Keep in mind that up here we have real numbers for low fuel consumption, 'pegged' to us is idling at a light.

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings

___Wayne, Sorry I didn't pay close enough attention to who was asking the question. I understand now that he really wasn't asking "How do you P&G " but rather "How do YOU P&G.

I think I'll just watch and read.

Your tach may read higher in D than in N, but you are actually using more gas in N than in D when coasting down a hill. In D, your kinetic energy keeps the engine spinning and the ECU can seal the valves (to reduce friction due to pumping losses) and cut off the fuel flow. You can tell it's doing that because the instant FCD is pegged at 100. In N, fuel has to keep flowing just to keep the engine from stalling. In N, you won't see the instant FCD pegged at 100. I've tested this by coasting down a hill in D with the I-FCD pegged, then shifting to N; the I-FCD immediately drops as the engine starts firing again.

^ in the prius simulation the ICE shuts off when you shift into neutral. Is it true when you coast in neutral and then put the gear back into drive again your going to get a nasty shock? Can it be avoided by rev matching? Also I'm very curious when you rev your engine in N I wonder how much gas you just wasted there.


Good observations, nice work guys.

i got around 20 km a liter when i drove a civic 5 spd using advanced hypermiler techniques
and now I drive a salvage nwh20 prius that gets almost to 25 km/l with 192,000 km to date.

The Prius shifts electronically, most of the functions of the shifter just activate different 'modes' in the car's computer, so for example switching to Reverse just tells the computer to run the main motor in reverse and switching to neutral tells the computer to not generate or use any power (engine off can happen but it may still spin depending on speed of car) and B mode will tell the computer to configure the main motor as a generator to slow you down more than the simulated engine drag that happens when you take your foot off the brake in D. There's no truly neutral mode in the Prius transmission, so no rev matching is necessary and no physical clunking will happen. I can't recall at the moment what the engine does when you press the gas pedal in neutral but essentially you don't control the engine with the gas pedal, once again the computer just reads it as an input and manages the gas and electric motors to do what you request. It is possible to rev the motor in park, but this causes charging and is a managed mode.

[IMG]http://schwa.kicks-***.net/img/PSD.jpg[/IMG]

The electronic control systems make for a very compact and mechanically simple and reliable 'transmission', so in the space normally associated with the transmission is where the two motors are, themselves replacing the starter and alternator.

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings

Schwa,

Perhaps you can explain a point regarding the PSD that I have been mulling over for a while: since the Prius drivetrain does not have a clutch, how does the system set up a glide condition where the engine does not spin ?

I have looked at Graham's animations of the PSD, and expect that the explanation is within, but am having trouble grokking the notion of ring sets spinning in either direction ..

R2-E2, 2G Prius.
Highway/City/Husband/Wife MPG: 56.5, as of 12/2005, 26K miles

Jac Nasser, Ford President: "We are planning to launch a hybrid version of
this car [P2000] within this year [1998]. We will also make FCEV available in
2004."

http://auto.howstuffworks.com/hybrid-car16.htm

The ICE is connected to the carrier (bracket holding the planets); as long as the sun/planetary/ring sytem can spin under the max rpm for 40mph, the carrier is stationary...ICE not turning. All force travels through the planets.

Probably the best way to see what goes on is the simulation (link in my sig), just turn it on and put it in drive, the engine shuts off and the main motor pushes the car. That's basically the condition you're talking about, essentially the gears spin letting power pass through, but the carrier stays put, so the ICE can be still.

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings

Thanks, Schwa. That simulation is really quite nice. But (and please correct me if I am wrong) it does not seem to model correctly the situation where the car is travelling faster than 43 miles per hour and ICE off.

R2-E2, 2G Prius.
Highway/City/Husband/Wife MPG: 56.5, as of 12/2005, 26K miles

Jac Nasser, Ford President: "We are planning to launch a hybrid version of
this car [P2000] within this year [1998]. We will also make FCEV available in
2004."

yeah lol i practice religiously on that simulator hoping one day when i get my hybrid, i can shatter records

ok maybe not relgiously but once in awhile i'll find Schwa's sig and try to aim for 100mpg!

i guess the only easy way to achieve 100 mpg is to only use electric motors and pray there's tons of hills to recharge that battery. Good stuff =D

i got around 20 km a liter when i drove a civic 5 spd using advanced hypermiler techniques
and now I drive a salvage nwh20 prius that gets almost to 25 km/l with 192,000 km to date.