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To meet the requirements for lower fuel consumption and emissions as well as higher performances, a “Variable Valve Timing - intelligent by Electric motor (VVT-iE)” system has been newly developed. The system has been firstly adopted to the intake valve train of the Toyota's new 4.6 and 5.0 litter V8 SI engine series. The VVT-iE is composed of a cam phasing mechanism connected to the intake camshaft and brushless motor integrated with its intelligent driver. The motor-actuated system is completely free from operating limitation caused from hydraulic conditions. This enjoys an advantage for reducing cold HC. The system also presents further reduction in fuel consumption.

The original Toyota Hybrid System (THS) was installed in the Prius and was introduced in 1997 as the world's first mass-produced hybrid passenger car. Since then, THS has been continuously improved. In 2003 THS-II (marketed as Hybrid Synergy Drive [HSD]), was installed in a new larger Prius. In 2006 HSD was installed in a Rear Wheel Drive Vehicle: the LEXUS GS450h. This system achieved both 4.5-liter class power performance and compact class fuel economy with outstanding emissions performance. In 2007, this system is expanded to a mechanical all-wheel-drive(AWD) in the LEXUS LS600hL(with new V8 engine). This paper will explain this hybrid system which achieved both V12 class power performance and mid-size class fuel economy, while meeting the most stringent emission standard SULEV as a full-size vehicle.

A new 2.0 ℓ DOHC 4-valve direct injection (DI) gasoline engine has been developed which features new technologies such as swirl intake ports to produce an optimum swirl in the cylinder by variable controlled swirl control valve, pistons with a concave combustion chamber, and high pressure fuel injection system to provide a fine fuel-air mixture cloud in the combustion chamber. These all help to control fuel-air mixture preparation and flame propagation under ultra lean, stratified combustion at partial loads. NOx emission is reduced by using an electrically controlled EGR system and an NOx storage-reduction catalyst. At higher loads, a homogeneous mixture is obtained with direct injection during the intake stroke. A seamless output torque transition between stratified charge and homogeneous charge condition is achieved by an electronic throttle control system.