Maker Pro
Maker Pro

Wheel motors - too good to be true?

P

Paul E. Schoen

The following is from a "Voltage Forum":
http://tinyurl.com/ogvr7

I checked the company website:
http://pmlflightlink.com/motors/wheelmotors.html

and found specs for their wheelmotors which seem reasonable enough
http://pmlflightlink.com/pdfs/eWheel.pdf

However, the power specs for the car seem way off base for any of the
listed wheel motors or any known technology, AFAIK. Particularly, the
assertion of 160 bhp per wheel. The torque of 750 N-m (552 ft-lb) is close
to the advertised maximum spec of 640 (160 cont), but the power is 14.4 kW,
or about 20 HP, at 900 RPM. I think somebody mistook the 160 Newton torque
for bhp, and ran crazy with it! Do you think the acceleration spec is
believable? An actual total torque of 2200 ft-lb for a 3600 lb vehicle,
with 24" dia tires, would provide about 0.7 G, and 0-60 in about 3.5
seconds.

So, aside from the overblown HP hoopla, this still looks like an impressive
vehicle. It's a shame they still feel a need to design and advertise so
much on the basis of raw HP and amusement park acceleration. It looks like
they could have made a still impressive car with half the power and perhaps
120 MPG, which would impress me a lot more than burning rubber.

Paul

============================================================================

June 29, 2006

Dear Jim,

BRITISH MOTOR SHOW - 20TH TO 30TH JULY 2006 EXCEL CENTRE LONDON

On behalf of PML Flightlink, I would like to invite you to visit us at the
upcoming British Motor Show at the Excel Centre, London. It runs from the
20th - 30th July. Please take a look at the website for more information
www.britishmotorshow.co.uk. We will be on stand 270.

PML will be exhibiting the new Super Mini QED, produced to demonstrate the
EW series wheel motors and generator technology co-ordinated on the vehicle
as a Quad Electric Drive system, together with additional new technology
developed in tandem, including Energy Management Systems and In Car
touch-screen interfaces.

Vital Statistics:

0 - 60 in 4.5 seconds!
Approx. 80mpg!
Approx. 150mph top speed!
No brakes?!

I have attached a report (see below) on the new Super Mini QED
specifications - it should be an interesting read.

The new Super Mini QED from PML demonstrates the future of CLEAN
transportation cleverly packaged in a stylish and desirable vehicle.

QED - Quod Erat Demonstrandum

Please let me know if you can make it. It would be great to see you there.

Best regards,
Chris Newman
Sales Manager

PML FlightLink Ltd. Riverwey Industrial Park, Newman Lane, Alton, Hants
GU34 2QW
Direct Phone +44 (0) 1420 594142
Switchboard +44 (0) 1420 594140
Fax +44 (0) 1420 83930
E-mail [email protected]

This message may contain confidential or legally privileged information. In
the event of an error in transmission, unauthorised recipients are
requested to contact the sender immediately and not to disclose or make use
of this information.

Super Mini QED - Quad Electric Drive

For the past 4 years PML has been quietly working on something of a literal
revolution. Its QED technology is set to move the Electric/Hybrid vehicle
market into Top Gear! With some notable car manufacturers releasing various
embodiments of so called "Hybrid Technology" the general public is becoming
more aware - at least of the terms, and to some extent, of the technology
itself.

Of course the term "Hybrid" has many levels of stratification in it's
realisation, starting with the "switch off the engine if the vehicle
remains stationary for more than a set time" through to so called "Parallel
Hybrids" which drive the wheels via the engine and gearbox as well as an
electric motor powered by a battery, along with a generator fitted to the
engine.

The problem with all the above remains the poor efficiency of the internal
combustion engine, which even on a good day returns no more than 20% of the
fuel it burns as usable mechanical energy to move the vehicle. Although IC
engines can have efficiencies of up to 40% this is rarely, if ever,
realised in practice due to the continuously varying loads and speeds
involved in a typical "real life" journey.

Battery technology is improving year by year and there are some interesting
options which look promising in the next 5 to 10 years. Today however, the
battery technology is still the limiting factor in realising a full utility
vehicle. Do not despair; there are ways to manage this!

It seems today that anyone with an environmental conscience has the limited
choice of a Toyota Prius or a Honda Civic! Of course there are other
vehicles on the market but they all require substantial sacrifice of
motoring pleasure and utility if your Green conscience is to be placated.

Well this does not have to be the case any longer. The PML solution, which
can be seen at the British Motor Show at the Excel centre, London from 18th
July this year, strips away all of the misconceptions about electric hybrid
vehicles to showcase a truly awesome car.

