Camless hydraulic valve timing system in combustion engines
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Publication date: 2011-11-01
Combustion Engines 2011,146(3)
The paper discusses the control of the operation of combustion engines through a camless electro-hydraulic valve timing system aiming at a lower exhaust emission and increased overall efficiency. The paper presents an electro-hydraulic valve system and a mathematical model of the fluid flow. The model was simulated in Matlab–Simulink for different geometrical parameters of the hydraulic system and electric control parameters in order to obtain a required valve lift and timing in the Toyota Yaris gasoline 1.3 l engine. The paper presents the Simulink model and the results of calculation in Simulink. Additionally, a comparison of engine parameters with a standard cam valve system and those of the camless hydraulic valve timing system have been shown for different engine speeds obtained from the simulation in GT-Power software. The obtained results show a significant increase of the engine torque and efficiency at higher engine speeds for the considered camless system in the Toyota Yaris gasoline engine. The paper showsboth the advantages and disadvantages of the described valve system.