Deisel Engines

[timtheenchanter]

I have owned and worked on old style deisel engines, both turbo and non, but i am intrigues as to the differance between a normal deisel engine and the new common rail and single point injection, can anyone shed some light?

Thanx

 

[empip]

Common Rail Fuel Injection
In the common rail system, fuel is distributed to the injectors from a high pressure accumulator, called the rail. The rail is fed by a high pressure fuel pump. The pressure in the rail, as well as the start and end of the injection in each cylinder are electronically controlled. Advantages of the common rail system include flexibility in controlling both the injection timing and injection rate. Stable pilot injections which can be delivered by the common rail have proven to lower the engine noise and the NOx emissions.

I once had a petrol engined, 'single point injection' system, the single injector was situated slose to the air inlet butterfly and fed fuel to the inlet manifold, this was not very successful... Felt ok, but was really an interim between carburettor and multi point injection I am thinking... There may well be other meanings for 'single point injection' in use .... More than that I cannot say.

Loads of stuff here :- http://en.wikipedia.org/wiki/Fuel_injection

 

[Hitachimad]

Older style diesels basically work with a pump on the engine with a feed to each individual injector. The pump timing controls when the diesel is injected into each cylinder. I think you know that anyway...

Common rail however, has a pump and an accumalator. Each injector is fed from a single 'common rail' which is contantly pressurised, somewhere around 1600bar i think. The injection of the fuel is controled by the electrics and injectors. They are dramatically different to older styles, the lower part of eact injector has parts made from piezo crystals, when the electrics apply power to the injector the crystals expand opening and closing the jet when neccessary.

 

[andy]

somewhere around 1600bar i think.

 

[empip]

somewhere around 1600bar i think.

Only a small volume tho' ...

Bosch is planning another leap in innovative development for the Common Rail in 2006. 'We are currently analyzing concepts to increase the pressure in the Common Rail to more than 2,000 bar at the injector by means of a booster without having to increase the system pressure as such. In a parallel approach, we are studying injectors with variable nozzle geometry', explains Dohle.

 

[andy]

they better still be compatable with veggie oil!

 

[Mick Leek]

I have seen a demo of an injector injecting while 0.5mm away from a 10mm thick piece of mild steel,

Lets just say spark errosion milling isnt a patch on squirting a liquid at enormous pressures...

Was like water hitting bog paper, straight through.. amazing to watch. wouldnt have beleived it if i hadnt seen it

 

[AdamW]

Best check those timing chains then. It's bad enough when piston hits valves, don't want to drill a hole through it with some diesel!