Take a standard BMW Mini One:

Discard the engine, the disc brakes, the wheels, and the gearbox. Add
instead four electric wheels, a lithium polymer battery, a large "super
capacitor", a very small IC engine with generator (so small it fits
alongside the spare wheel!), an energy management system and a sexy in-car
display module. Give the vehicle 3 modes of operation, Eco mode for in
town/city frequent start-stop operation, Normal mode for daily commuting
and equivalent ICE car operation and Sport mode for all the bells and
whistles you would expect from a super car.

Result: Super Mini QED

0 - 60mph 4.5sec (Mini Cooper S around 7.5sec)
Top speed (where allowed) approx. 150mph
Electric only operation time 4 - 5 hours commute at 50mph or less
Fuel economy approx. 80mpg (when powered by the generator)
No loss of passenger or boot space
Weight distribution and handling as original vehicle
3 driving modes Eco, Normal and Sport

"Look no brakes!"

All braking is performed by the wheel motors acting as very efficient
electrical generators which return almost all of the energy back to the
battery system. The beauty of this system is that unlike a conventional
vehicle your green conscience can be quite content even when accelerating
hard, since you are assured of collecting most of this expended energy
should you have to slow down quickly!

ABS - forget that pulsating foot!

Because the wheels are high performance motors, ABS comes as a standard
function built into each wheel's software. Now anti-skid can also be
applied to acceleration since the motor can smoothly control torque
delivery to/from the road in both cases. Slamming your foot to the floor
results in controlled maximum torque, giving the shortest possible stopping
or acceleration time.

Clever wheels!

No need for crude differential gears to share power between left and right
sides. The wheels are in constant communication with each other deciding
1000 times each second how much torque share is optimum for the current
driving conditions. Should one wheel detect a slippery surface and take
appropriate anti-skid actions, the other wheels are aware of this instantly
and adopt an appropriate compensating strategy to keep the vehicle as
stable as possible.

Brake horsepower? - schmorsepower!

Each wheel develops 160bhp!! Yes that is correct, 640bhp in total! The
original Mini One develops less than 100bhp with an engine that weighs
nearly double the weight of the four electric wheels! Apart from wheel
bearings there are no wearing parts in the electric wheels; this means the
horsepower stays for the life of the vehicle - and beyond!

Charging? - schmarging!

As the battery level reduces, the rear mounted engine/generator starts to
automatically top up the battery. So when you arrive at your destination
you can simply park the vehicle knowing that when you return the battery
will be replenished! Alternatively you can take advantage of lower cost
mains electricity and plug in to recharge. Driving along the motorway to
visit friends in Manchester - no need to worry about battery capacity or
how to recharge. As the level falls the generator is started to sustain an
average speed of 60 - 70mph with no further battery depletion.

Super capacitor - super acceleration!

Capacitors are used to store electrical energy. The difference between
batteries and capacitors is that capacitors can release/absorb their energy
10 times faster than a battery. For acceleration or power boost at higher
speeds the capacitor enables nitro-like performance, more than doubling the
power from the battery during these events. Very efficient energy recovery
means next to nothing is wasted during stop start city travel. The
capacitors also allow the battery to have an extended life by smoothing out
any peak loads.

Energy flow management

A significant key to super performance is optimum energy management.
Continuously deciding where energy flows should be - battery, super
capacitor, generator, wheels. By clever optimisation of the flows, best use
can be made of available reserves, allowing a fun driving experience whilst
protecting the planet.

Small engine and generator

The IC engine weighs a mere 15kg (less than 1/10th of the original Mini One
engine) and delivers 15kw. A high efficiency electrical generator is fitted
to the engine to provide power when the battery depletion level demands.
The key point is the engine is run at a continuous speed and load - which
results in optimum efficiency fuel conversion. After delivering the energy
to the battery system the mile equivalent translates to around 80mpg!

In-car display

With all this advanced technology the driver needs to have clear and
complete information presented to him. The in-car display module provides
the latest touch screen technology with intuitive display and scroll
options. Showing available mileage subdivided by battery and fuel along
with boost status, the display gives comprehensive information. Of course
the display shows speed and warning functions, but further it is GPRS
enabled allowing:

Remote diagnosis of any fault to allow the "AA" man to come prepared
Auto tracking of speed limits (optional!)
Auto management of generator to prevent inner city operation
History storage and system configuration interface.

PLUS:

Each of the 3 driving modes is selectable by a single touch of the in-car
display. Imagine starting your journey in the city in Eco mode then
selecting Normal mode as you reach the suburbs, and finally Sport mode as
you hit the open road. There is no other way to make your journey! What
more can be said?

