A sportscar concept CAD model

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machin
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Re: A sportscar concept CAD model

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autogyro wrote:Were you thinking of using part time four wheeled drive?
That's right... for exactly the reasons you infer: better weight distribution, and better traction for applying all that power in a lightweight car. I wasn't sure whether a single motor and a differential unit at the front would be better than two separate motors, but I was definitely thinking of keeping the flybrid rather than batteries....
marcush wrote:the whole S1 Elise could have easily weighed a LOT less for what it was.
If I were to build it I'd get you onboard to right those wrongs!
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autogyro
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Re: A sportscar concept CAD model

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Fywheel storage is OK, although I would suggest a combination of batteries and flywheel, best of both worlds and gives better packaging potential.
Dont use a flybrid CVT though, to heavy, use the induction charged sealed flywheel system, which is next generation, all CVTs sap energy to operate, very last year.
Front diff is also a no no, heavy and to many rotating bits to take account of plus mountings.
Use two motor/generators, lighter and only one moving part in each, diff action is control simplicity. Also if it is only part time 4WD exiting corners and on demand would be best IMO, then the front suspension and chassis does not have to be as heavy or bulky as for full time 4WD.
My ESERU would simply replace the trans axle but would be potentialy shorter and smaller, gives complete hybrid capability on the rear axle with no extra gearing or torque multipliers to fit. Easily drive 50 plus miles around Town with the IC engine turned off and still good performance with that.

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machin
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Re: A sportscar concept CAD model

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I must say, I'm not convinced by a mixture of batteries and flywheels... The Flybrid system is small a light enough that positioning it where I have will give pretty much the optimum weight distribution... so I don't need to put batteries all around the car to optimise that, plus the problem with any sort of system is that its total weight generally isn't directly proportional to its storage potential (the storage medium only being part of the weight of the system)... so the basic system may weigh "X" amount and have "Y" storage potential, but a storage of 2Y won't weigh 2X, more like 1.5X, so its always better to stick with one system, unless you're looking for redundancy, which I'm not.

The system as I envisaged it would have no direct (mechanical or electrical) connection between the engine and the Flybrid system (to draw off enough power from the IC engine to make permanent 4-wheel drive viable would add way too much weight), so full time 4-wheel drive wouldn't be on the agenda, as you say, it'd be used to provide power out of the corners (either adding to the IC engine in boost mode, or reducing the load on the IC engine in the "economy" mode).

I agree, there's a nice simplicity about induction based flywheel systems, although no method is 100% efficient of course....!
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autogyro
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Re: A sportscar concept CAD model

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So how will you drive the flybrid system?

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machin
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Re: A sportscar concept CAD model

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In any of my conceivable options the power transmission to and from the system would be from the front wheels via drive shafts. If we were to discount the CVT based system (which I admit is what I have modelled) the alternative would be to have two MGU's (or one with Diff) driven directly by the drive shafts from the front wheels. These would be electrically connected via integrated power electronics to the induction driven flywheel(s) (two contra-rotating wheels seems quite a neat solution) as the energy storage medium.

To charge the system in what I call "sport" mode (when the IC engine isn't being fully utilised to propel the vehicle), the front wheels effectively brake using the MGU's, in a way therefore the IC engine and MGU's are linked... by the road. Whilst from an energy point of view this isn't the most efficient method, it does keep weight down as the alternator on the engine only need provide auxiliary power, not harvest power from the engine to charge the KERS. This does mean that it is not possible to charge the KERS whilst the vehicle is at stand-still, but IC engine's aren't that efficient at low rpm and low load anyway, so I wouldn't be too worried about providing this capabililty anyway.
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autogyro
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Re: A sportscar concept CAD model

