I think nothing wrong with the graphs.xcel said:___The first Prius torque curve looks a little odd? With the 01-03 Prius and Camry, there is a less then
infinite slope through any acceleration/deceleration as there should be. If the 04 Prius had a change in Gs over 0 seconds as shown (at t=0) I dont believe it can? There is no such thing as an instantaneous change in Gs in 0 seconds in an automobile? Maybe the graph is exaggerated by some amount? The third derivative gives jerk and with the change as shown, I would have to say the graph isnt possible even with a top fuel dragster. At least not without tearing the fillings out of your teeth any time you were to floor the Prius at exactly 30 mph
___Frenchie, do you know where to find a US speced Power (HP) and Torque (Ft.-lbs) for an 04 Prius can be located? The look of the graph wouldnt change but the numbers and nomenclature would make it easier for us in the States and much of Canada to understand.
No. This is normal behaviour for an electric motor.I think Toyota is fudging the numbers by saying the Electrics can assist up to 295 Ft.-lbs of torque anywhere in the range of 0 1,200 RPM the instant (t=0 again) they come on line.
Wrong. Torque figures are usually given at the engine (or motor) shaft, because torque at the wheels depends on the gear... except in the Prius because there's only one gear (the Prius is so to speak always in "top gear").I also think they are taking the 295 Ft.-lbs. from the electric motors shaft instead of at the wheels like everybody else does.
Wrong again. Consider the different gear ratios, calculate the torque at the wheels and you'll see it's lower than on many cars in first gear.That torque value is simply way to high not to show some truly amazing performance numbers for something as light as the Prius imho.
This document (in French, German, English at least) can be found at toyota-media.com. It's a website for professional journalists, but you can subscribe for a 48h temporary access to all the files. I've downloaded some interesting documents on my hard drive, and could send them to PriusOnline but there's no place to put them...Frenchies curves seem to have been derived form a Toyota press release as well? Does anyone know where some real world HP/Torque curves are for either the 01-03 or the 04 Prius are?
I don't know which document you're referring to. I've seen some (about the old Japanese Prius) in which the engine was tested, and the peak torque was about 100 Nm, not 100 Ft-lb's (even in the USA is the metric system making some progress :wink: ).I found a paper done by Argonne (that or NREL or the Idaho government lab) that dyno tested the 01-03 Prius across a range of RPMs for emissions, SOC, and any other number of attributes except for pure HP and torque vs. RPM. The tables listed showed a maximum of just under 100 Ft.-lbs
The huge torque lasts only up to 30km/h, please refer to the right graph by frenchie.1967 R50/2 said:It is still unclear to me that why, with the near instantaneous torque, does the Prius have such mediocre 0-60 acceleration?
The battery is powerful enough at least the first 10 seconds for 0-60.1967 R50/2 said:Is the battery discharge not powerful enough to power the electric motors beyond 1200RPM? Or is it that the rate of discharge is not long enough to keep the motors turning for the required time?
It look you need more performance than good mileage. Prius is a consumer product and is well balanced, I think. In other words, maybe someone is not happy it's performance.1967 R50/2 said:In either case it would seem to be an issue of not enough discharge. If that is the case can anyone tell me why Toyota did use a larger battery pack? It's quite compact and only weighs about 45kg.
The specification is officially published, and Toyota can't be fudging there.xcel said:I think Toyota is fudging the numbers by saying the Electrics can assist up to 295 Ft.-lbs of torque anywhere in the range of 0 1,200 RPM the instant (t=0 again) they come on line.
You may be right, gross vs net. However the 295 Ft.-lb is still real number.xcel said:I also think they are taking the 295 Ft.-lbs. from the electric motors shaft instead of at the wheels like everybody else does. That torque value is simply way to high not to show some truly amazing performance numbers for something as light as the Prius imho.
Motor Performance Curve for both classic and '04.xcel said:___Frenchies curves seem to have been derived form a Toyota press release as well? Does anyone know where some real world HP/Torque curves are for either the 01-03 or the 04 Prius are?
Yes it does. As RSnyder suggested, you should have a look at Graham's enlightening web site to understand this.With that kind of torque, you would want the Prius drivetrain to stay at low RPMs almost continually yet the HSD doesnt seem to allow the use of all of that available torque at low RPMs as can be seen in the 0 - 30 or 0 - 60 mph figures?
Don't mix engine RPM with motor(s) RPM. Practically you can't hear the electric motors spinning. Rotation speed of MG2 (the "big" electric motor) is always directly proportional to vehicle speed, since there is a fixed gear ratio (about 4.1 if I remember correctly). Don't forget also that electricity is exclusively produced by the engine on the Prius; consequently, for maximum efficiency it's better to use directly engine mechanical energy when the engine can operate in its good efficiency zone. Experienced Prius drivers know that the key to maximum fuel economy is NOT to avoid thermal engine operation, but to force its operation in the optimum zone, hence avoiding low (and very high) engine RPMs.Flooring the Prius from a stop brings the ICE online practically instantaneously and with it, a heck of an increase in dB output which sounds like the RPMs are rising quickly?
"THS II uses an AC synchronous-type motor, which is a high-efficiency DC brushless motor with AC current. ", Toyota's official web site says.xcel said:What has me questioning Toyotas numbers is the steady maximum torque across the 0 - 1,200 RPM band. This is not normal electric motor behavior at all. What kind of motor(s) allow this?
The flat torque area only affects up to 20 MPH. I haven't seen any 0-20 MPH data.xcel said:With that kind of torque, you would want the Prius drivetrain to stay at low RPMs almost continually yet the HSD doesnt seem to allow the use of all of that available torque at low RPMs as can be seen in the 0 - 30 or 0 - 60 mph figures?
http://www.toyota.co.jp/en/tech/environ ... ystem.htmlxcel said:Flooring the Prius from a stop brings the ICE online practically instantaneously and with it, a heck of an increase in dB output which sounds like the RPMs are rising quickly? The only torque curves I have seen are from Toyota themselves and Frenchie provided curves that appear to be generated from a Toyota press release? The 4th graph in the Motor Performance graph from Toyota Japan actually states Shaft torque on its ordinate axis?
Using Graham's number, 72% of ICE torque goes to the power train and 28% torque goes to MG1.RSnyder said:A small fraction of its power output goes directly to the power train, but the bulk goes to electric power generated by MG1.
According to Graham's site, the proportion is unchanged, it's always 72%vs28%.RSnyder said:As wheel speed increases, the ICE is allowed to run at higher RPM and the power split increases its proportion directly to the wheels while reducing the proportion to MG1.
Just a quick note...RSnyder said:Under full acceleration, MG1 spins at it's highest permitted rate (10,000 RPM in the 2004, 8,000 RPM in the 2001-03), whereas even at 100 MPH, the drive train is only going 6,000 RPM in the 01-03, I think faster in the 04.