EcoModder Forum AirFlow BulletTruck Project (aerodynamic, modified Class 8 transport doubles MPG)

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Grand Imperial Poobah

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Quote:
 Originally Posted by JRMichler That series hybrid will need one huge electric motor. Just to throw out some numbers: Assume tires 40" diameter. Assume 80,000 lbs gross vehicle weight. Assume it needs to pull up a 10% grade at low speed. Assume geared for 1260 RPM at 55 MPH, that would be a 2.5:1 rear axle ratio. You would need 8000 lbs traction force plus another 1000 lbs for friction and whatnot. That's 9000 X 20 / 12 = 15,000 foot-lbs torque at the drive wheels. 15,000 / 2.5 = 6,000 ft-lbs at the drive motor. If the main engine is 450 hp, that would feed a 400 hp electric motor. The electric motor would be rated for 6,000 ft-lbs up to 350 RPM (400 hp). Above that, it would run in constant power mode. I'm not aware of any off the shelf electric motors anywhere close to those specs. Which would explain why the big manufacturers did not develop series hybrids for Class 8 trucks. In order to get the motor frame size down to where it will fit in the truck, I think it will need liquid cooling.
Your first two assumptions are correct.

Max grade on the interstate highway system in the U.S. is limited to 6%. A short 10% grade on a back road in Somewhere, USA should not be a problem.

Your 2.5:1 axle ratio assumption is incorrect. But I cannot elaborate in public.

I really cannot get into the math on the internet. I appreciate your calculations. All of our math is just physics and absolutely quantifiable.

Remember, in both Parallel and Dual Mode hybrid, the vehicle is powered exclusively by the electric motor only, during certain operation cycles.

A big manufacturer does indeed make off the shelf traction motors and motor/generators for our application. That application being a series hybrid Class 8 truck. The big manufacturer is Indiana based Remy. So the motors are not built in China, but in the good-ol' USA.

Large OEM's do currently make Series hybrid drive large-capacity buses, and large trucks such as garbage trucks. No OEM currently makes OTR Series hybrid drive trucks.

They are indeed liquid cooled and Dexron VI ATF is used as the coolant.

Remy's sister division, Delco Remy, has been a Partner of ours for four years now.

The torque and power curves shown below are not necessarily correct for our application, and are posted for your reference and perusal only.

Again, I appreciate your credentials and thoughtful calculations, but I really cannot elaborate any further on the internet.

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Last edited by Shepherd777; 03-09-2013 at 07:02 AM..

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 03-09-2013, 01:51 PM #172 (permalink) Master EcoModder     Join Date: Jan 2008 Location: Sanger,Texas,U.S.A. Posts: 16,154 Thanks: 24,289 Thanked 7,322 Times in 4,730 Posts Mechanical efficiencies of powertrain components The following numbers are from SAE Paper 881A, June,1964,by Univ. of Washington.(we'd have synthetic lubes to lower values a bit since then.Don't know about anything else): Component------------------------------------------------ Mech.Effic.% *4- to 6-speed trans.---------------------------------------------95 *Auxiliary trans.-------------------------------------------------- 95 *8- or more speed trans.------------------------------------------ 90 *Single drive axle------------------------------------------------- 96 *Tandem drive axle----------------------------------------------- 92 *Propeller shaft--------------------------------------------------- 98 -------------------------------------------------------------------------- Approximate Driveline Efficiency,% Transmission---------------------Single Axle-------------Tandem Axle *4-,5-,6-speed------------------- 89-09----------------------86 *With auxiliary----------------------84----------------------- 80 *With 4 wheel drive---------------- 84----------------------- 80 *8-0r more speed------------------ 86----------------------- 82 ------------------------------------------------------------------------- Pickup truck has a total driveline efficiency of 92%,with non-overdrive,manual trans. __________________ Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
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Quote:
 Originally Posted by JRMichler 777, All of which begs the question: If the steady state cruise power is so low, does such a truck really need a 13 to 15 liter low RPM engine? If the steady state power is down around 60 hp or less, could one of the engines such as the new Ford diesel in their medium duty trucks be used?
The big thing with a big truck is torque. It takes monster huge amounts of torque to get a load moving. Torque is also very important when going up hills.

