Thermal Performance of Commercial Vehicle Braking Process during the Vehicle Descending Speed Control on Roads with Long Length Steep Inclination - A Case Study

Abstract

Study about the performance of the service brakes and the retardation systems of commercial vehicles during the descending speed control on roads with long length steep inclination in Brazil. Mathematical models, based in the equations of the energy balance during the vehicle braking process are used. The thermal performance of the service braking system, of the engine cooling system, and of retarders, are verified for the established maximum safety speeds for a vehicle traveling downhill. The simulations are performed with programs elaborated in the Matlab-Simulink platform and with the vehicles as per the European norm ECE R13 requirements (test type II A) and the Brazilian norm requirement (NBR 10967) for the downhill functional test (test type III). The obtained results show that it is possible to have a forecast of the dissipated power in the engine and the retarder, of the capacity of dissipated heat of the radiator, and other parameters to guarantee the effective speed control of the vehicle, as per the requirements of the norms, even before the road test are performed.