[brian_]

OK, probably a really stupid thought here, but I'm pretty sure if this was the case, trains would use massive versions on automotive transmissions.

Heavy mining trucks commonly use diesel-electric powertrains, much like trains, and some of Caterpillar's heaviest models do use a mechanical transmission (check out their Mining Trucks - "AC" models are diesel-electric and other models are diesel with mechanical transmissions). These are big (the 797F has rated gross machine weight of 623,690 kg, of which 364,000 kg is payload), but trains are heavier, and relative to their mass they are much lower-powered. That means the trains spend a long time at very low track speed and a hydrodynamic coupling (such as the torque converter in a traditional automotive automatic) or clutch would slip a lot; effectiveness (torque to the wheels) and durability are more important than optimal efficiency. Trains have requirements that even heavy trucks do not, and pickup trucks certainly do not.

 

[brian_]

Forget for a minute the 10kw Harbor Freight piece--assuming you got one that actually had a reasonable output, then it would adjust for how much power was actually being USED by the system.

Yes, the output of any generator will be determined by the speed at which it is driven and the load on it.

I suspect brian_ would want one battery at least, to help with regen braking, and also so that the power has somewhere to go when you're sitting at a stoplight not using much/any power.

Yes, but not to allow idling... the solution for idling with a battery is to simply stop the engine when power isn't needed from it. In any hybrid the battery, in addition to supporting regenerative braking, allows the engine to stay within its range of efficient operation instead of having to follow either the highest peaks of demand or the lowest levels.

I don't know what "one" battery is intended to mean, since batteries come in all sizes and the number of batteries is irrelevant. But not much battery capacity is required for the benefits of hybrid operation - typically less than 1 kWh of capacity per ton of vehicle mass.

With the generator setup you can set the load such that the engine is in whatever torque peak (most efficient points in an engine's power curve--lower ones in the rpm band generally take less gas and usually make a little less power) it needs to be to make adequate power, and will be most efficient at WOT, so if you can get it to run at like 1200 RPMs and WOT, and make enough power for your needs, then it should run well and get like 50 mpg (assuming you have an engine that is a good size for the application). Additionally, if you put that much load on it, it should require little to no cooling, as it won't be losing much energy as heat when you lug it that much.

All of that is a good description of why a continuously variable transmission is good. Just realize that - without a battery - the engine must follow the power demand, so it will be required to run at far higher and much lower power than the most efficient point as the vehicle is driven. The result is that in the real world the electric transmission scheme doesn't have any advantage over any other continuously variable transmission... and they don't do much better than traditional transmissions with a reasonable number of ratios.

 

[brian_]

...
when speeds were much lower and bodies likely quite lighter altogether there actually used to be just a few unusual buses in the northeast usa which were basically a genset engine under the hood paired to trolleys-borrowed (not surprising given the similar axle sizes) traction motor .. somewhere around the 1910-1930's timespan that is

I unforuantely can't find any examples right now due to the way the web is (even an exact search for 'diesel-electric bus 1920' still dumps a lot of modern non-electric bus photos all over, oh well) but I do know at least two different ones had made their appearance in station-related photos in the usa 'classic trains' magazines for one thing tho

Sure, I can believe that was done, especially back when mechanical transmissions were relatively crude. More recent examples of series diesel-electric buses are hybrids... with a battery.

 

[JKReece]

Hence the reason I'm here asking for information; I don't know. I have no idea how a controller would work, although I'm pretty certain that at least the railroads have done it in controlling speed.

I'm talking about utilizing my already 44mpg 4cyl diesel engine to direct-power a 20kW 240V generator head, and then wiring through a controller, directly to a 240V motor that will produce at least the same 58hp as my diesel engine does.

I won't be adding any weight, because once I take out the transmission and put the generator head in its place, I will have almost the same weight. This mini-pickup weighs about 2600lbs.

I won't be adding batteries of any kind, because I will retain my original 12V electrical system for my p/u, along with my vacuum assist braking system, complete with discs and drums.

I am only changing the element that provides power to turn the rear axle; the drive motor. The drive motor will be attached to the yoke at the rear axle, in the place of where the drive shaft is now, to turn the axle. This just seems to simple to me. All I'm after here is for someone who actually knows how all of this works, to provide me with links to research the information so I can accomplish this, if it can actually even be done.

I see freight trains moving daily, so I know I'm not out of the ballpark here.

 

[sierrablue]

If you're already getting 44 mpg and refuse to add even a small battery (could you somehow use a 12V Li-ion and a step-down for it????? Seems unlikely but I guess you probably could), it sounds like you're really not going to gain anything with the swap, except maybe some low-end torque (which, being a diesel and a 2600 lb truck, shouldn't be an issue anyway).

 

[JKReece]

My intentional gain is MPG. I don't know how true this is yet, but with an electric drive, I should see upwards of 75-80MPG because the diesel engine will for the most part, just be idling, (1000 - 1200RPM?), to achieve the 60Hz needed to produce the 240V A/C power.

 

[JKReece]

I just checked the tag on the generator head. It says that it produces single phase, 20kW, 240V, 60Hz, 83.4Amps at 1800RPM. So that would be my operating RPM if I am reading this right.

 

[sierrablue]

I guess I have no idea where you're getting these numbers. With the 5-speed you ought to be able to short-shift it and keep it in a similar RPM range, and thus get similar mileage. At that point it all comes down to your foot and shifting.

