VVT-iE

VVT-iE, or Variable Valve Timing - intelligent by Electric motor is an automobile variable valve timing technology developed by Toyota for its Lexus brand. The Lexus VVT-iE system uses an electrically operated actuator to adjust and maintain intake camshaft timing. This system is unique from the previous VVT-i system, as the hydraulic actuator for the intake camshaft is no longer used. The exhaust camshaft timing is still controlled using a hydraulic actuator.

This system was first introduced on the 1UR engine fitted in the 2007 Lexus LS 460, in September 2006. The benefit of the electric actuation is enhanced response and accuracy at low engine speeds and at lower temperatures. Further, it ensures precise positioning of the camshaft for and immediately after engine starting, as well as a greater total range of adjustment. The combination of these factors allows more precise control, resulting in an improvement of both fuel economy, engine output and emissions performance.

The electric motor in the actuator spins together with the intake camshaft as the engine runs. To maintain camshaft timing, the actuator motor will operate at the same speed as the camshaft. To advance the camshaft timing, the actuator motor will rotate slightly faster than the camshaft speed. To retard camshaft timing, the actuator motor will rotate slightly slower than camshaft speed. The speed difference between the actuator motor and camshaft timing is used to operate a mechanism that varies the camshaft timing.

ee also

* Variable valve timing

External links

(Japanese) http://lexus.jp/models/ls/performance/engine/vvt-ie.html