Quad Quod
Electric Erat
Drive Demonstrandum

Summary:

Look No Brakes
High power wheel hub motors
Dual circuit operation
High reliability electronics
Anti skid braking and accelerating
Torque share/traction control

High Power Wheels
160 bhp (120kw) each wheel = 640bhp total
750Nm per wheel = 3000Nm total braking/acceleration torque
HI - Pa Drive technology

Provides world leading:
- Power to weight
- Reliability
- Safety
- Efficiency

Hand brake parking included in rear wheels

TMS - Torque Management system
Full ABS functionality - but smooth!
Anti skid acceleration control
Optimum differential and torque share
Full traction control
All functions smooth and fast!

EFM - Energy Flow Management
Manages energy flows between battery, capacitor, generator and wheels
Provides torque boost at high speeds for rapid overtaking
Optimises energy use/flows
Allows top speed of around 150mph

ICD - In Car display
Immediate selection of driving mode:
Eco
Normal
Sport

Provides full driver information service:
Speed
Range
Performance
Status
Energy flow map

Reports warnings of:
Low battery
Extreme temperatures
Other out of limit warnings

Future option to link to GPRS allows:
Journey / energy reserve matching
Prediction of journey radius available
Automatic speed limit control (optional!)
Driving license optimised speed constraints
Remote diagnosis of any system fault conditions
Auto reporting of breakdowns
Auto location for attending engineer

REG - Range Extending Generator
15kw continuous power allows normal cruising with zero battery impact
Optimised running conditions enable approx. 80mpg equivalent fuel
consumption
Compact unit weighs less than 40kg total
Operates automatically to charge battery when level drops to 50%

Battery system
21kw hr Lithium polymer
Over 2000 charge/discharge cycles to 80% dod = 10yr estimated useful life

Super Mini QED
High performance series hybrid
Full four wheel electric drive + range extending generator
No intrusion into base vehicle utility space
Weight distribution and handling same as base vehicle
No mechanical dynamic brakes
No gears or other mechanical transmission
Super high performance wheel hub drives
Dynamic torque distribution for skid free braking and acceleration
Top speed approx. 150mph
0 - 60mph 4.5sec

Super capacitors give boosted top end performance and optimum energy
management

Who are PML?

PML (originally Printed Motors Limited) invented and patented the printed
armature motor some 40 years ago. The printed armature motor was the first
"pancake" format motor and led the world in compact high performance
brushed motors. In the last 4 years, under private ownership, PML has
concentrated on the pancake format brushless electric traction "wheel
motor" development and wind turbine generators. This year marks the launch
of several new products pushing forward direct (gearless) motor drive
systems.

The mini project has been undertaken to demonstrate the super high
performance now possible from PML Hi - Pa drive and QED technology lead.
With very high efficiency, light weight and extreme levels of reliability
PML Wheel drive systems are suited to harsh environments needing extreme
levels of safety.

Set to take off in a big way, PML is a British company investing heavily in
R&D to take advantage of the benefits of super efficiency lightweight wheel
motor drive systems. In a global economic climate looking for steep changes
in transport efficiency improvements, PML is well positioned to take the
technological lead.

(Much of the data above is predicted and is dependent upon the terrain,
weather conditions, driving style etc. PML has used its best endeavours to
present accurate information, but accepts no liability for any errors
and/or omissions).
 
R

Ross Herbert

The following is from a "Voltage Forum":
http://tinyurl.com/ogvr7

I checked the company website:
http://pmlflightlink.com/motors/wheelmotors.html

and found specs for their wheelmotors which seem reasonable enough
http://pmlflightlink.com/pdfs/eWheel.pdf

However, the power specs for the car seem way off base for any of the
listed wheel motors or any known technology, AFAIK. Particularly, the
assertion of 160 bhp per wheel. The torque of 750 N-m (552 ft-lb) is close
to the advertised maximum spec of 640 (160 cont), but the power is 14.4 kW,
or about 20 HP, at 900 RPM. I think somebody mistook the 160 Newton torque
for bhp, and ran crazy with it! Do you think the acceleration spec is
believable? An actual total torque of 2200 ft-lb for a 3600 lb vehicle,
with 24" dia tires, would provide about 0.7 G, and 0-60 in about 3.5
seconds.

So, aside from the overblown HP hoopla, this still looks like an impressive
vehicle. It's a shame they still feel a need to design and advertise so
much on the basis of raw HP and amusement park acceleration. It looks like
they could have made a still impressive car with half the power and perhaps
120 MPG, which would impress me a lot more than burning rubber.