Horsepower is how fast you hit the wall. Torque is how far the wall moves after you hit it.

A series hybrid big rig would work, as long as the electric end has the torque to get up to 80 kilopounds moving from a standstill, and to keep it moving at least as good as a regular drivetrain up a long hill. It'd also need the battery power to keep it moving up a long hill. The smaller engine would still end up running flat out to keep putting power into the battery.

Fortunately, most long climbs are paired with long runs down hill, often as steep and long, so regenerative mode combined with the engine and generator to charge the battery up for the next climb.

What could be fairly easily done with today's technology is programming the drivetrain with a 3D route map to control the engine for the most efficient operation over every hill. Assume hill one is a 2,400 foot climb, a descent down to about 2,000 feet, followed immediately by a long slog to over 4,000 feet, followed by a descent down to about 3,000 feet. (A rough guesstimate of the run up Whitebird south of Grangeville, Idaho.)

Up AND down the first hump you'd want the engine going full throttle to ensure the battery is topped up so it wouldn't run out of juice partway up the big mountain. Once at the top of Whitebird, the engine could idle because the Camas Prairie is pretty darn flat, lots of downhill, most of the way to Lewiston, which is the lowest point in Idaho.

3D route map/control using GPS and repeated route automatic tuning could optimize fuel use. Live measurement data could be copied from one truck to another to speed up the learning/optimization process. That'd work best with identical trucks. With cellphone internet connections, the data could be streamed live and downloaded by other trucks following so their performance could be optimized in real-time for economy optimization when it's the first time a truck has taken the route.

How about a service selling route optimization data to owner/operators and fleet operators? Could be a sort of brokerage where truckers could upload their data and those who download it pay if they get better MPG than a previous run.

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Grand Imperial Poobah

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Quote:
 Originally Posted by JRMichler 777, I appreciate your detailed reply. I was not aware of the Remy motors. They are impressive. Much of my own motor experience was helping develop a liquid cooled permanent magnet servomotor. That motor was rated for 225 ft-lbs continuous torque and a base speed in the 1000 to 1500 RPM range depending on the exact stator winding. The motor itself was less than 10 inches diameter by about 16 inches long. The justification for a hybrid OTR truck makes a lot more sense when you mentioned running at 10% load. That's way below the BEP, even for a diesel. Plus the fuel wasted idling and during low speed maneuvering. Some number crunching indicates that you really went after friction and rolling resistance. Some of us would like to know what you did, and especially how applicable it would be to our vehicles. Or should I just reread Dice1's thread on thetruckersreport.com? All of which begs the question: If the steady state cruise power is so low, does such a truck really need a 13 to 15 liter low RPM engine? If the steady state power is down around 60 hp or less, could one of the engines such as the new Ford diesel in their medium duty trucks be used? In that case, the weight savings from a lighter engine, no transmission, and no APU should come close to covering the weight of generator, electric motor, drive, and battery pack. The battery pack would need to be on the order of 100 Kwh in order to handle the necessary power without catching fire or blowing up. I'll make a WAG and guess the BEP of a lighter engine to be around 2000 RPM. Which would imply a rear end ratio to get 2000 RPM at 55 MPH. And a high torque version of the HVH motor with the stator wound to get the base speed somewhere below that. Methinks that you have a goal of 20 MPG with your series hybrid. I'm not convinced that any of this is new to the engineering departments of the big manufacturers. Being an engineer myself, I would bet that the engineers are tearing their hair out with frustration that management won't listen to them. And that those same engineers have done work way beyond anything said in this thread.
"Much of my own motor experience was helping develop a liquid cooled permanent magnet servomotor. That motor was rated for 225 ft-lbs continuous torque and a base speed in the 1000 to 1500 RPM range depending on the exact stator winding. The motor itself was less than 10 inches diameter by about 16 inches long."

