Energy storage theory.

[xpensive]

Again, as a newcomer here I apologize if this has been dwelled over many times before, but anyway.

A 600 kg object, travelling at 294 kM/h and deacceccellerates to 147, reduces its moving energy with 500 kJ and when repeated four times adds up to 2000 kJ.
If this energy can be trapped and stored with a 50% efficiency under breaking, you will have 1000 kJ to unleash under accelleration.

1000 kJ equally spent, over say 5s, means 200kW, or 272 hp.

This tells me that there is a lot of potential here, but please allow me to be somewhat sceptical over the prospects to increse next years KERS storage of 400 kJ much more, when a 200 kW generator/motor would be a rather cumbersome unit, no?
Let alone a flywheel.

Besides, power-transfer from the rear wheels is one thing, but from the fronts?

WhiteBlue, or somebody else, please help me out here and correct me where I'm wrong?

[WhiteBlue]

If they continue the path mapped in 2005 they will go for AWK surely. I'm not so much concerned with the weight as I am with the control aspect. It would require to take control of accelerating and breaking largely away from the driver and back to electronic systems. There is a lot of ballast in an F1 car and I expect the KERS components to get down in weight quite dramatically once the suppliers have found out which system will attract all the investment. The drive technology used in F1 is basically the same that you see in robotics and machine tools plus some storage solutions that you do not need in those fields. The miniaturization and weight reduction in that field has taken leaps and bounds in the last years. The basic technologies are IGPTs, high power permanent magnets and batteries all which are subject to billons of R&D expenses in the last decade. The most serious player certainly is Japan in all of these fields. So expect companies like Fanuc or even component suppliers to play a role soon.

[twoshots]

My guesstimates would be that you've over estimated the available energy to charge your KERS system.

KERS is charged from the powertrain, limiting the available energy to that dissipated by the rear brakes. Then the KERS systems must not interfere with the ability of the driver to alter braking performance. As this will not be as fast to react as the driver would require it will only impart a retardation which does not compromise the cars balance. Then the efficiency of energy storage should be taken into consideration. In total I'd suggest an efficiency of 10% would seem to be a good system.

[machin]

Then the KERS systems must not interfere with the ability of the driver to alter braking performance. As this will not be as fast to react as the driver

I would assume that the system would be fully integrated with the brake and throttle pedals, such that any application of the brakes would start the energy storage, and application of the brakes harder would increase the amount of energy storage whilst at the same time applying the friction brakes. A very simple system arhitecture could be based around the same principles as power steering:- the driver applies a demand and when the demand is higher than the actual reading hydraulic fluid is directed towards the storage device to effect the storage... e.g. on a flywheel and CVT based KERS the hydraulic fluid would be used to raise the CVT ratio (and thus store energy). The same principle would used in reverse with this time the throttle being used to reduce the CVT ratio when a demand is placed on it (by pressing the throttle pedal). The response rate of such a system would be incredibly fast, as evidenced by the fact that power steering works so well.

[xpensive]

For twoshots:
If one of the incentives for KERS in F1 is to lead the way for the automotive industry in general, let's hope that ambitions are set a little higher than 10 %.

Imagine a 1500 kg car breaking from 110 km/h to 50 km/h, 10 % of that recuction of moving energy is no more than 21 kJ, which is a little less than 0.06 kWh.

Before that breaking exercise, the same car wasted 15 - 20 kWh during a half an hour stint of highway driving at 110 km/h, which is predominantly spent on overcoming air-resistance. No KERS will ever help you with that.

As usual, please correct where I'm wrong.

[dumbdave]

http://www.flybrid.co.uk/index.html

Flybrid claim up to 70% of braking energy recovered, which would certainly be more useful on a road car.
If they can actually achieve a full 70% im not sure, but i dont think 40-50% wil be beyond possibility with new systems.

[Ciro Pabón]

Not only they claim it: the Toyota Supra HV-R that won the 24 Hours of Tokachi gets a 70% efficiency, both ways. There is also claims of 90% efficiency both ways by commercial KERS manufacturers.

Weight is not much of an issue. I quote from Toyota's site:

"The hybrid system for the car will incorporate regenerative braking, a pair of 10kW in-wheel motors up front and a 150kW motor at the rear. It'll weigh in at a little over 2300 pounds."

However, if you want to watch a variety of engines, watch LeMans. I confess I'm not into F1 engines since 2005 or so, I prefer to watch endurance race designs.

Your estimates, xpensive, (which I haven't checked) seem reasonable. FIA's own figures are 400kJ per lap, giving 80 extra-hp for 6.7 seconds. According to Toyota's

The front wheel KERS is not rocket science, either. Just a couple of flywheels are enough. Sure, you need front axles, but some cars have them already.

