Study On Performance Of Engine Decompression Brake Based On Dynamic Mesh Technique

Decompression engine brake system has been standard equipment and trusted by users in Europe and other mature heavy truck markets. The reasons are as follo wings: on one hand, with the improvement of national legislation and user’s increasing awareness of safety, decompression braking system has gotten more attention because it’s ability to improve vehicle safety; on the other hand, with the use of decompression engine brake system, water spray can be removed, the use of brake pads reduced, which will benefit users a lot. Although the decompression engine brake system can improve safety and economic efficiency, the allocation ratio in the domestic truck is still very low, and the development and production is lagging behind. The system research on the performance of engine decompression brake is lacked of.This research work was supported by national natural science foundation (51276056)、state key laboratory of advanced design and manufacturing for vehicle body(61075002), physical model of engine is established referring to the entity, and it is meshed by dynamic mesh technology. The correctness and validity of calculation model and simulation methods for decompression engine brake are verified by a series of experiments. Simulations of decompression engine brake under different operating conditions are performed by numerical simulation, and the decompression brake and bleeding brake are compared, can provide guidance to improve the power of decompression brake.The main contents are as follows:(1)The mathematical model of decompression engine brake is established basing on the analysis of working principle. A three-dimensional simulation model is built in computational fluid dynamics software and then verified by experiments. It shows that this method is suitable for the study of decompression engine brake.(2)A3D simulation of working process of transient decompression engine brake is performed. Piston force and brake power under different parameters are obtained, then the changes of piston force and braking power with different parameters are analyzed. Decompression braking power improved based on the optimization of engine speed, valve opening and valve advance angle.(3)Piston force and braking power of decompression brake and bleeding brake are compared, then piston force under these two brake mode and the size and trends of braking power with parameter changes are analyzed.