Impact of unlimited KERS on chassis design?

[autogyro]

One M/G with a diff is 'probably' going to be heavier than two MGs.
The main problem though is that one MG would loose more energy in the gearing.
There would be far more moving parts and a wider and more complex mounting and packaging requirement as well.
Of course if allowed there would also be finer control over torque bias with two MGs.
With the expected objections to policing TC etc on the rear axle, I am sure one MG or multi segment MG would be the choice.
Three will be the number of MGs mounted IMO.
There is no benefit in full 4WD over mainly rear wheel drive in F1 because of the traction requirements. However handling can receive a significant benefit from torque control of the front wheels. The tyre guys on here might have some interesting comments, if they can apply their technology instead of guessing that is.

[WhiteBlue]

Let us assume that a system with three MGUs will be used with the power electronics and the storage in one unit and the energy stored and fed to the electric torque being 2.3 MJ/lap.

What kind of weight implications would we have from this on the front and rear of the car? Do you think 10KG more for the front MGUs and the drive shafts would be ok? And another 20 kg for the increased storage and power electronics in the rear?

I believe that the additional weight of the AWKERS against the 2009 KERS version could be compensated by the weight loss of the downsizing from V8 to turbo charged V4 or I-4. Just the weight would be more distributed to the front.

And what kind of performance gains would we get? If we assume a 700 bhp engine plus 10% power by KERS we would have 770 bhp total with the chance of gaining a lot more traction in slow corners. I think this is where an AWD F1 would make significant gains. Straight line speed is probably going to be similar as today. Acceleration should be better from slow corners than from fast corners again. I expect the 2013 cars to carry 45kg less fuel initially compared to today's cars due to improved fuel efficiency from the engine and KERS. Over the race that would be an average of 22 kg. So together with the front wheel torque we could see gains of one second per lap.

A lot will depend of the future downforce cuts. Theoretically next year downforce should be significantly slashed but I don't believe it will happen. Not unless they actually limit the fuel. Designers will simply pile on the downforce by wings again. Only cutting the fuel will force them to really limit aero forces and that is not due before 2013.

[autogyro]

I am not sure of the figures WB but the introduction of AWKERS with a higher allowed energy useage should restrict downforce increases.
Increases in wing downforce and 'drag' would be offset by increases in slow speed mechanical cornering and the potential to use less fuel for the same lap time.
If the four cylinder TC engines produce no more than 700 horsepower within this framework, I do not see aero running away before 2013.
In anycase the specific aero regulations are holding lap times pretty close as it is, so long as the pressure from the aero lobby does not open more loopholes.
I think WB that you are accurate with your estimated weights for KERS components at the present level of technology but I would expect significant weight reductions in the future.

[riff_raff]

I'd bet that if you did a trade study you'd find that a single MG and gear diff is the lighter weight option.

There is also the issue of reliability/safety to consider. Two separate, independent MG's connected to wheels on opposite sides of the car would present a control hazard if one of the MG's were to fail.

If the engines are turbocharged, how about putting the electric KERS (or more correctly "TERS") MG system onto the turbo spool? Electric assist turbo-compounding systems are already developed and could easily be incorporated. The high speed PM MG's in an electric assist turbo TERS would be much lighter and compact than a drivetrain KERS.

[WhiteBlue]

That system looks like something designed to avoid waste gates. If you fit a motor generator and a battery to a mid sized turbo you can use the elctric energy at low rpms to get the compression high enough without turbo lag. When the turbo is then producing too much power which you would normally blow off at a waste gate you simply use this power to produce electric energy. Neat system actually if you already have power electronics and storage for other purposes. But I don't think it will replace KERS from the wheels.

If you would use traditional electric assisted turbo compounding you would still need an electric motor at the driven wheels. So I don't see it as an alternative to KERS and AWKERS.

[xpensive]

I admit to be intrigued by the concept of HERS more than, while I know that BMW is working on it for road-use, the xtreme temperatures of F1 xhausts must make it an even more attractive propsition.

Would an xhaust flow of 1.5 m^3/sec (0.36 m^3/sec going in), a temperature of 700 C, be reasonable starting values?

The thermal power of said flow, given a density and Cp of 1.0, would equal 600 kW, all in relation to the atmosphere.

Mind-boggling numbers indeed, puts KERS into perspektive.

[WhiteBlue]

When the hot exhaust gases are almost fully expanded behind a turbo charger the temperatures are much lower due to the expansion. The problem of HERS is the need to use these lower temp gases to drive a working machine. One solution is to use fluids with high evaporating temperatures like those in refrigerators and use a heat exchanger to boild them. The steam can then drive another small turbine unit which provides all ancillary power or drives a generator.

On second thought I think that a two stage electrical assist turbo compounder would be best. One stage would use the expanding exhaust gases and the second would be driven by the refrigerator fluid. Both would work on the same shaft driving an electric generator.

[autogyro]

"riff_raff"
I'd bet that if you did a trade study you'd find that a single MG and gear diff is the lighter weight option.

There is also the issue of reliability/safety to consider. Two separate, independent MG's connected to wheels on opposite sides of the car would present a control hazard if one of the MG's were to fail.


