FOTA agrees to drop KERS from 2010

[xpensive]

60 000 Rpm sounds more reasonable than the 100 000 I've heard. That also reduces the energy stored in a 200 mm, 5 kg, disc or drum from 1400 to 500 kJ, which is close to what is required today. Counting efficiency and you might be right on the mark?

But 60 kRpm still means 63 m/s of surface-speed for that seal, if the shaft is 20 mm.

As for efficiency, 80% for such a system, through two electrical motors twice, would be impressive indeed.

Cooling requirements will still be there for those remaining 20% I guess?

Whatever bearings and seals intended, I think they will require some sort of attention at least.

[djos]

I like the vac pump Idea.

carbon also makes better sense from a saftey standpoint as well. it tends to turn into dust when it breaks inconel tubines tend to become bullets

I think the 80% is being a little optimistic it has to go through two electric motors twice. and accelerate a drum

I doubt they give it no attention just like any other part it will be torn down and inspected at least.

The beauty of the Williams system is that the Flywheel is a motor/generator unit and that's how they get the 80% efficiency as there is only 2 units to form the system, the Hybrid FlyWheel and the electric motor/generator used for recovering energy or transferring energy back into the drive train.

[xpensive]

Correct, but you still need two converters from mechanical energy to electrical and back, both units passed twice.

If each of the four passings has a 95% efficiency, then you will have a total efficiency of 81%, when (0.95)^4 equals 0.81.

I am by no means the electrical engineer to judge if a 95% efficiency is credible, anyone?

[flynfrog]

our solar car motor was 98 t specific rpms

keyboard is missing the letter that is first in the lpbet

[Giblet]

Correct, but you still need two converters from mechanical energy to electrical and back, both units passed twice.

If each of the four passings has a 95% efficiency, then you will have a total efficiency of 81%, when (0.95)^4 equals 0.81.

I am by no means the electrical engineer to judge if a 95% efficiency is credible, anyone?

the motor generator is a single unit, as the flybrid is also a dynamo and discharges it's stored kinetic energy as electricity.

2 passes?

[pipex]

Correct, but you still need two converters from mechanical energy to electrical and back, both units passed twice.

If each of the four passings has a 95% efficiency, then you will have a total efficiency of 81%, when (0.95)^4 equals 0.81.

I am by no means the electrical engineer to judge if a 95% efficiency is credible, anyone?

Yup, 95% sounds like a good figure to me.

[xpensive]

The way I see this, there is four passes in total?

1) Mechanical energy from wheels to electrical through the MGU.
2) Electrical energy to mechanical when charging the flywheel-rotor.
3) Mechanical energy from flywheel-rotor to electrical at discharge.
4) Electrical energy to mechanical to the wheels through the MGU.

If each pass has an efficiency of 95%, as pipex confirms, there is a total of 80%.

[pipex]

I agree xpensive, that should be the round-trip efficiency, four passes from what i can remember reading in a KERS presentation some time ago.
The figure of 95% could be peak efficiency or efficiency at a defined operating point. Well, for a electrical converter they don't vary that much. For the energy levels used 95% sounds reasonable because if you calculate the amount of losses they could be dissipated readily by a cooling system (kW range of rated power).
Although i think you know a lot more about cooling than me

[xpensive]

Let's give it a try pipex, imagine a 5% loss of a 60 kW charge/discharge is 3kW of heat for 6.6 seconds?

A typical toaster is 500-800 W, which means 3 kW is like releasing the combined heat of 4 to 6 toasters over 6.6 seconds.

I should think this is why the MGUs I have seen, Magneti Marelli's basically, has been water cooled?

As electrically ignorant as I can be, the same xample should apply for the electrical flywheel, no?

[pipex]

That seems the case xpensive, numbers should be like that i think. Not 100% sure, but we should be close...
I don't know if the flywheels themselves are watercooled, but i wouldn't be suprised if they were.

[WhiteBlue]

All high power MGUs and power electronic packages are water cooled. The air cooled units simply do not get anywhere near the performance per volume.

[xpensive]

I had no idea.

[Giblet]

4 passes indeed.

I thought the flybrid was spun up with direct mechanical energy, and the flybrid itself acted as a magneto, but there is a second unit that converts, like xpensive thought.

I think that the best system would be a turbine that spins from exhaust gasses, but instead of being linked to a compressor, and pumping air into the engine, requiring more fuel, it could spin the flywheel. That equals free power as the exhaust was just going out the back.

Sound idea?

[flynfrog]

I think a turbo would be more effcient as it is directly feeding the engine. If you use the energy to spin a fly wheel you have a more complex system with more losses

[Giblet]

You are missing the point, as this is a discussion about KERS, and this is a solution to use already free energy to spin the flywheel.

As you likely know, a turbocharger has two parts, a turbine, that spins from the exhaust, and a compressor, that compresses the intake air going into the engine.

I am proposing using only the turbine half of a turbocharger, and have the turbine shaft spin up the flywheel, likely through some gearing. A turbocharger is not free power, as you need to feed more air into the motor, and burn more fuel as your "cost".

Using this setup would be actual "free power", similar to a compound turbo engine. If you use the exhaust gasses to help spin your crankshaft, or in this case your kers unit, you are not effecting the mileage of the car.

From wiki:

A Turbo-compound engine is a reciprocating engine that employs a blowdown turbine to recover energy from the exhaust gases. The turbine is usually mechanically connected to the crankshaft but electric and hydraulic systems have been investigated as well. The turbine increases the output of the engine without increasing its fuel consumption, thus reducing the specific fuel consumption. The turbine is referred to as a blowdown turbine (or power-recovery turbine), as it recovers the energy developed in the exhaust manifold during blowdown, that is the first period of the exhaust process when the piston still is on its expansion stroke (this is possible since the exhaust valves open before bottom dead center).

EDIT: Sorry, yea did get what I was saying, but I think that feeding wasted exhaust gasses back into the engine with a mechanical conversion is the future, if the regs allow it.