VAG - DSG or CVT?

[Matra et Alpine]

tut-tut , ht, you KNOW there are always energy losses during conversions

Electric drivetrain is 90% efficient AND it has all that weight and mass ( cos you'll need batteries too even if just as buffers for the motors instantaneous needs ) EDIT: Thoug granted that is partially offset by the option of losign the gearbox and diffs

Trains NEED weigth as grip is low with steel on steel and they dont' have to start and stop every 100 yards in traffic. Different needs sets a different balance.

BUT I think in 10 years time we'll hopefully see in wheel motors at resonable costs ( hence limiting the extra weigth ). But hopefully we'll not need to combusion process either by then

[matek]

Brunnels trains would have been more stable had larger wheels allowing for less rotations for the same speed

And DSG is double clutch i remmeber you can also get a triple one cant you??? that shoudl be faster than the DSG??

[Matra et Alpine]

And DSG is double clutch i remmeber you can also get a triple one cant you??? that shoudl be faster than the DSG??

I think you're confusing triple PLATE clutches with double clutches.
The DSG has two separate clutches and layshafts in the gearbox. So one layshaft is changed to the next gear and then the clutch for that one engaged to the final drive. So VERY fast gear changes.

Triple ( and double ) PLATE clutches is just a way of getting more friction material onto the one clutch ( bikes often use 6 !!! )
Here's the EVO comp clutch .....

[hightower99]

tut-tut , ht, you KNOW there are always energy losses during conversions

Electric drivetrain is 90% efficient AND it has all that weight and mass ( cos you'll need batteries too even if just as buffers for the motors instantaneous needs ) EDIT: Thoug granted that is partially offset by the option of losign the gearbox and diffs

Trains NEED weigth as grip is low with steel on steel and they dont' have to start and stop every 100 yards in traffic. Different needs sets a different balance.

BUT I think in 10 years time we'll hopefully see in wheel motors at resonable costs ( hence limiting the extra weigth ). But hopefully we'll not need to combusion process either by then

I know that and I never said it is 100% efficient either!

anyways a compact electric drive train is lighter and more efficient than a mechanical one.

An electric generator/alternator can easily climb over 90% (typically 92-95%) efficiency. the wires that transfer the power and the small (very small) box with a few capacitors in it are also over 90% (typically around 95-97%) efficeint. And last but not least the electric motors can be over 90% (typically 90-95%) efficeint. In total the whole thing is about 79-88% effecient, that is pretty good against the roughly 75-80% of the mechanical system. Not to mention that trading a DSG 6 speed transmission, 3 differentials (talking AWD here) and assorted shafts out with a lightweight generator/alternator, small capacitor and computer control box, assorted cable and 4 electric motors sounds like a good trade when comparing weight. Obviously for a car alot of R&D is going to be put into weight saving material and space saving design.

[Matra et Alpine]

ht, you forgot to count *4* motors or it's a single motor PLUS all the drivetrain you've tried to exclude.

When you make it 4 motors it currently loses the match.

We , I'm sure . both agree that the future holds positive for hte motors whereas the gearbox is pretty much at the end of it's development path.

[hightower99]

ht, you forgot to count *4* motors or it's a single motor PLUS all the drivetrain you've tried to exclude.

When you make it 4 motors it currently loses the match.

We , I'm sure . both agree that the future holds positive for hte motors whereas the gearbox is pretty much at the end of it's development path.

Umm what?

ok the engine makes 100 kW then the generator makes 92-95 kW then the wires and computer controlled capcitor system takes it down to 87.4-92.15 kW then the 4 motors get between 21.85-23.0375 kW each of which the put between 19.665-21.886 kW to the road now the overall efficiency is 78.66-87.54% That is with the FOUR motors so I do not know what you did. I didn't exclude much at all now did I?

[Matra et Alpine]

WEIGHT ht weight

Also remember that your 100kW output from your fuel engine required 250kW input fuel energy.

So when you do it all taking the FULL energy cycle in the difference is minimal and currently you ahve 4 HGUE coisl and perma magnets in each wheel So efficiency to MOVE somethign takes a bigger hit.

[hightower99]

WEIGHT ht weight

Also remember that your 100kW output from your fuel engine required 250kW input fuel energy.

So when you do it all taking the FULL energy cycle in the difference is minimal and currently you ahve 4 HGUE coisl and perma magnets in each wheel So efficiency to MOVE somethign takes a bigger hit.