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It is a lot easier to harvest braking energy and to apply torque to a front steering axle using two electric motor/generators and electronic control.
Mechanical/pneumatic/hydrolic control over a CVT flybrid system on a front axle would be fraught with problems. It would also have to be geared through a torque balance (diff), which would be much heavier and there would be far higher torque loss from the gearing. The CVT on the flybrid also uses extra energy to move the toroidal disks draining even more energy. On top of all this, you have to control both the diff action and the braking balance with a mechanical system. (good luck for anyone who tries that Toyota have enough trouble as it is).
It is easy (relatively) with electronic control over two motor/generators. They would be light and this would allow a weight consistant with a 'part time' 4WD system keeping the front chassis weight down.
Porsche's Williams systems are for race with flywheel storage and for road with batteries. If you fit any form of decent hybrid system to a road car, it is wasted if the urban cycle cannot be performed on mostly electric alone to meet regulations at the least. This means batteries for the energy density. However, you also want to have a 'boost button' out of corners for handling and for overtaking. The only way to achieve both and balance the storage against the output for all possible needs is a system that uses both batteries and a flywheel.
Induction/sealed flywheel is the best. Electronic control can bleed current from the flywheel to the batteries to make space available when braking, if you do not do this the electric storage will be negligable and the system wasted.

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machin
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Re: A sportscar concept CAD model

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I'm not sure where you're going with the combined flywheel AND batteries; if you have enough battery capacity to "bleed current from the flywheel to the batteries" that implies you aren't using all your storage to its optimum. Remember both batteries and flywheels are, at the end of the day, storage devices, and using power electronics you can drive the MGU's in motor mode from the flywheels, even when the flywheel rotational speed is, relatively, low, so there's really no need for the batteries if you have the correct amount of storage in your flywheels to cater for all your envisaged operating scenarios... which for this car is driving quickly and efficiently along European B-roads.

Taking this last "mission statement" into account, I'm not an advocate of charging the KERS from the IC engine for "emission-free" driving. The conversion from mechanical energy to storage and back to mechanical (propulsive) energy is wasteful, especially if that energy is harvested when the IC engine is at low revs and low low load when IC engines aren't very efficient. In the "Sport" mode I described on the first page the operator would have to accept that there is some loss of effciency in harvesting energy from the IC engine when he's not using it to its full potential to charge the KERS... but remember, he'll probably still be driving fast, so engine load will be high... right when IC engines are most efficient, so the KERS is being charged when the engine is near its most optimum operating point.

I'm also against batteries from a life-cycle management point of view; better to keep with flywheels from that perspective, although a small auxiliary battery is of course needed to start the IC engine!
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autogyro
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Re: A sportscar concept CAD model

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The car is good machin, great job.
Like you say if a 'kers' boost is all you want a flywheel system will do.
I also like your projected use of Ilmors five stroke engine, there is a lot of potential in that unit. It is a clever system similar in concept to a multi expansion steam engine. I have ideas for it in another application that I cant say much about unfortunately.
The problem with any future performance road car designs is going to be the urban cycle regulations machin (pays to keep this firmly in mind). This is the only reason for my suggestion to make the car fully hybrid and capable of electric only Town work. It is why Ferrari are converting ALL their cars to hybrid.
Without it future ic only powered cars will only be used in rural areas if they are very fuel efficient (maybe not even with that eventualy) and that means fairly low performance.
Flywheel only storage will not give a decent range.

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machin
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Re: A sportscar concept CAD model

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I agree, flywheel storage simply does not work for in-city zero-emission driving... one of the main problems being self discharge, which isn't good with flywheels.

It will be interesting to see which towns and cities adopt a zero-emission rule. I suspect it will only be true city-centres for the forseeable future, for example London's centre which currently applies congestion charging. There's simply too many vehicles, especially commercial vechicles, which would be affected at the moment for Governments to apply such a rule. Altho personally, being a big advocate of the greatest machine ever created (the bicycle), I'd welcome the move!

With this concept what I wanted to showcase was the technology that is available at the moment, and what can be done to improve the effieincy of IC-driven vehicles. My main thing is size and weight... cars are simply too big and cumbersome at the moment, and people demand too many luxuries in their cars... look at a current Ferrari... way too big.

That Ilmor 5-stroke is a beauty... very simple, I just hope somebody snaps up the design and starts building it on a large scale -it would be such a shame to see it go to waste....
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autogyro
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Re: A sportscar concept CAD model

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Ilmor only have a three cylinder OA five stroke at the moment.
Why V6 turbo machin?
Edit:
Sorry Machin, I just checked and the test engine Ilmor have is in fact turbocharged. I was thinking of the original spec when it was theory only.

