Abstract
The study aimed to analyse a closed-loop control strategy that adjusts the ignition timing and fuel injection to increase work output in the cylinder whilst ensuring knock safety and reducing cycle instability. The methodology was based on methods of energy (thermal) balance analysis, classification and analytical systematisation, structural-functional modelling, comparative analysis and analytical generalisation. It has been established that the thermal efficiency of an internal combustion engine (ICE) is the proportion of the fuel energy converted into useful work. The difference between theoretical and actual efficiency indicates the amount of energy lost due to mechanical and auxiliary processes. The energy balance reflects the distribution of fuel energy between useful work at the shaft, heat dissipation to the cooling system, losses with exhaust gases, and other types of losses, allowing the dominant directions of its utilisation to be identified. Increasing the efficiency is limited by rising pressures, temperatures and thermal loads; therefore, optimal heat release phasing is key, which must be maintained without detonation or excessive peaks. The study determined that injection and ignition parameters determine the combustion phasing and power output; and since injection alters ignition conditions, the ignition timing must be coordinated with the fuel strategy (particularly in a closed-loop system). Parameter optimisation is constrained by detonation, thermomechanical, emission and operational factors, which define the permissible range of settings. The study noted that automated control improves efficiency by optimising mixture formation and the combustion phase, and by reducing mechanical and auxiliary losses through coordinated control of the subsystems. The reduction in mechanical and auxiliary losses is achieved through a combination of tribological solutions and control of the units to avoid excessive energy consumption. The use of energy balance as a criterion and coordinated closed-loop control of ignition, fuel supply and auxiliary systems via the engine control unit (ECU) makes it possible to reduce dominant losses and improve the efficiency of the internal combustion engine within the limits of detonation and thermal load constraints. The practical significance lies in the ability of engineers to apply the results when calibrating the ECU during bench tests and engine tuning on the vehicle