Research On The Electromagnetic And Friction Integrated Brake With Variable Air Gap Width In Passenger Car

A new integration brake applied to passenger car and its controlling technology were been studied in this paper.The new brake is integrated by electromagnetic brake and friction brake,which solves the problem of "thermal failure" on the friction brake and improves the response speed and controlling accuracy of the braking system.A structure adjusting the air-gap width with temperature changing is integrated into the new-structure brake.The brake could significantly increase braking torque.Structure parameters were optimized designed after analyzing the feasibility of the new brake.Then,three working modes of integration brake were given after analyzing several typical braking condition of passenger car.Further,the distribution strategy of braking force and control methods.The controller of integration brake based on microprocessor was designed in this paper.The controller hardware circuit,the underlying software and braking control algorithm were given.By specifically analyzing each structure parameter impacting the electromagnetic braking torque,the parameters improving braking torque were found.The feasibility of the new brake was analyzed by finite element analysis.The 1/6 structure model of the electromagnetic was established in ANSYS.The model was simulated to estimate whether the new brake could work effectively.The controlling consequence of the two control technique,PID and fuzzy PID,were compared in MATLAB Simulink.Experimental study on the working performance of the electromagnetic brake was implemented.The finite element simulation results indicate that: when the brake was working,the iron temperature was highest while the heat expansion component was lowest;the largest temperature difference of the two components was 14 ℃ in retarder braking condition,was 54℃ in emergency braking condition.In the two braking conditions,the air gap width was declined slightly as a power function.The change rangeability were all under 0.1mm.The optimization results of the structure parameters indict: The working performance of electromagnetic brake is best when the ratio heat expansion component dividing the iron was 0.7;comparing PID,the fuzzy PID shows high steady precision,small oscillation and small overshoot magnitude.The experiment results indicate: in the retarder braking condition,the largest electromagnetic brake torque was 250 Nm when 10 A and 20 A current were given;in theemergency braking condition,the largest electromagnetic brake torque was 580 Nm when40A current were given to the coil.This paper come to the conclusion: the new electromagnetic brake with the temperature-adjusting the air-gap width with the new-structure brake can stably work.The new brake could increasing the braking torque as the initial air gap width is lower.The best initial air gap width could be given by adjusting the ratio heat expansion component dividing the iron.The control result on the integration brake of fuzzy PID is better than the PID.