Paul
SNIP

CSIRO developed a wheel motor having 98% efficiency for use on solar
powered vehicles in the Darwin - Adelaide Solar Car Challenge. I
checked out the cost a couple of years back and from memory the cheap
version was some AUD50K and the expensive version was about AUD70K.

http://www.csiro.au/csiro/content/standard/psz7,,.html
 
Paul said:
The following is from a "Voltage Forum":
http://tinyurl.com/ogvr7

I checked the company website:
http://pmlflightlink.com/motors/wheelmotors.html

and found specs for their wheelmotors which seem reasonable enough
http://pmlflightlink.com/pdfs/eWheel.pdf

[hybrid car specs snipped]

Refreshing to see a car maker touting actual performance advantages,
rather than the fact that they'll pay for part of the gas their vehicle
will guzzle.
(Much of the data above is predicted and is dependent upon the terrain,
weather conditions, driving style etc. PML has used its best endeavours to
present accurate information, but accepts no liability for any errors
and/or omissions).

Okay, so it's not *actual* performance yet, but on the right track.
Present "weak" hybrids are little more than a conventional drivetrain
with an electric booster. Direct-drive would let one drop the tranny,
clutch, differential, and weight and mechanical losses of same. Also,
with per-wheel drive the tiny on-board internal combustion engine,
de-coupled from the road, can then be run at optimum rpm and
torque...much more efficient.

The 21KWH LiPoly battery looks like a nasty wear item -- last time I
looked, LiIon cells were about $0.50 / WH.

Cheers,
James Arthur
 
P

Phil Hobbs

Paul said:
The following is from a "Voltage Forum":
http://tinyurl.com/ogvr7

I checked the company website:
http://pmlflightlink.com/motors/wheelmotors.html

and found specs for their wheelmotors which seem reasonable enough
http://pmlflightlink.com/pdfs/eWheel.pdf


[hybrid car specs snipped]

Refreshing to see a car maker touting actual performance advantages,
rather than the fact that they'll pay for part of the gas their vehicle
will guzzle.

(Much of the data above is predicted and is dependent upon the terrain,
weather conditions, driving style etc. PML has used its best endeavours to
present accurate information, but accepts no liability for any errors
and/or omissions).


Okay, so it's not *actual* performance yet, but on the right track.
Present "weak" hybrids are little more than a conventional drivetrain
with an electric booster. Direct-drive would let one drop the tranny,
clutch, differential, and weight and mechanical losses of same. Also,
with per-wheel drive the tiny on-board internal combustion engine,
de-coupled from the road, can then be run at optimum rpm and
torque...much more efficient.

The 21KWH LiPoly battery looks like a nasty wear item -- last time I
looked, LiIon cells were about $0.50 / WH.

Cheers,
James Arthur

Motors tend to have torque proportional to their volume. There's a
maximum feasible value of the B field, around 1 tesla. As you increase
the diameter, you win linearly because the torque is force X distance,
and linearly again because you can pack more wires into the
circumference of the rotor. In addition, you win torque linearly by
increasing the length. Multiplying out, you get torque proportional to
volume.

That means that the only way to get high torque out of a small motor is
to run it at high speed and gear it down. Disadvantage #1 for wheel
motors. Disadvantage #2 is that they have terribly high unsprung mass,
which makes for very poor handling, especially over bumps.

We'll have transmissions quite awhile longer, I think.

Cheers,

Phil Hobbs
 
D

Don Lancaster

Phil said:
Paul said:
The following is from a "Voltage Forum":
http://tinyurl.com/ogvr7

I checked the company website:
http://pmlflightlink.com/motors/wheelmotors.html

and found specs for their wheelmotors which seem reasonable enough
http://pmlflightlink.com/pdfs/eWheel.pdf



[hybrid car specs snipped]

Refreshing to see a car maker touting actual performance advantages,
rather than the fact that they'll pay for part of the gas their vehicle
will guzzle.

(Much of the data above is predicted and is dependent upon the terrain,
weather conditions, driving style etc. PML has used its best
endeavours to
present accurate information, but accepts no liability for any errors
and/or omissions).



Okay, so it's not *actual* performance yet, but on the right track.
Present "weak" hybrids are little more than a conventional drivetrain
with an electric booster. Direct-drive would let one drop the tranny,
clutch, differential, and weight and mechanical losses of same. Also,
with per-wheel drive the tiny on-board internal combustion engine,
de-coupled from the road, can then be run at optimum rpm and
torque...much more efficient.

The 21KWH LiPoly battery looks like a nasty wear item -- last time I
looked, LiIon cells were about $0.50 / WH.

Cheers,
James Arthur

Motors tend to have torque proportional to their volume. There's a
maximum feasible value of the B field, around 1 tesla. As you increase
the diameter, you win linearly because the torque is force X distance,
and linearly again because you can pack more wires into the
circumference of the rotor. In addition, you win torque linearly by
increasing the length. Multiplying out, you get torque proportional to
volume.

That means that the only way to get high torque out of a small motor is
to run it at high speed and gear it down. Disadvantage #1 for wheel
motors. Disadvantage #2 is that they have terribly high unsprung mass,
which makes for very poor handling, especially over bumps.

