Quote:
Originally Posted by UnknownJinX
A lot of the problems I mentioned are directly associated with diesel engines' fundamental operations, though. High soot & NOx emissions and more expensive construction(due to higher compression ratios) are things you can't change with it being a range extender.
(And how is a diesel engine less complex, anyway? Lack of spark plugs? But they need glow plugs to ensure proper cold start. Lack of a catalytic converter? But they need DEF injection system to keep NOx in check as well as soot filters to limit soot emissions, and DEF is a consumable item unlike a catalytic converter. Gotta throw a DEF tank warmer in there as well because that stuff has a relatively high freezing point. The only thing I can remotely think of is a VVT system, but that's barely anything in this day and age considering practically every gas car you can buy has it.)
And again, this is where economy of scale rears its ugly head again. Now you are asking manufacturers to R&D a dedicated diesel engine that is only useful for this specific application, then market it(incredibly large risk, again thanks to VW), all of that just for some marginal gain in efficiency. Meanwhile, they could just take an existing gas engine, modify it slightly so it can run on Atkinson cycle, then use it in a hybrid drivetrain. No fuss with marketing. What do you think manufacturers will do?
And really, the car is effectively an EV at this point, so I don't really care if it has an ICE anyway.
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There should be zero need to "reinvent the wheel" in terms of R&D for a diesel engine like this... Locomotives have been built like this for years with engines that put out FAR higher levels of voltage and current than what a car or truck would need. Additionally, the small 3-cylinder engines used in CUT/SCUT tractors have also been around for years and are commonly used for driving generators through the rear PTO on farms. These engines are designed to operate at a constant RPM which means they can be very specifically tuned and adjusted for both optimal fuel consumption AND minimal emissions. There's a lot of R&D that has already been done one these that can easily be re-used to create a diesel-electric power train for automotive use.
DEF is NOT used in engines under something like 115HP as it is not required. A 45-50HP diesel engine would be fairly capable of being used for nothing more than a small electrical powerplant. Even where DEF is required, variable RPM diesel engines consume somewhere around 1 gallon of it per 1000-ish miles of operation (give or take). With engines like I referred to above, there would be no need for DEF (although we all know the EPA would stick their noses into it at some point).
There are vehicles on the road that use engines that have been modified to run, at least part of the time, in Atkinson-Cycle "mode". But these engines are ALSO designed to be able to directly power the vehicle if need be. That's different than the concept of a diesel-electric setup.
Reduced complexity is derived from not just lack of spark plugs (which also don't require high-voltage / high-current plug wires or any sort of distributor / electronic ignition system) but also from "less stuff" throughout the entirety of the system. As you mentioned, no catalytic converter required on these kinds of systems). The varying RPM of engines in cars and trucks is why we have so many additional components to monitor and control exhaust outputs.