Many of you here have read my test results on coasting in neutral. GPSman has stated he gets the same results deadbanning in "L" or "D". I've always disagreed that you could coast deadbanning and get the same FE. Green FEH posted on http://www.cleanmpg.com/ yesterday that he seen an improvement coasting in "N" in his FEH. In addition, he also posted a patent number that explains why. We all need to thank Green FEH for this excellent find which explains why there is no regen in neutral and why coasting in neutral is a clear separation of the wheels and the gear set. This is a safety feature in case of a lock up or freeze of the motors and allow for AWD and neutral towing. Read the patent at http://www.freepatentsonline.com/6793034.html

GaryG

 

I think that makes perfect sense if the FEH actually disengages the drivetrain. I didn't see anything in that link that would nail that down as what happens in N however, although I suspect that is the case.

I think that there is an additional issue here with respect to driver input and control over the drivetrain. I have found improved economy by pulsing up to speed, and then without lifting off the throttle, placing it into N, vs. reducing throttle.

The transition is more abrupt, but the electronics handle all of the details so that there is no revving at all, and the transition to gliding is as efficient as it can possibly be with no steady speed cruising.

Just experimenting and driving aound last evening, I was able to push my economy to 40.7 mpg after 20 minutes of driving - without holding anybody up that wasn't exceeding the speed limit.

I also found that multiple mild hills produce the highest efficiency particularly if speed can be kept under 40 mph and the ICE off on the downhills. When returning back to the flatter areas, my economy sank back into the high 30's.

 

Ok, missed this part by Green FEH:

 

If these two methods are actually different, a big if... then maybe, as posted below, there is no NET gain. And net gain is the bottom line, right?

There may be SOME conditions in which neutral coasting is better, and some when it is not. Each person just needs to try and see.

 

Only if deadbanding disengaged the output shaft would they have the same effect IMO. If there was the drastic change in gliding by deadbanding as there is in "N" coasting, I would have recommended it long ago. Disegageing the FEH in "N" means there is no power flow through the transmission and there is a physical disconnect of the output shaft. Not seeing an energy flow on the Nav Sys does not mean a disconnect has been made. In fact, there are many signs that energy is flowing through regen and energy flowing to electrical systems from the HV battery without drive arrows. A lost of drive arrows can occur in all shift positions and a drive arrow to the battery can occur with the shift selector in "N" where the output shaft is disengaged, RIGHT?

GaryG

 

Very early on, say about March of 2005 it was discovered that the gear selector lever in the Ford Escape Hybrid ( FEH ) was nothing more than a computer joystick. The gear selector is electronic, and it is used to send signals to a computer, or control center. The computer control then changes the behavior of the vehicle. "Drive by Wire' as some say.

It was demonstrated by a Ford engineer that while traveling in a forward direction at high speed, nothing at all will happen if the gear select is placed in Reverse. The computer sees this as an unreasonable request, and ignores it. Nothing mechanical happens.

It has also been demonstrated that when coasting at high speeds ( interstate speeds, 65-75 MPH ) and the gear select is placed in Neutral, nothing at all happens. If engine brake was occuring, it will continue. If regen brake was occuring, it will continue. The computer also sees this request as unreasonable, and ignores it. Nothing mechanical happens.

Shifting from D to L while accelerating, nothing mechanical happens. After all, this car has only one permanent, but continuously variable planetary gear.

Shifting from D to L while decelerating something does happen. But nothing mechanical happens. There is only a change in software. The car evokes regenerative brakes, if possible, and engine brake if the HV battery is full, or the slowing power of regen is insufficient to match driver demand.

So what happens when shifting to Neutral under non-demanding conditions?
Nothing physical, or mechanical. In Neutral, all electrical power is cut off to both the larger traction motor/generator, and the smaller starter motor/generator.
This is a "simulated" ( as expressed by Ford ) neutral state.

In neutral, under 6mph or while stopped, if in EV, the ICE cannot restart.
In neutral, over 6mph, while in EV, the ICE can start. Why?

REMEMBER, in this car, Neutral is an electrical process, not a mechanical one.
Since all power is cut to the starter in N, it cannot restart the ICE. Hence, the car's wheels, and forward momentum start the car. Under 6mph, there is not enough kenetic energy to start the ICE.

So claims that N "disconnects" your wheels from the drivetrain as you may expect, are false. If that were true, then there would be no way for the Engine to start in N, and it can and does.

Questions?

 

Tonite was cold and damp. I was coasting in EV down a long 2% road in N. This mild 2% is not enough to speed me up, but is just enough for me to maintain a steady 30 MPH for a mile or more. I do it all the time. Due to the cold ( I guess ? ) my engine came on ( in N )to heat things up. My car sped up with a noticable surge of power in N while the ICE cranked up. ( 3 seconds? ) My speed sped from 30 MPH to 32 MPH and then leveled off and stayed at 32 MPH and resumed coast mode. I was in N the whole time. While this effect was probably not desired, and not by design, it illustrates that things are still "connected" in N.

 

I strongly suspect the one-way clutch is what makes neutral towing possible. If there is a clutching mechanism, that would allow the shaft normally connected to the ICE to turn freely at speed, thus preventing the motor generator from overspeeding.

As to the idea that the permanent magnet motor would generate high current when spinning freely, it's not true because there's no field being generated by the stator coils unless the TCM puts one there. There would be some small currents from the residual field in the winding, but these are inconsequential compared to what the system applies when using the motors as either generators or motors.

FYI -- Just returned from a round trip to Seattle, and without even trying was able to achieve 29.7 MPG in my 4WD FEH. Considering the amount of 70MPH territory covered between Portland and Seattle I'm very pleased with this performance.

 

Thanks for the input Steve. I 'think' we both have similar impressions.

 

This is an interesting discussion....The question I have is why no one seems to think there is just a "normal" clutch between the ICE and the rest of the transaxle. I have the NAV and there are frequent times when I can see the vehicle in a complete idle state while stationary.... the ICE is turning at 1000 RPM, but on the energy flow diagram there is no energy shown going anywhere. So what exactly is that 1000RPM going to other than turning one plate of a clutch? Its not generating electricity because there is no flow to the battery or the motor.....

A normal "clutch" solves most of the questions. If it opens when the car is in neutral then the car would exhibit less drag when neutral shifting.

As for matching speeds in a running engine with a transaxle.... I'm not a mechanic but that problem seems to have been solved along time ago. Every time a normal automatic transmission shifts the gear ratio changes and the RPM in the engine has to change to match the new RPM for the new ratio..... people do it by ear on manuals.

As for towing.... I can't tell you if there is another disconnect between the wheels and the CVT or not.

So I'm just asking... is there some reason everyone thinks there isn't any "clutch"?