Engines

VVT-i (Variable Valve Timing with intelligence)
Why VVTI

In contrast to the fixed valve timing of conventional engines, the VVT-I system is an computer controlled mechanism that continually varies the timing for opening and closing the intake valves in accordance with the vehicle's operating conditions.

By determining the level of performance that is demanded of the engine at a given time by way of the driver's accelerator operation and the engine rpm, the VVT-I enables the overall performance of the engine to be enhanced all the way from the low to the high rpm range.

Design

VVT-I is comprised of three major components

1.The electronic control unit(ECU), which calculates optimum intake valve timing based on engine operating conditions.

2.The oil control valve (OCV), which controls hydraulic pressure under the ECU's instruction and

3.The VVT pulley, which continuously changes the intake valve timing using hydraulic pressure.

The VVT-I is an engine control system that has achieved high levels of the seemingly opposing performances of Higher power out-put, Lower fuel consumption, Cleaner exhaust gases.

How VVT-I will help ?



 

Engines - D-4D

D-4D High technology, clean diesel

Originally introduced in Europe in the top selling Avensis range, D-4D is widely recognised as one of the most advanced diesel technologies on the market today. Toyota D-4D engines are available on select models of Yaris, Yaris Verso, Corolla Verso, Innova, Avensis, Avensis Verso, RAV4, Land Cruiser and Previa models.

Until recently, diesel engines relied on relatively simple technology with a low-pressure mechanical injector delivering fuel to a pre-combustion chamber in the cylinder head, where a single ignition - fired by the intense heat of high compression - takes place.

The system was reasonably fuel efficient but lacked precision and refinement, leading to vibration and noise. Fuel combustion can be incomplete, allowing smoke and other emissions to pass into the exhaust.

D-4D components
Toyota's common rail system makes use of a high pressure pump and intelligent, computer controlled injectors to deliver precisely the right amount of fuel, at precisely the right time, directly into the centre of the combustion chamber.

Click the labels to learn more about D-4D components:
Follow us
Printed on maandag 24 november 2014

CSS is deactivated in the browser