We'll have transmissions quite awhile longer, I think.

Cheers,

Phil Hobbs


Disadvantage number three and the real biggie, is that a parallel hybrid
can get half its peak power from the ICE and half from the electric motors.

In-wheel motors thus have to be a lot larger if all power is to be
funneled through them.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com
 
N

nospam

Don Lancaster said:
Disadvantage number three and the real biggie, is that a parallel hybrid
can get half its peak power from the ICE and half from the electric motors.

But then they were only talking about a lawnmower sized ICE so it wouldn't
make much difference. I think they got some sums seriously wrong or have a
lot of wishful thinking.

What is the charging efficiency of LiPoly batteries? A quick look at the
Sanyo site and it was talking about a 2.15Ah battery being charged at 2.15A
for 3 hours. Didn't look too promising running a small ICE efficiently so
you can loose half it's output charging batteries?
--
 
Phil said:
Paul said:
The following is from a "Voltage Forum":
http://tinyurl.com/ogvr7

I checked the company website:
http://pmlflightlink.com/motors/wheelmotors.html

and found specs for their wheelmotors which seem reasonable enough
http://pmlflightlink.com/pdfs/eWheel.pdf


[hybrid car specs snipped]

Refreshing to see a car maker touting actual performance advantages,
rather than the fact that they'll pay for part of the gas their vehicle
will guzzle.

(Much of the data above is predicted and is dependent upon the terrain,
weather conditions, driving style etc. PML has used its best endeavours to
present accurate information, but accepts no liability for any errors
and/or omissions).


Okay, so it's not *actual* performance yet, but on the right track.
Present "weak" hybrids are little more than a conventional drivetrain
with an electric booster. Direct-drive would let one drop the tranny,
clutch, differential, and weight and mechanical losses of same. Also,
with per-wheel drive the tiny on-board internal combustion engine,
de-coupled from the road, can then be run at optimum rpm and
torque...much more efficient.

The 21KWH LiPoly battery looks like a nasty wear item -- last time I
looked, LiIon cells were about $0.50 / WH.

Cheers,
James Arthur

Motors tend to have torque proportional to their volume. There's a
maximum feasible value of the B field, around 1 tesla. As you increase
the diameter, you win linearly because the torque is force X distance,
and linearly again because you can pack more wires into the
circumference of the rotor. In addition, you win torque linearly by
increasing the length. Multiplying out, you get torque proportional to
volume.

That means that the only way to get high torque out of a small motor is
to run it at high speed and gear it down. Disadvantage #1 for wheel
motors.

But the above wouldn't preclude a short motor of large diameter--a
pancake motor--or a toroidal-shaped motor. The large diameter would
provide torque, and the short and/or hollow structure would save
weight.

I confess to being motor-ignorant and mostly taking the PML
Flightlink people at their word. They claim 4.2Kw (5.6hp) continuous
power for their model EW25/30, with a mass of 8.5Kg. Given the
phenomenon of 300g CD-ROM motors run at 400W-to-1.3Kw, e.g.
http://www.flyelectric.ukgateway.net/croc.htm, the PML Flightlink
figures didn't seem outrageous.
Disadvantage #2 is that they have terribly high unsprung mass,
which makes for very poor handling, especially over bumps.

8.5Kg *is* a chunk to add to the unsprung mass, but there are some
savings too--don't forget to subtract the brake disc/drum,
calipers/shoes (which PML eliminates), and axles/linkages. (Dunno how
much these amount to--Google's s/n ratio was horrible.)

It would all seem to come down to how much power one *really*
needs.[1]

Cheers,
James Arthur

[1] I measure my Acura as needing 14 hp (10.4 KW) cruising at 60 mph
(96 Kph). It has a 113 hp (84 Kw) engine--about 8x oversized--to
accommodate acceleration. In turn, I calculate roughly 68 hp (51 KW)
needed to accelerate 0-60 mph in 10 leisurely seconds, so at least 54
hp (40 Kw) reserve is needed in bursts. Electric motors should be good
in this respect, having high peak capability.

Torque-wise my car produces 13.7 N-m peak @ 5,500 rpm, versus the
EW25/30's rated 42 N-m @ stall (continuous), 168 N-m @ stall, peak
(30sec), per motor.

Finally, my Acura's EPA-rated for 30 highway MPG, but I average 37,
for a calculated overall gasoline-to-locomotion efficiency of 21%.
 