Then you will appreciate the specs of the Remy High Torque motors that we will be using. The HT specs are the right hand column:

"The justification for a hybrid OTR truck makes a lot more sense when you mentioned running at 10% load."

And I was schooled in the exact HP number just last week. I assumed 10% power @ 55 mph was 10% of Rated Load. Rated Load is 450 hp @1800 rpm. So 10% would of course be 45 hp. In actuality, while traveling at 55 mph, that 10% power reading on our digital display is 10% of engine load at that specific 1225 rpm. So, believe it or not, on level ground and loaded, we we using closer to only 30 hp. And the person who schooled me is one of the foremost diesel engine guys in the world.

"Some number crunching indicates that you really went after friction and rolling resistance. Some of us would like to know what you did, and especially how applicable it would be to our vehicles. Or should I just reread Dice1's thread on thetruckersreport.com?"

Regarding friction, all synthetic lubes. The extent of the rolling resistance mods were using 10 tires instead of 18. Elimiated as much parasitic loss as possible. None of this stuff is a secret to anyone here, or race car folks. Mr. Dice is a good guy and he has some good ideas. He gets great mileage with his rig, and runs well. However we do not currently use molecular modified wheel bearings, as he advocates.

"All of which begs the question: If the steady state cruise power is so low, does such a truck really need a 13 to 15 liter low RPM engine? If the steady state power is down around 60 hp or less, could one of the engines such as the new Ford diesel in their medium duty trucks be used?"

Gee, if you put it that way, I guess you just answered your own question.

"In that case, the weight savings from a lighter engine, no transmission, and no APU should come close to covering the weight of generator, electric motor, drive, and battery pack. The battery pack would need to be on the order of 100 Kwh in order to handle the necessary power without catching fire or blowing up."

Yes, exactly.

"Methinks that you have a goal of 20 MPG with your series hybrid."

20+ mpg, actually. Remember big rigs do like 95% highway driving. And around town, the batteries and super-capacitors will be doing the work.
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Last edited by Shepherd777; 03-10-2013 at 12:16 PM..

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Grand Imperial Poobah

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Quote:
 Originally Posted by Galane The big thing with a big truck is torque. It takes monster huge amounts of torque to get a load moving. Torque is also very important when going up hills. Horsepower is how fast you hit the wall. Torque is how far the wall moves after you hit it. A series hybrid big rig would work, as long as the electric end has the torque to get up to 80 kilopounds moving from a standstill, and to keep it moving at least as good as a regular drivetrain up a long hill. It'd also need the battery power to keep it moving up a long hill. The smaller engine would still end up running flat out to keep putting power into the battery. Fortunately, most long climbs are paired with long runs down hill, often as steep and long, so regenerative mode combined with the engine and generator to charge the battery up for the next climb. What could be fairly easily done with today's technology is programming the drivetrain with a 3D route map to control the engine for the most efficient operation over every hill. Assume hill one is a 2,400 foot climb, a descent down to about 2,000 feet, followed immediately by a long slog to over 4,000 feet, followed by a descent down to about 3,000 feet. (A rough guesstimate of the run up Whitebird south of Grangeville, Idaho.) Up AND down the first hump you'd want the engine going full throttle to ensure the battery is topped up so it wouldn't run out of juice partway up the big mountain. Once at the top of Whitebird, the engine could idle because the Camas Prairie is pretty darn flat, lots of downhill, most of the way to Lewiston, which is the lowest point in Idaho. 3D route map/control using GPS and repeated route automatic tuning could optimize fuel use. Live measurement data could be copied from one truck to another to speed up the learning/optimization process. That'd work best with identical trucks. With cellphone internet connections, the data could be streamed live and downloaded by other trucks following so their performance could be optimized in real-time for economy optimization when it's the first time a truck has taken the route. How about a service selling route optimization data to owner/operators and fleet operators? Could be a sort of brokerage where truckers could upload their data and those who download it pay if they get better MPG than a previous run.
"The big thing with a big truck is torque. It takes monster huge amounts of torque to get a load moving. Torque is also very important when going up hills."

