Based On 4RB4 Engine VVT Technology Design Optimization And Simulation Test Study

The flowing smoothly of intake stroke is the basis of working normally of engine.Intake and exhaust timing of the conventional gasoline is fixed,which can not meet the ventilation demand of different operating conditions of gasoline engine.The variable valve technology can change intake flowrate in overall conditions by changing intake and exhaust timing 、valve lift,which can help obtain the optimum intake flowrate in each working condition.Many studies have shown that intake timing can improve power of heavy load and perfect fuel economy of partial load.The members use VVT technology to optimize engine performance.,which build one-dimensional simulation model of engine by GT-power and validate the model.The members analyzed the effects of exhaust timing on the state parameters of engine’s ventilation stroke by changing exhaust timing.This paper provide data support by the study of engine power and fuel consumption effects of exhaust timing.The results showed that:As the exhaust valve opening earlier,the smaller the average gas mass flow inlet manifold,the higher inlet average temperature,inlet average pressure almost no influence,the lower the average pressure and temperature of top center compression stroke,the smaller torque.As the exhaust valve opening later,the greater the average gas mass flow inlet manifold,the lower the inlet average temperature,the inlet average pressure has almost no influence,the higher the average pressure and temperature of top center compression stroke,the bigger torque.When the Exhaust late open Angle at a certain time,which will continue,the inlet average temperature will be higher,the lower the average pressure and temperature of top center compression stroke,the smaller torque.Exhaust valve opened early or late can lead to an increased amount of exhaust gas in cylinder,pump gas loss reducing,the combustion duration extension,specific fuel consumption increase,lead to rising cycle fluctuation,combustion stability.The NOx can be significantly reduced by using the exhaust gate early or late.At the speed 2000r/min,when IMEP = 2bar,the emissions of HC are reduced from 10% to 15%,and the HC discharge increases as the amount of exhaust gas increases.In this paper,the structure of cylinder head,VVT oil channel,CAM shaft,sprocket,and machine oil pump were redesigned for VVT in gasoline engine.The modified gasoline engine is tested,the ignition preangle and the air-burn ratio are calibrated,and the optimum exhaust VVT phase is obtained under different conditions.After the exhaust VVT,the medium speed segment(1600r/min-4000r/min),the torque average increased by 3% ~ 5%.At the same time,the increase in torque is about 1.5% to 2% lower than the average oil consumption.Torque increases at 2400r/min at 169.5 Nm,and torque increases to 5.2%.Meet the design development requirement.