| Cam-type switching is becoming widely used in the automotive sector and the user feel is one of the most important performance indicators of switches.The gear mechanism is primarily the main factor which affects the user feel and the design of groove profile is the key to designing cam-type switching mechanism.Traditionally,engineers designed the cam profile of switching mechanism by virtue of past experiences and the final design can only be determined after several rounds of physical model fabrication-Functional Verification-redesign cycle.The traditional development mode of the switch is limited by high cost,long cycle and poor product performance,and therefore the design method and dynamics simulation of cam-type switching mechanism are researched by using reverse design and numerical simulation techniques.In order to quantify the description of user feel for cam-type switches,the indicator system of user feel characters is established based on force feedback curves,and the system is facilitating the switch design for improving user feel.The force feedback analytical model is established on the basis of analyzing the working principle and structure of switching mechanism.The comparison of the calculation results and the measurements indicates that the analytical model is reliable.In order to design the cam profile for meeting requirements of the target force feedback curve point by point in a cycle,the relationship equations between the internal elastic potential energy and the external work of the mechanism is established,and then the iterative reverse design algorithm of cam profile based on energy principle is put forward.The expression equations and the differential equations of cam profile by using B-spline and polynomial are established to describe the complex geometry of cam profile,and the design examples show that B-spline curve equations are more accurate and beneficial for improving the design quality.The parametric design system of cam-type switch gear mechanism is developed by using MATLAB and SolidWorks 3D modeling software,which involves the force feedback calculation,automatic reverse design of cam profile and the automatic three-dimensional parametric modeling of switching mechanism,and the software can output the CAD model for the following dynamic simulations.Two dynamics models for switch gearing mechanism,which are multi-rigid body dynamics model by using MSC.ADAMS dynamics software and the multi rigid-flexible hybrid dynamic model by using ABAQUS finite element software,are established,and the dynamics of the switch gearing mechanism by using the cam profile from reverse design are simulated.The simulation results show that both models are capable of outputting the force feedback results,and the cam profile from the reverse design can meet the requirements of the force feedback.The rigid-flexible hybrid dynamic model is advantageous in considering the effects of the material elasticity on force feedback,and thus the hybrid model is closer to the actual working conditions.The research results of cam profile reverse design method based on user feel characteristic and the dynamic simulations for Cam-type switching mechanism,are facilitating to overcome the difficulties of complex quantitative relationship expression between force feedback and cam profile,validating switch performance and the reverse design of cam profile.The newly established developing mode of cam-type switching mechanism based on design-simulation validation cycle is advantageous of short developing cycle time,higher efficiency and better design quality. |
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