Don said:
Phil said:
Paul E. Schoen wrote:

The following is from a "Voltage Forum":
http://tinyurl.com/ogvr7

I checked the company website:
http://pmlflightlink.com/motors/wheelmotors.html

and found specs for their wheelmotors which seem reasonable enough
http://pmlflightlink.com/pdfs/eWheel.pdf



[hybrid car specs snipped]

Refreshing to see a car maker touting actual performance advantages,
rather than the fact that they'll pay for part of the gas their vehicle
will guzzle.


(Much of the data above is predicted and is dependent upon the terrain,
weather conditions, driving style etc. PML has used its best
endeavours to
present accurate information, but accepts no liability for any errors
and/or omissions).



Okay, so it's not *actual* performance yet, but on the right track.
Present "weak" hybrids are little more than a conventional drivetrain
with an electric booster. Direct-drive would let one drop the tranny,
clutch, differential, and weight and mechanical losses of same. Also,
with per-wheel drive the tiny on-board internal combustion engine,
de-coupled from the road, can then be run at optimum rpm and
torque...much more efficient.

The 21KWH LiPoly battery looks like a nasty wear item -- last time I
looked, LiIon cells were about $0.50 / WH.

Cheers,
James Arthur

Motors tend to have torque proportional to their volume. There's a
maximum feasible value of the B field, around 1 tesla. As you increase
the diameter, you win linearly because the torque is force X distance,
and linearly again because you can pack more wires into the
circumference of the rotor. In addition, you win torque linearly by
increasing the length. Multiplying out, you get torque proportional to
volume.

That means that the only way to get high torque out of a small motor is
to run it at high speed and gear it down. Disadvantage #1 for wheel
motors. Disadvantage #2 is that they have terribly high unsprung mass,
which makes for very poor handling, especially over bumps.

We'll have transmissions quite awhile longer, I think.

Cheers,

Phil Hobbs


Disadvantage number three and the real biggie, is that a parallel hybrid
can get half its peak power from the ICE and half from the electric motors.

In-wheel motors thus have to be a lot larger if all power is to be
funneled through them.

But the internal combustion engine (ICE) is the *last* place you want
to draw peak power from, since it means the ICE has to be so grossly
oversized compared to cruising requirements. ICEs have abysmal output
at low rpm, necessitating a monsterous beast for decent acceleration,
e.g., from a stoplight. Thereafter you're stuck lugging around a huge
chunk of metal, running inefficiently at a fraction of its rated power.

The chief advantage a hybrid promises is the ability to run a much
smaller ICE optimized for your *average* load, while relying on the
flexibility and efficiency of the electrical motors and support system
to provide peak power. Small electrical motors can provide large
intermittent bursts. ICEs, I'm told, can be twice as efficient when
operated at optimum torque & rpm.

Cheers,
James Arthur
 
J

Jim Thompson

On 5 Jul 2006 10:30:35 -0700, [email protected] wrote:

[snip]
But the internal combustion engine (ICE) is the *last* place you want
to draw peak power from, since it means the ICE has to be so grossly
oversized compared to cruising requirements. ICEs have abysmal output
at low rpm, necessitating a monsterous beast for decent acceleration,
e.g., from a stoplight. Thereafter you're stuck lugging around a huge
chunk of metal, running inefficiently at a fraction of its rated power.

The chief advantage a hybrid promises is the ability to run a much
smaller ICE optimized for your *average* load, while relying on the
flexibility and efficiency of the electrical motors and support system
to provide peak power. Small electrical motors can provide large
intermittent bursts. ICEs, I'm told, can be twice as efficient when
operated at optimum torque & rpm.

Cheers,
James Arthur

But V8's are so-o-o-o much fun ;-)

...Jim Thompson
 
Jim said:
On 5 Jul 2006 10:30:35 -0700, [email protected] wrote:

[snip]
But the internal combustion engine (ICE) is the *last* place you want
to draw peak power from, since it means the ICE has to be so grossly
oversized compared to cruising requirements. ICEs have abysmal output
at low rpm, necessitating a monsterous beast for decent acceleration,
e.g., from a stoplight. Thereafter you're stuck lugging around a huge
chunk of metal, running inefficiently at a fraction of its rated power.

The chief advantage a hybrid promises is the ability to run a much
smaller ICE optimized for your *average* load, while relying on the
flexibility and efficiency of the electrical motors and support system
to provide peak power. Small electrical motors can provide large
intermittent bursts. ICEs, I'm told, can be twice as efficient when
operated at optimum torque & rpm.

Cheers,
James Arthur

But V8's are so-o-o-o much fun ;-)

...Jim Thompson

Varrroooommmm!
We all like to go fast, but you *can* save a lot of fuel if you're
willing to take a little longer winding up. With Arizona gas--seems
juicier than CA gas--I got 41 or 42 mpg cruising @ 85 last time I
checked.

