An Approach for Heavy-Duty Vehicle-Level Engine Brake Performance Evaluation

An innovative analysis approach to evaluate heavy-duty vehicle downhill engine brake performance was developed. The vehicle model developed with GT-Drive simulates vehicle downhill control speeds with different engine brake retarding powers, transmission gears, and vehicle weights at sea level or high altitude. The outputs are then used to construct multi-factor parametric design charts. The charts can be used to analyze the vehicle-level engine brake capabilities or compare braking performance difference between different engine brake configurations to quantify the risk of engine retarding power deficiency at both sea level and high altitude downhill driving conditions. The methodology and the models can address the following topics in steady-state operation with a robust engine analysis approach: (1) design criteria of the engine brake in vehicle system integration, (2) vehicle braking capability evaluations, (3) comparison between different engine brakes or different transmissions at both sea level and high altitude, (4) vehicle braking power shortage analysis and risk evaluation, (5) extra absorbed power and energy of service brakes of the vehicle due to retarding power shortage, and (6) comprehensive interactions among engine brake design, calibration, transmission selection, and operation factors including engine brake full or partial retarding power levels, parasitic losses (i.e., engine auxiliaries, vehicle drag, and tire rolling resistance), vehicle weight, downhill road grade, transmission gear selection, vehicle downhill driving speed limit, and maximum engine speed limit.