Chris Ellis concept for front wheel KERS


Some cars, as conventional as the Lincoln Mercury Mariner, by Ford, use a 70 Kwatts electric engine, directly charged (something F1 doesn't allow) by the engine, with front or all wheel drive.

People has been knocking on FIA's doors, asking them to be more forward thinking. I don't know how many times, probably since 2002 or so, people has said in this forum that fuel or energy limitation is the key.

F1 is falling the way of software industry, where Microsoft claims to be a force for innovation (a bit of a cynicism, if you ask me). If F1 hadn't had freedom for engine research, things like the common rail, direct injection, hydraulic valves, superchargers or turbo would have come from other sources, at other pace.

The fact is that many teams, probably, will use commercial KERS units, and they have known efficiency and energy figures. Torotrak and Xtrac have sites I've browsed, when I was thinking about rotational inertia (btw, their systems have output disks that rotate in the opposite sense of the input disk and a clever CVT: that elliminates or, at least, diminishes any inertia from the unit).

Xtrac unit: a clever CVT using viscously coupled input-output disks and a flywheel. That's it: 5 kilos.


There is some hope, I think, for F1 KERS: BMW's KERS will use an electric system, or so I read some time ago. They claim they can reach energy density superior to current hybrids. Let's wait and see.

Some days, I'm not so sure about my "hope". It seems FIA is headed toward engines and KERS units that are as important for development as spark plugs: you can buy them at the supermarket.

If I were doing R&D in F1 today (keep dreaming), I don't know where I would like to work. Probably, not at the KERS unit. I'm thinking that with a limited team budget and limited by all the "research" sides, probably Torotrak or the manufacturers will overtake F1 KERS units in the long run.

[xpensive]

Ooops, afraid that I have to correct myself:
If one of the incentives for KERS in F1 is to lead the way for the automotive industry in general, let's hope that ambitions are set a little higher than 10 %.

Imagine a 1500 kg car breaking from 110 km/h to 50 km/h, 10 % of that recuction of moving energy is no more than 56 kJ, which is a little less than 0.015 kWh.

Before that breaking exercise, the same car wasted 15 - 20 kWh during a half an hour stint of highway driving at 110 km/h, which is predominantly spent on overcoming air-resistance. No KERS will ever help you with that.

As usual, please correct where I'm wrong, though I did it myself this time.

[twoshots]

Hmmm, I wasn't thinking about the CVT component. That should be reasonably fast.

That said, if we take Flybrid's claim of 70% efficiency of braking energy recovered, then you will still only get 70% of the energy removed from the powertrain, which only effects the rear wheels. (On a road car without Max's rules and regs it's different.) So if you have 40% of braking energy dissipated through the rear wheels and 70% efficiency of that energy recovered you get 28% efficiency. That's assuming that the rear brakes remove zero energy from the system.

But this is all F1 specific. Going forward, Max's rules will allow a full wheel implementation.

It's also worth bearing in mind with F1 that the KERS unit may not be able to impart a sufficient retardation force under hard braking which still leaves some loss to the brakes.

I'm sure if Max let's the teams actually develop the technology the efficiency will increase quite quickly.

[xpensive]

Again, a correction to the original calc's:

A 600 kg object, travelling at 294 kM/h and deacceccellerates to 147, reduces its moving energy with 1500 kJ and when repeated four times adds up to 6000 kJ.
If this energy can be trapped and stored with a 50% efficiency under breaking, you will have 3000 kJ to unleash under accelleration.

1000 kJ equally spent, over say 10s, means 300kW, or 400 hp.

This tells me that there is a lot of potential here, but please allow me to be somewhat sceptical over the prospects to increse next years KERS storage of 400 kJ much more, when a 300 kW generator/motor would be a rather cumbersome unit, no?
Let alone a flywheel.

Besides, power-transfer from the rear wheels is one thing, but from the fronts?

[machin]

I think the weight of the flywheel system at least won't be that bad, The flywheel in Flybrid's system weighs just 5kg's, and spins at 65,000 rpm! Do the sums and that speed means 400kJ's from 5kg's actually means the radius of gyration is actually pretty small.....

[xpensive]

65000 Rpm? Now you are talking, now I understand things a little better, but what about safety?

[machin]

The flywheel and the box it is held within have been subjected to an F1 style crash test with no problems.... This was in Racecar Engineering over a year ago, so maybe the speeds have increased by now....

[dumbdave]

Flybrids still runs at 64500rpm for the F1 system, but i've heard numbers as hign as 150,000 or even 200,000 (not sure where though..possibly on here).

[xpensive]

For machine:
Interesting this, I took the time to crack sume numbers and indeed, a 166 mm diameter flywheel, 30 mm thick and made of solid steel, will actually weigh 5 kg and store 400 kJ at 65 000 Rpm.

Next question, how du you gear it from the engine, gearbox or frontwheels speed up to the 65000 Rpm needed?