Edis
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Re: A sportscar concept CAD model

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machin wrote:In any of my conceivable options the power transmission to and from the system would be from the front wheels via drive shafts. If we were to discount the CVT based system (which I admit is what I have modelled) the alternative would be to have two MGU's (or one with Diff) driven directly by the drive shafts from the front wheels. These would be electrically connected via integrated power electronics to the induction driven flywheel(s) (two contra-rotating wheels seems quite a neat solution) as the energy storage medium.

To charge the system in what I call "sport" mode (when the IC engine isn't being fully utilised to propel the vehicle), the front wheels effectively brake using the MGU's, in a way therefore the IC engine and MGU's are linked... by the road. Whilst from an energy point of view this isn't the most efficient method, it does keep weight down as the alternator on the engine only need provide auxiliary power, not harvest power from the engine to charge the KERS. This does mean that it is not possible to charge the KERS whilst the vehicle is at stand-still, but IC engine's aren't that efficient at low rpm and low load anyway, so I wouldn't be too worried about providing this capabililty anyway.
If you use two electric machines for the front axle you still need some sort of mechanical coupling in between them to be able to control the torque distribution and to take advantage of the full power offered by the machines.

However, I think there are simpler ways to get the job done. I would start with a mechanical 4WD system, with clutch packs attached to the three diffs all under electronic control. That way you can control the torque distribution how you like it, and the system will provide a 'passive' ABS system which should help kinetic energy recovery and brake balance. You would also not be limtied to front wheel braking by the KERS system.

Between the engine and the 4WD system you then have two good tranmission options. Go with a mechanical gearbox with an electrical machine attached in parallel (like current F1 KERS and many current hybrids), or two motors and the engine attached to a planetary gearset just like Toyota and Ford make their full hybrids (sometimes called eCVT). That way the function of the motors are only to provide tractive power or to function as a brake with the KERS system, they have no torque distribution function. That is instead handled by a system that is proven in WRC and several high performance 4WD vehicles already.

The traction motor will also replace the conventional startermotor and alternator which saves some weight. Compared to the conventional alternator it's also much more efficient (an alternator is only around 50% efficient), and compared to the conventional starter it can start the engine much faster, meaning that it only needs to start then engine during acceleration. In certain load points it can also use power from the engine to charge the energy storage unit. This is beneficial since the BSFC of an engine can in some load points be reduced quite a lot when you put the engine under a bit more load.

Then I would replace the compound engine with a simpler and more efficient design. There are 'diesel' engines which operate on high octane fuels using a partially premixed charge. These can reach efficienties over 50%, and don't have the NOx and PM problems a diesel have. The engine could also use a pneumatic camless valve system. That would also allow energy storage in the form of compressed air, which has some benefits.

As for battery based storage vs. flywheel storage I think it depends on what the car is going to be used for. Williams hybrid system supply a 48 kg flywheel which can provide 120 kW. This can be matched by batteries, where suppliers such as A123Systems claim around 5 kW/kg for th cells alone. The question is the lifetime, flywheels generally can survive more charge/discharge cycles than a battery and they can also be transported by air freight without restriction. The battery on the other hand can store more energy per weight, and it has a low self discharge rate. So for racing use, I would pick a flywheel, and for road use I would go with batteries. With batteries it's also possible to place prismatic cells under the chassi for a low center of gravity and good weight distribution.

autogyro
autogyro
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Re: A sportscar concept CAD model

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Edis wrote:
machin wrote:In any of my conceivable options the power transmission to and from the system would be from the front wheels via drive shafts. If we were to discount the CVT based system (which I admit is what I have modelled) the alternative would be to have two MGU's (or one with Diff) driven directly by the drive shafts from the front wheels. These would be electrically connected via integrated power electronics to the induction driven flywheel(s) (two contra-rotating wheels seems quite a neat solution) as the energy storage medium.

