High compression spark ignition engine with Variable Compression Ratio using Active Combustion Chamber.

Abstract In this article Authors present the continuation of the calculations for theoretical ACC engine cycle, considering additionally “VCR function” – changeable compression level. For this purpose the self-acting volume change, realized by ACC system, was used. The ACC system was adjusted appropriately to control the compression level. The analysis is based on three cases, representing delayed, premature and optimal reaction of ACC system. Reactions are presented in form of plots with indicated pressure in the combustion chamber. As the result of the conducted analysis and interpretation of obtained graphs, the calculation approach of compression ratio for ACC presented in previous article is being challenged. For the optimal reaction of ACC system, the theoretical operation schematics are devised and presented in the key points of the work. Based on the schematics, the values of theoretical efficiency were calculated for different cycles of theoretical ACC engine, in which regulation of compression ratio takes place. Moreover, the presented analysis includes graphs with optimal courses of indicated pressure for significantly different work parameters of ACC engine, showing its regulation possibilities. Also the time scaled graphs (with millisecond as basic time unit) are presented to show the possibilities of dynamic ACC systems, which are comparable with the combustion time (from 3 to 0,5 ms). In this paper the general discussion is started about the compression ratio in more complex kinematic systems including ACC.