Re: Toyota says no evidence 'runaway' Prius happened

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wrote:


What benefit or purpose is there to having a car creep forward when there's no go-pedal input? Plus,if your foot is on the brake,such a "feature" still consumes battery power despite the car being stopped.

It's still an automatic,as the tranny is controled by electonics and not by a mechanical shift lever and clutch.Its internal construction more closely resembles an auto tranny than a manual.

No argument there.

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Jim Yanik
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In a car where the driver doesn't have to constantly use a big stick to manually stir a box full of gears, drivers of such vehicles are used to a particular type of behavior from the vehicle.
Toyota evidently attempted to avoid frightening the herd with strange and unfamiliar things, such as presenting them with an "automatic" that does not creep forward when the brake pedal is released. And so the Prius mimics the traditional "automatic" that everybody knows so well, even though it doesn't actually _need_ to behave that way.
As for power consumption, I'm guessing that there is _no_ drain through the electric motor when the brake pedal is depressed hard enough to hold the car still. The PCM, which is already consuming power by virtue of being in its "RUN" state, will monitor the brake pedal position, and will only feed power to the electric motor if your foot lets the brake pedal up to the point where the PCM decides that it should start making the car move. I can't see that monitoring should consume any more power than the PCM would consume in any case while in the "RUN" postion.
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Because it's an automatic transmission (no manual shift required) car, and every automatic trans car that's been sold since day 1 has (by necessity) the creep feature.
Toyota worked very hard to hide the magic and make this behave, for all intents and purposes, just like the automatic Corolla that the buyer just traded in.
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wrote:

SO? just because gas engines were stuck with that inherent trait means you copy it?
I note that that "automatic creep" got many people in trouble via "unintended accelleration",because they didn't keep their foot on the brake when they placed the trtanny into "drive",and it lurched forward,THEN they jammed on the gas instead of the brake. that "lurch" was the initiator.
Worse,in an electric car,that creep means you are using battery power even though you aren't applying the GO-pedal;a waste of scarce battery power.

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On the other hand, think of stopped traffic on a slight incline. Cars that do not have that creep often slide back a foot or two as the driver moves his foot from the brake to the gas pedal before starting from stop because most drivers are too clueless to use handbrake when starting on an uphill. That causes cars to bump into tailgaters behind them. The creep feature acts as a manual brake in such cases, preventing such fender benders.
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Yes--because their goal is to SELL CARS, and the public expects that cars behave in certain ways.
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Bullshit. You're using battery power only when you're in D and you're not using the brakes.
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wrote:

that's the parameters stated for this debate; the car creeps in gear with no brakes applied and no go-pedal input. try to keep up.
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Nasty wrote:

My dad's Ford Five Hundred has a CVT. The controls are marked like those of an automatic, with P, R, N, D and either low or 1.
Jeff
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Just don't confuse the two systems like many seem to do. Your dad's Five Hundred and my friend's Freestyle have a cone and belt CVT which varies the effective size of the driving and driven pulleys to change ratios, it still requires a torque converter, reverse gear of some sort, and a high pressure hydraulic pump to apply tension to the stainless steel belt.
The PSD in a Toyota hybrid mimics a CVT by varying the speed difference between the 2 motor/generators to change ratios. It has no torque converter or reverse gear and just has a small fluid pump to keep the bearings lubed.
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Daniel who wants to know wrote:

Just to be clear, the Toyota system is still a CVT, but of a completely different type.
A Ford transmission with a belt? That sounds funny. A belt carrying the load in a big car's transmission? It's a steel belt, though. And heavy duty. I have seen the working model at NY Auto Show.
Jeff
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Nasty wrote:

A manual transmission.
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AZ Nomad wrote:

Wow. There really is no limit to stupidity. Do you know ANYTHING about a Prius?
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Never having driven a Prius, I'm dependent on others' descriptions of its behavior.
I gather the Prius is set up so that it mimics a conventional car's automatic transmission "creep" when at a standstill and in Drive. The "creep" would be provided by activating the electric propulsion motor when the brakes are released, the amount of activation being in inverse proportion to foot pressure on the brake pedal.
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Tegger wrote:

Tegger, my comment was NOT directed at you. Pleased be assured of that.
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My question is:Why have that creep? It means the motor consumes power even while you have the brake on. What purpose does it have?
Gas motors HAVE to idle and it's a characteristic of auto trannies to transfer torque even at idle;thus the creep. Theoretically,there should be no movement without pedal input in an electric car.
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No, it doesn't.
There's no "push" against the brakes while the brakes are on, as with a fluid-drive automatic transmission. The electric motors are not being energized until the brake pedal is let up, then they're energized and the car creeps.
Frankly, this is MUCH better than not having it creep at all. Imagine grandma letting up on the brake pedal to ease the car out of the garage, but instead of a tiny bit of creep she has to put her foot onto the go pedal to make the car go. WHAM! she gives it too much go pedal, and she slams the back corner of the car into the garage door frame.
Yeah, that creep is a GOOD thing.
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Yes,it HAS to use battery power to "creep"; the electric motor doesn't produce force without it.
and I'm told the engine is not even on until battery power drops to some point and/or over a certain speed.

How do you know this? Is this mentioned somewhere in the manual? Got a CITE for it?
Because,frankly,if releasing the brake applies power to the motor,then there would be a surge to overcome inertia just like if "grandma" applied the go-pedal. It may be slight,but still some lurch as the motor spins up.

Grandma (and Grandpa) evidently STILL does that....

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You're missing the point.
You say "the motor consumes power even while you have the brake on". No, it doesn't.
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Yes,it does.
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