Influence of Cylinder Deactivation (CDA) on Combustion and Emission Characteristics and Fuel Economy of Direct-Injection Spark-Ignition Engine

To quantitatively expound the mechanism of using cylinder deactivation (CDA) technology to improve the partial-load fuel economy of a direct-injection spark-ignition engine, bench test was carried out to investigate the combustion and emission characteristics and fuel economy of the engine in the CDA and full-cylinder modes. Moreover, numerical simulation was used to quantitatively analyze the energy balance and determine the effects of various factors on fuel saving of the CDA engine. The results show that, in comparison with the full-cylinder mode, the ignition delay and combustion duration are shortened, the peak values of the in-cylinder pressure and heat release rate are increased, and the cyclic variation of combustion is reduced in the CDA mode. In addition, HC and CO emissions are reduced, while NOx emissions are increased in the CDA mode. Under the test conditions, the fuel economy of the CDA engine is improved by 8.2% to 15.8%. In comparison with the full-cylinder mode, the in-cylinder heat-transfer losses and pumping losses in the CDA mode are reduced, which contributes to the fuel saving rates by 80% to 111.9% and 30.3% to 37.4%, respectively. While the friction losses and exhaust energy are increased, resulting in the decrease in the fuel saving rates by -9.2% to -20.3% and -1.2% to -26.5%, respectively. Therefore, the reduction of in-cylinder heat-transfer losses is the most important fuel-saving factor for CDA engines. © 2020, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.