We review variable valve actuation (VVA) concepts and also present the results of our work in the creative synthesis of these devices. We begin with a comprehensive survey of existing VVA devices. We then describe our work on four VVA concepts which we have explored in considerable detail. These include hydraulic lost-motion variable-lift systems, in both the direct acting and the roller-finger-follower configurations, several valve deactivation mechanisms with unique features, a variable valve-lift mechanism, and a variable-lift and duration concept. These devices differ in their complexity and versatility but offer a spectrum of design solutions applicable to a range of products. The strengths and weaknesses of these different approaches are discussed and analyzed, and some test results are presented.

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