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Old 06-26-2010, 05:58 AM   #11 (permalink)
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Pulse and glide is a proven technique for a significant increase in mileage, because it limits engine operation to only the most efficient ranges of RPM and load.

The problem has always been, how do you maintain a constant vehicle speed, while employing P&G?

How do you design a power train system that maximizes the potential gains from improved aero and lower rolling resistance?

To accomplish this you MUST disconnect the engine from the wheels, while maintaining constant velocity, at every legal speed.

You MUST have some form of capacitive storage for the energy generated by the engine, that can be applied to the power train in precise and constantly changing levels,thus allowing the engine to cycle on and off at varying frequencies depending on average sustained load.

The application of that power as well as the storage of same power MUST be accomplished at levels of efficiency approaching that of a conventional manual transmission. Wheel to wheel regeneration of braking energy MUST exceed 80%, not including aero and rolling resistance factors.

The system MUST automatically compensate fro any improvement in aero or rolling resistance without having a directly connected engine's efficiency fall off as sustained load is decreased.

No hybrid electric vehicle can overcome the cumulative losses inherent in the multiple conversions of energy necessary to provide power to the wheels with the engine off at freeway speeds.

My system reduces the parts count by about 25 % per vehicle, while providing regenerative braking efficiencies of over 80%, wheel to wheel. It can be done by replacing the rear axle in a FWD car with a launch assist unit in its simplest configuration.

Even this most basic system would allow constant speed P&G by increasing the load on the engine during the pulse phase, then applying that same stored energy to the rear wheels while the FWD power train is in neutral with the engine shut off.

Now you do not have to use the vehicle's mass as capacitive storage, and suffer the consequences of the frustration of other drivers when you are constantly accelerating and decelerating.

You do not have to suffer the much higher aero losses of the exponential effects of drag at your peak pulse speeds.

In fact no other drivers around you would even realize that you are actually turning your engine on and off regularly, and the cycling between running and not running would be automatic, controlled by the percentage of your stored reserve capacity.

P&G goes back to WW2 and even before.

ALSO;

For those who are convinced that battery powered vehicles are the future, what I have just describes, in no way, is restricted to any particular fuel or motor configuration. The energy path to regenerate the capacitive storage can be by any means, without exception or limitation.


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Mech

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Old 06-26-2010, 06:10 AM   #12 (permalink)
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Quote:
Originally Posted by Arragonis View Post
F1 cars used a system called KERS (Kinetic Energy Recovery System) which could store regenerative energy in a flywheel or battery system (depending on team) and release it as extra power when the driver hit a button. Its advantages were a burst of speed to help overtaking which is a criticism of F1 at the moment - the cars are so closely matched that overtaking is rare.

The system wasn't universally liked and a lot of teams would run a car with and one without and often find the advantage on long straights was nullified by the extra weight on corners. Some teams didn't bother at all.

It was abandoned after the end of the 2009 season.

Other systems have also been used including hydraulics, air compression etc.
Yes and if we all drove INDY cars in round tunnels, we could just climb the walls and pass another car inverted on the ceiling. The down force is so great on those Formula 1 and Indy types that they could actually do what I just described.

KERS was much more than that. It was an attempt by the racing organizations to add some relevance to their sports. Comparing a passenger vehicle to any racing car today is like comparing a hang glider to a space shuttle. The only thing they have in common is they both "fly".

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Mech
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Old 06-26-2010, 09:56 AM   #13 (permalink)
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The problem has always been, how do you maintain a constant vehicle speed, while employing P&G?
You don't. Just let the vehicle speed change. Except at hills, where the elevation of the vehicle is used as energy storage for no extra cost, reducing the speed variations.
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Old 06-26-2010, 11:18 AM   #14 (permalink)
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Quote:
Originally Posted by NiHaoMike View Post
You don't. Just let the vehicle speed change. Except at hills, where the elevation of the vehicle is used as energy storage for no extra cost, reducing the speed variations.
Absolutely.

In a perfect world you could have the hills at the perfect grade so you could maintain speed uphill at the perfect BSFC for your car. Then you could coast, with the engine off on the down slope.

Under those perfect circumstances you could P&G and maintain a constant speed.

My solution allows for P&G benefits without perfect grades, or even dedicated driving techniques for absolute mileage.

In a 60-0 panic stop, you have less than 25 revolutions of the wheels to recover all of the energy stored in the mass of your car as inertia.

Hybrids have proven than engine off techniques with literally thousands of restarts are practical. 10 seconds engine on and 30 seconds engine off, would be practical at speeds up to 50-55 MPH, at higher speeds the percentage of engine on time would be higher. In heavy stop and go traffic the engine on time could go to less than 10%, in some cases even less than 5%.

Understanding the fact that almost any engine producing 20 HP at 1500 RPM, is capable of producing 30 additional HP on half again as much fuel, gives you the potential benefit of P&G operation. Fuel mileage can be doubled by eliminating all but highest efficiency operational states of the engine.

This is demonstrated by the new 305 HP Mustang that averaged 48 MPG at 48 MPH. I wonder what it would get if it was P&G ed at the same average speed, with engine off coasting.

My guess would be 55-65 MPG.

