Does the electric engine have more torque or gasoline?

The torque at RPM is what needs to be looked in thinking about your question.

The torque of the gas engine is listed at 82 lb-ft at 4200 RPM.

The torque of the traction motor is listed at 295 lb-ft at 0-1200 RPM.

The beauty of an electric motor is that it develops quite high torque at low rotational speeds. This is utilized in diesel-electric locomotives in getting a heavy train into motion. As the traction motors increase in RPM the total torque falls off.

The internal combustion engine has very little torque at low RPM, thus the need for either an automatic or manual gearbox to allow the RPM get up to give the wanted torque.

One of the beauties of the Prius is that the electric motor has good torque to get moving and the gas engine then takes over when it can operate at higher RPM.

If anyone finds errors in what I have said please point them out.

 

<div class='quotetop'>QUOTE(Perk @ Jul 19 2007, 04:19 PM) [snapback]481776[/snapback]</div>

Said just fine. I will also add that the Prius already has several computers that do a very good job managing the balance between the ICE and the MGs.

Torque can be multiplied through gearing, but the gearing adds complexity and frictional losses. One of the beauties of an electric motor is that it can be used to directly drive a heavy load, without all of the normal transmission gears.

Tom

 

Well answered already.

By any normal metric, an electric motor will give you more usable torque - for size, weight, cost, etc. You can gear it to offer the torque wherever you'd like. My EVs only have an electric motor of course. And without changing gears, I can spin the tires from a stop (at ZERO RPM and no clutch) in the same gear that I can cruise at 80mph. Show be the coffee-can-sized gas engine that can do that! (just getting your ICE to zero RPM while still "running" will be a good enough trick for me!)

 

<div class='quotetop'>QUOTE(Perk @ Jul 19 2007, 04:19 PM) [snapback]481776[/snapback]</div>

I would add that, in my opinion, Toyota has done a masterful job in blending the ICE and the electric motor(s) mechanically (PSD) and with the computer controls. I very much enjoy driving the Prius because the power transmission is so smooth.

 

Hi All,

Good answers to the what the original poster meant to say. But a comment on the terminology. An engine is a device for converting heat energy into other useful forms of energy. Cars have an engine which converts the heat of combustion of the fuel into shaft energy (a shaft which will resist torque at some rpm).

A motor is any device used to create motion - MOTor > MOTion. The engine in a car is also a motor, besides the electric motors in the Prius.

That said, there are electric engines. Devices which convert heat energy directly into electricity. The Prius does not have any of these however. They are a hot ongoing topic of research, and recent advances have been made. When they become practical, the series hybrid car, with an electric engine prime-mover may be revolutionary.

 

Maybe it's just me, but how does an ICE engine convert heat in any way? From what I understand about engines, which is very little believe you me, is that it converts the stored energy in the fuel to mechanical energy.

Same goes with the electric engine, except it converts the electric energy to mechanical energy.


Am I wrong?

 

Any ICE converts heat energy into motion. It does so by the expansion of gas, the expansion is caused by heat. The heat is released during the chemical breakdown of the gasoline (it burns). As the gas expands it cools and the energy released is converted into mechanical motion (kinetic energy). The Atkinson cycle engine that we have in the Prius is particularly good at extracting the maximum amount of energy from the gas that is expanding. Due to the long expansion stroke.

An excellent description of the Prius THS II system is at:

http://www.toyota.co.jp/en/tech/environment/ths2/index.html

(thanks again, Ken, for the link).

The Prius actually adds the torque from the electric motor to the torque from the engine. Or you could state it the other way around. Either way, one assists the other, and while the ICE tends to rev. a lot you do get a good kick in the pants when you depress the throttle.

The above link and the brochure for the car list the torque of the electric motor as 400 N-m (Newton metres), which, curiously, converts to 295 ft-lbs.

 

<div class='quotetop'>QUOTE(Alexstarfire @ Jul 19 2007, 10:18 PM) [snapback]481936[/snapback]</div>

Yes.

 

Wondering how can I utilize the most of the electric motor's torque? Was thinking of doing the EV mode mod so the car will be on the electric only,then I'll get that torque. I have tried turning the traction control off and the tires squeak for a sec for a super tiny burn out.

 

I wouldn't bother doing the EV mode mod, the valid uses of it are a select few cases. Any others is just an opportunity for inefficiency. If you want to find the greatest torque, just play with the "go" pedal - somewhere around the 3/4 mark. Just pull back from where the ICE wants to "take off" and feel how the car drives.

The ICE and 2 MG's are designed to work as a unit and the motor/generators are not designed to provide the primary means of propulsion outside of how the HSD is designed to work.

How did you do this? I wouldn't try this on an ongoing basis, you stand to severely damage components of the HSD.

hope this helps

 

In EV mode, power to MG2 (the electric motor you are talking about) is restricted by the battery power limit, which is significantly lower limit than MG2's capacity. To get full MG2 power, the ICE (gasoline engine) must be running and spinning MG1 as a generator. Plus some of the ICE's torque will be passing through the mechanical path to the wheels, and adding to MG2's output.

 

Thanks I'll have to try playing with the gas pedal.

is for a Gen 3 but works that same on Gen 2.

I'll throw this here just for fun

It's me on an icy road with traction off.

 

You are playing with fire.

It is your car to do as you want to, but maintenance mode is for doing workshop procedures and not what you are demonstrating.

You can cause serious damage to the MG's in the transaxle with what you are doing.

It's up to you, but just letting you know.

 

Before I post this, Motor/Generator2 RPM and Engine RPM are virtually unrelated. M/G2 RPM is directly related to tire speed, the faster you are going, the less M/G2 torque you have.

 

Diesel-electric locomotives (the non-"AC" variety) utilize a "dc transmission" and so-called "series" traction motors. These develop their maximum torque at stall, hence the Diesel-electric's legendary ability to start a train even on a 1 percent ascending grade, which most "steamers" found this exceptionally hard to do.

The latest in Diesel-electric locomotive technology is an "ac transmission" in which inverters accept about 1200-2400 volts dc from the prime-mover/alternator/rectifier, and invert this to variable frequency three-phase ac.

"Ac transmission" Diesel-electric locomotives are even more capable in starting trains, and the regenerative braking (called "dynamic braking" in the industry's lingo) down to zero MPH is possible, whereas regenerative braking with "dc transmission" Diesel-electric locomotives falls off towards zero MPH.

Hence "ac transmission" Diesel-electric locomotives have found a niche in moving Powder River Basin coal from Wyoming to power plants in the south and east, whereas "dc transmission" Diesel-electric locomotives retain their dominance in general purpose services, including "drag" freight and "time" freight, particularly on routes from container ports on the west coast to Chicago or Dallas/Ft. Worth, and then on to the eastern markets. "Dc transmission" Diesel-electric locomotives cost dramatically less than an "ac transmission" Diesel-electric locomotive of equivalent net HP.

So, the Prius, with its "ac transmission" is well-matched to its mission function.