You seem to be skipping something here?

Yes I agree that the 100 kW out of the motor needs at least 250 if not 300 kW of fuel but that really is irrelevant because the efficiency of the power motor is not in question, just the drive train. In actual drive line efficiency (what really matters) the electric drive train beats the mechanical by a little under 10% and that is alot.

The motors at the wheels only need a max capacity of 25 kW so they are pretty small motors. They are also replacing many of the mechanical componants (brakes, universal joints and drive shafts) All they need are a few suspension arms and a shock absorber and spring. Also note that weight of rotating parts (one of the major drains of power) is almost eliminated only the power motor internals and the traction engine internals and wheels and tires need to be moved as opposed to power engine internals, flywheel/clutch, transmission, 3 differentials, 2 large propshafts, 4 short drive shafts, 4 brake discs, at least 4 universal joints, wheels and tires.

I am pretty confident that a well designed electric drive train will add a performance edge over mechanical drive trains. The only downfall is the price which will of course tower over mechanical systems for a long time.

[Matra et Alpine]

You seem to be skipping something here?

Yes I agree that the 100 kW out of the motor needs at least 250 if not 300 kW of fuel but that really is irrelevant because the efficiency of the power motor is not in question, just the drive train. In actual drive line efficiency (what really matters) the electric drive train beats the mechanical by a little under 10% and that is alot.

The motors at the wheels only need a max capacity of 25 kW so they are pretty small motors.

Nope. You are assuming equal traction at all times.
A vehicle HAS to specify the wheel motors to be able to provide at laast 50% of the torque of an existing vehicle or it will compromise preformacne.

They are also replacing many of the mechanical componants (brakes, universal joints and drive shafts)

erm. NO
You still need brakes.
Electric brakes cannot approach the efficiency of mechanical and if you DO make the motors big enough to generate enough eletromagnetic torque then they are 1) FECKING HUGE adn 2) generate MASSIVE amounts fo heat.
You're confusign re-genreative brakgin and REAL braking there.
Drive shafts are a moot point.
As I had said earlier this may become less of an issue in a few years... BUT right now the motors ar BIG adn you do NOT want all that as unsprung weight in a real car. So you STILL have the driveshafts.

All they need are a few suspension arms and a shock absorber and spring. Also note that weight of rotating parts (one of the major drains of power) is almost eliminated only the power motor internals and the traction engine internals and wheels and tires need to be moved as opposed to power engine internals, flywheel/clutch, transmission, 3 differentials, 2 large propshafts, 4 short drive shafts, 4 brake discs, at least 4 universal joints, wheels and tires.

Well as already shown you still need 75% fo all of that

I am pretty confident that a well designed electric drive train will add a performance edge over mechanical drive trains. The only downfall is the price which will of course tower over mechanical systems for a long time.

Price and SIZE and WEIGHT.
See above, you've not factored in all the requirements of the vehicle.
I concur in a number of years these will be less of an issue.
But until then ... our current magnetic materials, electric windings and vehicel expectations dont' make it viable beyond the VERY expensive or enforced ZEV domains

[hightower99]

Nope. You are assuming equal traction at all times.
A vehicle HAS to specify the wheel motors to be able to provide at laast 50% of the torque of an existing vehicle or it will compromise preformacne.

This is slightly confusing. Don't you mean that the engines should be rated at atleast half of the output POWER?

I don't really think so if it runs constant AWD maybe having slightly larger engines might help (around 30-40 kW) for when some wheels are slipping and power is transfered to the other motors. But even if the engines are still only 25 kW then only having one wheel in traction can still move a relatively heavy vehicle out of trouble. There is no need for more powerfull engines than 40 kW (note the power engine is only 100 kW output so this is not an exotic car for the sake of this discussion.)

erm. NO
You still need brakes.
Electric brakes cannot approach the efficiency of mechanical and if you DO make the motors big enough to generate enough eletromagnetic torque then they are 1) FECKING HUGE adn 2) generate MASSIVE amounts fo heat.
You're confusign re-genreative brakgin and REAL braking there.
Drive shafts are a moot point.
As I had said earlier this may become less of an issue in a few years... BUT right now the motors ar BIG adn you do NOT want all that as unsprung weight in a real car. So you STILL have the driveshafts.