But of course.

"Fortunately, most long climbs are paired with long runs down hill, often as steep and long, so regenerative mode combined with the engine and generator to charge the battery up for the next climb."

Correct. And as a side benefit, weight is further saved as no compression (Jake) brake is required.

"What could be fairly easily done with today's technology is programming the drivetrain with a 3D route map to control the engine for the most efficient operation over every hill."

Your thought on this aligns precisely with mine. And going downhill, the ICE would be completely shut off as the A/C, Power Steering, and Air Compressor are all high-voltage.
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Quote:
 Originally Posted by JRMichler I'm not convinced that any of this is new to the engineering departments of the big manufacturers. Being an engineer myself, I would bet that the engineers are tearing their hair out with frustration that management won't listen to them. And that those same engineers have done work way beyond anything said in this thread.
I bet this statement is VERY true. Competition improves the breed, so there's only a need to be half a step better than anyone else at a given time and that equals slow progress. If the shareholders are happy, it ain't broke so don't fix it.
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 03-11-2013, 04:49 AM #178 (permalink) Master EcoModder   Join Date: Jul 2009 Location: idaho Posts: 282 Thanks: 0 Thanked 96 Times in 74 Posts In several market segments, Ford doesn't appear to believe in going head to head VS their competition. The original Thunderbird was created as a response to the Corvette and heavily trounced in sales for three years. Then Ford threw away the best selling American sports car by making it a four seater. Several times Ford has looked at making another Corvette beater but has never done it. The GT's target wasn't GM, it was Ferrari and Lamborghini, which it could handily stomp into the track, for less money. Except for 1970-1973, the Mustang has always been built with the engine farther forward than the Camaro, compromising its weight balance VS the Camaro, making it a more difficult vehicle to get to perform well on race tracks. Why build it that way? The vehicle Ford's customer's have been wanting for decades (probably as far back as the 1950's) is one just like the Suburban, but with the Ford name. What has Ford made? Nothing even close until the four door Explorer which was a lot smaller. GM countered with the shorter wheelbase Yukon and Tahoe. Ford lobs back an ICBM with the gigantic Excursion. When that flops, Ford misses by "that much" with the Explorer XL, a longer wheelbase version without the rear wheels cutting into the rear doors. But still smaller than the Suburban. Why can't Ford get a clue? We want a Corvette beater that doesn't cost three times more. We want a Mustang designed to be intrinsically better handling. We want a Surburban sized family hauler, not smaller, not larger. Ford sold huge numbers of the little Mazda based Courier pickup. Those trucks are still crazy popular. People will still pay good money for ones with the bottom of the bed, half the doors and fenders rusted away - as restoration projects. A new truck that size *not an inch larger* would sell millions in the USA. It's as if that company surveys the people then does exactly the opposite of what people say they want. Modern manufacturing methods have enabled the ability to make a profit on automobile production numbers in the low thousands, yet most of the companies seem to be oblivious to that, they only want to make vehicles they think will sell at least a few hundred thousand or a million or more, with a very few exceptions for niche markets that have a strongly brand loyal customer base. In some of those, they keep production artificially low when they could actually sell as many as they could run off the production line.
 03-11-2013, 02:10 PM #179 (permalink) gone   Join Date: Apr 2012 Posts: 98 Lincoln #4 - '93 Lincoln Town Car Executive Thanks: 72 Thanked 7 Times in 7 Posts A lot of people forget that a little torque can be multiplied by lower gearing. Also, a tractor/trailer used for city delivery over an eight hour work day will spend over six hours only needing 100 hp and 200 hp for approximately one hour total.
Grand Imperial Poobah

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Quote:
 Originally Posted by ACEV A lot of people forget that a little torque can be multiplied by lower gearing.
“Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.” Archimedes

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