Hello!
here is some nice info about VVTL-i.........i am sharing....
1st all knows...
VVT-i=Varaible Valve Timing-Intelligent
VVTL-i=Variable Valve Timing and Lift-Intelligent..
Toyota’s VVTL-i is the most sophisticated VVT design. Its powerful functions include:
1..Continuous cam-phasing variable valve timing
2..Two-stage variable valve lift plus valve-opening duration
3..Applied to both intake and exhaust valves.
Like VVT-i, the variable valve timing is activated by shifting the phase angle of the whole camshaft forward or reverse by means of a hydraulic actuator attached to the end of the camshaft. The timing is calculated by the engine management system(ECU) with engine speed, acceleration, going up hill or down hill etc....
VVTL-i
What makes the VVTL-i superior to the ordinary VVT-i is the "L", which stands for Lift (valve lift) as everybody knows........
VVTL-i Working......!
Toyota’s system uses a single rocker arm follower to actuate both intake valves (or exhaust valves). It also has 2 cam lobes acting on that rocker arm follower, the lobes have different profile - one with longer valve-opening duration profile (for high speed), another with shorter valve-opening duration profile (for low speed). At low speed, the slow cam actuates the rocker arm follower via a roller bearing (to reduce friction). The high speed cam does not have any effect to the rocker follower because there is sufficient spacing underneath its hydraulic tappet.
When speed has increased to the threshold point, the sliding pin is pushed by hydraulic pressure to fill the spacing. The high speed cam becomes effective. Note that the fast cam provides a longer valve-opening duration while the sliding pin adds valve lift.VVTL-i offers variable lift, which lifts its high speed power output a lot
Courtesy:Autozine...
Thanxxx
