At my little machine shop here I make some parts for a manufacturer of all electric cars.
The recent spurt in gasoline prices made me start thinking. Hey! Maybe I need to get me one of them things to go to work in!
So, I looked at their web site. Now, I don't mind making parts for them. After all, it helps earn me a living. But what a piece of crap! It has a 30 mile range. Ok, I can live with that. I live 8 miles from work. And, if need be I can charge it both at work and at home. No problem.
Problem is, it can only go 25 mph. Maybe I could live with that, but I doubt it. But I do live in a relatively cool part of the country. This car has no heater. At least they didn't advertise it as having one. They did brag that the car has (a) headlight, windshield wipers! and brakes on ALL FOUR wheels!
Ok, I don't think I want one of them now.
But I started thinking. I can drag out my old Vega that's been sitting in the garage for fifteen years. It gets a steady 27 to 31 mpg. Pretty good for not even having to buy it.
But how about a little creativity?
So, I get this idea.
Why hasn't (maybe they already have and it didn't work out?) somebody tried the Green Goat theory on a car?
Let's start with a substantial vehicle. One that can haul a good heavy load. I just got back from hauling over a thousand pounds of product to a customer. I can't do that in a Prius. (sp?)
So, let's take a diesel powered Suburban, or a diesel chevy pickup. Let's go with a diesel crew cab pickup. We need some ROOM in this lugger.
We pull the transmission out. Maybe sell it. It's worth some serious money if it works.
In place of the transmission we mount a fabricated bell housing and attach a good strong generator. A generator that runs its full rated power at 1800 rpm. Or, maybe less. 900 rpm.
Low rpm generator tied to a moderate horsepower diesel engine. The engine in the vehicle is the original. It has the power to move the vehicle fairly easily.
We now need some sort of electric motor.
We might have to custom build this unit.
I'm thinking something designed with similar load characteristics to a locomotive traction motor, but obviously much smaller in power, size, and weight.
This traction motor is mounted between the frame rails just ahead of the differential, and is connected to the differential via a short standard drive shaft. Because it's short, we use constant velocity joints instead of universal joints.
Use load controls connected to the former gas pedal, and even a small bank of batteries for not only starting, but so the vehicle can be moved around short distances without even starting the engine.
The engine would always run at a standard rpm, and if designed right at a very efficient rpm.
We need a traction motor capable of delivering, at a rough guess, about 100 to 150 horsepower. This is more than enough to move the vehicle, but we need to have reserve power. I'm not being very generous on reserve power, but it should get the job done.
Personally, I'd like to see about 400 shaft horsepower. But that's for later.
What are the chances something like this could make a notable increase in fuel economy for a large vehicle?
The main contributor to efficiency would be the constant speed of the engine.
Pitfalls are that wide open throttle would still cause the engine, through the governor, to open its throttle to maintain the same rpm under load.
Also, that it still takes W horsepower to move X weight for Y idstance in Z amount of time. Not considering drag coefficients.
Anyone know of any attempts to try something like this?
It could also be done with a gasoline engine, but I used diesel as an example.
Mark D. - The bottom of the information curve