Development of Second Generation of Gasoline P-ZEV Technolgy

This paper describes the second generation of the partial zero emission vehicle (P-ZEV) technology that was developed for use on the Nissan Sentra CA sedan sold in California.^1,2 The second-generation engine has been adopted on a mass-produced model marketed in Japan. Besides continuing the super ultra low emission vehicle (SULEV) performance of the Sentra CA, the second-generation technology incorporates a compact, two-stage HC trap catalyst system. The system has been substantially reduced in size and cost as a result of improving the catalyst and the substrate and reducing the total catalyst volume by optimizing the control method.

Moreover, the second-generation P-ZEV technology includes an electrically actuated continuously variable swirl control valve of the high-speed jet type, a high-response electrically actuated EGR valve and catalyst model control based on the use of an air-fuel ratio sensor. Besides contributing to low emission levels, these components are also used to achieve the maximum fuel economy improvement through innovative control of the engine operating conditions. As a result, the improved engine greatly reduces both fuel consumption and CO₂ emissions to comply with Japan fuel economy standards to be enforced in 2010. These various improvements have resulted in the development of a production engine that combines outstanding emission performance with superior fuel economy to meet the environmental requirements of the 21st century.