I dont *think* Im confused. Its possible sure.
But I even drew you a picture direct from Dodge on the Cummins exhaust circuit.
You do have some nomenclature errors though.
EGR is Exhaust Gas Recirculation - So you dont "use" more or less EGR. To use would be to consume. EGR is a strategy that is never consumed.
The EGR valve opens and closes to divert more or less exhuast gas back through the intake channel to be "re-burned" in combustion.
That said DEF or Diesel Exhaust Fluid isnt injected ever until well down stream of the EGR circuit.
And your last statement is only partially correct. EGR is primarily used to reduce NOx.
DPF (Diesel Particulate Filters) are used to reduce PM (particulate matter) and DEF is used in an SCR (Selective Catalyst Reduction) scheme to reduce NOx and SOx.
Now all three have some benefits to the other systems. But those 3 independent strategies are best at those 3 emission targets.
I'm not saying you are "wrong" and I'm not trying to argue. Im just explaining how the system works for the benefit of other readers.
See its pretty interesting how all this came to be. There is this whole bit of EPA legislation.
Specifically
NESHAP RICE 40 CFR part 63 subpart zzzz and
NSPS CI ICE 40 CFR part 60 subpart IIII
See those brought about all this technology to stationary engines as well as on highway engines. It was game changing back in 2004-2006. So as a result Cummins took market leaders from 10 key market segments and took them Indianapolis and trained them and then those guys spent the next 18 months going around to all the Cummins dealers and training their people.
I'd be glad to go to a theoretical level with you, or an application level if you'd like and explain why the strategies are actually and how they work, and what fuel and air programming strategies are altered on a factory tune in order to incorporate it.
But in short if you will just look at where the DEF is injected in the above diagram I think you understand what Im saying.
Now it is possible, maybe, that you got confused and got your alphabet soup backwards. Because when combining the two topologies, you do use less DEF if you have a proper functioning EGR maybe thats what you meant?