It is now common practice on EVs to have two motor/generators, one on each drive wheel, at least on rear wheel drive EVs.
Failure of one motor is taken care of with safety maps in the control units.
IMO two MGs on the front axle is a far safer route, especialy with a light weight part time 4WD system. The MGs have only one moving part, so mechanical failure is very unlikely. Any electrical faults should result only in a free wheel situation.
IMO two MGs would be much lighter than one with a differential.
In fact it could still be one MG with a split shaft but I wont go into that.

[autogyro]

When the hot exhaust gases are almost fully expanded behind a turbo charger the temperatures are much lower due to the expansion. The problem of HERS is the need to use these lower temp gases to drive a working machine. One solution is to use fluids with high evaporating temperatures like those in refrigerators and use a heat exchanger to boild them. The steam can then drive another small turbine unit which provides all ancillary power or drives a generator.

It becomes a difficult task to extract energy from the exhaust gas after most has already been taken using a turbocharger for induction charging.
This charging is only needed for part of the ic operating cycle and suffers from 'lag' it is therefore not as efficient full cycle as usualy described.
The new turbocharged formula will see the end of EBDs however.
If the regulations were to be more open, I would supercharge for the benefit of cylinder scavenging on a two stroke and use a turbo/generator to harvest electrical energy from the exhaust. This would make far better use of the turbo, which would be kept under constant load.

[xpensive]

When the hot exhaust gases are almost fully expanded behind a turbo charger the temperatures are much lower due to the expansion. The problem of HERS is the need to use these lower temp gases to drive a working machine. One solution is to use fluids with high evaporating temperatures like those in refrigerators and use a heat exchanger to boild them. The steam can then drive another small turbine unit which provides all ancillary power or drives a generator.

It becomes a difficult task to extract energy from the exhaust gas after most has already been taken using a turbocharger for induction charging.
...

I would recomment a class in classic physics, thermodynamics perhaps?

[timbo]

That system looks like something designed to avoid waste gates. If you fit a motor generator and a battery to a mid sized turbo you can use the elctric energy at low rpms to get the compression high enough without turbo lag. When the turbo is then producing too much power which you would normally blow off at a waste gate you simply use this power to produce electric energy. Neat system actually if you already have power electronics and storage for other purposes. But I don't think it will replace KERS from the wheels.

As F1 engines are spending more that a half of the lap at full throttle on all tracks, I think it is viable option.
I strongly believe, that powering all auxiliarities with electricity (pumps, using electro-magnetic valves, this turbo-thngy etc) has more potential to increase efficiency and reduce exhausts than KERS.

[WhiteBlue]

When the hot exhaust gases are almost fully expanded behind a turbo charger the temperatures are much lower due to the expansion. The problem of HERS is the need to use these lower temp gases to drive a working machine. One solution is to use fluids with high evaporating temperatures like those in refrigerators and use a heat exchanger to boild them. The steam can then drive another small turbine unit which provides all ancillary power or drives a generator.

It becomes a difficult task to extract energy from the exhaust gas after most has already been taken using a turbocharger for induction charging.
..

I would recomment a class in classic physics, thermodynamics perhaps?

What kind of problem do you see in mine and AG's statement? I don't think it is wrong to say that expanded gases have lower temperatures than the primary exhaust temperature in the cylinder head.

As F1 engines are spending more that a half of the lap at full throttle on all tracks, I think it is viable option.
I strongly believe, that powering all auxiliarities with electricity (pumps, using electro-magnetic valves, this turbo-thngy etc) has more potential to increase efficiency and reduce exhausts than KERS.

I do not believe in the assertion that F1 engines are on full power for more than 50% of the time on all tracks. Even more important I think that full power percentages will trend down significantly from 2013 with the new sporting regulations severely restricting fuel loads. F1 cars will simply not carry enough fuel to run as much on high power as they do now. The strategy to be fastest will be an increase in over all efficiency and partial load efficiency. Whoever does the best job will run the longest with high power setting. I agree on the potential of electric ancillaries. Obviously I do not agree with the KERS opinion.

[xpensive]

The power consumption of the TC was covered earier, when I grossy underestimated the same. But even if the contraption steals as much as 100 kW, there's still plenty of thermal energy to recover, perhaps as much as 400 - 500 kW is lost.

[autogyro]

That system looks like something designed to avoid waste gates. If you fit a motor generator and a battery to a mid sized turbo you can use the elctric energy at low rpms to get the compression high enough without turbo lag. When the turbo is then producing too much power which you would normally blow off at a waste gate you simply use this power to produce electric energy. Neat system actually if you already have power electronics and storage for other purposes. But I don't think it will replace KERS from the wheels.

As F1 engines are spending more that a half of the lap at full throttle on all tracks, I think it is viable option.
I strongly believe, that powering all auxiliarities with electricity (pumps, using electro-magnetic valves, this turbo-thngy etc) has more potential to increase efficiency and reduce exhausts than KERS.

I completely agree within the projected new turbo regulations, it is another potential method for harvesting energy.
It does not compete with energy recovered from braking using a AWKERS system though.

[autogyro]

The power consumption of the TC was covered earier, when I grossy underestimated the same. But even if the contraption steals as much as 100 kW, there's still plenty of thermal energy to recover, perhaps as much as 400 - 500 kW is lost.

This is why I would prefer to supercharge and use the turbocharger under constant load to drive a generator.
Harvesting energy from the exhaust with or without a turbocharger is still difficult at present.
I agree it is a large source of energy well worth developing technology to make use of.