UkrainianProfessional Education

Abstract

The article examines modern valve timing and lift adjustment systems used in spark-ignition automotive engines, which enhance power output and reduce harmful exhaust emissions. The object of the study: Control systems for the intake valve timing mechanism. The aim of the study: analysis of the main methods of regulating valve timing and lift and their impact on internal combustion engine performance. Research method: Analytical. The article explores the design and operating principles of variable valve timing (VVT) systems in spark-ignition engines. It has been established that modern engine manufacturers employ a unified approach to dynamic valve timing regulation, utilizing engine oil pressure to adjust the camshaft's angular position via a valve timing adjustment mechanism. Additionally, it has been determined that camshaft torque can be leveraged to enhance the efficiency of VVT systems. Various types of variable valve lift (VVL) systems are analyzed. In general classification, VVL systems are divided into discrete variable valve lift (DVVL) systems and continuously variable valve lift (CVVL) systems. Discrete VVL systems operate by switching between different cam profiles and are widely adopted across manufacturers, with diverse implementations. In contrast, CVVL systems enable continuous regulate airflow into the cylinders, ensuring a smooth power output transition at any engine speed or load. It is also noted that CVVL systems can be either mechanically or hydraulically actuated. The findings presented in this article can be used for further analysis and enhancement of existing valve timing and lift systems

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