Rolls's Crazy Engine Idea No. 22: Cvt Via Electrically Coupled Generator And Motor.

[Bond]

Lets say peak power was at 5k and you wanted to generate this peak power so had full throttle, what would stop the motor revving to say 6k? That is what I am trying to understand.

Engine produces

150kw @ 3000rpm

180kw @ 4000rpm

200kw @ 5000rpm.

170kw @ 6000rpm

You need to access that 200kw so the throttle is open 100%. It cant go over 5000rpm because the engine makes less power above 5000rpm.

You can vary rpm using the throttle to achieve what you want or you can vary load on the engine using the variable hydraulics. It would be a combination of both

Edited September 15, 2011 by Bond

[rob82]

The generator would be the smart part of the system as it regulates its magnetic feild inconjunction with the demand from the APP sensor and the engine's delivered torque.

This would be alot more effienent than a hydraulic system by about 20-30 percent hence why Caterpillars new 795F is electrodrive.

[Bond]

Is it more efficient weight wise?, power wise? cost wise? simplicity wise?

[Bond]

You cannot base everything on the fact that CAT use this system in large dump trucks where weight and cost are of little issue. The systems i have been talking about are also made by CAT...does that mean they are superior....NO. The 20-30% efficiency may come from regenerative braking where energy is stored while travelling down the pit and then used later on

Edited September 15, 2011 by Bond

[GTSBoy]

WIth the motor and generator combination, could you not just use an AC -> AC motor? There are no inverters, regulators, nothing needed, you could literally just wire them directly together removing a point of inefficiency.

If you just wire them together with nothing smart in the middle, then you have no way to modulate the speed of the vehicle separately to the engine speed. Your ECVT is then not a CVT, just an expensive coupling.

[Rolls]

If you just wire them together with nothing smart in the middle, then you have no way to modulate the speed of the vehicle separately to the engine speed. Your ECVT is then not a CVT, just an expensive coupling.

Couldn't you just use the engines throttle to modulate speed. If you have more throttle you get more revs and power, hence the motor delivers more power. Less throttle means it delivers less throttle. You are right, this wouldn't be a true CVT then, but it would have of the benefits of a CVT, being able to hold a motor at peak power without a gearbox changing gears and dropping you out of the powerband.

It would be better with a control system, but a control system requires a huge ass VSD, inverters, AC -> DC etc which is another stage of inefficiency's.

[GTSBoy]

Couldn't you just use the engines throttle to modulate speed. If you have more throttle you get more revs and power, hence the motor delivers more power. Less throttle means it delivers less throttle. You are right, this wouldn't be a true CVT then, but it would have of the benefits of a CVT, being able to hold a motor at peak power without a gearbox changing gears and dropping you out of the powerband.

It would be better with a control system, but a control system requires a huge ass VSD, inverters, AC -> DC etc which is another stage of inefficiency's.

Um, no, you couldn't. Think about it a bit more. The generator turns at exactly the same speed as the engine. If it is an AC generator then it will spit out a varying voltage and frequency, which if you hook it straight up to an AC motor will make the AC motor do pretty much the same as the generator is doing. Same speed. No gearing, nothing useful. If the generator is DC, then the gen will output a voltage that depends on the engine speed, and the DC motor that is hooked up to it will just spin at the same speed as the generator. As I said, an expensive coupling.

You could have different speeds between generator and motor by having different windings on them - ie you could make one 4 pole and one 6 pole and get a different synchronous speed on AC stuff. And if you were crazy you could put multiple windings into one or both of them and switch between them but this would only give you a number of different gears, not CVT.

You very much need to be able to chop the power that comes out of the generator into little pieces and smirsh it around and then feed it into the motor to give you the result you're looking for.

[Rolls]

Of course, with an AC motor the speed is going to be proportional to the hz, the hz of course is exactly the same rpm the engine is doing hence it would be like having a single gear which is as you said just an expensive coupling.

So you would either need a VSD or convert it to DC and control it this way.

[rob82]

You cannot base everything on the fact that CAT use this system in large dump trucks where weight and cost are of little issue. The systems i have been talking about are also made by CAT...does that mean they are superior....NO. The 20-30% efficiency may come from regenerative braking where energy is stored while travelling down the pit and then used later on

I was mearly comparing electro drive to a hydraulic based system. Considering most variable displacement axial piston pumps are around 50-60% efficient.

And there is no regenerative braking on the 795F - just a really big resistor and cooler fan!

[Bond]

I don't think the powerband in a turbo petrol is small enough to warrant this setup. How about just hooking up an 8 speed Auto.

[Rolls]

I don't think the powerband in a turbo petrol is small enough to warrant this setup. How about just hooking up an 8 speed Auto.

This really is the ultimate way to go, with 8 gears you could quite effectively utilise a power band that is even only 1k wide.

[iseekool]

All hypothetical.

Assuming the system will be used as normal road going car.

Most power is required for acceleration, once at a constant speed your power requirement will be much less and once you start braking, you can use this energy to regenerate.

So I was thinking you can have a diesel engine running at its most effiecient RPM/powerband constantly, this then drives the electric motors and charges some sort of super capacitor/s.

The diesel engine idles down to a slower speed when the car is stationary or when generation is not required.

When the car accelerates the capacitors discharge into the electric motors to assist the power generated by the diesel engine for the burst of power required for acceleration. Once at constant speed the diesel engine's electricity output should be enough to sustain the an constant speed and slight acceleration.

When the car slows down, it will use regenerative braking to charge the capacitors, and the diesel engine can idle down earlier if needed.

[iseekool]

This really is the ultimate way to go, with 8 gears you could quite effectively utilise a power band that is even only 1k wide.

Lexus IS-F

[bubba]

I nominate this for Best Technical Post of the Year award!

[karma_syke]

i don't wanna talk to a scientist, those mother f**kers lying and getting me pissed.

LOL

[Rolls]

i don't wanna talk to a scientist, those mother f**kers lying and getting me pissed.

LOL

A-Z of shit music, triple J absolutely destroy them, f**king hilarious