal results.The folding height is reduced by 12%.(3)This paper analysed the working conditions of the portable scooter and the structural characteristics of the folding frame,and made a lightweight design of the folding frame.Ansys Workbench was used to analyze the statics of folding frame.Based on optimization design theory and static analysis results,an optimization model of folding frame was established.The structural dimensions of each part of the frame were optimized in batches by step optimization method.The optimized structure size is verified,and the quality of folding frame is reduced by 28.4%,and the lightweight effect is obvious.(4)The impact problem of locking device in brake mechanism was analyzed and optimized by analytic method.The motion equation of the follower of the locking device is established,and the quintic polynomial curve was used to optimize the contour of the locking cam in view of the impact problem of the device.The motion simulation of the locking device was carried out to verify the optimization results in ADAMS.The results show that the acceleration of the follower decreases greatly and the rigid impact of the mechanism is eliminated.At the same time,the phenomenon of motion uncertainty of the follower of this kind of cam mechanism is found,and the location of the phenomenon of motion uncertainty is pointed out.This paper provides some reference for the optimization design of folding mechanism and locking device of portable scooter through the above research and analysis.