# [EVDL] Dyson working on EV



## EVDL List (Jul 27, 2007)

> On 26 Jun 2008 at 11:30, Mark Fowler wrote:
> 
> > "An electric car doesn't go far enough. It could do. Electric motors
> > can do that," he said ...
> ...


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## EVDL List (Jul 27, 2007)

> Jeff Miller <[email protected]> wrote:
> 
> > Dyson probably plans to use
> > some form of reduction gear box and a smaller much higher speed motor
> ...


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## EVDL List (Jul 27, 2007)

there are RC plane motors in that class. We've kicked them around a bit, 
but too small for anything but bicycles, and need quite a gearbox to be 
efficient. Possibly rely heavily on propeller wash to cool, and may 
expect a short lifespan. But very light for the output.

oh and BTW F1 cars rev to 17K+ and so, almost, do street-based 
motorcycles just as a point of interest.

John



> Zeke Yewdall wrote:
> > ...
> > for some military application
> > PM motors that were something like 5 horsepower for something the size of a
> ...


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## EVDL List (Jul 27, 2007)

>From the maker of the bagless vacuum to the gasless motorcar
I dont see it happening although I credit his intentions.

I personally would like to have a DC kit with zebra battery packs
to convert whats on the road now or offer them for kit cars.

eg 
wouldnt most 16 year olds and others love a T model speedster
replica in fibreglass with a zebra and a Warp 9 or an Aluminium bodied
Milkvan with a couple of zebras and direct drive 13 inch?

-----
There is a pleasure in the pathless woods,
There is a rapture on the lonely shore,
There is society, where none intrudes,
By the deep Sea, and music in its roar;
I love not Man the less, but Nature more. - George Byron
-- 
View this message in context: http://www.nabble.com/Dyson-working-on-EV-tp18125003p18126541.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

> "Zeke Yewdall" <[email protected]> wrote:
> 
> > Horsepower is directly related to rotaional speed and as such
> >> you
> ...


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## EVDL List (Jul 27, 2007)

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## EVDL List (Jul 27, 2007)

> Evan Tuer <evan.xxx[email protected].xxx> wrote:
> > On Thu, Jun 26, 2008 at 3:35 AM, EVDL Administrator <[email protected]> wrote:
> >> On 26 Jun 2008 at 11:30, Mark Fowler wrote:
> >>
> ...


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## EVDL List (Jul 27, 2007)

> EVDL Administrator wrote:
> > On 26 Jun 2008 at 11:30, Mark Fowler wrote:
> >
> >
> ...


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## EVDL List (Jul 27, 2007)

> Mark Fowler wrote:
> 
> > http://www.independent.co.uk/environment/green-living/dyson-working-
> > on-new-generation-of-fast-green-cars-852023.html
> ...


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## EVDL List (Jul 27, 2007)

> Zeke Yewdall wrote:
> >> Dyson probably plans to use some form of reduction gear box and a
> >> smaller much higher speed motor instead of the high torque low
> >> speed series wound motors we are all so fond of here...
> ...


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## EVDL List (Jul 27, 2007)

> Neon John <[email protected]> wrote:
> 
> >
> > There are several problems that have to be dealt with to make this idea
> ...


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## EVDL List (Jul 27, 2007)

> Jeff Miller wrote:
> > Obviously the reporter screwed the pooch here. F1 cars turn faster than 10K
> > RPM but only 12K or so last I had heard. Clearly the DDM motors are turning
> > around 50K RPM and the writer just messed up. Dyson probably plans to use
> ...


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## EVDL List (Jul 27, 2007)

Maybe when he followed F1 in the 60s =^D
Either way torque is what counts not high rpm on the street.
This helps with durability and overall efficiency.
If you can make an efficient direct drive electric 
hub motor max at 1500 rpm it is all thats needed.





