For auto engineers- use of old concepts?


#1

For the enginers:How sad to watch our old technology of using energy to bring our vehicles to speed, only to dissipate that energy as heat when we brake. Why do we not store and re-use that energy? I could rephrase the question first in the mechanical analog, then electrical:

In the mechanical analog, a flywheel, perhaps 100-200 lbs. would be mounted on a low friction bearing with clutch/ gear connections to the drive to wheels. Braking

would couple the tire/wheel motion into the flywheel, translating the vehicle kinetic energy into flywheel angular momentum. The flywheel would spin freely while vehicle is stopped or slowed, and then at startup, this stored energy would

be returned via gears/clutch to motion of the vehicle.

The electrical analog recognizes that electric motors reversed become generators, or that moving a metallic object thru a magnetic field generates an electric current. Either could be used to have wheels slow up by converting the energy directly into electric current. This

could in principle be used to charge a battery, or a capacitor bank if battery charging is too slow.

In short- is there not a better way than

to waste energy bringing vehicles to speed

by diddipating it as heat?


#2

this is exactly what happens in the hybrid electric/gas vehicles.


#3

These ideas have been applied. The rotating mass to store energy has been built into at least one train. A rotating mass in a car probably wouldn’t work because the gyroscopic effect would hinder the vehicle when it tried to change direction.
Regenerative braking is already in use, also.


#4

Electric cars use your electrical analog routinely. Your mechanical analog is never used because with a flywheel that massive the throttle response would be dismal. The only way to get anything like an effective response to throttle input would be the use of an extremely powerful motor, which would offset any savings the flywheel provided.


#5
Well your ideas are good.  In fact they are using many of them in some newer cars, especially the hybrid cars.  The problem is the technologies as used in cars are not mature yet.  That is there may well be a lot of possible improvements in the emplimetation. Each idea adds weight, complexity and cost to the car which are negatives.  

Frankly I have been amazed with how well they have done in the hybrids when it comes to reliability of these new technologies in cars.  I have not been surprised with the relatively small improvements to mileage that have resulted or the higher prices.  When it comes to technology IMO we are doing very well, but we have a while to go.  There is room for improvement, but it is not going to result in 100 mpg cars for the general public.  It is just one tool to help solve the real long term problems.

#6

Completely re-learn how to drive and the benefit of kinetic energy recovery braking becomes moot. You don’t have to be the first car to the next red light.

Always look to see what the signal lights are doing as far ahead as you can see, not just the next intersection. On a route that you drive daily, learn the timing of the lights so you don’t need to brake for them.

Just as important, keep at least a five or 10 second space between you and whoever is ahead of you, that way, you don’t have to ride your brakes down a hill just because the car ahead of you is doing so or have to come to a unplanned stop because the car ahead of you suddenly stopped to make a right turn into a driveway turning on his turn signals about the same time he started braking (thanks a lot).

In slow-and-go congested freeway traffic, don’t be too quick to accelerate when the cars ahead of you go, let a gap open up ahead of you and when their brake lights come on let the gap close, often they will go again just as you reach them and you won’t have to stop.

Get real good at this and your gas mileage will embarrass the hybrids. Your gas mileage will also go “upside down” that is, your city gas mileage will match or exceed your highway gas mileage.

I think the biggest obstacle in the way of technology like this is the fact that a lot of consumers will gladly pay $30,000 to $40,000 for a car because it is big and luxurious or because it can go from zero to 60 in under 5 seconds, but, very few people were interested in paying that much for a sub-compact car because it gets 70mpg.