关键词: 发动机, 辅助制动, 制动扭矩, 排气背压

Abstract:

A mathematical model of the engine supplementary brake was set up through discussing the working processes of engine supplementary brake. 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 simulations and experimental tests. The results show that the cylinder pressure increases with speed and the peak pressure phase is more near the top dead center(TDC) under the higher speed conditions. The brake torque increases with the engine speed increase. The de-compressure brake has a maximum brake torque while the engine brake has the minimum brake torque. When the engine speed is constant, the bleeding brake and the de-compressure brake have a corresponding optimal exhaust valve lash, respectively. The higher the speed is, the bigger the exhaust valve lash is. The higher the exhaust back pressure is, the more the brake torque is.

Key words: engine, supplementary brake, brake torque, exhaust back pressure