_______________________________________________
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-----
There is a pleasure in the pathless woods,
There is a rapture on the lonely shore,
There is society, where none intrudes,
By the deep Sea, and music in its roar;
I love not Man the less, but Nature more. - George Byron
-- 
View this message in context: http://www.nabble.com/Dyson-working-on-EV-tp18125003p18146473.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev


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## EVDL List (Jul 27, 2007)

> The next problem is rotational inertia and its multiplication back through 
> the
> gearbox. The necessarily very high (numerical) ratio of the gearbox means
> that even though the motor's rotor is undoubtedly light, its inertia is

A minor note - but you may be surprised to hear that actually the motor 
rotor's inertia is multiplied by the SQUARE of the gear ratio. Its actually 
quite a big deal when you're talking about adding a 50:1 gearbox versus a 
10:1 (25 times more).

> This is most critical when transitioning from power to decel or vice 
> versa.
> Even a tiny bit of backlash in the drivetrain gets translated into large
> forces.

A really well made planetary gearset will handle this ok (but might be very 
expensive). - but mostly the backlash issue is fairly minor compared to the 
above mentioned inertia, bearing, and lubrication problems.

> Lots of progress in several areas since then, of course, but one still has 
> to
> ask the question whether all that complication is worth whatever minor 
> gains
> in efficiency and weight there might be over more conventional AC motors 
> that
> spin in the sub-15,000 RPM range.

It certainly would be easy to eat up whatever gained efficiency in 
lubrication friction and gearing efficiency.

Me, I'm thinking the plan is to skip the gearbox and use really tiny tires - 
hahaha

Jon 

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## EVDL List (Jul 27, 2007)

> OHMyGod! wrote:
> 
> > Either way torque is what counts not high rpm on the street.
> > hub motor max at 1500 rpm it is all that's needed.
> ...


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## EVDL List (Jul 27, 2007)

Every gear interface creates some amount of loss. Every bearing also sucks
away a little energy. When you have a high reduction gear box like you
would need to step down 100,000 RPM down to 800 RPM or so you will lose alot
in the process. And then with that high strung motor he might even need a
multispeed box. Basically it is an approach maybe not the right one but it
is certainly one way to get to the answer. In the end someone may take one
of the high speed motors and couple it up with a system that makes sense.

Gas turbine engines spin along up to 50K RPM and the loads their bearings
and gears see are quite amazing. Those are cooled by a fine mist of turbine
oil which has the viscosity of water if not thinner. Those bearings and
gears routinely last 20,000 hours in an airplane with nothing but oil and
filter changes. In theory that is equivalent to more than a million miles
in a car. The trade off is that the tolerances on those bearings and gears
are very VERY tight and rather pricey because of it. So you can make a
bearing last but it will cost you. If memory server turbine oil was 8 bucks
a quart 10 years ago.

Have a good night
Jeff

-----Original Message-----
From: Zeke Yewdall [mailto:[email protected]]
Sent: Thursday, June 26, 2008 6:44 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Dyson working on EV




> Neon John <[email protected]> wrote:
> 
> >
> > There are several problems that have to be dealt with to make this idea
> ...


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## EVDL List (Jul 27, 2007)

But I bet these would sound extra cool, like some jet revving up!

Joe

Jeff Miller wrote:

>Every gear interface creates some amount of loss. Every bearing also sucks
>away a little energy. When you have a high reduction gear box like you
>would need to step down 100,000 RPM down to 800 RPM or so you will lose alot
>in the process. And then with that high strung motor he might even need a
>multispeed box. Basically it is an approach maybe not the right one but it
>is certainly one way to get to the answer. In the end someone may take one
>of the high speed motors and couple it up with a system that makes sense.
>
>Gas turbine engines spin along up to 50K RPM and the loads their bearings
>and gears see are quite amazing. Those are cooled by a fine mist of turbine
>oil which has the viscosity of water if not thinner. Those bearings and
>gears routinely last 20,000 hours in an airplane with nothing but oil and
>filter changes. In theory that is equivalent to more than a million miles
>in a car. The trade off is that the tolerances on those bearings and gears
>are very VERY tight and rather pricey because of it. So you can make a
>bearing last but it will cost you. If memory server turbine oil was 8 bucks
>a quart 10 years ago.
>
>Have a good night
>Jeff
>
>-----Original Message-----
>From: Zeke Yewdall [mailto:[email protected]]
>Sent: Thursday, June 26, 2008 6:44 AM
>To: Electric Vehicle Discussion List
>Subject: Re: [EVDL] Dyson working on EV
>
>
>


> Neon John <[email protected]> wrote:
> >
> >
> >
> ...


