sled4fun

Diesel Hybrid technology seems to work great in a train. If a Cummins in our truck were to just idle it would use about 1 gallon per hour +/-. I know it would easily put out enough power for a 20kw or more generator head. Then have it power two high output motors at the front and rear diff. input flanges. No transfer case, no transmission just a fly bywire.

Now for the question. How much generator and how many amps would be needed to run these motors I am seeing on some of these electric cars?

Some of these motors are putting out some pretty good power.

Would you have to run a battery bank? or could it just be direct?

I think that it is just trading of the inefficiencies of the transmission & transfer case for possibly a more efficient transmission.

What do you think?

BC847

The typical diesel locomotive isn't a "True" hybrid in the sense that we're seeing coming into consumer transportation.

The typical set-up is the diesel engine spinning the generator that in turn, powers the traction motors.

There's a couple of distinct advantages in the locomotive setting.

- One can keep the engine in it's most efficient RPM by altering the loading of the main generator [done by varying the exciter coils of the main generator itself ( my terminology is off)]. A little alternator attached to the engine crankshaft provides the excitation power for this. Said power is what makes the magnetic fields of the main generator.

- Considering the above, one doesn't need a mechanical transmission as is typical of a direct mechanical drive.

That gets us moving.

The true hybrid vehicle will most likely also use regenerative braking. That's where the traction motor becomes a generator itself when braking thus, the energy of motion is put back into the battery.

The typical diesel/electric locomotive does the same thing but, the energy of motion is converted to heat by way of big electrical resistors mounted to the top of the locomotive. That's what all the big fans up there are about. When regenerative braking the train, the energy of motion is converted to heat, then dumped to the atmosphere.

Because of the tremendous power typical of diesel/electric locomotives (3600hp is common with godly torque), 600 volts is a common working voltage so as to keep the conductor sizes smaller than your leg. That in turn also helps reduce the footprint of the traction motors (usually one per truck).

With the above, some overall efficiency is sacrificed to facilitate getting it to the wheels in a minimal package. That roughly one square inch of surface contact between the wheel and rail has to tote it all.




It all gets back to how much tractive effort do you want at the wheels of your vehicle? 300hp? You'll need to cypher what voltage and number of phases you can economically stand so as to determine the physical size of the generator and traction motors. Ever seen an industrial 350hp three phase 460vac motor? It's about the size of a common 4'x4'x'4' chest freezer give or take a foot or so. Weighs a LOT!



It goes on, and on, and on, . . . . ..


Umm, . . . .. generally speaking.

RJ285

A hydraulic transmission is the way to go. Hydraulics are 97% efficient at transfering energy. A hydraulic pump on the motor, and a hydraulic motor on each diff. Mega amounts of torque are possible due to stored energy on demand.

96_12V

Sorry to do this - but could you name your source for this statement?

I work in the gear industry, and have never heard anything like this.

bentwings

A 300hp hydraulic motor would present a new definition to the word "noise".

MikeyB

Lot of tractors have hydrostatic drives. The big drawback is what happens when the 'throttle' is closed. Talk about a engine brake. Could be dangerous on slick roads.

MikeyB

shortround

There was an article, some time back, in Global Security or one of the other defense publications that Dodge built some trucks with a 75 hp electric motor driving each wheel. I think the suspension was all independent. Power was the 5.9. Interesting article. DARPA was doing some research on engine and drive train noise levels along with different power systems. I'll see if I can dig it out.

JD730

Throttle closing wouldn't be a big deal, no different than doing what right now. Pulling the hydrostatic system into stop would make for an interesting situation.

International made some big ones, 100+hp. I know guys that have them and they love them for light work, making hay, square or round, loader work, etc... Plowing all day is probably not a good idea, think of how much heat has to be dissipated and how much fuel is wasted in making that heat.

One pull I go to every year there's a big IH hydro that pulls. Does alright, but just doesn't pull like the gear drive tractors do.

RJ285

I am a Kettering student and my friend co-ops at a company called Hybra-drive Systems LLC. They have working prototypes right now that use a variable displacement hydraulic pump. I believe their working with the military on hummers (6.2L) and they might be working with UPS. Pretty sweet stuff, I'm just not sure how much can be said about it. Website is Hybra-drive.com.

They experimented with hydraulic drive trains back when they started making electric hybrid locomotives. Not sure why they chose one over the other. The technology probably wasn't there yet.

Truckman0097

Kettering?? Ohio?

RJ285

Kettering University, Flint, MI. Used to be GMI before '99.

Truckman0097

Gotcha - I kind of figured you meant somewhere a little farther north since the company you mentioned is a MI comp....

DevilzTower

SR,

the idea definitely sounds cool, but I'm sure it would be cost prohibitive to implement in a light duty truck unless DARPA can get over some hurdles in the electric drive system. I really like the idea and have tossed it around a few times trying to find ways to reduce cost, but using 4 drive motors has the distinct advantage of getting completely rid of the driveline. This opens up interior options for smaller vehicles and makes packaging of the interior a lot easier. Just like having the system space of front wheel drive except with all wheel drive power and traction.

I'm pretty sure they the super sized mining trucks use this system, a big diesel engine acting as a generator with electric motors inside each wheel hub... I think??? well I just checked out CAT's site on their 380ton truck the 797B and it's a conentional drive system, so maybe I'm blowing smoke.

Mlucas

Well, you are kinda right.
A single brand new motor may have an efficiency of as much as 97% or so, but that is just the one component. You would have to drive the motor (which has an efficiency of 95%) then determine losses in your lines.
at most, .95 X .95 would only get you 90% efficiency.....ontop of this, you still need to calculate in your motor loss's. Wait till those motors & pumps start getting some hours on them.....

Hydraulics are, IMO, only functional in a drive application where the overall size of the hydraulic motor is benefitial over a conventional drive system. (where a direct/gear'd drive is undesirable). The speeds must also be lower if any life is to be maintained.

confused89

The engine would have to run at two different rpm ranges if the type of hybrid system you are talking about were to be put into a truck. One a high idle and the other at goverened speed for the engine. The high idle would produce a steady amount of energy needed. Under hard useage the engine would go to goverened speed to keep up with the demand for energy. It would stay at that rpm until the batteries have charged. Then you would need an extensive cooling package for the batteries and a seperate one for the engine. It all becomes to complicated and too big to fit in a dodge. I worked on a bus that had this very system with an ISB in it and the cooling system for it was 26 gallons. That is a little to big to be putting on a dodge.