Tweeking computer program possible ?

1) No missing EV from Toyota engineers; it is the EPA which makes that user-selectable option infeasible. The engineers left it in for us to install without the EPa getting involved. I thank them for this every time I use it.
2) Drum brakes are satisfactory for all but repeaed high-speed stops. If you complain about the top speed of 104mph, then I guess you need brains more than disk brakes.
3) Creep mode? It behaves like every auto trany car I've driven, creeping in drive, even backing if on a slope.
4) Simulated engine drag is INTENDED to "waste" energy by slowing the car when the battery can't take any more regen. Saves those rear brakes, too.

Power/economy were systems engineering decicions, not marketing decisions.

"tranny with a torque converter"... oh brother, you don't have ANY idea how it works, do you? Maybe you should srite for a Detroit nespaper...

 

The 50,000,000 lines of code figure was from a car mag like car and driver, motor trend, etc. I don't remenber which one because I look through so many. I can't pass a magazine rack w/o picking up a car mag. I don't know if the number is truely believable but, from the same source a regular car has about 4-5 million.
The 650 patent number is from a car mag.

 

http://www.answers.com/topic/torque-converter

This is a torque converter definition that is a bit obsolete, but accurate, and a bit more thorough than the usual automotive jargon. I consider the Synnergy drive an electrical version. But this semantics arguement is going nowhere and irrelevent.

The issue is whether the car can be made more controllable for conditions to get better economy.

From what I read here every new calibration changes things, sometimes for the worse and sometimes for the better hopefully.

 

1 Precisely my point. The EPA issue involves the lawyers. The regulators used to ban leveling headlights too, but at least that got changed.

2 What you calll satisfactory I call unsafe. No point in argueing it. The main safety issue for me is drums stop braking much at all when they get wet. The top speed comment you make I don't even understand or know what you are referring to.

3 Creep mode I hate. If you like it it must be because you are used to normal automatics. I avoid them.
4 I'm not talking about the drag from B mode and saving brakes. Just the nomal waste caused by regen when not getting in the exact coast spot on the accelerator or going into neutral. I drove 3 different cars for over 10 years that coasted full time and I want the feature back again. You don't that is fine.

Precisely why Toyota should give us some driver set up choices for something more meaningful than how long the courtesy light stays on or how many pushes it takes to unlock the passenger doors. The mfd is wasted even for this irrelevent stuff!

Options in software are virtually free and would allow the car to satisfy far more people.

Anyways, I see some of the same arguements on semantics going on in the Honda Civic threads. I also came across the post from TidelandPrius that gives me some hope for the next version of the Prius:

http://priuschat.com/index.php?showtopic=11543&hl=

 

How to disable is in the manual

 

Its my understanding that we are caught between a rock and a hard spot...

"UNLESS" we can get a really nice size lithium bank that can handle the large energy transfers both directions...

We need the NiMH batterys because they allow tremendous energy transfers back and forth without getting hot.. "unlike the same size lithium"

At the same time the NiMH are at risk of limited lifespan if they are discharged too deeply... especially if one of the many cells reaches zero charge and reverses polarity!

Toyota has "on purpose" fixed it to maintain battery lifespan.... you can alter it and get better performance at the expense of limited battery life...or even risking damage.

The better alternative is to wait till Lithium gets cheaper and put a big enough bank in to handle the current... they will allow lower drainage without hurting them as much.

They presently have kits "if you want to pay 12K" for them, that will do exactly what you speak of.. they alter the computer settings to drain the lithium batteries further and at the same time get you up to 250 mpg!... That figure is based on "plugging your car in at night also".. and doing less than 30 mile round trips..
If you go farthur than the batteries can last.. then you go back to standard hybrid technology with similiar gas mileage.

These kits are expected to drop to 4 - 5 K if the toyota or others adopt them...

 

Sorry if I missed something important here.

First the overdrive name is just a name relating what the Prius does to conventional cars with overdrive that I am used to. But I did not invent the name or apply it first to the Prius. The web info you want me to read refers to it as heuretical mode, or negative-split mode, but any way you name it it is the state where the motor and generator swap their usual roles and economy goes up segnificantly.

Downshifting with a Prius is like most any other car. Engine rpm goes up in relation to drive shaft speed. The fact that it is continuously variable and done electrically instead of with gears really shifting, plus the car is doing it for you, makes little difference.

Regarding rpm vs economy changes you'd be more aware if you normally drove a manual transmission car or had a tach on your Prius. The effect is quite clear and unambiguous.

Clearly if you care to go over hills at 70 mph you would not like overdrive. With a Prius it is automatic though, I just want the the switching a bit different, like I wish most automatic's I've owned had different shit settings. Now some cars give you some limited choices.

Regarding my car I got it last December. I have close to 15000 miles on it. And I read the papers I could find and got the service manual set long before I decided to order the car. I'm not totally confused and I'm very happy with the car and the mileage I get, at least in summer.

 

I seriously doubt you can do better than the software in selecting the effective ratios. You can't possible know the effects on battery SOC and life, gear speeds, economy, and power as well as a computer program that has considered all driving conditions and equipment reliability. You MIGHT (and it by no means clear that lower RPM means better economy in a Prius) inprove one factor liek economy under narrow conditions, but you will be sacrificing all the other considerations in so doing.

