Automotive advancements

[Maraschino Larry]

I think the integration with the instrument cluster/steering wheel controls may fix those kind of gripes too... I'd sure love to play with one in person to form a better opinion!

[Maraschino Larry]

Whenever we hear bold claims like a 25 percent reduction in fuel consumption brought about by a very innovative idea, we’re always skeptical, as one needs to be in these situations, as discernment is important and it needs to stay balanced for us to make the best decisions.
However, when a big name like Volvo makes such a claim, and backs it up with reasonably detailed information, one has to pay closer attention, right?

So, how are they improving fuel efficiency by up to 25 percent? Well, Volvo’s solution is KERS – kinetic energy recovery system. Their system, known as Flywheel KERS, “is fitted to the rear axle. During retardation, the braking energy causes the flywheel to spin at up to 60,000 revs per minute. When the car starts moving off again, the flywheel's rotation is transferred to the rear wheels via a specially designed transmission.”

This is complimented by the fact that the internal combustion engine (ICE) shuts off as soon as the driver applies the brakes, so that the energy of the flywheel can be stored and then used when the car sets off again. The Swedes claim the system works best in city traffic, because “the flywheel's stored energy is sufficient to power the car for short periods,” and this allows the engine to be turned off for around half of the entire driving time. It is a system specifically designed to work at its most efficient in stop-start traffic.

What’s even more interesting is that the system can also boost performance, and the S60 test car they used could reach 62 mph or 100 km/h in 5.5 seconds, though it was not mentioned what ICE engine was used in the prototype.

Volvo has been working on “flywheel propulsion assistance” since the 1980s, when they first fitted the system to a 260 model. However, being made of steel, it was deemed too heavy and the idea was put to the side. Now, the new experimental unit is made out of carbon fiber, has a diameter of 20 cm (7.9 inches) and weighs considerably less, at around six kilos (13 pounds).

[professor science]

This is a nice way to eliminate batteries from the equation. Porsche has been doing something similar in their racing hybrids and will be present in the 918.



I might have to do a few calculations to see how realistic this is.

If 100% efficient this is more than legit. I checked both 5kg solid cylinders and hollow cylinders with diameter of 0.2 m and a vehicle mass of 2000 kg. Final speed varies between 44 m/s and 63 m/s, which is ~150-225 km/h. If the entire system is 20% efficient it can, theoretically, accelerate the car to 72 km/h to 100 km/h (depending on the hollow vs. solid cylinder model). (I'm also neglecting aerodynamic drag)

[tripwalking]

I imagined the dinky cars that you pull back and then they go... Those were the best.


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[Mandeep D]

Interesting that to make it work, they have a lightweight flywheel. Traditionally flywheels are heavy beasts.

[Maraschino Larry]

Was my initial thought too... came across this comment on the matter:

This is the most interesting part of KERS: that kinetic energy increases linearly with mass but increases with the square of RPM.

A 60,000 RPM flywheel that weighs 10 lbs will have the same kinetic energy as a 30,000 RPM flywheel that weighs 40 lbs. You can store more energy in a smaller device when you increase the RPM!

[professor science]

Linear kinetic energy is governed by Ek = (mv^2)/2
Rotational Energy is governed by Er = (Iw^2)/2 where I is the moment of interiat and w is actually omega and is the rotational frequency. double freq = 4x energy. so you can double freq and quarter mass and get same energy.

[Maraschino Larry]

Rob there is no need to state the obvious

[professor science]

haha. sorry for talking down to you

[Mandeep D]

Was my initial thought too... came across this comment on the matter:

This is the most interesting part of KERS: that kinetic energy increases linearly with mass but increases with the square of RPM.

A 60,000 RPM flywheel that weighs 10 lbs will have the same kinetic energy as a 30,000 RPM flywheel that weighs 40 lbs. You can store more energy in a smaller device when you increase the RPM!

You must also outpace the additional losses of additional rpm (linear), and the conversion in the gearbox to achieve the higher rpm.

[professor science]

I've been thinking about this recently

Some of the benefit of having multiple gear changes is that at a set road speed, a higher gear will have lower RPM. Low RPM = smaller losses due to friction.

Could we not look at diesels from this point of view as well? They typically operate at lower RPM than gas motors, let's say 1/2 the typical RPM range (for arguments sake). If you can live with 1/2 the typical RPM range, and keep engine mass constant, then you will require 1/4 the energy to accelerate the engine to operating speed than a comparable gas motor. So now we can actually quadruple engine mass and still be even with a gas motor on energy needed to accelerate and still be better on internal frictional losses (though it may be worse on the crank bearings due to added reciprocating mass). (I know that it's not perfect, but in essence it's not invalid).

Cool!

[Maraschino Larry]

Pretty remarkable numbers for 1984... I wonder what ended up being the failure of this advancement.

[Dreamstate]

Carbon fiber is like whoah.
Good test of it's strength here.

[professor science]

thank you for sharing the knowledges.

[mushroom_curry]

Via Gregosh

http://m.youtube.com/watch?feature=yout ... b8tGX-HPQE


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[Maraschino Larry]

I hadn't read up on the P1 before watching the TGUK segment and I was left speechless. That car is absolutely fucking incredible. How can it weight what it does and house a hybrid system and active hydraulic aero and suspension? And the looks, I'm in love. I am not a super/hyper car person but this thing has me in awe.

[mushroom_curry]

Yup. It really has me excited about cars in general.
Which episode was this car covered in? One of the first 3 this season??


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[mushroom_curry]

Which is impossibru unless I fell asleep during an ep


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[Maraschino Larry]

Lol... #2. I've still yet to watch #3

[Dreamstate]

It's a whole new thing

[mushroom_curry]

Ya I guess I fell asleep during 2. Damnit...


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[mushroom_curry]

IT'S A WHOLE NEW THING. I KNOW I'VE SAID THAT BEFORE BUT...


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[Dreamstate]

[Maraschino Larry]

wowwowow

[mushroom_curry]

heeeeeeeeeeeeeeeelll naw?!