Study On The Improvement Of The Performance For CG150 Motorcycle Engine

With the rapid development of the Automobile industry, energy crisis, environmental pollution and traffic congestion problems have attracted attentions from each parts of our society. So people have a higher request for the performance of the motorcycle engine. Therefore government regulations state that for two rounds of motorcycle and two rounds of deft motorcycle from 2010 July 1st, atmospheric pollutants must meet the "nationalâ…¢" emission regulations.In the topic, CG150 motorcycle engine was optimized with the method of combining simulation calculation and test. Through structure optimization, cooperating to install two stages of three-way catalysts and secondary gulp, eventually the engine don't only met"Chinaâ…¢"emission, but power performance and the economy performance were also superior to the original engine. The main researches were as follow:1. At the basis of the original CG150 motorcycle engine, installing two stages of three-way catalyst , the size of each engine parts and performance parameters were obtained through measuring and test. One-dimensional model of CG150 motorcycle engine was built with BOOST software, then the model was demarcated with the indicator diagram and speed characteristic WOT curve from test. Through comparing improvement results under the two conditions of the maximum power and torque, the results showed that the error of simulation calculation was less than 10%, which met the application requirements. Modeling process needed mainly parameters: geometric size and wall temperature of engine components, valve lift curve, flow coefficient with variation of valve lift, cylinder pressure curve, motored power, etc.2. With the CG150 motorcycle engine model, which were respectively simulated, changing compression ratio, ignition advance Angle, piston groups, ports and intake pipe length. The results showed that of the ports optimization and piston groups lightening were most significant for improvement of power performance. Increasing the ignition advance Angle followed for improvement of power performance.3. According to the simulation results, optimization ports, piston groups lightening, changing ignition advance angle were taken in turn. Through the test the improvement accuracy were tested. The results showed that the simulation calculation and test results of CG150 motorcycle are consistent. Because combustion chamber of CG150 motorcycle engine was smaller, the power performance wasn't sensitive for ignition advance angle.4. At the same time, the original engine was taken the following measures: installing three-way catalysts, lightening piston groups, optimizing the air ports, adding a gasket in middle of the intake manifold and carburetor, installing secondary gulp. Through experiments inlet and exhaust pressure wave, the combustion characteristics, power, economy and emission performance were respectively compared between the original engine and the optimization engine. The results showed that intake and exhaust performance could be further improved through changing the length of intake manifold under the maximum power and torque condition. After the engine optimized, the most explosive pressure of engine increased, the moment of the most explosive pressure happened in advance. The maximum pressure rise rate increased slightly. The moment of combustion start was advanced, combustion duration was shortened. On the curves of speed characteristics at wide-open-throttle, the power and torque of engine were improved, and specific fuel consumption was reduced. The emissions of engine met"China III"emissions regulation.