Featured NYT: To Power the Future, Carmakers Flip on 48-Volt Systems

maybe

 

They are simpler than a Prius? In what universe?

 

Still profit making complex service I presume.

 

I confess I don't understand the logic behind the interviewee's train of thought.

The article says,"But the more integrated applications of the technology, amounting to what’s known as a mild hybrid system, offer the greatest value — up to 70 percent of the benefit of a full hybrid at 30 percent of the cost, according to industry analysts." One might think that Toyota, and possibly others, have developed sufficient expertise to mitigate a substantial amount of that cost.

Show us the numbers, please.

 

Well that would be true if you were using year 2000 injectors, but all things are not equal. GDI has improved rapidly, and higher NOx and particulates come mainly from poor mixing from the injectors and droplets of gasoline hitting hot cylinder walls. Solutions for this are already out. Longer strokes along with swirling intake and miller cycle (late intake valve closing) and spraying into the middle of the cylinder alleviate most of the problems. The problems come in cold starts and high loads while warming, along with valves that close down too late in the cycle for for the gas to mix. This can be taken care of with using port injection along with direct injection or higher pressure better injection. US regulations are on the somewhere on the path to reduce from 10 mg/mi to 3 mg/mi in 2021, and 1 mg/mi in 2025. These new designs are for at least the 2021 standards.

Think of it in this fairly simple way, the new toyota 2.5L pi+di 14:1 expansion stroke engine in the camry hybrid, could be replaced with the same engine logic but with a 10:1 expansion stroke along with an electric supercharger and intercooler with intake pressure at 1.4 atmospheres after the intercooler. The engine should actually run cooler and at lower rpm at load, with less pollution, because cooling takes place at the intercooler after compression, instead of at the exhaust stroke. Of course you can run higher boost and this will increase particulates, and replacing it this way would be a waste of money.

For very high boost you would use higher pressure injectors and port injection. Port injection would be used at cold start, very late valve closing, and high load. If boost and load are pushed enough, as delphi has in some of their prototypes a gasoline particulate filter can be used. There are no technical hurdles only cost. For a car like the camry hybrid why pay more, but a higher powered car could definitely benefit. Adding a efficient turbo charger that provides low boost at low rpm with an electronic supercharger can provide major efficiency gains.

The accelerated move is mainly driven by european regulatory changes and the diesel scandal. There are big bonuses with 48V and electric superchargers in europe, and if they replace a cheating diesel, and advance the technology, I like them much better than old regulations.

Not the prius, but the lexus ls hybrid, for sure ;-)

30% of the cost, yes I think that is true. 70% of the benefit? That doesn't make any sense at all to me. IMHO a 48V Bas + 2L turbo charged and electric supercharged I4 engine with spitfire cylinder deactivation with a automatic 7 speed transmission may really outperform the Hyhi 6 cylinder hsd system at 30% of the cost. Just doing 48v bas and some really smart cylinder deactivation and smart valving probably will cost 50% of what is in the camry hybrid system, but only provide 30% of the benefits. But my guess is they are talking about some euro or japanese test not epa or real world.

 

The new(2019?) Ram 1500 will have one these systems standard on the V6, and as an option on the V8.

The M/Gs and ICE dance is not simple.

Toyota is still charging around $3000 and up for the HSD. These 48 volt systems will retail around $1000. The cost savings come from using smaller components and not needing to mess with the high voltages and required safety systems.

As for efficiency improvements, what people forget is that the Prius' fuel efficiency stems from its ICE; there is only using gasoline for an energy source. The efficiency improvements from the gen2 to gen3 to gen4 nearly all came from improvements in the ICE. The electrical side helps by allowing the ICE to shut down at times, and to run in its more efficient range at others.

These mild systems will provide the gains of shutting off while stopped, some of them for shutting down while coasting, and then a little by assisting from a stop and when the ICE is under high loads. The 70% likely includes engine downsizing, so a simple bolt on to an existing car would not net as high of a gain.

The higher voltage will also allow emission improvements that aren't always tied to efficiency ones. A catalytic converter heater can now be added to help with start up emissions. It even allow longer ICE off times.

 

I would say "simpler" isn't the right word, but "easier for a conventional automaker to understand" is more correct.

It's easier to tack a system onto their existing powertrain, than completely design a new transmission concept... even if the new concept is mechanically far simpler.

 

Being mechanically simpler also doesn't mean low cost. The Ioniq is a full hybrid that is returning near the gen4 Prius. Its hybrid system with traditional transmission could cost less than the Prius' because it works with smaller, less powerful motors, which require smaller inverters and controllers to match them.

 

I believe this is a push from part suppliers. Two of the pictures are from a delphi system test. Delphi says cost to manufacturers of skip fire + that full 48V system will be about $1500, skip fire alone $350. Skip fire is cylinder deactivation system and software that varies a 4 cylinder engine between 1,2,3, or 4 cylinders with better nvh than poor systems on 6 cylinder engines just going between 6 and 3. GM is going to try it out in the 2019 chevy silverado V8.
2019 Chevy, GMC Trucks Get Smarter Cylinder Deactivation | News | Car and Driver | Car and Driver Blog

Now this is much less complicated ;-) than 2 mode. If we go 200 hp or lower though, and hsd, or ford or gm's similar systems are less complicated. GM is not using a downsized turbo + electric supercharged engine which would make the truck more efficient. This is a simple reliable pushrod V8 with modern tech of BAS and skip fire it can go down to 2 cylinders or 1.3 L, but the current models often deactivate 4 cylinders going to 2.6 L and either way the frictional losses stay the same. I'm not expecting much, but it should be good for more than the 10% the 0.45 kwh 48V BAS system with a 10 kw mg gives it in this years model.
Compare Side-by-Side

 

Ok, I think I see the problem.

Something called "back EMF" is the voltage generated as a motor spins faster and faster. This limits the current needed to provide the torque from a motor. A higher voltage, 144V, means the motor can max its current rating at higher rpm than a lower, 48V, supply.

If the 48V advocates are able to fool mechanical engineers that they can provide low end torque above idle rpm, well I don't go hunting for "brown gas" advocates unless they come here. Let God and Muther Nature answer.

Bob Wilson

 

Thanks for the compare @austingreen
Now I remember when the reduced cylinder idea started Matt Garrett - Cadillac V8-6-4 Home Page
I'm not saying that I know 48v superchargers are dub, I'm sure there is a use case somewhere that it fits
very well. The local service dept($) ?