It being a diesel, you shouldn't be pulling a ton of RPMs anyway right? And because of all of the low-end torque of the diesel you should be able to shift it at like 1800-2000 right? And either way it's going to be idling at stop lights and such, so I would think it would be a wash, or it would be LESS efficient if anything, if it's stuck around 1800.

And as @brian_ (thanks for your patience!) said, if you refuse to use ANY batteries, then the RPMs are going to be all over the place, and frankly will have to be stalled at stop lights and such, correct? Which is good from a fuel perspective, but diesels don't like being shut off and then fired right back up again, correct?

 

[JKReece]

I guess I have no idea where you're getting these numbers. With the 5-speed you ought to be able to short-shift it and keep it in a similar RPM range, and thus get similar mileage. At that point it all comes down to your foot and shifting.

The numbers I am using for my truck are those from real-life experience. The numbers I just quoted for the generator head are from the tag on the generator head

It being a diesel, you shouldn't be pulling a ton of RPMs anyway right? And because of all of the low-end torque of the diesel you should be able to shift it at like 1800-2000 right? And either way it's going to be idling at stop lights and such, so I would think it would be a wash, or it would be LESS efficient if anything, if it's stuck around 1800.

I am imagining that I can have a switch that will electronically set the RPM's at 1800 when needed and turned on. I don't have a tach on this truck, so I don't know what 1800RPM sounds like, but if there is a need for it to idle, then I can just turn off the switch and let the engine rest at idle. The 5-speed transmission just comes out because there will no longer be a need for 5-speed gearing. The power will be controlled through the motor.

And as @brian_ (thanks for your patience!) said, if you refuse to use ANY batteries, then the RPMs are going to be all over the place, and frankly will have to be stalled at stop lights and such, correct? Which is good from a fuel perspective, but diesels don't like being shut off and then fired right back up again, correct?

No reason at all for the RPM's to be all over the place, because I can go outside right now and start it up, hold it at whatever is higher than idle, and it doesn't raise or lower in RPM's all by itself. That makes no sense anyway. When I would be at a traffic light, there would be no reason to adjust the RPM's, because I will not have deleted my original 12V electrical system that now provides power to all of my lights and turn signals. And yes, you are correct, diesel engines are designed to run, so turning it off and starting it back up again would be detrimental to the life-expectancy, so hence the electrically controlled 1800RPM switch that can be turned off when need be.

 

[JKReece]

Remember this when you're thinking about offering information; I am building a 20kW generator that will produce 240V A/C power, to supply that electricity to an electric drive motor. That's it. The generator just happens to be bolted in my pickup and it has wheels. This would be nothing different than you buying a 20kW generator to provide emergency backup power for your home. I'm just using it in a different application, and regulating the speed of the electric drive motor with a controller. That's all.

 

[cricketo]

Remember this when you're thinking about offering information; I am building a 20kW generator that will produce 240V A/C power, to supply that electricity to an electric drive motor. That's it. The generator just happens to be bolted in my pickup and it has wheels. This would be nothing different than you buying a 20kW generator to provide emergency backup power for your home. I'm just using it in a different application, and regulating the speed of the electric drive motor with a controller. That's all.

With a 20kW generator you're still short more than 2 times on power. Is your generator single phase ?

 

[JKReece]

Yes it is. And this is exactly the information I am seeking here. People like you who know what it would take to accomplish this, and you're telling me I already have an insufficient power supply. So now my questions are being answered. Thank you!

 

[cricketo]

So then your setup would look something like

1PH generator [3PH AC -> DC -> 1PH AC] -> VFD [AC-> DC -> 3PH AC] -> induction motor

Do you see any problems with that ?

 

[JKReece]

If I had your knowledge and knew how to read everything you just posted, I might be able to provide an answer.

My thinking was to have a single phase, 20kW 240V A/C power plant, providing 240V A/C power to a direct-drive A/C motor, with reduced voltage to the motor as necessary, and I say this, because I have only seen one A/C motor that was rated to have 144V connected to it.

 

[cricketo]

Have you seen a lot of single phase motors above 10HP ? I don't believe I've ever seen voltage/rpm regulation for a single phase motor.

 

[JKReece]

This is why I came here. I’ve just begun researching this and I obviously have a lot to learn.

I do know that in the locomotive, the A/C power is rectified to D/C, and then back to A/C power going to the drive motors. The D/C power is used for on-board electronics and the such, and they do have a battery bank for that.

I already have a complete D/C power system, so I don’t require that part of this puzzle.

 

[cricketo]

Sounds like you've decided that you need a single phase 27HP (20kW) motor for your project, and some way to control the RPMs for it. Leaving aside the second part, you should shop around and see if you can find such motor in existence. I don't believe they exist, not even close.

 

[JKReece]

Why would I want a 20kW motor? I said I have 20kW’s of 240V electricity. I want a 240V, (or other applicable motor), that will provide at least the same 58hp as I have now. If the A/C motor isn’t sufficient to supply the power I’m after, and it would then require a D/C motor, then it appears that I would have to rectify my A/C power so it can provide sufficient D/C power to the motor.

 

[cricketo]

You're limited to 20kW right now from your power source. You can't get 58HP (43kW) from a 20kW power source, regardless of the type of motor you hook up to it. What am I missing ?

 

[JKReece]

Ok, now I think I’m understanding what you’re referring to.

So I need to go after a D/C motor, as I see those readily available at 60+hp. Yes/No?