I just towed a heavy load a very long distance and have "loads" of data to share in a future thread dedicated to the topic.

I noticed on many occasions, at highway speed of 55-60 MPH the generator motor wasn't turning at all. ( I have my ScanGauge programmed to read RPM of all 3 motors. ) ( lots of times I saw an RPM of -1 which I equate to zero )

The ICE was definately putting out horsepower.

If a motor/generator isn't turning, is it putting out horsepower?
By definition, NO.

Generally speaking,

Power = work divided by time
Work = mass x distance moved

 

Interesting that the generator was not turning. I would have expected Ford to have programmed it (& the traction motor) to at least turn slowly for good bearing lubrication. Maybe the -1 indicates it to be turning over slowly as a motor.

The formulas in the post above are not quite right .

(See: http://en.wikipedia.org/wiki/Power_(physics) for a quick discussion)

Work = force x distance (note the absence of a time reference)(Note that mass is not part of the equation - you can do the same work to different masses and the result would be different velocities of the respective masses)

Power = work per unit of time (eg 1 horse power = 550 ft-lbs per second or
1 watt = 1 joule per second)
The common way of representing the math makes it appear as a division.

 

gpsman1 is CORRECT, if MG1 is not turning then NO HP is being produced...

just TORQUE....!!

If the e/CVT's planetary gear ratio between the MG1 and the ICE is 3:1 (it will be something close to that) and the ICE is producing 60 ft/lbs of torque then MG1 will be producing 20 lbs of torque in order to remain stationary and not be driven "counter" to the ICE drive.

How do you think the FEH remains stationary when the ICE is idling at 800 RPM...??

MG1 & MG2 are turning COUNTER to the ICE.

As someone has said already the e/CVT is simply a SUMMING machine, summing four inputs/outputs, the ICE, MG1, MG2, and the drive shaft to the front differential.

When the HSD must produce its maximum level of HP and assuming the hybrid battery SOC is sufficient for doing so the ICE will be producing 75% of the torque while MG1 adds in the other 25%

My 3:1 assumption is based on the fact that the ICE is limited to ~5000RPM while MG1 can easily reach 3 times that, or more.

 

"...Work = mass x distance moved.."

What is the equation for doing "work" used to prevent a mass from moving..??

Say standing in front of a car holding it stationary on a steep hill..??

 

Anyone who has had high school physics should realize that that equation is wrong. Work, Energy and Torque all have the same units. Power is energy/time or torque/time or work/time. And yes, Williard, if you do not translate an object you have not done any work by definition. You can hold that car back for eternity and you will not have changed its potential energy one nanojoule, so you have not done any work.

As far as the planetary gearset, yes any torque input must be countered. If the ICE is running and the vehicle is not moving, the torque from the ICE is being absorbed (or countered if you will) by the generator. Obviously when moving all of the ICE torque (minus losses) can be absorbed by the wheels with the generator and motor torque being near zero (not equal to zero due to rotational losses.)

 

If a brake was applied to the generator to hold it stationary by force, then no electrical current would need to be expended.

All the torque, power, whatever you wish to use to describe it, from the ICE would go to turning the wheels. Sometimes you get an "engine only drive" condition, where most of the time you have a "hybrid drive" condition.

 

There are no brakes, clutches, not even one-way clutches, involved in the operation of the e/CVT. If you want the ICE to drive the wheels then you MUST either be putting power into the MG's or taking enough power out of them so they do not freewheel.

Think of what happens with a simple open differential if one wheel has no traction...

NO GO....

The e/CVT's planetary gearset is simply a more complex differential, if you do not somehow restrain the MG's to prevent them from freewheeling the sum of torque delivered to the front differential by the ICE will be virtually ZERO.

 

"...if you do not translate an object you have not done any work by definition.."

First, in the case of holding the car from rolling downhill I suspect the "object" being translated might be somehow related to the energy, WORK, my body is expending in the process.

The food I ate last evening is being "translated" into "work" via the muscles in my body.....

 

There has to be some type of clutch. How else can you flat tow the FEH?

 

FACT: The Traction motor can spin forward, or reverse.
FACT: The Generator motor can spin forward, or reverse.
FACT: The ICE can only spin on one direction, let's call that "forward".
FACT: There is a one-way clutch on the engine to prevent either of the electric motors from attempting to spin the ICE backwards.

FACT: There is mention of a "generator brake" in the Ford manuals, and there are Ford published block diagrams showing the position of a generator brake.

I have never seen an actual photo of the generator brake, so I don't know the type, size, or exact position.

FACT: The traction motor and generator motor "free wheel" spin when the car is being towed. This is totally acceptible and Ford engineered it to have this capability. This is due to the FACT that this car has no true "Neutral" and the gears of the planetary transmission are always in mesh.

The FEH/MMH only has a "simulated" neutral. Neutral in this car means electrical power is removed from both motors only. All the gears remain in mesh. I designed a simple experiment to prove this and you can try the same.

Put the car's front wheels in the air on jack stands.
Start the ICE, then place the car in simulated neutral.
The wheels will turn very slowly in neutral if they are in the air and there is no friction with the road to hold them steady. Not much torque mind you, but it is greater than zero. ( sometimes you will need to push start the wheels in moton, but then they will spin on their own in "neutral" )

HTH,
-John