Common rail injection in TDCi engines!

[anu_mech]

Sir,
i wished to know that what TDCi engines in a automobile do? To be specific the word "common rail injection" is troubling me..
regards
anumeha

[gohm]

It is a form of direct injection allowing higher pressures and greater control by the ECU using solenoid valves. Not being mechanically driven they are not dependent on engine speed(cams/pumps). Better atomization is thus achieved.

[anu_mech]

can i get the thing in detail, somewhere....

[gohm]

what specific details are you looking for?

[anu_mech]

by details i mean the how and whys of the system.....

[gohm]

Start with this Wikipedia page, it explains the basics really well:

Common rail - Wikipedia, the free encyclopedia

[zaki_whiz03]

sir how is it driven if it is not driven mechanically using engine energy?

[anu_mech]

it is controlled through engine control unit(ECU), which is electronic control not mechanical,
sir, thanx for the link
i'l ask for futher reading if needed

[pankajvig]

anumeha, apart from the difference that the injectors in any derivative of the CRDI technology are not mechanically driven, the added advantage that we get is the injetion control timing and the amount of injections in the power stroke. As in the conventional diesel engine we have a single injection in a power stroke unlike that CRDI relies on a carefully chosen generally four to five injections per power stroke divided very carefully over the full power stroke (of this four to five injections the one being very noteworthy and very popular is termed as the pilot injection in which very small fuel is injected just before the main injection to produce a small explosion just before the main explosion so that there is less rattling and the pressure curve rises rapidly but smoothly). this gives us a very tight control over the emissions and the engine noise. as the electronics are continiously monitoring everything the injection only occurs at peak pressure which ensures that there is no black smoke which you will normally see in any engine fitted with mechanical pumps.