There is no torque multiplication as in a torque converter; the PSD maintains a fixed torque allocation.

I've driven stick shift cars for 10 years, and am always very aware of what an automatic is doing. I modulate shift points and torque by very controlled throttle control in an automatic. In the Prius, none of that is necessary or nearly as effective, since it is LOAD, not SPEED, that primarily determines the engine RPM. But again, SOC, battery temperature, etc. are considered by the ECU which I cannot do in real time.

 

In the Prius the relationship between ICE RPM and fuel economy is far more complex than in a vehicle with a tradition transmission.

All engines have a PRM/Load point where they are most efficient at any given speed and grade. That's why Semis have many more gear ratios available than passenger cars, and why there is a trend to 5 and 6 speed automatics these days.

But, even then, you can't keep the ICE at the perfect RPM all the time.

The limitation of traditional transmissions is that the energy the ICE produces only has one place to go, to the wheels.

The Prius doesn't have that problem. It can 'split' off part of the energy at any given RPM, to drive the wheels directly, drive the Generator to drive the Motor to help drive the wheels, charge the battery while still applying power to the wheels, or draw energy from the battery to the Motor to help drive the wheels.

This allows it to effectively de-couple ICE RPM from car speed/load and run the ICE at it's most efficient speed/load while the car moves at an entirely different speed/load.

This is especially important with the Atkinson Cycle engine which has a torque curve much closer to a diesel than to a normal Otto cycle ICE. At it's most efficient point, its very very efficient, but outside that point it drops off more rapidly than an Otto cycle, so keeping constant RPM and avoiding sudden acceleration of the ICE is critical.

While you are driving at a constant speed, the computers in the Prius are juggling all of the available options to keep the ICE at it's efficiency peak while wasting as little energy as possible. That's why the Prius gets better highway mileage than an ICE-only car of comparable displacement/weight.

Your wish for an 'overdrive' is overly simplistic for the way the Prius operates.

If you want to think of it that way, the Prius ALWAYS has an overdrive available, at nearly any speed.

It may shift from ICE only to charge to assist and back several times a minute whle driving on flat ground at constant speed in order to maximize efficiency.

For example, if a gust of wind slows the car, it can instantaneously inject electrical energy from the batteries to counter it without changing the ICE RPM at all, and especially without surging it thus wasting the initial fuel load normally required for increased power. It can then regenerate that energy in the next moment by upping the ICE a couple of RPM and running a little through the generator, for a much lower total energy expenditure than if it had to modulate the ICE rapidly and widely for every change.

Those equations and programs are not simple, and if you think you can come up with a simple way to do better, I have pretty serious doubts about that, and frankly, my money is on the Toyota Engineers to understand and program their system best.

 

No. The Prius does not have anywhere near 50 million lines of code.

Stop to think about how many 50 million is. I'd be surprised if the entire window xp and office suite had over 5 or 10 million lines. That's a whole lot more than toyota has into Prius. Maybe 400,000 or 500,000 lines if it's actually big.

The prius interface is fairly simple in computer terms. It has a small and limited api. You code up 50 million lines and then hit the start button. 45 minutes later when that is all activated, you can head down the road.

I say BS and no way. It's small and streamlined for speed and simplicity.

Too bad it isn't built with AI and will learn your driving patterns, habbits and terrain. Then, adjust parameters to crank the mileage.

Some settings that would be fun to get our hands on are: The built in fake tranny creep and decelleration drag thing.

 

If Prius can really get that reported typical 65 mpg I doubt it will come from the engine mods. I expect it will be from the battery motor changes, and the software tuning.
We'll see when the car comes out.

Toyota can go much further to adapt the code to the driver, and the terrain than they have done to up to now. Maybe we'll be offered better code updates once the stalling problem type bugs get fixed and they think of new things for the new model, that would adapt to our cars too. it is not just a matter of the torque conversion ratios.

 

I suspect it's done in a rather simple way, using programmable feedback loops. I agre with Tempus that the Toyota engineers have probably done a pretty good job of optimizing these loops, since they understand the details of the car better than any of us.

 

I quite agree the loops are optimized for some general case, but there are driver differences and terrain differences that make them just plain wrong sometimes.

I would like manually chosen settings, but Toyota may add more intelligence to the program over time too and make the car work more properly for varied conditions.
They already do this a bit for the battery slow speed mode, but not for cruising speeds as far as I can tell.

Most of my problems would be solved if my car ever did as you describe! It approaches that in the summer, but not in winter since the battery just about shuts down. Hopefully the next one will be able to use Lithium and do a bit more of the correcting you describe so my rpms don't go up and down constantly for slight grade variations killing my mpg.

 

I seriously doubt you read this anywhere. 50 million SLOC is one heck of a lot and is pure BS! The space shuttle has 420,000 SLOC and ground control control support of the shuttle has 1,400,000.
Search for "Space Shuttle".
The Maintenance Data Processing System (MDPS) for the Navy's F/A-18 and F-14 aircraft was 920,716 Ada SLOC and it is a very complex and impressive system. I should know - I, along with 17 others, spent 5 years writing it and with the click of a mouse button I just counted every single line. Granted, we also wrote about 20 million SLOC of test & validation code as well.

Principal Software Engineer RTSC, LLC