Driving And Parking Brake Performance Research Of Rear Disc Brake

The research topic is derived from the school-enterprise cooperation projects and aims to the phenomenon of insufficient parking brake force and brake drag in the practical application.As an important part to guarantee the automobile driving safety,the braking system has always been a hot topic among researchers.Limited by the low braking efficiency of drum brake,it is gradually replaced by the disc brake and how to realize the parking function in the rear disc brake first won the attention of foreign scholars.In the existing disc brake,a set of mechanical structure is installed inside the brake cylinder which can realize the function of parking with the advantages of compact structure,safty and reliablility.In this thesis,the research object is this kind of hydraulic disc brake with both driving brake and parking brake function.Currently,the technology of this kind of brake is still in the hands of foreign and domestic parts enterprises mainly produce their own brakes by importing foreign parts,changing size and testing but without the capacity to design the key parts.Therefore insufficient parking brake force and brake drag phenomenon are always occurred after installing these kind of brakes.This thesis mainly aims at the two problems above and the work has carried out as follows:(1)The first part illustrates the home and abroad research progress of disc brakes mainly including parking brake structure in the rear disk brake as well as the realization of brake clearance adjusting function of and the principle of piston retraction;(2)For the research object-the ball-ramp disc brakes,the second part analyses its working principle and the key technologies from the perspective of parking force direction conversion mechanism,adjusting mechanism,etc.With the combination of theoretical analysis and calculation method,this thesis derives the relationship between the driver hand brake input force and axial piston push force;(3)Based on dynamics analysis software LMS Motion,the third section builds the dynamic simulation analysis model of parking brake mechanism of ball-ramp disk brake and take more attention on the dynamics modeling process,the simplicity thought of modeling,etc.Through changing ball groove shape parameter of the screw and drive shaft as well as the screw thread parameters,the thesis try to look for important influential factors on parking brake performance;(4)Aiming at the brake drag phenomenon,the last section establishes the axisymmetric finite element model from the angle of the piston retraction principle and based on the finite element theory.The model includes seal groove,rectangular seal and the piston.Besides,it puts forwards three evaluation index which are normal contact force between the seal and piston,piston displacement before and after the brake and friction loss respectively.And it analyzes the influence of front seal groove angle,corner angle,seal groove outer diameter and the sealing groove width on the performance of piston retraction.This thesis' work has played a role to put forward more research on the rear disc brake with the function of driving brake and parking barke function and it also can provide reference and thinking for brake parts manufacturers to further raise the brake development level in our country.