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This paper introduces a two-step CDA mechanism equipped with an electro-mechanical switching system, which can be applied to OHC valve trains with end pivot rocker arms, and can operate two valves simultaneously with a single cam. The electro-mechanical switching system is driven by a dedicated solenoid, so the latching and unlatching processes are not affected by the temperature and pressure of the engine oil. Therefore, not only the dynamic stability can be secured at the time of mode switching but also the operation delay time can be kept short enough. To verify the effect of the CDA system on the fuel economy, a four-cylinder 2.0L gasoline engine with the intake port injection was selected and tested on an engine dynamometer. The effect of the present apparatus was evaluated by measuring the fuel economy of the engine in the two test modes: Federal Test Procedure-75 (FTP-75) and Worldwide Harmonized Light Vehicles Test Procedure (WLTP).

This paper introduces a two-step variable valve actuation (VVA) mechanism equipped with an electronic switching system, which can be applied to OHC valve trains with end pivot rocker arms. The electronic switching system is driven by a dedicated solenoid and is not affected by the temperature or pressure of the engine oil. Therefore, not only can the dynamic stability be secured at the time of mode switching but the operation delay time can also be kept short enough. Several models of two-step VVA mechanisms were fabricated and the operability of the mechanism and switching system was experimentally confirmed. The two-step VVA mechanism developed in this study can also be used as a cylinder deactivation (CDA) system by assigning the lift of the low-speed cam to be zero. By attaching a roller to the portion of the rocker arm that is in contact with the base cam, the problem of pad wear, which is often present in CDA mechanism, is also fundamentally solved.