Scooting Through Intersections w/o Big Motors & Super Caps

[Bret Cahill]

A 50 kg spring could get a 1,000 kg vehicle up to 15 mph.

Instead of using a high HP motor with a lot of rare earth materials
driving up the cost of an electric vehicle it might be better to just
use a spring for some of the regenerative braking and use a lower hp
motor.

This approach would get you through intersections. On the down side
getting up to freeway speeds might take longer than a diesel Rabbit.


Bret Cahill

 

[fungus]

On Dec 19, 3:26 am, Bret Cahill <BretCah...@peoplepc.com> wrote:

Instead of using a high HP motor with a lot of rare earth materials
driving up the cost of an electric vehicle it might be better to just
use a spring for some of the regenerative braking and use a lower hp
motor.

The amount of extra cogs, levers and other assorted
bits of metal needed would be horrendous.

 

[Bret Cahill]

Instead of using a high HP motor with a lot of rare earth materials
driving up the cost of an electric vehicle it might be better to just
use a spring for some of the regenerative braking and use a lower hp
motor.

The amount of extra cogs, levers and other assorted
bits of metal needed would be horrendous.

A spiral spring, rachet and release pin.

It would be cheap and easy to prototype the same with a 5 kg spring on
a bicycle which generally doesn't go much over 25 km/hr for commuting
anyway.


Bret Cahill

 

[Bob Masta]

On Mon, 19 Dec 2011 20:13:14 -0800 (PST), Bret Cahill
<BretCahill@peoplepc.com> wrote:

Instead of using a high HP motor with a lot of rare earth materials
driving up the cost of an electric vehicle it might be better to just
use a spring for some of the regenerative braking and use a lower hp
motor.

The amount of extra cogs, levers and other assorted
bits of metal needed would be horrendous.

A spiral spring, rachet and release pin.

It would be cheap and easy to prototype the same with a 5 kg spring on
a bicycle which generally doesn't go much over 25 km/hr for commuting
anyway.

It's not clear exactly what you propose. I gather you are
trying to capture braking energy for subsequent use in
acceleration. How does the spring interact with the brakes?
You mention "ratchet"; are you proposing brake calipers that
(somehow) totally grab the wheel and then as the wheel turns
a bit that winds the spring a bit, then the ratchet releases
the calipers and they re-grab the wheel in another spot?
Sounds like a jerky ride!

Similar questions about how you'd transfer the spring energy
back to the wheel later. Seems like the key to this whole
idea is a special transmission of some sort, which would be
the *real* invention here!

Best regards,


Bob Masta

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[dlzc]

Dear Bret Cahill:

On Dec 19, 9:13 pm, Bret Cahill <BretCah...@peoplepc.com> wrote:

Instead of using a high HP motor with a lot of rare
earth materials driving up the cost of an electric
vehicle it might be better to just use a spring for
some of the regenerative braking and use a lower
hp motor.

The amount of extra cogs, levers and other assorted
bits of metal needed would be horrendous.

A spiral spring, rachet and release pin.

It would be cheap and easy to prototype the same with
a 5 kg spring on a bicycle which generally doesn't go
much over 25 km/hr for commuting anyway.

Regenerative braking would work. Generator off the wheel, powering a
supercap. Run the charge through the generator to act as drive motor.

No transmission.

But you only get out less than you put in, so your wish for not having
"a high HP motor" will not be met.

David A. Smith

 

[Bret Cahill]

Instead of using a high HP motor with a lot of rare
earth materials driving up the cost of an electric
vehicle it might be better to just use a spring for
some of the regenerative braking and use a lower
hp motor.

The amount of extra cogs, levers and other assorted
bits of metal needed would be horrendous.

A spiral spring, rachet and release pin.

It would be cheap and easy to prototype the same with
a 5 kg spring on a bicycle which generally doesn't go
much over 25 km/hr for commuting anyway.

Regenerative braking would work.  Generator off the wheel, powering a
supercap.  Run the charge through the generator to act as drive motor.

That'll eventually improve but it's a lousy round trip efficiency
right now.

No transmission.

But you only get out less than you put in,

That's why it's desirable to keep the number of energy conversion
components down.

so your wish for not having
"a high HP motor" will not be met.

There's no question that for freeway commuting situations it wouldn't
work. Either you would have to use a 1600 kg spring to get the same
car up to 100 kph or you'd have to get DoT to lower the speed limits
near ramps and intersections.

There may be some niche markets where 100% of the driving is in city
traffic or rural. If you want to get on the freeway you'd want to
wait until traffic is very light.


Bret Cahill

 

[fungus]

On Dec 20, 5:13 am, Bret Cahill <BretCah...@peoplepc.com> wrote:

The amount of extra cogs, levers and other assorted
bits of metal needed would be horrendous.