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## EVDL List (Jul 27, 2007)

Lets crunch some numbers on that one just for fun.
HP=(TorquexRPM)/5250
HP for motorcycle with 12,000 RPM 200 ftlb torque motor =
12000*200/5250=457.14HP
HP for car with 2000rpm and 1,000,000 ftlb torque motor =
2000*1000000/5250=380952.38HP

Now obvisously I have simply worked from the numbers provided and I have
assumed perfect performance here but let us continue that thought for the
fun of it.
A motorcylce weighs very little which is why they are so fast. Let us say
300 pounds
A car weighs a bunch which is why it takes so much more to get it moving
along. Let us say 5000 pounds.
Power to weight ratio is the real trick I think we would all agree right?
The bike has 1.5238 HP per pound which is astonishing!
The car has 76.2 HP per Pound which means it must be powered by some form of
high explosives because I have never heard of any vehicle with that kind of
power to weight ratio.

In fact about the only thing I can think of that actually moves and has
380,952 horse power is a rather large airplane Say 747? Maybe A380? So if
I had a million foot pounds of torque up to 2000 RPM I would have to believe
that I might be "traction limited".

Ah and who needs to waste time shifting gears. With that small high speed
motor you would have to change gears to keep it from exploding.

Does this really relate to our discussions here? Possibly as it does
effectively demonstrate the importance of Torque vs. HP. I would suggest
that if the goal was to build an electric airplane the choice would clearly
be the small light high speed motor but as weight is not quite as critical
we can choose heavier alternatives that provide us the acceleration that we
need to get our mass moving off of a stop light.

I have been leaning towards 72 volt Mars or 72 volt Perm-132 motors in
lighter applications than conversions of course. I was thinking one per
back wheel to avoid having a differential and could even tweak power
slightly during corners to get the best performance. That would probalby
require seperate controllers but that is fine by me as it offers a limp
along capability if you blow a controller. Those motor are light and
produce good power. The Perm132 provides constant 9.7 HP at 72 volts and
3480 RPM with a peak capability of 19.7 HP while only weighing 22 pounds.
The nice thing is it's torque is nice and flat so you get the same torque
across the range which would be desireable for direct drive. As the forces
of speed build on the car so does the power so you should get a nice
constant acceleration. At low speed you have good torque to get moving. If
the car gets heavier you could go to four wheel drive or teaming them up but
at some point the weight dictates moving to a series wound monster. Of
course, being perm magnet, regen gets a little easier if that is desired.

Hopefully I have not strayed to far off topic but I fear I have and with
that closing thought I am guessing this specific thread will end.


-----Original Message-----
From: Ryan Stotts [mailto:[email protected]]
Sent: Thursday, June 26, 2008 8:39 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Dyson working on EV




> OHMyGod! wrote:
> 
> > Either way torque is what counts not high rpm on the street.
> > hub motor max at 1500 rpm it is all that's needed.
> ...


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## EVDL List (Jul 27, 2007)

Traditional gear reductions arn't efficient or practical at 30K rpm,
look at harmonic drives, they have a very small rotating mass for their
ratios.
http://www.roymech.co.uk/Useful_Tables/Drive/Harmonic_Gears.html (there
are ones without flexible part.)

rpm is a way to get more out than is otherwise possible when the ruling
body fixes displacement. Just like if they limited the lbs of electric
motor.
Higher rpm costs. It is not a linear curve, it is relativly fat up to
4K-5K rpm. The work and dollars more than double at 10K rpm and start to
climb steeply after that.

so choosing to use an excessively high rpm is self defeating. We have
the speed limit translating into wheel rpm as a constraint. For each
design the motor weight goes down, heating goes up and gear train losses
increase as rpm goes up for a given power. For each design, there will
be a compromise where they meet.

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## EVDL List (Jul 27, 2007)

Ryan read what Jeff explains for some idea of what you presented.

The reference was for a hub motor for the road not drag race but if you want
to play whos the fastest boy racer then my choice of wheel diameter and tire
thickness and my low 2000rpm motor with 1 million LBS of torque would be
like
comparing an RC motor to a Keith Black top fueller.

