|
Re: why no supercharged diesels ?
[ QUOTE ]
[ QUOTE ]
...were mechanically driven with a clutch to drop out when the purpose was no longer needed as in the case of 2 12V EMD's and 1 V8-EMD engine....
[/ QUOTE ]
really? were they roots type blowers?? i'm just wondering how that wouldn't cause problems if the blower vanes no longer were driven. i guess i'm looking at it as if the vanes weren't turning than they would basically block the intake air flow and the turbo would have to force the charge through the vanes.
or, is it the case that since the clutch disengages while running, so that means that the intake charge keeps the blower vanes turning, but really just kinda "coasting"????
i guess i could see that better if it were a centrifugal compressor/blower, but doing that to a positive displacement roots-type seems strange to me.
but a lot of things seem strange to me.... [img]/ubbthreads/images/graemlins/biggrin.gif[/img]
[/ QUOTE ]
The EMD engines use a centrifugal blower/supercharger (since it performs both functions) which is driven either by the engine or by the exhaust turbine with an overrunning clutch which, when the exhaust flow comes up at higher loads, will disengage from the engine and drive the compressor at turbine speed instead.
For whatever it's worth, positive displacement pumps of any kind are generally only used in the small end of a range, be they air compressors, supercharger/blowers, or water pumps, etc., and centrifugal usually takes over above a certain volume in industrial settings.
Birken
|