To charge the system in what I call "sport" mode (when the IC engine isn't being fully utilised to propel the vehicle), the front wheels effectively brake using the MGU's, in a way therefore the IC engine and MGU's are linked... by the road. Whilst from an energy point of view this isn't the most efficient method, it does keep weight down as the alternator on the engine only need provide auxiliary power, not harvest power from the engine to charge the KERS. This does mean that it is not possible to charge the KERS whilst the vehicle is at stand-still, but IC engine's aren't that efficient at low rpm and low load anyway, so I wouldn't be too worried about providing this capabililty anyway.
If you use two electric machines for the front axle you still need some sort of mechanical coupling in between them to be able to control the torque distribution and to take advantage of the full power offered by the machines.

Diff control can be achieved purely electronicaly.

However, I think there are simpler ways to get the job done. I would start with a mechanical 4WD system, with clutch packs attached to the three diffs all under electronic control. That way you can control the torque distribution how you like it, and the system will provide a 'passive' ABS system which should help kinetic energy recovery and brake balance. You would also not be limtied to front wheel braking by the KERS system.

Sounds like you would be building something with more gears and torque transfer devices than a steam power station.

Between the engine and the 4WD system you then have two good tranmission options. Go with a mechanical gearbox with an electrical machine attached in parallel (like current F1 KERS and many current hybrids), or two motors and the engine attached to a planetary gearset just like Toyota and Ford make their full hybrids (sometimes called eCVT). That way the function of the motors are only to provide tractive power or to function as a brake with the KERS system, they have no torque distribution function. That is instead handled by a system that is proven in WRC and several high performance 4WD vehicles already.

This is the hugely complex and power sapping method that companies like Ferrari have in all their patents I have looked into. Completely out of date. CVT transmissions use huge amounts of energy just to keep the disks or cones driving and changing ratio, last centuries technology. I have already pointed this out to Williams and they no longer use CVTs.

The traction motor will also replace the conventional startermotor and alternator which saves some weight. Compared to the conventional alternator it's also much more efficient (an alternator is only around 50% efficient), and compared to the conventional starter it can start the engine much faster, meaning that it only needs to start then engine during acceleration. In certain load points it can also use power from the engine to charge the energy storage unit. This is beneficial since the BSFC of an engine can in some load points be reduced quite a lot when you put the engine under a bit more load.

The electric engine part of a hybrid or kers system can indeed replace the starter and generator, however it needs a good control system because of the different voltages involved. Because my system is an integral part of the actual gearbox and not an externaly or internaly driven 'extra' unit it can be used for all such purposes and can drive the vehicle without the ice even running.

Then I would replace the compound engine with a simpler and more efficient design. There are 'diesel' engines which operate on high octane fuels using a partially premixed charge. These can reach efficienties over 50%, and don't have the NOx and PM problems a diesel have. The engine could also use a pneumatic camless valve system. That would also allow energy storage in the form of compressed air, which has some benefits.

Fo the best ice application I would further modify the Ilmore five stroke engine into a three stroke two stroke turbocharged engine with sleeve valves. I cannot say more on the control system.

As for battery based storage vs. flywheel storage I think it depends on what the car is going to be used for. Williams hybrid system supply a 48 kg flywheel which can provide 120 kW. This can be matched by batteries, where suppliers such as A123Systems claim around 5 kW/kg for th cells alone. The question is the lifetime, flywheels generally can survive more charge/discharge cycles than a battery and they can also be transported by air freight without restriction. The battery on the other hand can store more energy per weight, and it has a low self discharge rate. So for racing use, I would pick a flywheel, and for road use I would go with batteries. With batteries it's also possible to place prismatic cells under the chassi for a low center of gravity and good weight distribution.
Your points are exactly why I would use a combination of lighter flywheel and batteries. This allows self discharge of the induction spun flywheel into the batteries but keeps a flywheels rapid application of energy for boost along with a decent range. Also a flywheel partly charged or uncharged gives storage available at all times with a power range source, so that deceleration energy harvesting will always be available and not wasted as with a fully charged system.

autogyro
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Re: A sportscar concept CAD model

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Edis wrote:
machin wrote:In any of my conceivable options the power transmission to and from the system would be from the front wheels via drive shafts. If we were to discount the CVT based system (which I admit is what I have modelled) the alternative would be to have two MGU's (or one with Diff) driven directly by the drive shafts from the front wheels. These would be electrically connected via integrated power electronics to the induction driven flywheel(s) (two contra-rotating wheels seems quite a neat solution) as the energy storage medium.

