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

Przemyslaw Kubiak,Adam Mrowicki,Michal Glogowski,Gianluca D'Errico,Tigran Soghabatyan

doi:10.14669/am.vol86.art1

Przemyslaw Kubiak, Adam Mrowicki + Show 3 more

Open Access

https://doi.org/10.14669/am.vol86.art1

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Abstract

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.

Highlights

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Authors conclude that the maximum attainable compression ratio in the ACC engine with VCR is equal to 30:1 and in the calculations for theoretical cycle this value is used
The equivalent compression ratio for any theoretical cycle realized by naturally aspirated ACC spark ignition engine, can be formulated as follows: Equivalent compression ratio for the ACC engine is expressed by the ratio between the lowest cumulative volume of crank-piston system and ACC system reached before top dead center in compression stroke, and the highest cumulative volume of crank-piston system and ACC system, reached in bottom dead center for compression stroke

Summary

Introduction

111 DDDeeepppaaarrrtttmmmeeennnttt ooofff VVVeeehhhiiicccllleeesss aaannnddd FFFuuunnndddaaammmeeennntttaaalllsss ooofff MMMaaaccchhhiiinnneee DDDeeesssiiigggnnn,,, LLLooodddzzz UUUnnniiivvveeerrrsssiiitttyyy ooofff TTTeeeccchhhnnnooolllooogggyyy,,, 111///111555. The work of four-stroke internal combustion engine, equipped with a compression ratio adjustment is possible due to many technical solutions [16,24]. These usually differ in the mean and place of regulation [3,6]. Authors conclude that the maximum attainable compression ratio in the ACC engine with VCR is equal to 30:1 and in the calculations for theoretical cycle this value is used. This is the reason why it is crucial to determine experimentally the real compression ratio for the ACC engines. Whereas in the four stroke, whose results are presented in this article, this value was limited to 17,5:1 because of construction restrictions

ACC engine efficiency

ACC engine with VCR

Findings

Conclusions