A spiral spring, rachet and release pin.

How will you allow the driver to adjust the
braking force created by the spring? He needs
to be able to brake both gently and hard.

Similarly the startup, you can't just release
the spring and shoot him off. It needs to
be a controlled release in proportion to the
position of the gas pedal.

 

[m II]

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Bret Cahill wrote:

A 50 kg spring could get a 1,000 kg vehicle up to 15 mph.

Instead of using a high HP motor with a lot of rare earth materials
driving up the cost of an electric vehicle it might be better to just
use a spring for some of the regenerative braking and use a lower hp
motor.

This approach would get you through intersections. On the down side
getting up to freeway speeds might take longer than a diesel Rabbit.

A flywheel may be a better idea, but that has it's own problems.


mike


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[Bret Cahill]

The amount of extra cogs, levers and other assorted
bits of metal needed would be horrendous.

A spiral spring, rachet and release pin.

How will you allow the driver to adjust the
braking force created by the spring? He needs
to be able to brake both gently and hard.

This isn't like regenerative braking which stores 16X more energy, 100
kph-0.

The spring could even be wound up by the 20 kW motor at intersections.

Similarly the startup, you can't just release
the spring and shoot him off. It needs to
be a controlled release in proportion to the
position of the gas pedal.

If you don't need to scoot through an intersection, you don't use the
spring, at least not all of it energy in the spring. A clutch would
make sense.


Bret Cahill

 

[fungus]

On Dec 20, 5:13 am, Bret Cahill <BretCah...@peoplepc.com> wrote:

It would be cheap and easy to prototype the same with a 5 kg spring on
a bicycle which generally doesn't go much over 25 km/hr for commuting
anyway.

I think that pursuing a mechanical system for
bicycles is a dead end. The overall amount of
energy is small and smoothness of capture
& release is even more critical than a car.
It needs clutches, gearboxes, things to grab
onto the wheels...that all sounds big, heavy
and inefficient to me.

Even assuming 50% efficiency the shove you'll
get from braking at a stop/start intersection just
doesn't seem worth it.

As a rider I don't see stop/start intersections as
much of a problem anyway, not compared to going
up hills.

I think a much better idea would be a small dynamo
which charges up a capacitor as you ride. This would
be connected to an electric motor which can provide
boost when you press a button on the handlebars.

The dynamo could even have a 'high charge' mode
which you could activate to increase the amount of
energy being captured when you're going down a hill.
Dynamos produce drag when they're active so it would
act like a brake to slow you down as well as storing
the energy - double win!

A fully charged supercapacitor could easily launch
you away from an intersection and provide a lot of
help for going up a short hill.

 

[Bret Cahill]

Instead of using a high HP motor with a lot of rare earth materials
driving up the cost of an electric vehicle it might be better to just
use a spring for some of the regenerative braking and use a lower hp
motor.

The amount of extra cogs, levers and other assorted
bits of metal needed would be horrendous.

A spiral spring, rachet and release pin.

It would be cheap and easy to prototype the same with a 5 kg spring on
a bicycle which generally doesn't go much over 25 km/hr for commuting
anyway.

It's not clear exactly what you propose.  I gather you are
trying to capture braking energy for subsequent use in
acceleration.  How does the spring interact with the brakes?
You mention "ratchet"; are you proposing brake calipers that
(somehow) totally grab the wheel and then as the wheel turns
a bit that winds the spring a bit, then the ratchet releases
the calipers and they re-grab the wheel in another spot?
Sounds like a jerky ride!

Similar questions about how you'd transfer the spring energy
back to the wheel later.  Seems like the key to this whole
idea is a special transmission of some sort, which would be
the *real* invention here!

There is at least one patent for a spring mechanism for a bicycle.
The spring fits inside the hub. Assuming the dimensions of the hub in
the drawing are similar to conventional, there is no way the spring
could weigh anywhere near the 5 kg that would make it worthwhile.

Some work has been done on carbon nanotube springs as "batteries"
which weigh 3 orders of magnitude less than steel springs but cost 3
orders more. As a replacement for a gas tank and/or batteries for
motor vehicles the weight may be ok but the cost would be over $5
million.

It would be better to use carbon nanotubes for regenerative braking
but even then it would be hundreds of dollars for a bicycle and
thousands for a motor vehicle. This is just to scoot through the
intersection.

To get a 1 ton motor vehicle up to freeway speeds might take $100,000
worth of nanotubes. The round trip efficiency is good but you can
buy a lot of rare earth magnets and supercaps with 100K.

What we need is a material that is somewhere in between steel and
carbon nanotubes in price as well as energy density.

Bob Masta

              DAQARTA  v6.02
   Data AcQuisition And Real-Time Analysis
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