To charge the system in what I call "sport" mode (when the IC engine isn't being fully utilised to propel the vehicle), the front wheels effectively brake using the MGU's, in a way therefore the IC engine and MGU's are linked... by the road. Whilst from an energy point of view this isn't the most efficient method, it does keep weight down as the alternator on the engine only need provide auxiliary power, not harvest power from the engine to charge the KERS. This does mean that it is not possible to charge the KERS whilst the vehicle is at stand-still, but IC engine's aren't that efficient at low rpm and low load anyway, so I wouldn't be too worried about providing this capabililty anyway.
If you use two electric machines for the front axle you still need some sort of mechanical coupling in between them to be able to control the torque distribution and to take advantage of the full power offered by the machines.

Diff control can be achieved purely electronicaly.

However, I think there are simpler ways to get the job done. I would start with a mechanical 4WD system, with clutch packs attached to the three diffs all under electronic control. That way you can control the torque distribution how you like it, and the system will provide a 'passive' ABS system which should help kinetic energy recovery and brake balance. You would also not be limtied to front wheel braking by the KERS system.

Sounds like you would be building something with more gears and torque transfer devices than a steam power station.

Between the engine and the 4WD system you then have two good tranmission options. Go with a mechanical gearbox with an electrical machine attached in parallel (like current F1 KERS and many current hybrids), or two motors and the engine attached to a planetary gearset just like Toyota and Ford make their full hybrids (sometimes called eCVT). That way the function of the motors are only to provide tractive power or to function as a brake with the KERS system, they have no torque distribution function. That is instead handled by a system that is proven in WRC and several high performance 4WD vehicles already.

This is the hugely complex and power sapping method that companies like Ferrari have in all their patents I have looked into. Completely out of date. CVT transmissions use huge amounts of energy just to keep the disks or cones driving and changing ratio, last centuries technology. I have already pointed this out to Williams and they no longer use CVTs.

The traction motor will also replace the conventional startermotor and alternator which saves some weight. Compared to the conventional alternator it's also much more efficient (an alternator is only around 50% efficient), and compared to the conventional starter it can start the engine much faster, meaning that it only needs to start then engine during acceleration. In certain load points it can also use power from the engine to charge the energy storage unit. This is beneficial since the BSFC of an engine can in some load points be reduced quite a lot when you put the engine under a bit more load.

The electric engine part of a hybrid or kers system can indeed replace the starter and generator, however it needs a good control system because of the different voltages involved. Because my system is an integral part of the actual gearbox and not an externaly or internaly driven 'extra' unit it can be used for all such purposes and can drive the vehicle without the ice even running.

Then I would replace the compound engine with a simpler and more efficient design. There are 'diesel' engines which operate on high octane fuels using a partially premixed charge. These can reach efficienties over 50%, and don't have the NOx and PM problems a diesel have. The engine could also use a pneumatic camless valve system. That would also allow energy storage in the form of compressed air, which has some benefits.

Fo the best ice application I would further modify the Ilmore five stroke engine into a three stroke two stroke turbocharged engine with sleeve valves. I cannot say more on the control system.

As for battery based storage vs. flywheel storage I think it depends on what the car is going to be used for. Williams hybrid system supply a 48 kg flywheel which can provide 120 kW. This can be matched by batteries, where suppliers such as A123Systems claim around 5 kW/kg for th cells alone. The question is the lifetime, flywheels generally can survive more charge/discharge cycles than a battery and they can also be transported by air freight without restriction. The battery on the other hand can store more energy per weight, and it has a low self discharge rate. So for racing use, I would pick a flywheel, and for road use I would go with batteries. With batteries it's also possible to place prismatic cells under the chassi for a low center of gravity and good weight distribution.
Your points are exactly why I would use a combination of lighter flywheel and batteries. This allows self discharge of the induction spun flywheel into the batteries but keeps a flywheels rapid application of energy for boost along with a decent range. Also a flywheel partly charged or uncharged gives storage available at all times with a power range source, so that deceleration energy harvesting will always be available and not wasted as with a fully charged system.