Actually for normal braking the traction motors rated at 25 kW would be good enough but certainly a smaller lighter disc brake setup should be retained for emergency braking and hard braking.

Well as already shown you still need 75% fo all of that

You don't need a transmission or any of the differentials (that is already more than 25% of the total weight gone) Large prop shafts are gone as well as the smaller half shafts.

[Matra et Alpine]

This is slightly confusing. Don't you mean that the engines should be rated at atleast half of the output POWER?

Yes but I was ensuring that as we were talkgin in-wheel motors that it was realised that the torque output of the motor at zero revs was undestood to be needed to be high.

I don't really think so if it runs constant AWD maybe having slightly larger engines might help (around 30-40 kW) for when some wheels are slipping and power is transfered to the other motors. But even if the engines are still only 25 kW then only having one wheel in traction can still move a relatively heavy vehicle out of trouble. There is no need for more powerfull engines than 40 kW (note the power engine is only 100 kW output so this is not an exotic car for the sake of this discussion.)

That depends on the motor.
As I'd said earlier, current (!) motors aren't really up to that job and the closest being the Dutch wheel-thingy in the bus they demonstrate.
BUT THAT is MASSIVE to deliver the complex fields and control to provide good start-up torque AND speed adn brakign (sic)
Hence why I have stated regularly that I agree with the premise at some point in the future, but not there by any means for cars.
The Fetish costs $1/2M and uses a single high torque motor
You want to imagine what it woudl cost with another 3 of them ???

Actually for normal braking the traction motors rated at 25 kW would be good enough but certainly a smaller lighter disc brake setup should be retained for emergency braking and hard braking.

Erm, no there are diferreing needs for motor and gnerator/braking if you want high efficiency AND dissipate the heat etc. In industry it' scommon the have an ADDITIONAL braking unit on electric motors to avdoi the compromise to make both work.
The only "serious" attempt I've seen has again been the Dutch wheel-thingy and it is a VERY complex motor design to achieve that.
So some time in the future it's possible ... but all I'm pointing out is that the current technologies dont' match up to beign able to meet our needs.
Just as fuel is STILL the most efficient way of carrygin energy around with us, brakes are STILL the most effiicent way of providng large stoppign power capapble of dissipating the vasts amoutn of stored energy in the movign vehecle. The HEAT produced by an emergency stop from 100+mph woudl fry the coisl of a "normal" motor built in todays readily available technology. You can't get away from the basics of energy conservation
Your glib brakgin with 25kW motor astounded me ... WHERE do you dissipate that 25kW ... beacuse if you can't you fried the motor

You don't need a transmission or any of the differentials (that is already more than 25% of the total weight gone) Large prop shafts are gone as well as the smaller half shafts.

YOU only see them as unecessary as you are leaping forward 10-15 years to having technologies availabel that dont' exist/ are prohibitively expensive today.
I was trying to be REALISTIC in todays world ... not float Star-Trek solutions

What about the unsprung weight ? You will have an uncontrollable vehicle over bumps unless you get the current-gen mass motors OUT of the wheels.
Prop shafts do not NEED to weigh much at all.
My Quadra has used c/f props for 20 years now
Have you calculated how much IRON you woudl need to have a motor be effective across the range of a modern car AND operate as a braek withotu frying the coils ? Makes the steel in a drive shaft pale into insignificance
Also, dont' know what kind of diffs you are used to but a diff is less weight than a 1/4hp electric motore
So you end up mounting the motors inboard to avoid the unsprung weight issue. So there is 75% of all that guff needed

If you are going to suggest that these are NOT issues then pray do the math on the tesla and currents needed to drive a family car AND brake it without frying the coils ... and calculate the weight/size based on current gen electri motors. It will frighten you
BTW have you factored in the weight of cabling necessary to deliver 40kW to each wheel so that it doesnt' get hot ?????

[hightower99]

The Dutch bus thiny you keep talking about... is this it?


well you should read up about it again because you are missing something. The engines are huge because they are attached to a 10 metric tonne bus! and there is only the two back wheels as engines. This system does have some similarities but is actually quite different. Whereas this system has a small diesel that constantly charges a large pack of batteries, my system has a larger ICE and a much smaller pack of batteries (mostly just capacitors). One a normal car the electric traction motors would not be bigger than this:



These are engines on the Mitsubishi prototype car based on a Lancer EVO.

here:

The motors are actually not overly complicated at all and can be used at max power for braking, all the energy converted can be stored in high capacity capacitors and maybe a small battery pack. Braking is supplemented by a small disc brake system like on a normal car only much smaller. The disc brakes would help for emergency braking and alittle during normal hard braking.

