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I have now owned a Prius for two months. In many ways it compares very favourably with my previous vehicles which were either Jaguar or Mercedes but it doesn't do 60 miles to the imperial gallon or even 50. It does about 43 MPG. However I like it and it is a great fun car in days when most of the fun has gone out of motoring. As an engineer I would love to see a diagram of the power train. How is the engine connected to the electric motor and how does it connect and disconnect? does the transmission have a torque converter? Is the electric motor connected directly to the wheels. Where could I get this kind of deep technical information. Oh and I think they have done a great job on the styling but the alloy wheel covers are a bit strange and the lack of a coolant temperature guage is a nuisance here in Scotland where it is cold most of the time and you only switch the heater on when you can see that the coolant is at the correct temperature and why don't the doors lock automatically like they do in other quality cars. My Prius is a bit like my wife. She is not perfect but I love her anyway. Can anyone send me a power train diagram? I would be most grateful.
Kind regards from Bonnie Scotland.
Rennie Turnbull
 

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Rennie Turnbull said:
How is the engine connected to the electric motor and how does it connect and disconnect?

Can anyone send me a power train diagram?
By amazing cosmic coincidence, this morning I just finished creating an illustrated 5-page educational document to answer those very questions...

http://john1701a.com/prius/prius-psd_details.htm




It was written for a non-technical audience though. As an engineer, you'll obviously crave more. These may help with that...

http://john1701a.com/prius/prius-energy.htm

http://john1701a.com/prius/hybrid-type_full.htm

http://john1701a.com/prius/hybrid-type_full_details.htm

http://john1701a.com/prius/hybrid-type_full_operation.htm
 

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Prius Drive Train

" regards from Bonnie Scotland."
***********************************
Hello Rennie,
Welcome to Prius Land.. :D
The reply you are getting from John is as good as it gets. He's very well informed. I wouldn't even try to to add to his answers.
In case it isn't clear: The Prius does NOT have a torque converter. It's a pure planetary gear system. As I'm sure you've noticed by now; there is no changing of gear ratios. It takes some getting used to but after 2 yrs I like the way it works. Enjoy your car. ~jd~
 

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Rennie,
You mentioned the lack of coolant temp gauge. There is a fairly inexpensive ($127.00 US) device called a "Scan Gauge" that plugs into the under-dash OBD2 socket that will give you engine temps, 12v battery output, gas engine RPM's and a load of other information. I'm very pleased with mine.
The display is small backlighted black box that fits on the dash (or where ever) with Velcro. Good pics on their site. http://www.scanguage.com/

Those plastic wheel covers come off easily and there's a fairly attractive mag wheel underneath. The covers are apparently designed to provide a streamlining affect..? Some folks have elected to take them off but it tends to give the car a "Non-Prius" look. You can try it and see what you think.
How much is gasoline in Scotland..? ($2.65 US in S. California)
~jd~
 

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There is a great Java based Prius simulation on a Japanese web site. I have it bookmarked at work because the application is large enough that it doesn't place nicely behind a modem here at home. I'll either edit this post with the link, or I will post again in this thread with the link. I'll do that Monday morning, Pacific time if my job allows.

The simulation seems accurate with regard to the number of teeth on the gears and what the respective RPMs of MG1 and 2 and the ICE. I figure it is best for more general reference because there is no real ability to simulate road incline or weather influenced performance issues (wind, rain, snow). But I'm sure you want to understand how it works more than what happens when you have a head wind or are driving in heavy rain.
 

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No need to muck around with the heater controls. It's a full automatic climate control system. If the cabin needs heating, it won't start the blower until there's enough heat to actually be beneficial.
 

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Re: Prius Drive Train

JDavies said:
In case it isn't clear: The Prius does NOT have a torque converter. It's a pure planetary gear system. As I'm sure you've noticed by now; there is no changing of gear ratios. It takes some getting used to but after 2 yrs I like the way it works. Enjoy your car. ~jd~
I guess it's a matter of personal preference, but I love that there is no gear shifting.

I like it for practical objective reasons like more efficeincy, no wear and tear on a clutch mechanism, and less weight spent on energy losing elements like gears and more weight being spent on power producing (and reclaiming) motors and the ICE. The Prius CVT gear box is just the size of a soda can and has very few moving parts compaed with a manual or automatic. Once cars make the "shift" to CVT, I doubt anyone will want to shift back. Except, maybe classic car enthuiasts with 8-ball shifters and such... which is cool, so long as everybody doesn't have them, becasue they also pollute like crazy.

(I saw a classic Corvette from the 50's on the road the other day, gorgeous car. Where did American makers go wrong?)

Then there is the Prius driving characteristic which is superior. No gears to worry about ever. No lurches, no grinding, no slipping. No delicate clutch/brake/gas operations on hills. A CVT delivers power on demand. A manual or automatic often requires a wait to shift.

Btw, for future cars like Hydrogen powered in 30 years or so, does anyone think they'll have gears to shift? Of course not, they'll be pure electric, probably with a seperate motor for each wheel. Will they simulate a shift in software or something for driving pleasure? LOL. No way.
 

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The only other CVT implementation is the belt based system, and it has a problem of wear of the belt.

CVT via planetary gears has to have electric motor/generator, and thus becomes a hybrid.
 

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I cannot buy this car in the US.

I am skeptical that a friction-based CVT will have anywhere near the reliability required for high speed roads in the US and Europe.
 

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My thoughts exactly. Since it relies on friction to transfer the kinetic energy, AND the friction point shifts, the friction pad is a wear item and would need replacement at some point. No different than a belt based system, and may be more expensive to replace the wear item.

Now a hydrostatic system might have more promise.
 

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hyperion,

Ya gonna bash my "Dynaflusher" transmission in my 1950 Buick now? My Roadmaster model 50-72 [4-dr sedan 130 (inches of wheelbase--- overall length : 212") supposedly longer than even the Cadillac of that year] on a warm day could squeek out about 10 or 11 MPG with the Dynaflow. Needless to say, it hasn't been out on the road for quite a while with that kind of mileage.

I've heard it said that the slippage designed into that transmission is in the neighborhood of 10-15% (don't know) because in "Drive" there is NO SHIFTING of gears. From a stop when you tromp on it, you hear the 320 C.I., straight-eight engine wind up right away but you only creep off, slowly climb'g to highway speed [acceleration similar to my Peugeot Diesel, which I posted in another thread as 0 to 60 in 90 seconds (yes, 1 & 1/2 minutes)]. It was also equipped with "Armstrong" steer'g (NOT power), "Mash-hard" brakes (NOT power), & "Firecracker" (I mean Firestone) tires which were prone to frequent blowouts.

The Dynaflow did have a "directly connected"? low gear in "L". If you "tromped" it in "L" you could almost "chirp" the wheels & accelerate quickly up to the 35MPH limit , then shift into "D" to get up to highway speed (like getting on a highway on-ramp). That "direct-connection"? feature also allowed you to push-start or roll-start the car with a dead battery. Hmmm! I'm think'g that I ought to get that car out of mothballs (do moths really have those little things, hee,hee?). After all, I'm saving enough gas with my Prius to be able to afford a couple of trips around the block with the old Buick. Sorry for all the thread hi-jack'g I do.

Ken (in Bolton,Ct)
 
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