Toyota Launches New Hybrid Estima Minivan in Japan

[scooby_dooby]

Am I right in assuming it's not even a turbocharged engine, but rather a more inefficient naturally aspirated unit?

Japanese automakers make extremely efficient NA engines when they want to, over 100hp/litre.

 

[Squeak]

And mechanical transmissions do not? Piston engines running at non-optimal RPMs/loads do not? What about lugging around on a gearbox, clutch, differential and drive shafts unnecessarily even when running on electricity, does that not create losses? Wheel hub motors could do away with all of that.

I think this little Art Nouveau beauty is exactly what you want. Build 108 years ago by Ferdinand Porsche.

It was one of the fastest cars of it's time and won the Exelberg Rally in 1901 with Porsche himself driving (source Wikipedia).
I wonder why he didn't continue with that setup?

From what I've read, the transmission of a car steals at LEAST 10% of the power put out on the crankshaft and not seldom 5+ % more. That's not counting the uneven torque curve across the engine's RPM range or the weight of the transmission components. Trying to estimate the impact of that isn't really feasible, but I'd suspect a mechanical->electrical drive won't be all that rotten in comparison when all parameters are factored in. It'd save space too I might add!

It would be a lot more durable and easy to maintain too (less oil for example).

I would really like to see a small turbine instead of a piston engine used as the generator.
It would have plenty of time to rev up, without wasting fuel because of the buffer-battery, and it would be quieter and lighter than the piston equivalent. Turbine engines are also better suited for reusing exhaust heat and for direct water injection.

 

[ShootMyMonkey]

I wonder why he didn't continue with that setup?

I believe the history of electric powerplants in automotive applications is hardly a smooth one. That setup may have been just fine for 1901 when people would be in awe of speeds like 40 mph. But the efficiency and power output of electric motors probably didn't evolve quickly enough to keep up with the ICE in early on, though nowadays, the reverse is probably true. Edison was also a proponent of electric cars (not that he was biased in any way ), but the ICE utterly put them to shame in those days.

 

[Moloch]

Japanese automakers make extremely efficient NA engines when they want to, over 100hp/litre.

HP/liter is not the measurement of effciency, no matter what the ricers tell you.
A corvette with a 6 liter 400hp engine gets 30MPG on the highway (but mpg in the high teens in the city)
But oh no, it only makes 66Hp per liter, so it's crap right?
BSFC is a true measurement of engine effciency.
That's brake fuel consumption- how much fuel do you burn (in pounds per hour) per horsepower.
Btw adding a turbocharger is not usally a wise move for fuel economy.
With forced induction you need to run the fuel mixture richer (detonation= bad) and the turbo it's self is restriction when it's not spooled up and also you gotta run lower compression so it's not getting as much out of the fuel as it would with higher compression.
It's not so much the turbos themselves are bad, it's just what you have to do in order to accommodate one.
That said, it doen't seem to affect diesels much.

 

[KimB]

Except engine efficiency is only a part of the whole equation. The Corvette gets such good gas mileage on the highway for its engine because it is a very aerodynamic vehicle.

What you really need to calculate to get fuel efficiency is (total frictional force * speed) / (power/(gallons/hour)). In this equation, the air drag force is set by the aerodynamics of the car, and the fuel flow rate (gallons/hour) is whatever it has to be to obtain the desired speed, and power being the power output of the engine in these conditions.

In the above equation, then, the total frictional force that is seeking to slow the car down multiplied by the speed should exactly equal the power output of the engine (we're moving at constant speed here). Therefore, the result is exactly the fuel consumption rate, which could trivially be converted to miles/km per gallon. I claim that at highway travel speeds, by far the most dominant factor in the total frictional force is air friction.

Now, with all of that gesticulating, it is worth noting that a hybrid buys you next to nothing in a high-speed highway driving environment, for the simple reason that the primary pull of a hybrid vehicle is that when braking, that kinetic energy of the car is put into recharging the batteries. This isn't a situation that is often encountered for fast highway driving.

 

[WhiningKhan]

Btw adding a turbocharger is not usally a wise move for fuel economy.

Of course _adding_ a turbo won't help (edit: for a gasoline engine, that is), the idea is to design an engine with smaller displacement and get extra power from boost.

With forced induction you need to run the fuel mixture richer (detonation= bad) and the turbo it's self is restriction when it's not spooled up and also you gotta run lower compression so it's not getting as much out of the fuel as it would with higher compression.
It's not so much the turbos themselves are bad, it's just what you have to do in order to accommodate one.

Mixture and compression issues have been addressed since 80's with electronic control of boost pressure. While turbo does not actually improve the efficiency of the otto engine like it does for the diesel engine, other benefits are clear: you can build a lighter engine with smaller displacement to get superior power (and especially torque) than a larger engine - a 2.3L 4-cyl turbo can have better performance (_and_ economy) than a 3.0L normally aspirated V6. Of course, normally aspirated engines can be tuned to get more power, but the aforementioned efficient japanese engines typically rely on high RPM and have relatively low torque on lower RPM, which is not to my liking.

 

[Guden Oden]

Btw adding a turbocharger is not usally a wise move for fuel economy.

Not sure what you mean by "usually", but Saab has made several models using low-pressure turbochargers to increase low-RPM torque and fuel efficiency.

 

[ShootMyMonkey]

Yes, with the proper size turbo or supercharger, and the right gearing, forced induction can increase efficiency than N/A on a gas engine. On the condition that it's used like a daily driver, the main point is to get you power in the low RPM range, which is something that small turbochargers, or fixed-displacement superchargers can give you. You do, however, need the taller gearing to match so that the low-end power can be put to use. If the engine lacks torque, you end up having to force it into higher rpm ranges in order to accelerate, and if F/I can help you circumvent that, then so be it.

With a diesel, power is largely controlled by fuel and not so much by air. But the thing is, while you can keep throwing fuel into the chamber and make more power, when you run out of oxidizer, you get incomplete combustion and black smoke... so forced induction can mean you can guarantee more complete combustion even up in higher load conditions at the same rpm. All diesel really needs to be viable in the US is good biomass and/or synthetic production capacity, and the adoption of urea injection to deal with the NOx emissions.

 

[WhiningKhan]

Yes, with the proper size turbo or supercharger, and the right gearing, forced induction can increase efficiency than N/A on a gas engine.

Not the theoretical efficiency due to stoichiometric process and compression limitations, but real-life efficiency, which was my point.

With a diesel, power is largely controlled by fuel and not so much by air. But the thing is, while you can keep throwing fuel into the chamber and make more power, when you run out of oxidizer, you get incomplete combustion and black smoke... so forced induction can mean you can guarantee more complete combustion even up in higher load conditions at the same rpm.

Yes. Also, with compression ignition engine, it is obviously not a problem to have spontaneous ignition, as that is how the engine should be runnning anyway, i.e. the knocking issues don't have similar effect to theoretical efficiency.