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Mech
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Old 06-26-2010, 01:24 PM   #15 (permalink)
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...sounds like you want an automotive-version of the old German V2 "Buzz" bomb's engine, the pulse-jet engine (and some current home heater furnaces!), where combustion occurs as rapid "bursts" rather than long, slow, continuous burning.
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Old 06-26-2010, 02:18 PM   #16 (permalink)
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Quote:
Originally Posted by Old Mechanic View Post
KERS was much more than that. It was an attempt by the racing organizations to add some relevance to their sports.
Unfortunately most F1 fans and drivers saw it as an annoyance. Teams who used it sometimes would decide not to use it on certain circuits, and others who found it too expensive were locked out.

Also the teams using it at the start of the season had pretty much stopped by the end. There were some issues in very wet conditions too. So it was dropped.

Quote:
Originally Posted by Old Mechanic View Post
Comparing a passenger vehicle to any racing car today is like comparing a hang glider to a space shuttle. The only thing they have in common is they both "fly".
I agree, however I wanted to correct the impression in the post previous to mine about F1 teams currently evaluating regenerative energy systems. KERS was that evaluation and now nobody uses it. It was evalued, found wanting and abandoned in that environment.

Just like Hang Gliding is great fun, but not much use for launching or recovering satelites.

One of the teams bucked the trend on KERS and used a flywheel instead of batteries to store the extra power which I found interesting. Flywheels are kind of fascinating. A French power operator had a standby power system for one of their major computer systems running on a flywheel supported on magnetic bearings. It was made of carbon fibre so if it got out of balance it would shatter into powder, and it had up to 12+ hours of energy stored in it.

Obviously a battery can retain power for longer but it was an interesting alternative.
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Old 06-27-2010, 12:10 AM   #17 (permalink)
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Quote:
Originally Posted by Arragonis View Post
One of the teams bucked the trend on KERS and used a flywheel instead of batteries to store the extra power...
See here, just a dozen or so threads down in this section: http://ecomodder.com/forum/showthrea...ace-13310.html

The big advantage of flywheel storage, especially in a racing application, is that it's not really rate-limited. That is, with a battery you can only put energy in or take it out at a certain limited rate (which depends on battery chemistry etc), while a flywheel will basically take anything that doesn't melt the wires.
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Old 06-27-2010, 07:49 AM   #18 (permalink)
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Quote:
Originally Posted by Old Tele man View Post
...sounds like you want an automotive-version of the old German V2 "Buzz" bomb's engine, the pulse-jet engine (and some current home heater furnaces!), where combustion occurs as rapid "bursts" rather than long, slow, continuous burning.
My still living (at 89) father was standing on the top of a Red Cross building in London, when the first Buzz Bomb arrived.

He and his co-pilot were cheering the pilot, what they thought was one brave son of a gun, until they read about the pilot less flying bomb in the next days newspaper.

His first mission as a B17 pilot was bombing the launch ramps being built on the French coast. That mission was Dec 24, 1943. His last mission was June 6, 1944.

They had just completed their required 30 missions and were in London on R&R when they saw the first Buzz Bomb.

We just published his book "Feather Merchant".

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Old 06-27-2010, 08:08 AM   #19 (permalink)
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Quote:
Originally Posted by jamesqf View Post
See here, just a dozen or so threads down in this section: http://ecomodder.com/forum/showthrea...ace-13310.html

The big advantage of flywheel storage, especially in a racing application, is that it's not really rate-limited. That is, with a battery you can only put energy in or take it out at a certain limited rate (which depends on battery chemistry etc), while a flywheel will basically take anything that doesn't melt the wires.
One of the essential components of a purely mechanical flywheel energy recovery system, is a Infinitely Variable Transmission to store and apply the energy.

IVTs are very new technology. CVTs date back to the mid 1950s in automotive applications. I believe it was the Van Doorne Belt system that was first used in a DAF car in Europe (Holland or Belgium).

The problem was with the belt itself, and it took several decades for the belt technology to improve.

Nissan has recently extended the warranty on their CVTs to 10 years and 120k miles to address customer concerns about reliability.

10 years ago the EPA's hydraulic hybrid research efforts concluded that the "missing link" was a highly efficient IVT hydraulic transmission was the place where development should be concentrated. Even without that development they built a 3800 pound test mule vehicle that average 80 MPG.

NASA flywheel batteries for energy storage in space flight is also an interesting subject. 6 months at something like 95% of the original energy storage level.

Vacuum chamber, magnetic bearings, mega bucks, and not really practical for automotive applications.

I hope KERs is not dead yet. When you think that the first couple of years of development was actually competitive, compare that to the amount of time we have been chasing a practical BEV battery.

It's not that I am an opponent of chemical batteries. Think of it more as being an advocate of higher efficiency regardless of the means by which it is achieved as long as the trade offs are not safety and environmental risks.

regards
Mech
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Old 06-27-2010, 08:14 AM   #20 (permalink)
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What is pulse and glide?

Using higher BSFC engine operation to store energy in the mass of the vehicle itself and then allowing coasting to use that stored energy without additional fuel consumption during the coasting phase (engine off).

Does that make every car a hybrid?

Do we need to debate a definition?

Why waste time debating the specifics of a definition when the real issue is the effective use of energy.

Replace the mass of the vehicle with a flywheel and you no longer need to change speeds to accomplish the same thing.

If you can do this efficiently enough then you will get better mileage because you are not exponentially increasing the aero drag at your peak pulse speed.

regards
Mech


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