Performance Simulation Research Of Engine Supplementary Brake

Engine supplementary brake is a supplementary braking technology commonly used on heavy-duty vehicles or passenger cars. It can avoid overheat and wear even failure while the vehicles use brakes frequently down a long slope. At present, abroad engine supplementary braking is more mature, and the product has been serialized. But for the protection of its own technical data and potential market, foreign rarely publicly advanced supplementary brake technical information, while the domestic research, production and application for supplementary brake is still in infancy.In this paper, on the basis of current research of engine supplementary braking technology, the working progresses and principles of engine brake, exhaust brake, bleeding brake and De-compressure Brake are studied and analyzed. The power of these supplementary brakes is evaluated through both experimental and simulation methods to discuss the factors which can improve the brake power without disturbing normal working progress of the engine.In this paper, as the basis of the national "863" Project (2008AA11A116), it studies on the simulation research of supplementary brake on engine. The main work and innovations of the thesis are as follows:(1) The thermodynamics mathematics and simulation model for six-cylinder turbocharged diesel engine is established by software. Several common auxiliary breakings have been analyzed, for example, engine braking, exhaust supplementary brake, bleeding brake and the de-compressure engine brake, and the braking performance has also been studied with different supplementary braking.(2) According to reference parameters of the supplementary brake (including the exhaust valve lash, engine speed, exhaust back pressure, etc), the engine supplementary brake was analyzed with univariate and multivariate conditions by the method of numerical simulation. Engine cylinder pressure and brake torque were compared with different supplementary braking in order to evaluate the level of utilization of the maximum engine braking capability using the different engine brake.(3) The simulation results were verified by experimental methods. Experimental results and simulation results are relatively consistent to verify the accuracy of the simulation model. Calculation methods and conclusions can be used for engine retarder structure design and performance research.