I too am concerned about the massive unsprung weight issue but I have sketched a few suspension arm designs that leave only the wheel and tire as unsprung. Of course it still needs refinement and it isn't anything that can't be done. About weight Diffs normally weigh between 10-35 lbs. as far as I know. Getting rid of 3 of those is a good 30-105lbs. off the car.

[Matra et Alpine]

you confirmed AGAIN what I said ht ..... LOOK AT THE SIZE of the motors in teh EVO
Please engage brain

yes that's the one I meant and chosen because it is out actually getting real world usage unlike the EVO you cited which is a prototype with no info on cost or feasability for mass production. There are DOZENS ( prolly hundreds ) of "prototypes" shown to teh media. As I said, I was sticking with the dutch bus one as a real world in use example of current capability for production.
"Tomorrow" and the followign years will coninute to bring improvements.

BTW the motors ARE complicated ... you should read up on them.
They are typically multi-plated AND multi-cored stators adnd rotor with complex computer controlled switching to get the efficiencey, torque and braking all in the one package.
Are you just looking at the "big round thing" and thinking it looks simple ?

and oh look it has a disk brake !!
THAT is all that was said .... where did you get the idea it is "small" ?
There is one IN EACH WHEEL of the Evo and it's STANDARD size !!!
Please cite where you think the motor can brake as effectively ?
ANd I love how you've "stored" energy in a capacitor.
Do you have any electronics background ?
Do the calculation on how many Farads it woudl take to store 25Kw in 3-4 seconds ( emergency braking ) and the heat generated in the inefficincy of the conversion to chemical. You'll blow most commercial capacitors apart !!!!

Here's the breakdown of the EVO wheel ....



BTW if your design only has the wheel unsprung then you've got drive shafts BUT you tried to say they weren't there.
Problem with "design on teh hoof" is you trip up at every turn



erm .... you say your design si small capacitors ? How many Farads ?
( cos once you get about 1 you're actually running a cehmical battery )

[hightower99]

The motors in the EVO are not overly big imo.

Yes there is a disc brake system on each wheel but it is not standard EVO size. EVOs normally have huge brakes the ones in the electric system are akin to average car brakes.

Capacitors: You can buy them up to about 2 Farads I believe. 4 of those and you can store ALOT of energy.

My suspension design has very very short output shafts from the motor to the wheel, and are really only the bolts that hold the wheel on.

[Matra et Alpine]

Not as big as a full on race evo .... true, but not seen teh brakgin perforance of the end result either - it might be worse it might be better..> BUT those are not tiny liek you tried to imply with limited knowledge abotu how efficient electrical motor braking REALLY is !!
So can we put the nonsense that you dont' have disks and calipers as weight to bed then !!!!

You SEEN a 1Farad Capacitor ? ( Mate designed BIG computer power supplies, he had one of the first sinlge 1Farad capacitor. )
You COSTED one
Also, as I'd said earlier, by then you are actually running a BATTERY more than a capacitor. Also, charge or discharge them FAST and they warp with the heat and blow vents. ( For MOD tests he had to test the supply in worst conditions and yes they DID fill chambers with electrolyte when they went bang !! )
They are also NOT light
You've seemingly ignored efficiencies again and forgetting you have a limited rate you can get it IN adn out Please do the basic electronics math on teh energy transfer and losses ( which all go to heat ) and think the big picture through.

Wait, so really only bolts ... so THAT puts it out in teh unsprung weight.
You're going to have to draw that one for us.
To drop teh unsprung weight AND have a car that handled you will as a minimum have to put the motor output at the plane of the suspension pivot. With a driveshaft to the wheel. ANythign else is going to induce unwanted suspension input durign power and braking. You'll need to sketch this one.

The largest weight in a driveshaft is at the CV joints, NOT the tube itself.

I still contend that you've retained most of the drivetrain and braking as was first pointed out. Diff, centre prop and abotu hallf the drive shaft length. The diffs are the big winner in weight -- but it's coming from "good " places and isn't that much.