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.
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"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.