Abstract: A vacuum system for an engine with variable valve lift includes a controllable vacuum-forming valve at the entrance to the intake manifold and a programmable engine control module (ECM) to increase vacuum as desired within the manifold by modulating the valve as needed to optimize fuel economy. To provide vacuum brake assist, a brake booster diaphragm is connected conventionally to the manifold and a vacuum storage tank and check valve are disposed between the booster diaphragm and the manifold. During periods of vehicle deceleration, when engine load is low, the ECM may switch the VVL-controlled intake valves to a higher lift to increase the pumping capacity of the engine, while simultaneously partially closing the vacuum-forming valve to create vacuum in the intake manifold, the brake booster, and the vacuum storage tank at little or no expense to engine performance.

Abstract: Internal combustion engine variable valve timing control with a camshaft phaser for varying rotational phase between a camshaft and a crankshaft in response to a control command determined through a hybrid control strategy without resort to direct temperature measurement. For a range of phase errors requiring high response compensation, a control strategy emphasizing rapid response, such as a bang-bang strategy, is deployed. For a range of phase errors requiring high accuracy compensation, a control strategy emphasizing high precision, such as a proportional-plus-integral strategy, is deployed. The phase error ranges are updated periodically to account for changes in operating conditions. The control command includes an offset which varies in response to a periodically estimated control deadband to affirmatively account for the deadband with each issued control command.