Passenger Car Braking Performance Hydraulic Retarder And Constant Speed Simulation

Reliable braking performance is the important guarantee for vehicle’s safedriving. Auxiliary braking system appears in order to decrease the load ofactive braking system of coach. Hydraulic retarder is a kind of auxiliarybraking systems. Its volume is smaller, quality is lighter, and braking torque isbigger than any other auxiliary braking systems. So it has been applied to thecoach. However domestic research level is lower, many products rely onimports. The paper provides some certain basis for the development ofhydraulic retarder by designing parameters and simulating performance ofhydraulic retarder.The working principle and characteristics of the various kinds of auxiliarybraking system were introduced. Then the modern and traditional designmethods were introduced. Some structure parameters of hydraulic retarder of acoach were designed by similar design method. Then the3D model diagramsof stator and rotor were drawn using Pro/E software. The sub modules ofhydraulic retarder、crane brake、driving resistance、constant speed control andthe whole vehicle simulation model were built based on Matlab/Simulink.The simulation that the coach brakes when it equips with hydraulicretarder, on the different road and different weather is focused. It has acomparison between equipment hydraulic retarder or not on braking velocitycurve and braking displacement curve both on horizontal road and lastingdownhill road. Both on the conditions of usual and unusual weather, theconstant control simulation were to complete.The simulation result indicates hydraulic retarder is useful obviously:compared with only rely on active braking system and driving resistance,equipment with hydraulic retarder, the braking velocity and brakingdisplacement can be decreased either on horizontal road or lasting downhillroad; the coach can keep a constant speed with hydraulic retarder, and thebraking torque of hydraulic retarder is changed when the filling ratio is changed, the change value of the filling ratio must be proper, if it is too fewer,bus can reach a constant speed with a longer time, otherwise the vehicle speedwill always change and oscillation amplitude will increase; the coach can alsokeep a constant speed on the conditions of unusual weather on the highway.