What type of CVT is under the hood?

It is not a CVT. It is actually a planetary gear, and there is only 1 "gear".

 

It has been referred as an Electronic CVT.


Another website:
Toyota Prius - Power Split Device

 

planetary gear. wikipedia is your friend.

 

Well, forget that if you are interested in how your Prius works.

The Prius doesn't really have a CVT in any normal sense of the word. The Prius uses two electric motor/generators and a fixed set of planetary gears to transmit the power to the wheels. Some of the power from the engine is transmitted directly through the mechanical gear path, some is transmitted electrically through the two motor generators. The ratio of mechanical to electrical power transmission determines the effective gear ratio. Note that I use the term "effective". At no time does the physical gear ratio change. The electrical path allows for a nearly infinite number of effective gears, which is why you will often hear people use the term "eCVT", or electrical CVT.

Tom

 

So you -could- call it a "computer controlled magnetic CVT". No gear ratios are harmed.

 

You could also call it a flibbitty-widget, but it isn't.

 

The early internal Toyota documentation used the term flibbitty-widget, but that name was dropped before it went into production.

Tom

 

Epicyclic gearing?

[ame="http://en.wikipedia.org/wiki/Planetary_transmission"]Epicyclic gearing - Wikipedia, the free encyclopedia[/ame]




How Does a Planetary Transmission Work? | eHow.com

 

That's not the variable (virtual) ratio part of the system.

You need the planetary gear set, MG 1&2 plus the electrical/electronic control system to explain it.

Planetary gears are the most convenient and probably most efficient way to take care of the torque splitting, but other gear arrangements could be used.

 

Just for info
On the back of MG1 is an oval rotor.When it spins (being fixed to MG1) it produces two pulse waves, one sine one cosine. The ECM then knows what both MG1 & MG2 are doing by this particular unit called a resolver.
Actros

 

It's been described to you at different levels of detail in at least 3 correct ways. Ignore the posts that just mention planetary gears.

If you just want a label, it's called a eCVT.

If you want to understand how it works, study the link you quoted.

The MGs are an integral part of the eCVT, without them it wouldn't be a CVT

 

Are they doing something with the phase data or are they just using it to determine rpm?

 

Electric CVT, just like an EV with single speed.

eCVT is fundamentally different from the tradition CVT.

Tradition CVT (mechanical) uses physical ratio to multiply torque. eCVT uses electricity to multiply torque. Low gear in eCVT means juice to the electric motor. High gear to eCVT means just route anemic Atkinson cycle gas engine torque directly to the wheels.

The blending of two power sources creates the CVT effect. It is like no other transmissions before because they were designed and limited to work with a single power source. eCVT is the first to take advantage of two power sources and simplify the mechanics.

Not all transmissions in all hybrids take advantage of it. Honda IMA, Nissan Direct Hybrid drive, Hyundai Blue Drive all use mechanical transmissions with the same complex legacy parts. They'll try to market that it will give you the familiar feel (reads same jerk and lag). You now know better not to fall for it.

 

Might wanna check out the link and play with the flash demo of the eCVT.

Basically: Engine RPM = power produced. The rpms of the various MG supplies and converts power from one to the other. MGs produce the most torque when they're closer to 0 rpm, where as the ICE produces the most torque when its at max rpm.

Balancing all 3 allows the prius transmission to "Shift" from most power to most speed based on the rpms of the 3 components. At high speeds, the engine has nothing to push against to deliver power, so it changes the MG attached to the wheels and supplies power to the sun gear for the ICE to push against.

 

My favorite is following explanation by Graham Davies.

Continuously Variable Transmission

Ken@Japan

 

Prius never shift a gear. It shifts continously variable between the two hybrid powertrains. The end result is an ultimate drivetrain that does not require additional gearbox for "transmission".

 

I think this one is even better - more elaborate and the figures are animated. This is my personal favorite.

Whats Going On As I Drive?

 

Your original question was answered several times. The planetary gearing and the MGs *are* the CVT.

The problem here is that you have a pre-conceived idea about how transmissions work, but the one in the Prius is unlike anything you have ever seen. It takes some serious thinking to understand how it works. It is conceptually complex but mechanically simple.

Tom