Expanding the operating range of homogeneous charge compression ignition-spark ignition dual-mode engines in the homogeneous charge compression ignition mode

Abstract

Vehicle fuel economy benefit through the use of homogeneous charge compression ignition (HCCI) engine technology depends on the range of HCCI operating conditions. The range of HCCI operating conditions also determines the frequency of combustion mode transition over vehicle drive cycles. Based on test data in a single-cylinder HCCI engine, the constraints on HCCI operating regimes were analysed, including combustion roughness and knock, combustion timing control, breathing, thermal energy for mixture autoignition, and combustion efficiency. The constraints due to inadequate thermal energy and insufficient breathing depend on the HCCI approaches employed. The operating ranges of alternative approaches to HCCI systems are quite different. For the other constraints, conventional control methods were tested and analysed to expand the range of HCCI operating conditions to higher loads, and to improve combustion efficiency at light loads.