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machin
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Re: A sportscar concept CAD model

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If you use two electric machines for the front axle you still need some sort of mechanical coupling in between them to be able to control the torque distribution and to take advantage of the full power offered by the machines.
There are plenty of vehicles that use independant motors for each wheel... torque biasing is simply part of the speed control system, and doesn't need to be linked mechanically.
I would start with a mechanical 4WD system
Remember the Power split, even in the case when you have full KERS boost, is still far in favour of the rear wheels in this concept, where the engine, and hence most of the weight is, so traction will not be a problem... in this case there really is no need to use mechanical 4WD, this just adds weight and cost, -although I agree plenty of rally machinery has this capability, so it is a readily available technology and in a bigger, more powerful vehicle it would have its advantages. There's a further disadvantage of mechanical 4WD if it were applied to my vehicle; routing the tranmission from front to rear. What's not immediately obvious from the screenshots is the narrow cockpit area... the occupants sit literally shoulder to shoulder to reduce frontal area... the result is that there is no room for a transmission tunnel between the seats.
In certain load points it can also use power from the engine to charge the energy storage unit.
This is possible with a front mounted power unit that isn't connected to the ICE inside the car... the engine and MGU(s) are effectively connected via the road... so the KERS system harvests energy (i.e Brakes the front wheels) a small amount when the ICE isn't being fully utilised to charge the KERS unit, this is what I call "Sport" mode -when the car tries to keep the KERS system fully charged by utilising unused engine power (e.g during steady peed driving), even though it means burning more fuel to do so... although as you say, and I said in an earlier post, it'll be relatively efficient because the engine will be under higher load and hence BSFC is low.
So for racing use, I would pick a flywheel, and for road use I would go with batteries
I agree... I should have written it in my first post, but the ethos for the car is to cover a stretch of European B-roads (read "twisty"), at the same pace as one of today's supercars, but with far less fuel consumption. I'm less concerned with in-city driving, and therefore I'm not concerned with the flywheel's self-discharge problem that clearly is a major advantage to battery storage for stop-start driving. With this ethos in mind I would stick with the flywheel storage method; its almost perfect for the high charge rate, short storage time, high discharge rate, that this application requires.
Also a flywheel partly charged or uncharged gives storage available at all times with a power range source, so that deceleration energy harvesting will always be available and not wasted as with a fully charged system.
The problem I have with this approach is that it implies that you have storage that isn't being fully utilised (although I agree the storage won't be fully charged ALL the time!). Storage that isn't fully utilised means unecessary weight. Personally I'd rather have less storage which is fully utilised than have more storage that is only partially utilised. Reducing weight not only improves the economy of the car in a straight line, but also improves cornering ability... that means you can cover a given twisty road at the same average speed with less power (you're quicker through the corners, and therefore don't need to be as quick on the straights), and therefore you use less fuel for the same average speed over the given route.
I would use a combination of lighter flywheel and batteries.
As above; this application doesn't benefit from battery storage, although I agree that a different application that requires good stop-start efficiency or the capability to "pollute elsewhere" would benefit from battery storage.
This allows self discharge of the induction spun flywheel into the batteries but keeps a flywheels rapid application of energy for boost


In this application I'd just have a slightly bigger flywheel. Otherwise you'll just loose energy in the transfer process from flywheel to battery... I'm just not convinced by a mixed storage system in this application.....
Last edited by machin on 21 Apr 2010, 00:17, edited 3 times in total.
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autogyro
autogyro
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Re: A sportscar concept CAD model

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I agree machin and it has been a pleasure throwing some ideas about.
I hope this can continue as I firmly believe that this is the direction technology in all types of vehicles will take from now on.