High rpm brings it own issues of problems in cost and efficiency.
Otherwise 1ltr 50,000rpm engines would be powering your everyday
car with 15 speed manual gearboxes with at three 4 for reverse.
Imagine the claim cases for RSI, arthritis and impaired driving?

If you look at it logically Dyson is just after publicity and Ego points.
Also selling more suckers to suckers and a possible Delorean Mk2. 




> Ryan Stotts wrote:
> >
> > OHMyGod! wrote:
> >> Either way torque is what counts not high rpm on the street.
> ...


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## EVDL List (Jul 27, 2007)

There are two things I have been known to tell people

1) "Heat is the bullshit detector of efficiency claims"
2) "When someone says their product is high efficiency , and they can't
put their hand on it after it has run for 10 min, they are counting it's
use as a hotplate in their calculation."

The exhaust temperature of a micro turbine is around 900-1400 degrees
and at a high volume and velocity. If you have a use for this heat, then
it may be a good option.

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## EVDL List (Jul 27, 2007)

> Jeff Shanab <[email protected]> wrote:
> 
> >There are two things I have been known to tell people
> >
> ...


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## EVDL List (Jul 27, 2007)

> Jeff Shanab wrote:
> >
> > There are two things I have been known to tell people
> >
> ...


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## EVDL List (Jul 27, 2007)

> Jeff Shanab wrote:
> > Traditional gear reductions arn't efficient or practical at 30K rpm,
> > look at harmonic drives, they have a very small rotating mass for their
> > ratios.
> ...


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## EVDL List (Jul 27, 2007)

> Rick Beebe <[email protected]> wrote:
> 
> >Jeff Shanab wrote:
> >> Traditional gear reductions arn't efficient or practical at 30K rpm,
> ...


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## EVDL List (Jul 27, 2007)

> Neon John <[email protected]> wrote:
> 
> > I have a friend who was one of the approx 200 people Chrysler gave a turbine
> > car to in order to judge public attitudes toward the car. I think he kept it
> ...


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## EVDL List (Jul 27, 2007)

> Neon John <[email protected]> wrote:
> 
> > On Fri, 27 Jun 2008 11:05:48 -0400, Rick Beebe <[email protected]> wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

I love turbines more than most guys and I realize that they aren't very
practical in the automotive world. I guess they are more practical if you
want to melt the bumpers off of the tailgaters of the world though!!! 

-----Original Message-----
From: Evan Tuer [mailto:[email protected]]
Sent: Friday, June 27, 2008 10:41 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Dyson working on EV




> Neon John <[email protected]> wrote:
> 
> > I have a friend who was one of the approx 200 people Chrysler gave a
> turbine
> ...


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## EVDL List (Jul 27, 2007)

On Fri, 27 Jun 2008 17:40:41 +0100, "Evan Tuer" <[email protected]> wrote:

>On Fri, Jun 27, 2008 at 5:06 PM, Neon John <[email protected]> wrote:
>
>> I have a friend who was one of the approx 200 people Chrysler gave a turbine
>> car to in order to judge public attitudes toward the car. I think he kept it
>> two years. Strange that people didn't whine and march and protest and call
>> Chrysler the scum of the earth when they took THOSE cars back. Hmmmm. Guess
>> people were more grown up back then.
>
>Or at least they didn't have the internet 
>
>Anyway it's a bit different from the EV1 situation:

Not really. One group got a "free" lease and the other had to pay. In both
cases the cars remained the property of the manufacturers and in neither case
did ownership rights acrue. The difference is, back then people still
generally believed that the contracts they signed should be honored and the
sense of entitlement had not yet started to fester.

>
>Wikipedia says: 

Ah yes, the roulette wheel of knowledge.

One of the other turbine car drivers has a nice web site. I don't recall the
URL but it's easy to find. His information will be a bit more reliable than
Wikipedia.

I'm pretty sure my friend said that he was one of 200 drivers but I'd not
swear to it and am not interested enough to look it up 

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Beware the lollipop of mediocrity. Lick once and you suck forever.

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