James Arthur
(who once passed Gila Bend on I-8, going about the same speed as you)
(and also drove through your southern deserts one summer, 120F or so
outside, with heater on max and windows wide open to cool the engine.
Hot, but a dry heat ;-)
 
J

Jim Thompson

Jim said:
On 5 Jul 2006 10:30:35 -0700, [email protected] wrote:

[snip]
But the internal combustion engine (ICE) is the *last* place you want
to draw peak power from, since it means the ICE has to be so grossly
oversized compared to cruising requirements. ICEs have abysmal output
at low rpm, necessitating a monsterous beast for decent acceleration,
e.g., from a stoplight. Thereafter you're stuck lugging around a huge
chunk of metal, running inefficiently at a fraction of its rated power.

The chief advantage a hybrid promises is the ability to run a much
smaller ICE optimized for your *average* load, while relying on the
flexibility and efficiency of the electrical motors and support system
to provide peak power. Small electrical motors can provide large
intermittent bursts. ICEs, I'm told, can be twice as efficient when
operated at optimum torque & rpm.

Cheers,
James Arthur

But V8's are so-o-o-o much fun ;-)

...Jim Thompson

Varrroooommmm!
We all like to go fast, but you *can* save a lot of fuel if you're
willing to take a little longer winding up. With Arizona gas--seems
juicier than CA gas--I got 41 or 42 mpg cruising @ 85 last time I
checked.

In what kind of a vehicle? Motorcycle ?:)
James Arthur
(who once passed Gila Bend on I-8, going about the same speed as you)
(and also drove through your southern deserts one summer, 120F or so
outside, with heater on max and windows wide open to cool the engine.
Hot, but a dry heat ;-)

The benefit of buying a car in Arizona is that *everything* comes
standard with the "desert cooling package"... oversized radiator,
electric fans.

Monday I was stuck in traffic at about 3PM in the "Broadway Curve"
where I10 and US60 merge, due to a multi-car accident... debris strewn
from the merge point all the way to the Broadway exit :-(

Running the A/C, the engine temperature didn't rise enough to even be
visible on the gauge.

...Jim Thompson
 
Jim said:
Jim said:
On 5 Jul 2006 10:30:35 -0700, [email protected] wrote:

[snip]

But the internal combustion engine (ICE) is the *last* place you want
to draw peak power from, since it means the ICE has to be so grossly
oversized compared to cruising requirements. ICEs have abysmal output
at low rpm, necessitating a monsterous beast for decent acceleration,
e.g., from a stoplight. Thereafter you're stuck lugging around a huge
chunk of metal, running inefficiently at a fraction of its rated power.

The chief advantage a hybrid promises is the ability to run a much
smaller ICE optimized for your *average* load, while relying on the
flexibility and efficiency of the electrical motors and support system
to provide peak power. Small electrical motors can provide large
intermittent bursts. ICEs, I'm told, can be twice as efficient when
operated at optimum torque & rpm.

Cheers,
James Arthur

But V8's are so-o-o-o much fun ;-)

...Jim Thompson

Varrroooommmm!
We all like to go fast, but you *can* save a lot of fuel if you're
willing to take a little longer winding up. With Arizona gas--seems
juicier than CA gas--I got 41 or 42 mpg cruising @ 85 last time I
checked.

In what kind of a vehicle? Motorcycle ?:)

Sn-orrt!

No silly, Acura Integra.

Best,
James Arthur
 
S

Spehro Pefhany

Jim said:
Jim Thompson wrote:
On 5 Jul 2006 10:30:35 -0700, [email protected] wrote:

[snip]

But the internal combustion engine (ICE) is the *last* place you want
to draw peak power from, since it means the ICE has to be so grossly
oversized compared to cruising requirements. ICEs have abysmal output
at low rpm, necessitating a monsterous beast for decent acceleration,
e.g., from a stoplight. Thereafter you're stuck lugging around a huge
chunk of metal, running inefficiently at a fraction of its rated power.

The chief advantage a hybrid promises is the ability to run a much
smaller ICE optimized for your *average* load, while relying on the
flexibility and efficiency of the electrical motors and support system
to provide peak power. Small electrical motors can provide large
intermittent bursts. ICEs, I'm told, can be twice as efficient when
operated at optimum torque & rpm.

Cheers,
James Arthur

But V8's are so-o-o-o much fun ;-)

...Jim Thompson

Varrroooommmm!
We all like to go fast, but you *can* save a lot of fuel if you're
willing to take a little longer winding up. With Arizona gas--seems
juicier than CA gas--I got 41 or 42 mpg cruising @ 85 last time I
checked.

In what kind of a vehicle? Motorcycle ?:)

Sn-orrt!

No silly, Acura Integra.

Best,
James Arthur

Sounds about right. 5.5-6 l/100km at 135km/h. And lots of pep.


Best regards,
Spehro Pefhany
 
Phil said:
Paul E. Schoen wrote:

The following is from a "Voltage Forum":
http://tinyurl.com/ogvr7

I checked the company website:
http://pmlflightlink.com/motors/wheelmotors.html

and found specs for their wheelmotors which seem reasonable enough
http://pmlflightlink.com/pdfs/eWheel.pdf


[hybrid car specs snipped]

Refreshing to see a car maker touting actual performance advantages,
rather than the fact that they'll pay for part of the gas their vehicle
will guzzle.


(Much of the data above is predicted and is dependent upon the terrain,
weather conditions, driving style etc. PML has used its best endeavours to
present accurate information, but accepts no liability for any errors
and/or omissions).


Okay, so it's not *actual* performance yet, but on the right track.
Present "weak" hybrids are little more than a conventional drivetrain
with an electric booster. Direct-drive would let one drop the tranny,
clutch, differential, and weight and mechanical losses of same. Also,
with per-wheel drive the tiny on-board internal combustion engine,
de-coupled from the road, can then be run at optimum rpm and
torque...much more efficient.

The 21KWH LiPoly battery looks like a nasty wear item -- last time I
looked, LiIon cells were about $0.50 / WH.

Cheers,
James Arthur

Motors tend to have torque proportional to their volume. There's a
maximum feasible value of the B field, around 1 tesla. As you increase
the diameter, you win linearly because the torque is force X distance,
and linearly again because you can pack more wires into the
circumference of the rotor. In addition, you win torque linearly by
increasing the length. Multiplying out, you get torque proportional to
volume.

That means that the only way to get high torque out of a small motor is
to run it at high speed and gear it down. Disadvantage #1 for wheel
motors.

But the above wouldn't preclude a short motor of large diameter--a
pancake motor--or a toroidal-shaped motor. The large diameter would
provide torque, and the short and/or hollow structure would save
weight.

I confess to being motor-ignorant and mostly taking the PML
Flightlink people at their word. They claim 4.2Kw (5.6hp) continuous
power for their model EW25/30, with a mass of 8.5Kg. Given the
phenomenon of 300g CD-ROM motors run at 400W-to-1.3Kw, e.g.
http://www.flyelectric.ukgateway.net/croc.htm, the PML Flightlink
figures didn't seem outrageous.
Disadvantage #2 is that they have terribly high unsprung mass,
which makes for very poor handling, especially over bumps.

8.5Kg *is* a chunk to add to the unsprung mass, but there are some
savings too--don't forget to subtract the brake disc/drum,
calipers/shoes (which PML eliminates), and axles/linkages. (Dunno how
much these amount to--Google's s/n ratio was horrible.)

It would all seem to come down to how much power one *really*
needs.[1]

Cheers,
James Arthur

[1] I measure my Acura as needing 14 hp (10.4 KW) cruising at 60 mph
(96 Kph). It has a 113 hp (84 Kw) engine--about 8x oversized--to
accommodate acceleration. In turn, I calculate roughly 68 hp (51 KW)
needed to accelerate 0-60 mph in 10 leisurely seconds, so at least 54
hp (40 Kw) reserve is needed in bursts. Electric motors should be good
in this respect, having high peak capability.

Torque-wise my car produces 13.7 N-m peak @ 5,500 rpm, versus the
EW25/30's rated 42 N-m @ stall (continuous), 168 N-m @ stall, peak
(30sec), per motor.

Finally, my Acura's EPA-rated for 30 highway MPG, but I average 37,
for a calculated overall gasoline-to-locomotion efficiency of 21%.

Two updates to this topic:
1) A car-crazy pal reports that electric racers use chassis-mounted
motors, with flex-shats driving planetary reduction gears on the
wheels, fixing the sprung/unsprung weight problem.

2) http://www.elecdesign.com/Articles/Index.cfm?ArticleID=12857&pg=3

Mitsubishi's Lancer Evolution MIEV. It uses four outer-rotor in-wheel
motors on 20-in. wheels, each wheel-hub motor producing 50 kW and 518
Newton-meters of torque. 0 to 60 mph in < 8 seconds. Top speed ~110
mph.

Earlier in the same article:
"GM showed us a couple of battery-powered S-10 pickups that
had a 114-hp three-phase, liquid-cooled ac induction motor driving
the forward wheels, and separate wheel-hub motors for the back
wheels (Fig. 3).
[...]
In the new versions, the wheel hub motors provide a 60%
increase in torque when the driver calls for acceleration.
Each generates about 25 kW. They also add 33 lb to each
of the rear wheels, which is why they aren't used in the
front of the vehicle. And, they add the possibility of electric
anti-skid control."

Best,
James Arthur
 
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